//! Segmented journal for oversized values.
//!
//! This module combines [super::fixed::Journal] with [super::glob::Glob] to handle
//! entries that reference variable-length "oversized" values. It provides coordinated
//! operations and built-in crash recovery.
//!
//! # Architecture
//!
//! ```text
//! +-------------------+     +-------------------+
//! | Fixed Journal     |     | Glob (Values)     |
//! | (Index Entries)   |     |                   |
//! +-------------------+     +-------------------+
//! | entry_0           | --> | value_0           |
//! | entry_1           | --> | value_1           |
//! | ...               |     | ...               |
//! +-------------------+     +-------------------+
//! ```
//!
//! Each index entry contains `(value_offset, value_size)` pointing to its value in glob.
//!
//! # Crash Recovery
//!
//! On unclean shutdown, the index journal and glob may have different lengths:
//! - Index entry pointing to non-existent glob data (dangerous)
//! - Glob value without index entry (orphan - acceptable but cleaned up)
//! - Glob sections without corresponding index sections (orphan sections - removed)
//!
//! During initialization, crash recovery is performed:
//! 1. Each section's last valid entry is found by scanning backwards: an entry is valid
//!    only if its glob reference is in bounds (`value_offset + value_size <= glob_size`)
//!    and its value's checksum verifies
//! 2. Entries beyond the last valid one are skipped and the index journal is rewound
//! 3. Orphan value sections (sections in glob but not in index) are removed
//!
//! This allows async writes (glob first, then index) while ensuring consistency
//! after recovery: a trailing run of entries that became durable ahead of their value
//! bytes is rewound at the next init, whether the glob is short (range check) or covers
//! the ranges with garbage (checksum check). Entries below the last valid one are kept
//! without reading their values (monotonically increasing offsets make them range-valid),
//! so their checksums are verified lazily at `get_value()`, which can fail for a kept
//! entry if the underlying storage is corrupted. Rewinds (including the truncations
//! recovery itself performs) make both journals' truncations durable before returning,
//! so neither a dropped index entry nor the stale bytes it referenced can survive a
//! crash once later appends may reuse the freed offsets.
//!
//! When a checkpoint is provided ([Oversized::init_with_checkpoint]), recovery restores the
//! state instead of inferring one: each section below the checkpoint is adopted at its
//! validated terminal boundary (without reading values), the checkpointed section is
//! durably truncated to the committed size, and everything after it is removed. A
//! missing or damaged durable boundary fails init rather than being repaired. Other
//! committed damage the checkpoint covers surfaces lazily as read errors.
//!
//! Tracked recovery persists a per-section committed item count. Entries below the marker are
//! adopted once their index/value boundary is proven, entries above it are value-verified in
//! order, and the first invalid value truncates the section's remainder. Markers trail proven
//! syncs, publishing once a section is durable and idle (or on an empty flush).

use super::{
    fixed::{
        Config as FixedConfig, Journal as FixedJournal, RecoveryPreflight, Replay as FixedReplay,
    },
    glob::{Config as GlobConfig, Glob},
};
use crate::{
    Context, SyncCompletion,
    journal::{Error, durability::Barrier},
    metadata::{Config as MetadataConfig, Metadata},
};
use commonware_codec::{Codec, CodecFixed, CodecShared};
use commonware_runtime::{Error as RError, Handle, ReadOptions};
use commonware_utils::sequence::U64 as SectionKey;
use futures::{FutureExt as _, future::try_join};
use std::{
    collections::{BTreeMap, BTreeSet, HashSet},
    num::NonZeroUsize,
};
use tracing::{debug, warn};

/// Trait for index entries that reference oversized values in glob storage.
///
/// Implementations must provide access to the value location for crash recovery validation,
/// and a way to set the location when appending.
pub trait Record: CodecFixed<Cfg = ()> + Clone {
    /// Returns `(value_offset, value_size)` for crash recovery validation.
    fn value_location(&self) -> (u64, u32);

    /// Returns a new entry with the value location set.
    ///
    /// Called during `append` after the value is written to glob storage.
    fn with_location(self, offset: u64, size: u32) -> Self;
}

/// Configuration for oversized journal.
#[derive(Clone)]
pub struct Config<C> {
    /// Partition for the fixed index journal.
    pub index_partition: String,

    /// Partition for the glob value storage.
    pub value_partition: String,

    /// Page cache for index journal caching.
    pub index_page_cache: commonware_runtime::buffer::paged::CacheRef,

    /// Write buffer size for the index journal.
    pub index_write_buffer: NonZeroUsize,

    /// Write buffer size for the value journal.
    pub value_write_buffer: NonZeroUsize,

    /// Buffer size for sequential index recovery.
    pub replay_buffer: NonZeroUsize,

    /// Optional compression level for values (using zstd).
    pub compression: Option<u8>,

    /// Codec configuration for values.
    pub codec_config: C,
}

/// Recovery contract applied while opening the index and value journals.
///
/// Exactly one mode establishes their shared boundary: `Restore` uses an explicit checkpoint,
/// `Floors` preserves per-section validated prefixes while repairing any suffix, and `Infer`
/// derives the boundary entirely from journal contents.
enum Recovery<'a> {
    Restore { section: u64, index_size: u64 },
    Floors(&'a BTreeMap<u64, u64>),
    Infer,
}

/// Durable recovery state for a journal that validates every uncommitted value during replay.
struct Tracking<E: Context> {
    /// Durable committed item count for each retained section.
    metadata: Metadata<E, SectionKey, u64>,

    /// Completion of the marker generation currently being persisted.
    marker_sync_pending: Option<SyncCompletion>,

    /// Joint index/value durability proofs not yet fully published as markers.
    barriers: BTreeMap<u64, Barrier>,
}

impl<E: Context> Tracking<E> {
    /// Stage a changed marker while preserving absence as the canonical zero boundary.
    fn stage_marker(&mut self, section: u64, floor: u64) -> bool {
        let key = SectionKey::new(section);
        match self.metadata.get(&key) {
            None if floor == 0 => false,
            Some(stored) if *stored == floor => false,
            _ => {
                self.metadata.put(key, floor);
                true
            }
        }
    }

    /// Return the section's barrier, seeding a replacement at its staged floor.
    ///
    /// A staged floor never exceeds durably synced data, so it is the newest boundary a
    /// replacement barrier may claim without observing a completed sync.
    fn barrier(&mut self, section: u64) -> &mut Barrier {
        let floor = self
            .metadata
            .get(&SectionKey::new(section))
            .copied()
            .unwrap_or(0);
        self.barriers
            .entry(section)
            .or_insert_with(|| Barrier::new(floor))
    }

    /// Observe an in-flight marker without blocking and discard proofs it published.
    ///
    /// Returns whether a marker generation is still in flight.
    fn observe_marker_sync(&mut self) -> Result<bool, Error> {
        let Some(completion) = self.marker_sync_pending.as_mut() else {
            return Ok(false);
        };
        let Some(result) = completion.now_or_never() else {
            return Ok(true);
        };
        result.map_err(|err| Error::Metadata(crate::metadata::Error::Runtime(err)))?;
        self.marker_sync_pending = None;

        // Retire only barriers whose proof is fully published. A barrier still awaiting a
        // sync outcome protects a boundary beyond its marker and must survive to observe it.
        let metadata = &self.metadata;
        self.barriers.retain(|section, barrier| {
            let published = metadata
                .get(&SectionKey::new(*section))
                .copied()
                .unwrap_or(0);
            barrier.boundary() > published || !barrier.settled()
        });
        Ok(false)
    }
}

/// State for the one marker-aware replay performed while opening a tracked journal.
struct Validation {
    /// Cursor state for the section currently being replayed.
    current_section: Option<u64>,
    floor: u64,
    truncated: bool,

    /// First invalid position in each section, applied after replay releases the index journal.
    rewinds: Vec<(u64, u64)>,

    /// Whether replay yielded an error that makes the journal unavailable.
    failed: bool,
}

impl Validation {
    const fn new() -> Self {
        Self {
            current_section: None,
            floor: 0,
            truncated: false,
            rewinds: Vec::new(),
            failed: false,
        }
    }
}

/// Segmented journal for entries with oversized values.
///
/// Combines a fixed-size index journal with glob storage for variable-length values.
/// Provides coordinated operations and crash recovery.
///
/// Mutating functions consume the journal and return it only on success: an error (or a dropped
/// future) destroys the handle. [Oversized::replay] consumes the journal into an owned [Replay]
/// reader, which returns it via [Replay::finish] once exhausted. Mutations on pruned sections
/// fail with [Error::AlreadyPrunedToSection]. Check [Oversized::pruned] first to keep the
/// handle.
pub struct Oversized<E: Context, I: Record, V: Codec> {
    index: FixedJournal<E, I>,
    values: Glob<E, V>,
    tracking: Option<Tracking<E>>,
}

impl<E: Context, I: Record + Send + Sync, V: CodecShared> std::fmt::Debug for Oversized<E, I, V> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Oversized")
            .field("oldest_section", &self.oldest_section())
            .field("newest_section", &self.newest_section())
            .finish_non_exhaustive()
    }
}

impl<E: Context, I: Record + Send + Sync, V: CodecShared> Oversized<E, I, V> {
    /// Initialize with inferred crash recovery.
    ///
    /// Recovery infers the durable state: it finds each section's last valid entry (in
    /// bounds of the glob, checksum-verified) and rewinds the index journal to exclude
    /// the entries beyond it.
    pub async fn init(context: E, cfg: Config<V::Cfg>) -> Result<Self, Error> {
        let replay_buffer = cfg.replay_buffer;
        let journal = Self::init_inner(context, cfg, Recovery::Infer).await?;
        journal.recover_inferred(replay_buffer).await
    }

    /// Initialize with crash recovery restoring a durable checkpoint, as
    /// `(section, index size)`.
    ///
    /// Recovery keeps exactly the checkpointed state: each section below `section` is
    /// adopted at its validated terminal boundary, `section` is truncated to `index
    /// size`, and everything after it is removed. A missing or damaged boundary the
    /// checkpoint covers fails init with [Error::Corruption], while interior damage
    /// below a boundary surfaces lazily as read errors. Callers must only provide a
    /// checkpoint that was durably synced before it was published (see
    /// [crate::freezer::Freezer]).
    pub async fn init_with_checkpoint(
        context: E,
        cfg: Config<V::Cfg>,
        checkpoint: (u64, u64),
    ) -> Result<Self, Error> {
        let (section, index_size) = checkpoint;
        Self::init_inner(
            context,
            cfg,
            Recovery::Restore {
                section,
                index_size,
            },
        )
        .await
    }

    /// Initialize tracked recovery and return its required full replay.
    ///
    /// The caller must drain the replay and call [Replay::finish_tracked]. Entries below each
    /// durable marker are retained after their cross-journal boundary is proven. Entries above it
    /// are value-validated in order and the first invalid entry truncates its section.
    pub async fn init_with_metadata(
        context: &E,
        cfg: Config<V::Cfg>,
        metadata_partition: String,
        read_options: ReadOptions,
    ) -> Result<Replay<E, I, V>, Error> {
        let replay_buffer = cfg.replay_buffer;

        // Open the commit markers before the data they constrain.
        let metadata = Metadata::init(
            context.child("metadata"),
            MetadataConfig {
                partition: metadata_partition,
                codec_config: (),
            },
        )
        .await?;
        let floors = metadata
            .keys()
            .map(|key| {
                (
                    u64::from(key),
                    *metadata.get(key).expect("metadata key must have a value"),
                )
            })
            .collect::<BTreeMap<_, _>>();

        // Every advertised prefix is proven before ordinary suffix repair may mutate either
        // journal. An empty sidecar retains the legacy inferred-recovery behavior.
        let recovery = if floors.is_empty() {
            Recovery::Infer
        } else {
            Recovery::Floors(&floors)
        };
        let mut journal = Self::init_inner(context.child("oversized"), cfg, recovery).await?;
        journal.tracking = Some(Tracking {
            metadata,
            marker_sync_pending: None,
            barriers: BTreeMap::new(),
        });
        let mut replay = journal.replay(0, 0, replay_buffer, read_options).await?;
        replay.validation = Some(Validation::new());
        Ok(replay)
    }

    /// Open the index and value journals, reconciling them per the selected [Recovery] mode.
    async fn init_inner(
        context: E,
        cfg: Config<V::Cfg>,
        recovery: Recovery<'_>,
    ) -> Result<Self, Error> {
        let index_cfg = FixedConfig {
            partition: cfg.index_partition,
            page_cache: cfg.index_page_cache,
            write_buffer: cfg.index_write_buffer,
        };
        let index_context = context.child("index");
        let value_cfg = GlobConfig {
            partition: cfg.value_partition,
            compression: cfg.compression,
            codec_config: cfg.codec_config,
            write_buffer: cfg.value_write_buffer,
        };
        let value_context = context.child("values");

        let (index, values) = match recovery {
            Recovery::Infer => {
                let index = FixedJournal::init(index_context, index_cfg).await?;
                (index, Glob::init(value_context, value_cfg).await?)
            }
            Recovery::Floors(minimum_items) => {
                let preflight =
                    FixedJournal::preflight_floors(index_context, index_cfg, minimum_items).await?;
                let values = Glob::init(value_context, value_cfg).await?;
                Self::validate_value_floors(&values, &preflight)?;
                (preflight.finish().await?, values)
            }
            Recovery::Restore {
                section,
                index_size,
            } => {
                let preflight =
                    FixedJournal::preflight_restore(index_context, index_cfg, section, index_size)
                        .await?;
                let values = Glob::init(value_context, value_cfg).await?;
                let value_size = Self::validate_restore_values(&values, &preflight, section)?;
                let index = preflight.finish().await?;

                // The index truncation is already durable. Release its unreferenced values only
                // after that proof, preserving the index-first crash-recovery order.
                let values = values.rewind(section, value_size).await?;
                (index, values.sync(section).await?)
            }
        };
        Ok(Self {
            index,
            values,
            tracking: None,
        })
    }

    /// Drain the fixed journal's ordered recovery pass, then reconcile the value tail of each
    /// section. The replay buffer controls every forward index read.
    async fn recover_inferred(self, buffer: NonZeroUsize) -> Result<Self, Error> {
        let mut replay = self.replay(0, 0, buffer, ReadOptions::default()).await?;
        while let Some(result) = replay.next().await {
            result?;
        }
        replay.finish()?.repair().await
    }

    /// Return the value boundary owned by an optional terminal index entry.
    fn boundary_value_end(section: u64, entry: &Option<I>) -> Result<u64, Error> {
        let Some(entry) = entry else {
            return Ok(0);
        };
        let (offset, size) = entry.value_location();
        offset.checked_add(u64::from(size)).ok_or_else(|| {
            Error::Corruption(format!(
                "section {section} has an overflowing terminal value range"
            ))
        })
    }

    /// Perform crash recovery by validating index entries against glob contents.
    ///
    /// Only checks entries from the end of each section until one is valid. Since entries
    /// are appended sequentially and value offsets are monotonically increasing within a
    /// section, all earlier entries must be range-valid (their value checksums are
    /// verified lazily at read).
    async fn repair(mut self) -> Result<Self, Error> {
        let chunk_size = FixedJournal::<E, I>::CHUNK_SIZE as u64;
        let sections: Vec<u64> = self.index.sections().collect();

        let mut rewound_index = Vec::new();
        let mut rewound_values = Vec::new();
        for section in sections {
            let index_size = self.index.size(section)?;
            let glob_size = match self.values.size(section) {
                Ok(size) => size,
                Err(Error::AlreadyPrunedToSection(oldest)) => {
                    // This shouldn't happen in normal operation: prune() prunes the index
                    // first, then the glob. A crash between these would leave the glob
                    // NOT pruned (opposite of this case). We handle this defensively in
                    // case of external manipulation or future changes.
                    warn!(
                        section,
                        oldest, "index has section that glob already pruned"
                    );
                    0
                }
                Err(e) => return Err(e),
            };

            // Truncate any trailing partial entry
            let entry_count = index_size / chunk_size;
            let aligned_size = entry_count * chunk_size;
            if aligned_size < index_size {
                warn!(
                    section,
                    index_size, aligned_size, "trailing bytes detected: truncating"
                );
                self.index = self.index.rewind_section(section, aligned_size).await?;
                rewound_index.push(section);
            }

            // Values are reachable only through index entries.
            if entry_count == 0 {
                if glob_size > 0 {
                    debug!(section, glob_size, "truncating orphaned value bytes");
                    self.values = self.values.rewind_section(section, 0).await?;
                    rewound_values.push(section);
                }
                continue;
            }

            // Find last valid entry and target glob size
            let (valid_count, glob_target) = self
                .find_last_valid_entry(section, entry_count, glob_size)
                .await?;

            // Rewind index if any entries are invalid
            if valid_count < entry_count {
                let valid_size = valid_count * chunk_size;
                debug!(section, entry_count, valid_count, "rewinding index");
                self.index = self.index.rewind_section(section, valid_size).await?;
                rewound_index.push(section);
            }

            // Truncate glob trailing garbage (can occur when value was written but
            // index entry wasn't, or when index was truncated but glob wasn't)
            if glob_size > glob_target {
                debug!(
                    section,
                    glob_size, glob_target, "truncating glob trailing garbage"
                );
                self.values = self.values.rewind_section(section, glob_target).await?;
                rewound_values.push(section);
            }
        }

        // Make the truncations durable before appends can reuse the freed value ranges. A
        // dropped index entry that stayed durable would be adopted by a later recovery
        // referencing whatever bytes a subsequent append placed at its offsets, and stale
        // glob bytes that stayed durable would satisfy a later entry's range with another
        // record's frame.
        self.values = self.values.sync(&rewound_values).await?;
        self.index = self.index.sync(&rewound_index).await?;

        // Clean up orphan value sections that don't exist in index
        self.cleanup_orphan_value_sections().await
    }

    /// Verify every floor's terminal value extent before repair can mutate either journal.
    fn validate_value_floors(
        values: &Glob<E, V>,
        preflight: &RecoveryPreflight<E, I>,
    ) -> Result<(), Error> {
        for (&section, entry) in preflight.boundaries() {
            let required = Self::boundary_value_end(section, entry)?;
            if required == 0 {
                continue;
            }
            let retained = values.size(section)?;
            if retained < required {
                return Err(Error::Corruption(format!(
                    "section {section} retains {retained} value bytes, below the validation \
                     floor of {required}"
                )));
            }
        }
        Ok(())
    }

    /// Verify checkpoint-covered value extents against preflighted index boundaries, returning
    /// the checkpoint section's terminal value end.
    fn validate_restore_values(
        values: &Glob<E, V>,
        preflight: &RecoveryPreflight<E, I>,
        section: u64,
    ) -> Result<u64, Error> {
        // Every earlier section is immutable under the checkpoint, so its terminal index entry
        // must end exactly at the retained value length.
        for (&candidate, entry) in preflight.boundaries().range(..section) {
            let required = Self::boundary_value_end(candidate, entry)?;
            let retained = values.size(candidate)?;
            if retained != required {
                return Err(Error::Corruption(format!(
                    "section {candidate} index ends at value byte {required}, but its glob size is {retained}"
                )));
            }
        }

        // A value-only section below the checkpoint proves that covered index data was lost.
        if let Some(orphan) = values.sections().find(|candidate| {
            *candidate < section && !preflight.boundaries().contains_key(candidate)
        }) {
            return Err(Error::Corruption(format!(
                "section {orphan} has values but no index"
            )));
        }

        // The current section may retain a suffix, but it must cover its committed terminal value.
        let required = Self::boundary_value_end(section, &preflight.boundaries()[&section])?;
        if required > 0 {
            let retained = values.size(section)?;
            if retained < required {
                return Err(Error::Corruption(format!(
                    "section {section} retains {retained} of {required} committed value bytes"
                )));
            }
        }

        Ok(required)
    }

    /// Remove any value sections that don't have corresponding index sections.
    ///
    /// This can happen if a crash occurs after writing to values but before
    /// writing to index for a new section. Since sections don't have to be
    /// contiguous, we compare the actual sets of sections rather than just
    /// comparing the newest section numbers.
    async fn cleanup_orphan_value_sections(mut self) -> Result<Self, Error> {
        // Collect index sections into a set for O(1) lookup
        let index_sections: HashSet<u64> = self.index.sections().collect();

        // Find value sections that don't exist in index
        let orphan_sections: Vec<u64> = self
            .values
            .sections()
            .filter(|s| !index_sections.contains(s))
            .collect();

        // Remove each orphan section
        for section in orphan_sections {
            warn!(section, "removing orphan value section");
            (self.values, _) = self.values.remove_section(section).await?;
        }

        Ok(self)
    }

    /// Truncate value suffixes that became unreachable while fixed replay repaired index pages.
    async fn align_values_to_index(mut self) -> Result<Self, Error> {
        let sections = self.index.sections().collect::<Vec<_>>();
        let mut rewound = Vec::new();
        for section in sections {
            let target = Self::boundary_value_end(section, &self.index.last(section).await?)?;
            let retained = self.values.size(section)?;
            if retained < target {
                return Err(Error::Corruption(format!(
                    "section {section} retains {retained} of {target} indexed value bytes"
                )));
            }
            if retained > target {
                self.values = self.values.rewind_section(section, target).await?;
                rewound.push(section);
            }
        }
        self.values = self.values.sync(&rewound).await?;
        self.cleanup_orphan_value_sections().await
    }

    /// Find the number of valid entries and the corresponding glob target size.
    ///
    /// Scans backwards from the last entry until a valid one is found: an entry is valid
    /// only if its byte range fits within the glob and its value's checksum verifies.
    /// Returns `(valid_count, glob_target)` where `glob_target` is the end offset
    /// of the last valid entry's value.
    async fn find_last_valid_entry(
        &self,
        section: u64,
        entry_count: u64,
        glob_size: u64,
    ) -> Result<(u64, u64), Error> {
        for pos in (0..entry_count).rev() {
            match self.index.get(section, pos).await {
                Ok(entry) => {
                    let (offset, size) = entry.value_location();
                    let entry_end = offset.saturating_add(u64::from(size));
                    if entry_end <= glob_size && self.values.verify(section, offset, size).await? {
                        return Ok((pos + 1, entry_end));
                    }
                    if pos == entry_count - 1 {
                        warn!(
                            section,
                            pos, glob_size, entry_end, "invalid entry: glob truncated or corrupt"
                        );
                    }
                }
                Err(Error::ItemOutOfRange(_) | Error::Runtime(RError::InvalidChecksum)) => {
                    if pos == entry_count - 1 {
                        warn!(section, pos, "corrupted last entry, scanning backwards");
                    }
                }
                Err(err) => return Err(err),
            }
        }
        Ok((0, 0))
    }

    /// Reconcile durable markers with the retained state after tracked startup recovery.
    async fn reconcile_markers(mut self) -> Result<Self, Error> {
        let mut tracking = self
            .tracking
            .take()
            .expect("tracked replay preserves its recovery state");

        let mut dirty = false;
        for section in self.index.sections() {
            let items = self.index.section_len(section)?;
            dirty |= tracking.stage_marker(section, items);
        }
        if dirty {
            let marker;
            (tracking.metadata, marker) = tracking.metadata.start_sync().await?;
            tracking.marker_sync_pending = Some(marker.boxed().shared());
        }
        self.tracking = Some(tracking);
        Ok(self)
    }

    /// Lower tracked floors before an operation can free any bytes they authorize.
    async fn prepare_rewind(
        &mut self,
        section: u64,
        index_size: u64,
        remove_later: bool,
    ) -> Result<(), Error> {
        let Some(mut tracking) = self.tracking.take() else {
            return Ok(());
        };
        let items = index_size / FixedJournal::<E, I>::CHUNK_SIZE as u64;
        let mut dirty = false;

        if remove_later {
            tracking.metadata.retain(|key, _| {
                let keep = u64::from(key) <= section;
                dirty |= !keep;
                keep
            });
        }
        let key = SectionKey::new(section);
        if tracking
            .metadata
            .get(&key)
            .is_some_and(|floor| *floor > items)
        {
            tracking.metadata.put(key, items);
            dirty = true;
        }
        if dirty {
            tracking.metadata = tracking.metadata.sync().await?;
            tracking.marker_sync_pending = None;
        }

        if remove_later {
            tracking
                .barriers
                .retain(|candidate, _| *candidate <= section);
        }
        if let Some(barrier) = tracking.barriers.get_mut(&section) {
            barrier.truncate(items);
        }
        self.tracking = Some(tracking);
        Ok(())
    }

    /// Append entry + value.
    ///
    /// Writes value to glob first, then writes index entry with the value location.
    ///
    /// Returns `(self, position, offset, size)` where:
    /// - `position`: Position in the index journal
    /// - `offset`: Byte offset in glob
    /// - `size`: Size of value in glob (including checksum)
    pub async fn append(
        mut self,
        section: u64,
        entry: I,
        value: &V,
    ) -> Result<(Self, u64, u64, u32), Error> {
        // Write value first (glob). This will typically write to an in-memory
        // buffer and return quickly (only blocks when the buffer is full).
        let (offset, size);
        (self.values, offset, size) = self.values.append(section, value).await?;

        // Update entry with actual location and write to index
        let entry_with_location = entry.with_location(offset, size);
        let position;
        (self.index, position) = self.index.append(section, &entry_with_location).await?;

        // Track this section so a later sync can prove and publish its new length. A fresh
        // barrier claims only the staged floor, never the unproven pre-append prefix.
        if let Some(tracking) = &mut self.tracking {
            tracking.barrier(section);
        }

        Ok((self, position, offset, size))
    }

    /// Get entry at position (index entry only, not value).
    pub async fn get(&self, section: u64, position: u64) -> Result<I, Error> {
        self.index.get(section, position).await
    }

    /// Get the last entry for a section, if any.
    ///
    /// Returns `Ok(None)` if the section is empty.
    ///
    /// # Errors
    ///
    /// - [Error::AlreadyPrunedToSection] if the section has been pruned.
    /// - [Error::SectionOutOfRange] if the section doesn't exist.
    pub async fn last(&self, section: u64) -> Result<Option<I>, Error> {
        self.index.last(section).await
    }

    /// Get value using offset/size from entry.
    ///
    /// The offset should be the byte offset from `append()` or from the entry's `value_location()`.
    pub async fn get_value(&self, section: u64, offset: u64, size: u32) -> Result<V, Error> {
        self.values.get(section, offset, size).await
    }

    /// Consumes the journal and returns an owned [Replay] reader over index entries
    /// starting from `start_position` in `start_section`.
    ///
    /// Setup flushes the index journal's buffered pages so the reader observes every
    /// accepted write. Every backing index-journal read performed by the returned
    /// replay uses `read_options`, including reads after advancing to another
    /// section.
    pub async fn replay(
        self,
        start_section: u64,
        start_position: u64,
        buffer: NonZeroUsize,
        read_options: ReadOptions,
    ) -> Result<Replay<E, I, V>, Error> {
        let Self {
            index,
            values,
            tracking,
        } = self;
        let index = index
            .replay(start_section, start_position, buffer, read_options)
            .await?;
        Ok(Replay {
            index,
            values,
            tracking,
            validation: None,
        })
    }

    /// Start a joint data sync and publish only previously completed tracked boundaries.
    ///
    /// The returned handle covers only the requested data syncs. Marker generations trail
    /// data durability by design, and a marker failure surfaces as [Error::Metadata] when a
    /// later request observes it.
    pub(crate) async fn start_sync_tracked(
        mut self,
        sections: &BTreeSet<u64>,
        active: &BTreeSet<u64>,
    ) -> Result<(Self, Handle<()>), Error> {
        let mut tracking = self
            .tracking
            .take()
            .expect("tracked sync preserves its recovery state");
        let marker_pending = tracking.observe_marker_sync()?;
        let lengths = sections
            .iter()
            .map(|&section| Ok((section, self.index.section_len(section)?)))
            .collect::<Result<Vec<_>, Error>>()?;
        let ((index, index_handle), (values, values_handle)) = try_join(
            self.index.start_sync(sections),
            self.values.start_sync(sections),
        )
        .await?;
        self.index = index;
        self.values = values;
        let completion: SyncCompletion =
            async move { try_join(index_handle, values_handle).await.map(|_| ()) }
                .boxed()
                .shared();

        // Bind every selected target to the new joint completion. The recorded length becomes
        // publishable only once this completion is observed to have succeeded.
        for (section, length) in lengths {
            tracking.barrier(section).record(length, completion.clone());
        }

        // Do not mutate Metadata while its prior generation is in flight. Completed barriers stay
        // as debt and are published when their section is no longer active, or on an empty flush.
        if !marker_pending {
            let publish = tracking
                .barriers
                .iter_mut()
                .filter(|(section, _)| !active.contains(section))
                .map(|(&section, barrier)| (section, barrier.boundary()))
                .collect::<Vec<_>>();
            let mut metadata_dirty = false;
            for (section, floor) in publish {
                metadata_dirty |= tracking.stage_marker(section, floor);
            }
            if metadata_dirty {
                let handle;
                (tracking.metadata, handle) = tracking.metadata.start_sync().await?;
                tracking.marker_sync_pending = Some(handle.boxed().shared());
            }
        }

        self.tracking = Some(tracking);
        Ok((self, Handle::from_future(completion)))
    }

    /// Block until the selected data syncs are durable, surfacing any marker failure the
    /// completed generation already exposed.
    pub(crate) async fn sync_tracked(
        self,
        sections: &BTreeSet<u64>,
        active: &BTreeSet<u64>,
    ) -> Result<Self, Error> {
        let (mut journal, handle) = self.start_sync_tracked(sections, active).await?;
        handle.await?;
        journal
            .tracking
            .as_mut()
            .expect("tracking mode is preserved")
            .observe_marker_sync()?;
        Ok(journal)
    }

    /// Sync both journals for the given `sections`.
    pub async fn sync(mut self, sections: impl crate::Sections) -> Result<Self, Error> {
        if self.tracking.is_some() {
            let sections = sections.sections().collect::<BTreeSet<_>>();
            return self.sync_tracked(&sections, &sections).await;
        }

        let sections = sections.sections().collect::<Vec<_>>();
        (self.index, self.values) =
            try_join(self.index.sync(&sections), self.values.sync(&sections)).await?;
        Ok(self)
    }

    /// Start syncing both journals for the given `sections`.
    ///
    /// The returned handle completes once both journals' syncs complete, failing with the first
    /// error encountered. An error reported by the returned [Handle] is fatal to the journal:
    /// the caller must stop using the returned journal.
    pub async fn start_sync(
        mut self,
        sections: impl crate::Sections,
    ) -> Result<(Self, Handle<()>), Error> {
        if self.tracking.is_some() {
            let sections = sections.sections().collect::<BTreeSet<_>>();
            return self.start_sync_tracked(&sections, &sections).await;
        }

        let sections = sections.sections().collect::<Vec<_>>();
        let ((index, index_handle), (values, values_handle)) = try_join(
            self.index.start_sync(&sections),
            self.values.start_sync(&sections),
        )
        .await?;
        self.index = index;
        self.values = values;
        Ok((
            self,
            Handle::from_future(
                async move { try_join(index_handle, values_handle).await.map(|_| ()) },
            ),
        ))
    }

    /// Sync all sections.
    pub async fn sync_all(mut self) -> Result<Self, Error> {
        if self.tracking.is_some() {
            let sections = self.index.sections().collect::<BTreeSet<_>>();
            return self.sync(sections).await;
        }
        (self.index, self.values) = try_join(self.index.sync_all(), self.values.sync_all()).await?;
        Ok(self)
    }

    /// Prune both journals. Returns true if any sections were pruned.
    ///
    /// Prunes index first, then glob. This order ensures crash safety:
    /// - If crash after index prune but before glob: orphan data in glob (acceptable)
    /// - If crash before index prune: no change, retry works
    pub async fn prune(mut self, min: u64) -> Result<(Self, bool), Error> {
        // Remove and durably sync tracked floors before their section names can be deleted and
        // later reused.
        if let Some(mut tracking) = self.tracking.take() {
            let mut removed = false;
            tracking.metadata.retain(|key, _| {
                let keep = u64::from(key) >= min;
                removed |= !keep;
                keep
            });
            if removed {
                tracking.metadata = tracking.metadata.sync().await?;
                tracking.marker_sync_pending = None;
            }
            tracking.barriers = tracking.barriers.split_off(&min);
            self.tracking = Some(tracking);
        }

        let index_pruned;
        (self.index, index_pruned) = self.index.prune(min).await?;
        let value_pruned;
        (self.values, value_pruned) = self.values.prune(min).await?;
        Ok((self, index_pruned || value_pruned))
    }

    /// Derive the value boundary owned by `section`'s last entry after an index rewind.
    ///
    /// A rewind to zero may leave no section behind, which owns no value bytes.
    async fn rewound_value_end(&self, section: u64, index_size: u64) -> Result<u64, Error> {
        match self.index.last(section).await {
            Ok(Some(entry)) => {
                let (offset, size) = entry.value_location();
                offset
                    .checked_add(u64::from(size))
                    .ok_or(Error::OffsetOverflow)
            }
            Ok(None) => Ok(0),
            Err(Error::SectionOutOfRange(_)) if index_size == 0 => Ok(0),
            Err(e) => Err(e),
        }
    }

    /// Rewind both journals to a specific section and index size.
    ///
    /// This rewinds the section to the given index size and removes all sections
    /// after the given section. The value size is derived from the last entry.
    ///
    /// Both of `section`'s truncations are durable before this returns: a crash recovers
    /// `section` to either its pre-rewind or its post-rewind state. Each journal removes
    /// its later sections (newest first) before truncating `section`, and those removals
    /// carry the storage layer's removal durability.
    pub async fn rewind(mut self, section: u64, index_size: u64) -> Result<Self, Error> {
        self.prepare_rewind(section, index_size, true).await?;

        // Rewind index first (this also removes sections after `section`)
        self.index = self.index.rewind(section, index_size).await?;

        // Derive value size from last entry (section may not exist if empty)
        let value_size = self.rewound_value_end(section, index_size).await?;

        // Make the index truncation durable before the values are rewound: rewinding the
        // values frees their ranges for reuse by later appends, and a dropped index entry
        // that stayed durable would be adopted referencing whatever bytes a later append
        // placed at its offsets.
        self.index = self.index.sync(section).await?;

        // Rewind values (this also removes sections after `section`)
        self.values = self.values.rewind(section, value_size).await?;
        self.values = self.values.sync(section).await?;
        Ok(self)
    }

    /// Rewind only the given section to a specific index size.
    ///
    /// Unlike `rewind`, this does not affect other sections.
    /// The value size is derived from the last entry after rewinding the index.
    ///
    /// Both truncations are made durable before returning (see [Self::rewind]).
    pub async fn rewind_section(mut self, section: u64, index_size: u64) -> Result<Self, Error> {
        self.prepare_rewind(section, index_size, false).await?;

        // Rewind index first
        self.index = self.index.rewind_section(section, index_size).await?;

        // Derive value size from last entry (section may not exist if empty)
        let value_size = self.rewound_value_end(section, index_size).await?;

        // Make the index truncation durable before the values are rewound (see Self::rewind).
        self.index = self.index.sync(section).await?;

        // Rewind values
        self.values = self.values.rewind_section(section, value_size).await?;
        self.values = self.values.sync(section).await?;
        Ok(self)
    }

    /// Get index size for checkpoint.
    ///
    /// The value size can be derived from the last entry's location when needed.
    pub fn size(&self, section: u64) -> Result<u64, Error> {
        self.index.size(section)
    }

    /// Get the value size for a section, derived from the last entry's location.
    pub async fn value_size(&self, section: u64) -> Result<u64, Error> {
        match self.index.last(section).await {
            Ok(Some(entry)) => {
                let (offset, size) = entry.value_location();
                offset
                    .checked_add(u64::from(size))
                    .ok_or(Error::OffsetOverflow)
            }
            Ok(None) | Err(Error::SectionOutOfRange(_)) => Ok(0),
            Err(e) => Err(e),
        }
    }

    /// Returns true when `section` is below the prune floor.
    ///
    /// The floor only tracks prunes from the current execution and resets at init, so a
    /// section pruned in a previous execution reports false.
    pub fn pruned(&self, section: u64) -> bool {
        self.index.pruned(section)
    }

    /// Returns the oldest section number, if any exist.
    pub fn oldest_section(&self) -> Option<u64> {
        self.index.oldest_section()
    }

    /// Returns the newest section number, if any exist.
    pub fn newest_section(&self) -> Option<u64> {
        self.index.newest_section()
    }

    /// Destroy all underlying storage.
    pub async fn destroy(mut self) -> Result<(), Error> {
        // Remove tracked floors first so an interrupted destroy can only force conservative
        // recovery of any pair data left behind.
        if let Some(tracking) = self.tracking.take() {
            tracking.metadata.destroy().await?;
        }
        try_join(self.index.destroy(), self.values.destroy())
            .await
            .map(|_| ())
    }
}

/// Owned replay reader over an [Oversized]'s index entries.
///
/// Yields `(section, position, entry)` in order. Dropping the reader before it is exhausted
/// destroys the journal: recovery is re-initialization. Call [Replay::finish] on an exhausted
/// reader to get the journal back.
pub struct Replay<E: Context, I: Record, V: Codec> {
    index: FixedReplay<E, I>,
    values: Glob<E, V>,
    tracking: Option<Tracking<E>>,
    validation: Option<Validation>,
}

impl<E: Context, I: Record + Send + Sync, V: CodecShared> Replay<E, I, V> {
    /// Returns the next `(section, position, entry)`, or `None` once every section is
    /// exhausted.
    ///
    /// An index error ends the section that produced it, and iteration continues with
    /// the next section. A value-verification error is returned without ending its
    /// section and dooms the tracked replay: finishing it fails with
    /// [Error::ReplayFailed]. Errors while mutating storage to repair a section, and
    /// [Error::ReplayInterrupted], end the replay.
    pub async fn next(&mut self) -> Option<Result<(u64, u64, I), Error>> {
        loop {
            let result = self.index.next().await?;
            let (section, position, entry) = match result {
                Ok(entry) => entry,
                Err(err) => return Some(Err(err)),
            };
            let (tracking, validation) = (&self.tracking, &mut self.validation);
            let Some(validation) = validation else {
                return Some(Ok((section, position, entry)));
            };

            // Each section validates forward from its durable floor. Once one value fails, later
            // entries in that section are outside the retained prefix and are not yielded.
            if validation.current_section != Some(section) {
                validation.current_section = Some(section);
                validation.floor = tracking
                    .as_ref()
                    .expect("tracked replay preserves its recovery state")
                    .metadata
                    .get(&SectionKey::new(section))
                    .copied()
                    .unwrap_or(0);
                validation.truncated = false;
            }
            if validation.truncated {
                continue;
            }
            if position < validation.floor {
                return Some(Ok((section, position, entry)));
            }

            let (offset, size) = entry.value_location();
            match self.values.verify(section, offset, size).await {
                Ok(true) => return Some(Ok((section, position, entry))),
                Ok(false) => {
                    validation.rewinds.push((section, position));
                    validation.truncated = true;
                }
                Err(err) => {
                    validation.failed = true;
                    return Some(Err(err));
                }
            }
        }
    }

    /// Returns the journal.
    ///
    /// Fails when the reader was not fully drained or yielded an error: the journal is
    /// destroyed and recovery is re-initialization.
    pub fn finish(self) -> Result<Oversized<E, I, V>, Error> {
        if self.validation.is_some() {
            return Err(Error::ReplayFailed);
        }
        Ok(Oversized {
            index: self.index.finish()?,
            values: self.values,
            tracking: self.tracking,
        })
    }

    /// Finish marker-aware startup recovery and return the tracked journal.
    pub async fn finish_tracked(self) -> Result<Oversized<E, I, V>, Error> {
        let Some(validation) = self.validation else {
            return Err(Error::ReplayFailed);
        };
        if validation.failed {
            return Err(Error::ReplayFailed);
        }
        let mut journal = Oversized {
            index: self.index.finish()?,
            values: self.values,
            tracking: self.tracking,
        };

        // Apply each section's first invalid position only after replay releases the index
        // journal, then publish the exact retained lengths as the next marker generation.
        let chunk_size = FixedJournal::<E, I>::CHUNK_SIZE as u64;
        for (section, items) in validation.rewinds {
            let index_size = items.checked_mul(chunk_size).ok_or(Error::OffsetOverflow)?;
            journal = journal.rewind_section(section, index_size).await?;
        }
        journal
            .align_values_to_index()
            .await?
            .reconcile_markers()
            .await
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use commonware_codec::{FixedSize, Read, ReadExt, Write};
    use commonware_cryptography::Crc32;
    use commonware_macros::test_traced;
    use commonware_runtime::{
        Blob as _, Buf, BufMut, BufferPooler, Runner, Storage as _, Supervisor as _, WriteOptions,
        buffer::paged::{CacheRef, corrupt_page},
        deterministic,
        mocks::{DelayedSyncContext, PendingSyncs, SyncFaultContext, drive_pending_syncs},
    };
    use commonware_utils::{NZU16, NZUsize};

    /// Convert offset + size to byte end position (for truncation tests).
    fn byte_end(offset: u64, size: u32) -> u64 {
        offset + u64::from(size)
    }

    /// Test index entry that stores a u64 id and references a value.
    #[derive(Debug, Clone, PartialEq)]
    struct TestEntry {
        id: u64,
        value_offset: u64,
        value_size: u32,
    }

    impl TestEntry {
        fn new(id: u64, value_offset: u64, value_size: u32) -> Self {
            Self {
                id,
                value_offset,
                value_size,
            }
        }
    }

    impl Write for TestEntry {
        fn write(&self, buf: &mut impl BufMut) {
            self.id.write(buf);
            self.value_offset.write(buf);
            self.value_size.write(buf);
        }
    }

    impl Read for TestEntry {
        type Cfg = ();

        fn read_cfg(buf: &mut impl Buf, _: &Self::Cfg) -> Result<Self, commonware_codec::Error> {
            let id = u64::read(buf)?;
            let value_offset = u64::read(buf)?;
            let value_size = u32::read(buf)?;
            Ok(Self {
                id,
                value_offset,
                value_size,
            })
        }
    }

    impl FixedSize for TestEntry {
        const SIZE: usize = u64::SIZE + u64::SIZE + u32::SIZE;
    }

    impl Record for TestEntry {
        fn value_location(&self) -> (u64, u32) {
            (self.value_offset, self.value_size)
        }

        fn with_location(mut self, offset: u64, size: u32) -> Self {
            self.value_offset = offset;
            self.value_size = size;
            self
        }
    }

    fn test_cfg(pooler: &impl BufferPooler) -> Config<()> {
        Config {
            index_partition: "test-index".into(),
            value_partition: "test-values".into(),
            index_page_cache: CacheRef::from_pooler(pooler, NZU16!(64), NZUsize!(8)),
            index_write_buffer: NZUsize!(1024),
            value_write_buffer: NZUsize!(1024),
            replay_buffer: NZUsize!(4096),
            compression: None,
            codec_config: (),
        }
    }

    /// Test configuration sized so each index page holds exactly one entry.
    fn entry_cfg(pooler: &impl BufferPooler) -> Config<()> {
        let mut cfg = test_cfg(pooler);
        cfg.index_page_cache =
            CacheRef::from_pooler(pooler, NZU16!(TestEntry::SIZE as u16), NZUsize!(8));
        cfg
    }

    /// Simple test value type with unit config.
    type TestValue = [u8; 16];

    #[test_traced]
    fn test_oversized_append_and_get() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            // Append entry with value
            let value: TestValue = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
            let entry = TestEntry::new(42, 0, 0);
            let (position, offset, size);
            (oversized, position, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");

            assert_eq!(position, 0);

            // Get entry
            let retrieved_entry = oversized.get(1, position).await.expect("Failed to get");
            assert_eq!(retrieved_entry.id, 42);

            // Get value
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_crash_recovery() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate oversized journal
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append multiple entries
            let mut locations = Vec::new();
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Simulate crash: truncate glob to lose last 2 values
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");

            // Calculate size to keep first 3 entries
            let keep_size = byte_end(locations[2].1, locations[2].2);
            blob.resize(keep_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should recover and rewind index
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First 3 entries should still be valid
            for i in 0..3u8 {
                let (position, offset, size) = locations[i as usize];
                let entry = oversized.get(1, position).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);

                let value = oversized
                    .get_value(1, offset, size)
                    .await
                    .expect("Failed to get value");
                assert_eq!(value, [i; 16]);
            }

            // Entry at position 3 should fail (index was rewound)
            let result = oversized.get(1, 3).await;
            assert!(result.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_persistence() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(123, 0, 0);
            let (position, offset, size);
            (oversized, position, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Reopen and verify
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            let retrieved_entry = oversized.get(1, position).await.expect("Failed to get");
            assert_eq!(retrieved_entry.id, 123);

            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_sync() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // One sub-page entry/value per section stays buffered until synced.
            let mut located = Vec::new();
            for section in 1u64..=3 {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                located.push((section, position, offset, size, value));
            }

            // Sync sections 1 and 3 (both index and values); a nonexistent section (99) is
            // skipped, not an error.
            oversized = oversized
                .sync(&[1, 3, 99])
                .await
                .expect("Failed to sync sections");
            drop(oversized);

            // Only the synced sections survive the unclean drop, with both index and value durable.
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");
            for &(section, position, offset, size, value) in &located {
                let result = oversized.get(section, position).await;
                if section == 2 {
                    assert!(result.is_err(), "unsynced section 2 must not be durable");
                    continue;
                }
                assert_eq!(result.expect("synced entry durable").id, section);
                let retrieved = oversized
                    .get_value(section, offset, size)
                    .await
                    .expect("synced value durable");
                assert_eq!(retrieved, value);
            }

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    /// Assert that every entry recovery adopted in section 1 reads back the value that was
    /// appended with it.
    async fn assert_adopted_entries_consistent(
        oversized: &Oversized<deterministic::Context, TestEntry, TestValue>,
    ) {
        let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
        for position in 0..oversized.size(1).expect("size") / chunk {
            let entry = oversized.get(1, position).await.expect("Failed to get");
            let (offset, size) = entry.value_location();
            let value = oversized
                .get_value(1, offset, size)
                .await
                .expect("adopted entry must reference durable bytes");
            assert_eq!(
                value, [entry.id as u8; 16],
                "entry {} must read back the value appended with it",
                entry.id
            );
        }
    }

    #[test_traced]
    fn test_oversized_rewind_truncation_durable_before_offset_reuse() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            // One fully durable entry/value pair.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Rewind entry 1 away and append entry 2 at entry 1's glob offset, then crash
            // between the value sync and the index sync: entry 2's bytes (same size, valid
            // checksum) become durable at the exact range entry 1 referenced. Only the
            // durable truncation in `rewind` prevents recovery from resurrecting entry 1
            // pointing at entry 2's value. The range and checksum checks cannot reject it.
            oversized = oversized.rewind(1, 0).await.expect("Failed to rewind");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            oversized.values = oversized
                .values
                .sync(1)
                .await
                .expect("Failed to sync values");
        });

        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert_eq!(
                oversized.size(1).expect("size"),
                0,
                "rewound entry must not be revived over reused value bytes"
            );
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_recovery_never_adopts_entries_for_lost_values() {
        // Crash 1: entry 1 becomes durable but its value does not (an index write surviving
        // a crash its value bytes did not).
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized.index = oversized.index.sync(1).await.expect("Failed to sync index");
        });

        // Boot 2: recovery rewinds entry 1 (its range is out of bounds) and must make that
        // truncation durable. A new append then reuses entry 1's offset. Crash 2 lands
        // after the value sync and before the index sync.
        let (_, checkpoint) =
            deterministic::Runner::from(checkpoint).start_and_recover(|context| async move {
                let mut oversized: Oversized<_, TestEntry, TestValue> =
                    Oversized::init(context.child("second"), test_cfg(&context))
                        .await
                        .expect("Failed to reinit");
                assert_eq!(
                    oversized.size(1).expect("size"),
                    0,
                    "entry without durable value bytes must be rewound"
                );
                (oversized, _, _, _) = oversized
                    .append(1, TestEntry::new(2, 0, 0), &[2; 16])
                    .await
                    .expect("Failed to append");
                oversized.values = oversized
                    .values
                    .sync(1)
                    .await
                    .expect("Failed to sync values");
            });

        // Boot 3: without a durable truncation in recovery, the index would still hold
        // entry 1, now range-valid over entry 2's bytes.
        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_rewind_fails_when_truncation_cannot_be_made_durable() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            // One fully durable entry/value pair.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Boot 2: the glob cannot be synced, so `rewind` must fail rather than return
            // with a values truncation that is not durable (later appends could otherwise
            // reuse entry 1's still-durable value range).
            let faulty_values = SyncFaultContext {
                inner: context.child("second"),
                fail_partition: "test-values".into(),
            };
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(faulty_values, test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert!(
                oversized.rewind(1, 0).await.is_err(),
                "rewind must fail when its truncation cannot be made durable"
            );
        });

        // The index truncation was made durable before the failure, so the dropped entry
        // must not be adopted at recovery.
        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert_eq!(oversized.size(1).expect("size"), 0);
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_recovery_glob_truncation_durable_before_offset_reuse() {
        // Crash 1: the index truncation is durable but the glob still holds entry 2's
        // frame (the state a crash inside `rewind` leaves behind).
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            oversized.index = oversized
                .index
                .rewind(1, chunk)
                .await
                .expect("Failed to rewind index");
            oversized.index = oversized.index.sync(1).await.expect("Failed to sync index");
        });

        // Boot 2: recovery truncates the glob to entry 1's end and must make that
        // truncation durable. Entry 3 (same size) then reuses entry 2's freed range.
        // Crash 2 lands after the index sync and before the values sync.
        let (_, checkpoint) =
            deterministic::Runner::from(checkpoint).start_and_recover(|context| async move {
                let mut oversized: Oversized<_, TestEntry, TestValue> =
                    Oversized::init(context.child("second"), test_cfg(&context))
                        .await
                        .expect("Failed to reinit");
                (oversized, _, _, _) = oversized
                    .append(1, TestEntry::new(3, 0, 0), &[3; 16])
                    .await
                    .expect("Failed to append");
                oversized.index = oversized.index.sync(1).await.expect("Failed to sync index");
            });

        // Boot 3: without a durable glob truncation in recovery, entry 3 would be
        // adopted referencing entry 2's still-durable frame.
        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_rewind_crash_between_truncations_recovers_post_rewind() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            // Two fully durable entry/value pairs.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Replay `rewind(1, chunk)`'s steps up to the worst crash point: the index
            // truncation is durable but the freed value bytes are not yet rewound.
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            oversized.index = oversized
                .index
                .rewind(1, chunk)
                .await
                .expect("Failed to rewind index");
            oversized.index = oversized.index.sync(1).await.expect("Failed to sync index");
        });

        // Recovery must truncate the orphaned value bytes and land on the post-rewind
        // state.
        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            assert_eq!(oversized.size(1).expect("size"), chunk);
            let entry = oversized.get(1, 0).await.expect("Failed to get");
            let (offset, size) = entry.value_location();
            assert_eq!(
                oversized.values.size(1).expect("glob size"),
                byte_end(offset, size),
                "orphaned value bytes must be truncated"
            );
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_start_sync_completion_means_recoverable() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            let (_oversized, handle) = oversized.start_sync(1).await.expect("Failed to start sync");
            handle.await.expect("sync must complete");
            // Crash: everything covered by the completed handle must survive.
        });

        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            assert_eq!(oversized.size(1).expect("size"), chunk);
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_sync_values_failure_recovers_clean() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            let faulty_values = SyncFaultContext {
                inner: context.child("first"),
                fail_partition: "test-values".into(),
            };
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(faulty_values, test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");

            // The value sync fails, so the caller is never acknowledged. The index sync
            // may still land, but recovery must not adopt an entry whose value bytes never
            // became durable.
            assert!(oversized.sync(1).await.is_err(), "value sync must fail");
        });

        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert_eq!(
                oversized.size(1).expect("size"),
                0,
                "entry without durable value bytes must be rewound"
            );
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_start_sync_values_failure_recovers_clean() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            let faulty_values = SyncFaultContext {
                inner: context.child("first"),
                fail_partition: "test-values".into(),
            };
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(faulty_values, test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");

            // The value sync fails, so the handle must surface the failure and the caller
            // is never acknowledged.
            let (_oversized, handle) = oversized.start_sync(1).await.expect("Failed to start sync");
            assert!(handle.await.is_err(), "value sync must fail");
        });

        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            assert_eq!(
                oversized.size(1).expect("size"),
                0,
                "entry without durable value bytes must be rewound"
            );
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_start_sync_dropped_handle_driven_by_next_sync() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");

            // Drop the handle without observing it: the next sync must wait for the
            // started syncs and complete the work.
            let (oversized, handle) = oversized.start_sync(1).await.expect("Failed to start sync");
            drop(handle);
            oversized.sync(1).await.expect("Failed to sync");
        });

        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            assert_eq!(oversized.size(1).expect("size"), chunk);
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_recovery_rejects_entry_with_torn_value_bytes() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            // One fully durable entry/value pair.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Append entry 2, make its index entry durable, then persist the glob's LENGTH
            // over entry 2's range without its bytes (writeback-mode metadata journaling):
            // overwrite the frame with same-length garbage and sync the values journal.
            let (offset, size);
            (oversized, _, offset, size) = oversized
                .append(1, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            oversized.index = oversized.index.sync(1).await.expect("Failed to sync index");
            oversized
                .values
                .inject(1, offset, vec![0xFF; size as usize])
                .await
                .expect("Failed to overwrite value bytes");
            oversized.values = oversized
                .values
                .sync(1)
                .await
                .expect("Failed to sync values");
        });

        // Entry 2's range fits within the glob, so only the checksum check can reject it.
        deterministic::Runner::from(checkpoint).start(|context| async move {
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), test_cfg(&context))
                    .await
                    .expect("Failed to reinit");
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            assert_eq!(
                oversized.size(1).expect("size"),
                chunk,
                "entry with torn value bytes must be rewound"
            );
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_scans_past_torn_interior_index_page() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Use page size = entry size so each entry is on its own page.
            let cfg = entry_cfg(&context);

            // Create five durable entry/value pairs.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");
            for i in 1..=5u8 {
                (oversized, _, _, _) = oversized
                    .append(1, TestEntry::new(i as u64, 0, 0), &[i; 16])
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Corrupt the CRC record of the THIRD entry's index page: the backward open
            // scan stops at the (valid) last page, so the torn page survives in bounds.
            let physical_page = TestEntry::SIZE as u64 + 12;
            let (index_blob, size) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open index blob");
            assert_eq!(size, 5 * physical_page);
            index_blob
                .write_at(
                    2 * physical_page + TestEntry::SIZE as u64,
                    vec![0xFF; 12],
                    WriteOptions::SYNC,
                )
                .await
                .expect("Failed to corrupt index page");
            drop(index_blob);

            // Corrupt the fourth and fifth values so the backward scan must walk past
            // their entries and read the torn page.
            let (values_blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open values blob");
            values_blob
                .write_at(60, vec![0xFF; 20], WriteOptions::SYNC)
                .await
                .expect("Failed to corrupt value");
            values_blob
                .write_at(80, vec![0xFF; 20], WriteOptions::SYNC)
                .await
                .expect("Failed to corrupt value");
            drop(values_blob);

            // Recovery scans past the invalid tail values and the torn page (surfaced
            // as a checksum failure, not a generic read error) to the last valid pair.
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            assert_eq!(oversized.size(1).expect("size"), 2 * chunk);
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_restore_discards_beyond_checkpoint() {
        let executor = deterministic::Runner::default();
        let (_, checkpoint) = executor.start_and_recover(|context| async move {
            // One committed entry, then torn state beyond the checkpoint: entries in
            // section 1 and 2 whose index becomes durable ahead of their values.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            (oversized, _, _, _) = oversized
                .append(2, TestEntry::new(3, 0, 0), &[3; 16])
                .await
                .expect("Failed to append");
            oversized.index = oversized
                .index
                .sync(&[1, 2])
                .await
                .expect("Failed to sync index");
        });

        // Restore truncates to the checkpoint without validating the discarded state.
        deterministic::Runner::from(checkpoint).start(|context| async move {
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            let oversized: Oversized<_, TestEntry, TestValue> = Oversized::init_with_checkpoint(
                context.child("second"),
                test_cfg(&context),
                (1, chunk),
            )
            .await
            .expect("Failed to reinit");
            assert_eq!(oversized.size(1).expect("size"), chunk);
            assert_eq!(oversized.newest_section(), Some(1));
            assert_adopted_entries_consistent(&oversized).await;
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_restore_does_not_repair_discarded_sections() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = entry_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("seed"), cfg.clone())
                    .await
                    .expect("failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(0, 0, 0), &[0; 16])
                .await
                .expect("failed to append checkpoint entry");
            for id in 1..=3 {
                (oversized, _, _, _) = oversized
                    .append(2, TestEntry::new(id, 0, 0), &[id as u8; 16])
                    .await
                    .expect("failed to append discardable entry");
            }
            oversized = oversized.sync_all().await.expect("failed to sync");
            drop(oversized);

            // The valid final page hides this interior hole from Writer::new. Restore owns no
            // bytes in section 2 and must remove it without first repairing and syncing it.
            corrupt_page(
                &context,
                &cfg.index_partition,
                &2u64.to_be_bytes(),
                1,
                TestEntry::SIZE as u64,
            )
            .await;

            let pending = PendingSyncs::default();
            pending.arm();
            let delayed = DelayedSyncContext {
                inner: context,
                pending: pending.clone(),
            };
            let chunk = TestEntry::SIZE as u64;
            let oversized: Oversized<_, TestEntry, TestValue> = drive_pending_syncs(
                &pending,
                Oversized::init_with_checkpoint(delayed.child("restore"), cfg, (1, chunk)),
            )
            .await
            .expect("checkpoint restore failed");

            // Restoring an already exact checkpoint syncs its index and values once each. Any
            // additional durability work came from repairing data that restore discards.
            assert_eq!(pending.calls(), 2);
            oversized.destroy().await.expect("failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_restore_incomplete_section_errors() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Two committed sections
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            (oversized, _, _, _) = oversized
                .append(2, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync_all().await.expect("Failed to sync");
            drop(oversized);

            // Truncate section 1's values, simulating lost durable state below the
            // checkpoint
            let (blob, len) = context
                .open("test-values", &1u64.to_be_bytes())
                .await
                .expect("Failed to open values blob");
            blob.resize(len - 1).await.expect("Failed to resize");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // The checkpoint covers the damaged section, so init must fail. Nothing is
            // repaired, so the failure persists across restarts.
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            for instance in ["second", "third"] {
                let result: Result<Oversized<_, TestEntry, TestValue>, Error> =
                    Oversized::init_with_checkpoint(
                        context.child(instance),
                        test_cfg(&context),
                        (2, chunk),
                    )
                    .await;
                assert!(matches!(result, Err(Error::Corruption(_))));
            }
        });
    }

    #[test_traced]
    fn test_oversized_restore_adopts_interior_index_corruption() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            for (child, seed_child, restore_child, checkpoint) in [
                (
                    "checkpoint_section",
                    "seed_checkpoint_section",
                    "restore_checkpoint_section",
                    (1, 3 * TestEntry::SIZE as u64),
                ),
                (
                    "earlier_section",
                    "seed_earlier_section",
                    "restore_earlier_section",
                    (2, TestEntry::SIZE as u64),
                ),
            ] {
                let mut cfg = entry_cfg(&context);
                cfg.index_partition = format!("test-index-{child}");
                cfg.value_partition = format!("test-values-{child}");

                // Persist three entries in section 1 and a later checkpoint candidate. One entry
                // per integrity page makes the damaged page strictly interior.
                let mut oversized: Oversized<_, TestEntry, TestValue> =
                    Oversized::init(context.child(seed_child), cfg.clone())
                        .await
                        .expect("failed to init");
                for id in 0..3 {
                    (oversized, _, _, _) = oversized
                        .append(1, TestEntry::new(id, 0, 0), &[id as u8; 16])
                        .await
                        .expect("failed to append");
                }
                (oversized, _, _, _) = oversized
                    .append(2, TestEntry::new(3, 0, 0), &[3; 16])
                    .await
                    .expect("failed to append later section");
                oversized = oversized.sync_all().await.expect("failed to sync");
                drop(oversized);

                // Checkpoint recovery trusts the completed durability boundary and reads only its
                // terminal entry. Arbitrary post-commit bit rot remains a lazy read error.
                corrupt_page(
                    &context,
                    &cfg.index_partition,
                    &1u64.to_be_bytes(),
                    1,
                    TestEntry::SIZE as u64,
                )
                .await;
                let (blob, expected_size) = context
                    .open(&cfg.index_partition, &1u64.to_be_bytes())
                    .await
                    .expect("failed to open index");
                let expected = blob
                    .read_at(0, expected_size as usize, ReadOptions::default())
                    .await
                    .expect("failed to snapshot damaged index")
                    .coalesce();
                drop(blob);

                let oversized: Oversized<_, TestEntry, TestValue> =
                    Oversized::init_with_checkpoint(
                        context.child(restore_child),
                        cfg.clone(),
                        checkpoint,
                    )
                    .await
                    .expect("checkpoint restore should adopt the covered prefix");
                assert!(matches!(
                    oversized.get(1, 1).await,
                    Err(Error::Runtime(RError::InvalidChecksum))
                ));
                drop(oversized);

                let (blob, actual_size) = context
                    .open(&cfg.index_partition, &1u64.to_be_bytes())
                    .await
                    .expect("failed to reopen index");
                assert_eq!(actual_size, expected_size);
                let actual = blob
                    .read_at(0, actual_size as usize, ReadOptions::default())
                    .await
                    .expect("failed to read damaged index")
                    .coalesce();
                assert_eq!(actual.as_ref(), expected.as_ref());
            }
        });
    }

    #[test_traced]
    fn test_oversized_restore_adopts_rotted_committed_value() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Two committed sections
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), test_cfg(&context))
                    .await
                    .expect("Failed to init");
            let (offset, size);
            (oversized, _, offset, size) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            (oversized, _, _, _) = oversized
                .append(2, TestEntry::new(2, 0, 0), &[2; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync_all().await.expect("Failed to sync");

            // Corrupt entry 1's committed value in place (sizes unchanged)
            oversized
                .values
                .inject(1, offset, vec![0xFF; size as usize])
                .await
                .expect("Failed to corrupt value");
            oversized.values = oversized.values.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Restore adopts the section without probing its values: the corruption
            // surfaces at read on exactly the affected entry.
            let chunk = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            let oversized: Oversized<_, TestEntry, TestValue> = Oversized::init_with_checkpoint(
                context.child("second"),
                test_cfg(&context),
                (2, chunk),
            )
            .await
            .expect("Failed to reinit");
            assert!(matches!(
                oversized.get_value(1, offset, size).await,
                Err(Error::ChecksumMismatch(_, _))
            ));
            let entry = oversized.get(2, 0).await.expect("Failed to get");
            let (offset, size) = entry.value_location();
            assert_eq!(
                oversized
                    .get_value(2, offset, size)
                    .await
                    .expect("Failed to get value"),
                [2; 16]
            );
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_replay_empty_finishes_immediately() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            // An empty journal's reader is exhausted from the start
            let replay = oversized
                .replay(0, 0, NZUsize!(1024), ReadOptions::default())
                .await
                .expect("Failed to replay");
            let oversized = replay.finish().expect("failed to finish replay");
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_replay_propagates_read_options() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let (context, recordings) = commonware_runtime::mocks::RecordingContext::new(context);
            let cfg = test_cfg(&context);
            let page_cache = cfg.index_page_cache.clone();
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Evict the index page so replay must exercise the backing journal read.
            page_cache.clear();
            let mut replay = oversized
                .replay(1, 0, NZUsize!(1024), ReadOptions::DONT_CACHE)
                .await
                .expect("Failed to replay");
            recordings.clear();

            // The adapter must preserve the caller's policy on the lazy refill.
            let (section, position, entry) = replay
                .next()
                .await
                .expect("missing replay item")
                .expect("Failed to read replay item");
            assert_eq!((section, position, entry.id), (1, 0, 1));

            let reads = recordings.snapshot().reads;
            assert!(!reads.is_empty());
            assert!(
                reads
                    .iter()
                    .all(|options| *options == ReadOptions::DONT_CACHE)
            );

            assert!(replay.next().await.is_none());
            replay
                .finish()
                .expect("failed to finish replay")
                .destroy()
                .await
                .expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_replay_finish_before_drain_fails() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(1, 0, 0), &[1; 16])
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            let replay = oversized
                .replay(0, 0, NZUsize!(1024), ReadOptions::default())
                .await
                .expect("Failed to replay");
            assert!(matches!(replay.finish(), Err(Error::ReplayFailed)));
        });
    }

    #[test_traced]
    fn test_oversized_prune() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            // Append to multiple sections
            for section in 1u64..=5 {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }

            // Prune sections < 3
            (oversized, _) = oversized.prune(3).await.expect("Failed to prune");

            // The public accessor mirrors the guard
            assert!(oversized.pruned(1));
            assert!(oversized.pruned(2));
            assert!(!oversized.pruned(3));

            // Sections 1, 2 should be gone
            assert!(oversized.get(1, 0).await.is_err());
            assert!(oversized.get(2, 0).await.is_err());

            // Sections 3, 4, 5 should exist
            assert!(oversized.get(3, 0).await.is_ok());
            assert!(oversized.get(4, 0).await.is_ok());
            assert!(oversized.get(5, 0).await.is_ok());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_empty_section() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create oversized journal
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append to section 2 only (section 1 remains empty after being opened)
            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(2, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(2).await.expect("Failed to sync");
            drop(oversized);

            // Reinitialize - recovery should handle the empty/non-existent section 1
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // Section 2 entry should be valid
            let entry = oversized.get(2, 0).await.expect("Failed to get");
            assert_eq!(entry.id, 1);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_all_entries_invalid() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append 5 entries
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Truncate glob to 0 bytes - ALL entries become invalid
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            blob.resize(0).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should recover and rewind index to 0
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // No entries should be accessible
            let result = oversized.get(1, 0).await;
            assert!(result.is_err());

            // Should be able to append after recovery
            let value: TestValue = [99; 16];
            let entry = TestEntry::new(100, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 0);

            let retrieved = oversized.get(1, 0).await.expect("Failed to get");
            assert_eq!(retrieved.id, 100);
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_multiple_sections_mixed_validity() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate multiple sections
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Section 1: 3 entries
            let mut section1_locations = Vec::new();
            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                section1_locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Section 2: 5 entries
            let mut section2_locations = Vec::new();
            for i in 0..5u8 {
                let value: TestValue = [10 + i; 16];
                let entry = TestEntry::new(10 + i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(2, entry, &value)
                    .await
                    .expect("Failed to append");
                section2_locations.push((position, offset, size));
            }
            oversized = oversized.sync(2).await.expect("Failed to sync");

            // Section 3: 2 entries
            for i in 0..2u8 {
                let value: TestValue = [20 + i; 16];
                let entry = TestEntry::new(20 + i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(3, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(3).await.expect("Failed to sync");
            drop(oversized);

            // Truncate section 1 glob to keep only first entry
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let keep_size = byte_end(section1_locations[0].1, section1_locations[0].2);
            blob.resize(keep_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Truncate section 2 glob to keep first 3 entries
            let (blob, _) = context
                .open(&cfg.value_partition, &2u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let keep_size = byte_end(section2_locations[2].1, section2_locations[2].2);
            blob.resize(keep_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Section 3 remains intact

            // Reinitialize
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // Section 1: only position 0 valid
            assert!(oversized.get(1, 0).await.is_ok());
            assert!(oversized.get(1, 1).await.is_err());
            assert!(oversized.get(1, 2).await.is_err());

            // Section 2: positions 0,1,2 valid
            assert!(oversized.get(2, 0).await.is_ok());
            assert!(oversized.get(2, 1).await.is_ok());
            assert!(oversized.get(2, 2).await.is_ok());
            assert!(oversized.get(2, 3).await.is_err());
            assert!(oversized.get(2, 4).await.is_err());

            // Section 3: both positions valid
            assert!(oversized.get(3, 0).await.is_ok());
            assert!(oversized.get(3, 1).await.is_ok());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_corrupted_last_index_entry() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Use page size = entry size so each entry is on its own page.
            // This allows corrupting just the last entry's page without affecting others.
            // Physical page size = TestEntry::SIZE (20) + 12 (CRC record) = 32 bytes.
            let cfg = entry_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append 5 entries (each on its own page)
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Corrupt the last page's CRC to trigger page-level integrity failure
            let (blob, size) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");

            // Physical page size = 20 + 12 = 32 bytes
            // 5 entries = 5 pages = 160 bytes total
            // Last page CRC starts at offset 160 - 12 = 148
            assert_eq!(size, 160);
            let last_page_crc_offset = size - 12;
            blob.write_at(last_page_crc_offset, vec![0xFF; 12], WriteOptions::SYNC)
                .await
                .expect("Failed to corrupt");
            drop(blob);

            // Reinitialize - should detect page corruption and truncate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // First 4 entries should be valid (on pages 0-3)
            for i in 0..4u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);
            }

            // Entry 4 should be gone (its page was corrupted)
            assert!(oversized.get(1, 4).await.is_err());

            // Should be able to append after recovery
            let value: TestValue = [99; 16];
            let entry = TestEntry::new(100, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 4);

            let retrieved = oversized.get(1, 4).await.expect("Failed to get");
            assert_eq!(retrieved.id, 100);
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_all_entries_valid() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append entries to multiple sections
            for section in 1u64..=3 {
                for i in 0..10u8 {
                    let value: TestValue = [(section as u8) * 10 + i; 16];
                    let entry = TestEntry::new(section * 100 + i as u64, 0, 0);
                    (oversized, _, _, _) = oversized
                        .append(section, entry, &value)
                        .await
                        .expect("Failed to append");
                }
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Reinitialize with no corruption - should be fast
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // All entries should be valid
            for section in 1u64..=3 {
                for i in 0..10u8 {
                    let entry = oversized
                        .get(section, i as u64)
                        .await
                        .expect("Failed to get");
                    assert_eq!(entry.id, section * 100 + i as u64);
                }
            }

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_single_entry_invalid() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate with single entry
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Truncate glob to 0 - single entry becomes invalid
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            blob.resize(0).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // Entry should be gone
            assert!(oversized.get(1, 0).await.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_last_entry_off_by_one() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let mut locations = Vec::new();
            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Truncate glob to be off by 1 byte from last entry
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");

            // Last entry needs: offset + size bytes
            // Truncate to offset + size - 1 (missing 1 byte)
            let last = &locations[2];
            let truncate_to = byte_end(last.1, last.2) - 1;
            blob.resize(truncate_to).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // First 2 entries should be valid
            assert!(oversized.get(1, 0).await.is_ok());
            assert!(oversized.get(1, 1).await.is_ok());

            // Entry 2 should be gone (truncated)
            assert!(oversized.get(1, 2).await.is_err());

            // Should be able to append after recovery
            let value: TestValue = [99; 16];
            let entry = TestEntry::new(100, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 2);

            let retrieved = oversized.get(1, 2).await.expect("Failed to get");
            assert_eq!(retrieved.id, 100);
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_glob_missing_entirely() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Delete the glob file entirely
            context
                .remove(&cfg.value_partition, Some(&1u64.to_be_bytes()))
                .await
                .expect("Failed to remove");

            // Reinitialize - glob size will be 0, all entries invalid
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // All entries should be gone
            assert!(oversized.get(1, 0).await.is_err());
            assert!(oversized.get(1, 1).await.is_err());
            assert!(oversized.get(1, 2).await.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_can_append_after_recovery() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let mut locations = Vec::new();
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Truncate glob to keep only first 2 entries
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let keep_size = byte_end(locations[1].1, locations[1].2);
            blob.resize(keep_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Verify first 2 entries exist
            assert!(oversized.get(1, 0).await.is_ok());
            assert!(oversized.get(1, 1).await.is_ok());
            assert!(oversized.get(1, 2).await.is_err());

            // Append new entries after recovery
            for i in 10..15u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append after recovery");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Verify new entries at positions 2, 3, 4, 5, 6
            for i in 0..5u8 {
                let entry = oversized
                    .get(1, 2 + i as u64)
                    .await
                    .expect("Failed to get new entry");
                assert_eq!(entry.id, (10 + i) as u64);
            }

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_glob_pruned_but_index_not() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate multiple sections
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for section in 1u64..=3 {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Simulate crash during prune: prune ONLY the glob, not the index
            // This creates the "glob pruned but index not" scenario
            use crate::journal::segmented::glob::{Config as GlobConfig, Glob};
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");
            (glob, _) = glob.prune(2).await.expect("Failed to prune glob");
            glob = glob.sync_all().await.expect("Failed to sync glob");
            drop(glob);

            // Reinitialize - should recover gracefully with warning
            // Index section 1 will be rewound to 0 entries
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Section 1 entries should be gone (index rewound due to glob pruned)
            assert!(oversized.get(1, 0).await.is_err());

            // Sections 2 and 3 should still be valid
            assert!(oversized.get(2, 0).await.is_ok());
            assert!(oversized.get(3, 0).await.is_ok());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_index_partition_deleted() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate multiple sections
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for section in 1u64..=3 {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Delete index blob for section 2 (simulate corruption/loss)
            context
                .remove(&cfg.index_partition, Some(&2u64.to_be_bytes()))
                .await
                .expect("Failed to remove index");

            // Reinitialize - should handle gracefully
            // Section 2 is gone from index, orphan data in glob is acceptable
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Section 1 and 3 should still be valid
            assert!(oversized.get(1, 0).await.is_ok());
            assert!(oversized.get(3, 0).await.is_ok());

            // Section 2 should be gone (index file deleted)
            assert!(oversized.get(2, 0).await.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_index_synced_but_glob_not() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append entries and sync
            let mut locations = Vec::new();
            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Add more entries WITHOUT syncing (simulates unsynced writes)
            for i in 10..15u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            // Note: NOT calling sync() here
            drop(oversized);

            // Simulate crash where index was synced but glob wasn't:
            // Truncate glob back to the synced size (3 entries)
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let synced_size = byte_end(locations[2].1, locations[2].2);
            blob.resize(synced_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should rewind index to match glob
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // First 3 entries should be valid
            for i in 0..3u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);
            }

            // Entries 3-7 should be gone (unsynced, index rewound)
            assert!(oversized.get(1, 3).await.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_glob_synced_but_index_not() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Use page size = entry size so each entry is exactly one page.
            // This allows truncating by entry count to equal truncating by full pages,
            // maintaining page-level integrity.
            let cfg = entry_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append entries and sync
            let mut locations = Vec::new();
            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Simulate crash: truncate INDEX but leave GLOB intact
            // This creates orphan data in glob (glob ahead of index)
            let (blob, _size) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");

            // Keep only first 2 index entries (2 full pages)
            // Physical page size = logical (20) + CRC record (12) = 32 bytes
            let physical_page_size = (TestEntry::SIZE + 12) as u64;
            blob.resize(2 * physical_page_size)
                .await
                .expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - glob has orphan data from entry 3
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First 2 entries should be valid
            for i in 0..2u8 {
                let (position, offset, size) = locations[i as usize];
                let entry = oversized.get(1, position).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);

                let value = oversized
                    .get_value(1, offset, size)
                    .await
                    .expect("Failed to get value");
                assert_eq!(value, [i; 16]);
            }

            // Entry at position 2 should fail (index was truncated)
            assert!(oversized.get(1, 2).await.is_err());

            // Append new entries - should work despite orphan data in glob
            let mut new_locations = Vec::new();
            for i in 10..13u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append after recovery");

                // New entries start at position 2 (after the 2 valid entries)
                assert_eq!(position, (i - 10 + 2) as u64);
                new_locations.push((position, offset, size, i));

                // Verify we can read the new entry
                let retrieved = oversized.get(1, position).await.expect("Failed to get");
                assert_eq!(retrieved.id, i as u64);

                let retrieved_value = oversized
                    .get_value(1, offset, size)
                    .await
                    .expect("Failed to get value");
                assert_eq!(retrieved_value, value);
            }

            // Sync and restart again to verify persistence with orphan data
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Reinitialize after adding data on top of orphan glob data
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), cfg)
                    .await
                    .expect("Failed to reinit after append");

            // Read all valid entries in the index
            // First 2 entries from original data
            for i in 0..2u8 {
                let (position, offset, size) = locations[i as usize];
                let entry = oversized.get(1, position).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);

                let value = oversized
                    .get_value(1, offset, size)
                    .await
                    .expect("Failed to get value");
                assert_eq!(value, [i; 16]);
            }

            // New entries added after recovery
            for (position, offset, size, expected_id) in &new_locations {
                let entry = oversized
                    .get(1, *position)
                    .await
                    .expect("Failed to get new entry after restart");
                assert_eq!(entry.id, *expected_id as u64);

                let value = oversized
                    .get_value(1, *offset, *size)
                    .await
                    .expect("Failed to get new value after restart");
                assert_eq!(value, [*expected_id; 16]);
            }

            // Verify total entry count: 2 original + 3 new = 5
            assert!(oversized.get(1, 4).await.is_ok());
            assert!(oversized.get(1, 5).await.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_partial_index_entry() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append 3 entries
            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Simulate crash during write: truncate index to partial entry
            // Each entry is TestEntry::SIZE (20) + 4 (CRC32) = 24 bytes
            // Truncate to 3 full entries + 10 bytes of partial entry
            let (blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let partial_size = 3 * 24 + 10; // 3 full entries + partial
            blob.resize(partial_size).await.expect("Failed to resize");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should handle partial entry gracefully
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First 3 entries should still be valid
            for i in 0..3u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);
            }

            // Entry 3 should not exist (partial entry was removed)
            assert!(oversized.get(1, 3).await.is_err());

            // Append new entry after recovery
            let value: TestValue = [42; 16];
            let entry = TestEntry::new(100, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 3);

            // Verify we can read the new entry
            let retrieved = oversized.get(1, 3).await.expect("Failed to get new entry");
            assert_eq!(retrieved.id, 100);
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get new value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_only_partial_entry() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate with single entry
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Truncate index to only partial data (less than one full entry)
            let (blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            blob.resize(10).await.expect("Failed to resize"); // Less than chunk size
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should handle gracefully (rewind to 0)
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // No entries should exist
            assert!(oversized.get(1, 0).await.is_err());

            // Should be able to append after recovery
            let value: TestValue = [99; 16];
            let entry = TestEntry::new(100, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 0);

            let retrieved = oversized.get(1, 0).await.expect("Failed to get");
            assert_eq!(retrieved.id, 100);
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_crash_during_rewind_index_ahead() {
        // Simulates crash where index was rewound but glob wasn't
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Use page size = entry size so each entry is exactly one page.
            // This allows truncating by entry count to equal truncating by full pages,
            // maintaining page-level integrity.
            let cfg = entry_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let mut locations = Vec::new();
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Simulate crash during rewind: truncate index to 2 entries but leave glob intact
            // This simulates: rewind(index) succeeded, crash before rewind(glob)
            let (blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            // Physical page size = logical (20) + CRC record (12) = 32 bytes
            let physical_page_size = (TestEntry::SIZE + 12) as u64;
            blob.resize(2 * physical_page_size)
                .await
                .expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - recovery should succeed (glob has orphan data)
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First 2 entries should be valid
            for i in 0..2u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);
            }

            // Entries 2-4 should be gone (index was truncated)
            assert!(oversized.get(1, 2).await.is_err());

            // Should be able to append new entries
            let pos;
            (oversized, pos, _, _) = oversized
                .append(1, TestEntry::new(100, 0, 0), &[100u8; 16])
                .await
                .expect("Failed to append");
            assert_eq!(pos, 2);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_crash_during_rewind_glob_ahead() {
        // Simulates crash where glob was rewound but index wasn't
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let mut locations = Vec::new();
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Simulate crash during rewind: truncate glob to 2 entries but leave index intact
            // This simulates: rewind(glob) succeeded, crash before rewind(index)
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let keep_size = byte_end(locations[1].1, locations[1].2);
            blob.resize(keep_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - recovery should detect index entries pointing beyond glob
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First 2 entries should be valid (index rewound to match glob)
            for i in 0..2u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);
            }

            // Entries 2-4 should be gone (index rewound during recovery)
            assert!(oversized.get(1, 2).await.is_err());

            // Should be able to append after recovery
            let value: TestValue = [99; 16];
            let entry = TestEntry::new(100, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 2);

            let retrieved = oversized.get(1, 2).await.expect("Failed to get");
            assert_eq!(retrieved.id, 100);
            let retrieved_value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, value);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_get_value_invalid_size() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            let (offset, _size);
            (oversized, _, offset, _size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Size 0 - should fail
            assert!(oversized.get_value(1, offset, 0).await.is_err());

            // Size < value size - should fail with codec error, checksum mismatch, or
            // insufficient length (if size < 4 bytes for checksum)
            for size in 1..4u32 {
                let result = oversized.get_value(1, offset, size).await;
                assert!(
                    matches!(
                        result,
                        Err(Error::Codec(_))
                            | Err(Error::ChecksumMismatch(_, _))
                            | Err(Error::Runtime(_))
                    ),
                    "expected error, got: {:?}",
                    result
                );
            }

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_oversized_get_value_wrong_size() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            let (offset, correct_size);
            (oversized, _, offset, correct_size) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Size too small - will fail to decode or checksum mismatch
            // (checksum mismatch can occur because we read wrong bytes as the checksum)
            let result = oversized.get_value(1, offset, correct_size - 1).await;
            assert!(
                matches!(
                    result,
                    Err(Error::Codec(_)) | Err(Error::ChecksumMismatch(_, _))
                ),
                "expected Codec or ChecksumMismatch error, got: {:?}",
                result
            );

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_values_has_orphan_section() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate with sections 1 and 2
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for section in 1u64..=2 {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Manually create an orphan value section (section 3) without corresponding index
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");
            let orphan_value: TestValue = [99; 16];
            (glob, _, _) = glob
                .append(3, &orphan_value)
                .await
                .expect("Failed to append orphan");
            glob = glob.sync(3).await.expect("Failed to sync glob");
            drop(glob);

            // Reinitialize - should detect and remove the orphan section
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Sections 1 and 2 should still be valid
            assert!(oversized.get(1, 0).await.is_ok());
            assert!(oversized.get(2, 0).await.is_ok());

            // Newest section should be 2 (orphan was removed)
            assert_eq!(oversized.newest_section(), Some(2));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_values_has_multiple_orphan_sections() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate with only section 1
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [1; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Manually create multiple orphan value sections (2, 3, 4)
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");

            for section in 2u64..=4 {
                let orphan_value: TestValue = [section as u8; 16];
                (glob, _, _) = glob
                    .append(section, &orphan_value)
                    .await
                    .expect("Failed to append orphan");
                glob = glob.sync(section).await.expect("Failed to sync glob");
            }
            drop(glob);

            // Reinitialize - should detect and remove all orphan sections
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Section 1 should still be valid
            assert!(oversized.get(1, 0).await.is_ok());

            // Newest section should be 1 (orphans removed)
            assert_eq!(oversized.newest_section(), Some(1));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_index_empty_but_values_exist() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Manually create value sections without any index entries
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");

            for section in 1u64..=3 {
                let orphan_value: TestValue = [section as u8; 16];
                (glob, _, _) = glob
                    .append(section, &orphan_value)
                    .await
                    .expect("Failed to append orphan");
                glob = glob.sync(section).await.expect("Failed to sync glob");
            }
            drop(glob);

            // Initialize oversized - should remove all orphan value sections
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // No sections should exist
            assert_eq!(oversized.newest_section(), None);
            assert_eq!(oversized.oldest_section(), None);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_orphan_section_append_after() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate with section 1
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [1; 16];
            let entry = TestEntry::new(1, 0, 0);
            let (offset1, size1);
            (oversized, _, offset1, size1) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Manually create orphan value sections (2, 3)
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");

            for section in 2u64..=3 {
                let orphan_value: TestValue = [section as u8; 16];
                (glob, _, _) = glob
                    .append(section, &orphan_value)
                    .await
                    .expect("Failed to append orphan");
                glob = glob.sync(section).await.expect("Failed to sync glob");
            }
            drop(glob);

            // Reinitialize - should remove orphan sections
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Section 1 should still be valid
            let entry = oversized.get(1, 0).await.expect("Failed to get");
            assert_eq!(entry.id, 1);
            let value = oversized
                .get_value(1, offset1, size1)
                .await
                .expect("Failed to get value");
            assert_eq!(value, [1; 16]);

            // Should be able to append to section 2 after recovery
            let new_value: TestValue = [42; 16];
            let new_entry = TestEntry::new(42, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(2, new_entry, &new_value)
                .await
                .expect("Failed to append after recovery");
            assert_eq!(pos, 0);

            // Verify the new entry
            let retrieved = oversized.get(2, 0).await.expect("Failed to get");
            assert_eq!(retrieved.id, 42);
            let retrieved_value = oversized
                .get_value(2, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(retrieved_value, new_value);

            // Sync and restart to verify persistence
            oversized = oversized.sync(2).await.expect("Failed to sync");
            drop(oversized);

            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), cfg)
                    .await
                    .expect("Failed to reinit after append");

            // Both sections should be valid
            assert!(oversized.get(1, 0).await.is_ok());
            assert!(oversized.get(2, 0).await.is_ok());
            assert_eq!(oversized.newest_section(), Some(2));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_no_orphan_sections() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate with sections 1, 2, 3 (no orphans)
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for section in 1u64..=3 {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Reinitialize - no orphan cleanup needed
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // All sections should be valid
            for section in 1u64..=3 {
                let entry = oversized.get(section, 0).await.expect("Failed to get");
                assert_eq!(entry.id, section);
            }
            assert_eq!(oversized.newest_section(), Some(3));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_orphan_with_empty_index_section() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate section 1 with entries
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [1; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Manually create orphan value section 2
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");
            let orphan_value: TestValue = [2; 16];
            (glob, _, _) = glob
                .append(2, &orphan_value)
                .await
                .expect("Failed to append orphan");
            glob = glob.sync(2).await.expect("Failed to sync glob");
            drop(glob);

            // Now truncate index section 1 to 0 (making it empty but still tracked)
            let (blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            blob.resize(0).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should handle empty index section and remove orphan value section
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // Section 1 should exist but have no entries (empty after truncation)
            assert!(oversized.get(1, 0).await.is_err());

            // Orphan section 2 should be removed
            assert_eq!(oversized.newest_section(), Some(1));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_orphan_sections_with_gaps() {
        // Test non-contiguous sections: index has [1, 3, 5], values has [1, 2, 3, 4, 5, 6]
        // Orphan sections 2, 4, 6 should be removed
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create index with sections 1, 3, 5 (gaps)
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for section in [1u64, 3, 5] {
                let value: TestValue = [section as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Manually create orphan value sections 2, 4, 6 (filling gaps and beyond)
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");

            for section in [2u64, 4, 6] {
                let orphan_value: TestValue = [section as u8; 16];
                (glob, _, _) = glob
                    .append(section, &orphan_value)
                    .await
                    .expect("Failed to append orphan");
                glob = glob.sync(section).await.expect("Failed to sync glob");
            }
            drop(glob);

            // Reinitialize - should remove orphan sections 2, 4, 6
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg)
                    .await
                    .expect("Failed to reinit");

            // Sections 1, 3, 5 should still be valid
            for section in [1u64, 3, 5] {
                let entry = oversized.get(section, 0).await.expect("Failed to get");
                assert_eq!(entry.id, section);
            }

            // Verify only sections 1, 3, 5 exist (orphans removed)
            assert_eq!(oversized.oldest_section(), Some(1));
            assert_eq!(oversized.newest_section(), Some(5));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    /// Bytes appended after an index was truncated or removed cannot replace its authenticated
    /// prefix.
    #[test_traced]
    fn test_recovery_discards_index_extension_after_prefix_loss() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Seed two sections with one synced entry each, so both hold durable values.
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");
            for section in 1..=2 {
                (oversized, _, _, _) = oversized
                    .append(section, TestEntry::new(section, 0, 0), &[section as u8; 16])
                    .await
                    .expect("Failed to append");
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Keep both value blobs, but erase one index by truncation and the other by removal.
            // Replace each with two complete pages of bytes that have no valid checksum slots.
            for section in 1..=2u64 {
                let (blob, original_size) = context
                    .open(&cfg.index_partition, &section.to_be_bytes())
                    .await
                    .expect("Failed to open index blob");
                if section == 1 {
                    blob.resize(0).await.expect("Failed to truncate index");
                    blob.sync().await.expect("Failed to sync index truncation");
                } else {
                    drop(blob);
                    context
                        .remove(&cfg.index_partition, Some(&section.to_be_bytes()))
                        .await
                        .expect("Failed to remove index");
                }
                let (blob, _) = context
                    .open(&cfg.index_partition, &section.to_be_bytes())
                    .await
                    .expect("Failed to recreate index blob");
                blob.write_at(
                    0,
                    vec![0; usize::try_from(original_size * 2).unwrap()],
                    WriteOptions::SYNC,
                )
                .await
                .expect("Failed to extend index");
            }

            // Recovery must not adopt the checksum-less extensions as index data: both
            // sections come back empty (the original entries are gone with their prefixes)
            // and the truncation is durable.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to recover extended index");
            for section in 1..=2u64 {
                assert!(matches!(
                    oversized.get(section, 0).await,
                    Err(Error::ItemOutOfRange(0))
                ));
                let (_, recovered_size) = context
                    .open(&cfg.index_partition, &section.to_be_bytes())
                    .await
                    .expect("Failed to reopen index blob");
                assert_eq!(recovered_size, 0);

                // The recovered sections accept new entries from position zero.
                let position;
                (oversized, position, _, _) = oversized
                    .append(section, TestEntry::new(section, 0, 0), &[section as u8; 16])
                    .await
                    .expect("Failed to append after recovery");
                assert_eq!(position, 0);
            }
            oversized = oversized.sync_all().await.expect("Failed to sync sentinel");
            drop(oversized);

            // The sentinel entries written after recovery survive a clean reopen.
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), cfg)
                    .await
                    .expect("Failed to reopen sentinel");
            for section in 1..=2u64 {
                let entry = oversized
                    .get(section, 0)
                    .await
                    .expect("Sentinel index missing");
                let (offset, size) = entry.value_location();
                assert_eq!(entry.id, section);
                assert_eq!(
                    oversized
                        .get_value(section, offset, size)
                        .await
                        .expect("Sentinel value missing"),
                    [section as u8; 16]
                );
            }
            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_glob_trailing_garbage_truncated() {
        // Tests the bug fix: when value is written to glob but index entry isn't
        // (crash after value write, before index write), recovery should truncate
        // the glob trailing garbage so subsequent appends start at correct offset.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            // Append 2 entries
            let mut locations = Vec::new();
            for i in 0..2u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Record where next entry SHOULD start (end of entry 1)
            let expected_next_offset = byte_end(locations[1].1, locations[1].2);
            drop(oversized);

            // Simulate crash: write garbage to glob (simulating partial value write)
            let (blob, size) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            assert_eq!(size, expected_next_offset);

            // Write 100 bytes of garbage (simulating partial/failed value write)
            let garbage = vec![0xDE; 100];
            blob.write_at(size, garbage, WriteOptions::SYNC)
                .await
                .expect("Failed to write garbage");
            drop(blob);

            // Verify glob now has trailing garbage
            let (blob, new_size) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            assert_eq!(new_size, expected_next_offset + 100);
            drop(blob);

            // Reinitialize - should truncate the trailing garbage
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First 2 entries should still be valid
            for i in 0..2u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);
            }

            // Append new entry - should start at expected_next_offset, NOT at garbage end
            let new_value: TestValue = [99; 16];
            let new_entry = TestEntry::new(99, 0, 0);
            let (pos, offset, _size);
            (oversized, pos, offset, _size) = oversized
                .append(1, new_entry, &new_value)
                .await
                .expect("Failed to append after recovery");

            // Verify position is 2 (after the 2 existing entries)
            assert_eq!(pos, 2);

            // Verify offset is at expected_next_offset (garbage was truncated)
            assert_eq!(offset, expected_next_offset);

            // Verify we can read the new entry
            let retrieved = oversized.get(1, 2).await.expect("Failed to get new entry");
            assert_eq!(retrieved.id, 99);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_entry_with_overflow_offset() {
        // Tests that an entry with offset near u64::MAX that would overflow
        // when added to size is detected as invalid during recovery.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            // Use page size = entry size so one entry per page
            let cfg = entry_cfg(&context);

            // Create and populate with valid entry
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [1; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Build a corrupted entry with offset near u64::MAX that would overflow.
            // We need to write a valid page (with correct page-level CRC) containing
            // the semantically-invalid entry data.
            let (blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");

            // Build entry data: id (8) + value_offset (8) + value_size (4) = 20 bytes
            let mut entry_data = Vec::new();
            1u64.write(&mut entry_data); // id
            (u64::MAX - 10).write(&mut entry_data); // value_offset (near max)
            100u32.write(&mut entry_data); // value_size (offset + size overflows)
            assert_eq!(entry_data.len(), TestEntry::SIZE);

            // Build page-level CRC record (12 bytes):
            // len1 (2) + crc1 (4) + len2 (2) + crc2 (4)
            let crc = Crc32::checksum(&entry_data);
            let len1 = TestEntry::SIZE as u16;
            let mut crc_record = Vec::new();
            crc_record.extend_from_slice(&len1.to_be_bytes()); // len1
            crc_record.extend_from_slice(&crc.to_be_bytes()); // crc1
            crc_record.extend_from_slice(&0u16.to_be_bytes()); // len2 (unused)
            crc_record.extend_from_slice(&0u32.to_be_bytes()); // crc2 (unused)
            assert_eq!(crc_record.len(), 12);

            // Write the complete physical page: entry_data + crc_record
            let mut page = entry_data;
            page.extend_from_slice(&crc_record);
            blob.write_at(0, page, WriteOptions::SYNC)
                .await
                .expect("Failed to write corrupted page");
            drop(blob);

            // Reinitialize - recovery should detect the invalid entry
            // (offset + size would overflow, and even with saturating_add it exceeds glob_size)
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // The corrupted entry should have been rewound (invalid)
            assert!(oversized.get(1, 0).await.is_err());

            // Should be able to append after recovery
            let new_value: TestValue = [99; 16];
            let new_entry = TestEntry::new(99, 0, 0);
            let (pos, new_offset);
            (oversized, pos, new_offset, _) = oversized
                .append(1, new_entry, &new_value)
                .await
                .expect("Failed to append after recovery");

            // Position should be 0 (corrupted entry was removed)
            assert_eq!(pos, 0);
            // Offset should be 0 (glob was truncated to 0)
            assert_eq!(new_offset, 0);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_empty_section_persistence() {
        // Tests that sections that become empty (all entries removed/rewound)
        // are handled correctly across restart cycles.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Create and populate section 1 with entries
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            for i in 0..3u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                (oversized, _, _, _) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Also create section 2 to ensure it survives
            let value2: TestValue = [10; 16];
            let entry2 = TestEntry::new(10, 0, 0);
            (oversized, _, _, _) = oversized
                .append(2, entry2, &value2)
                .await
                .expect("Failed to append to section 2");
            oversized = oversized.sync(2).await.expect("Failed to sync section 2");
            drop(oversized);

            // Truncate section 1's index to 0 (making it empty)
            let (blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            blob.resize(0).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // First restart - recovery should handle empty section 1
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Section 1 should exist but have no entries
            assert!(oversized.get(1, 0).await.is_err());

            // Section 2 should still be valid
            let entry = oversized.get(2, 0).await.expect("Failed to get section 2");
            assert_eq!(entry.id, 10);

            // Section 1 should still be tracked (blob exists but is empty)
            assert_eq!(oversized.oldest_section(), Some(1));

            // Values are reachable only through index entries, so recovery removes the orphaned
            // bytes before the section can be reused.
            let new_value: TestValue = [99; 16];
            let new_entry = TestEntry::new(99, 0, 0);
            let (pos, offset, size);
            (oversized, pos, offset, size) = oversized
                .append(1, new_entry, &new_value)
                .await
                .expect("Failed to append to empty section");
            assert_eq!(pos, 0);
            assert_eq!(offset, 0);
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Verify the new entry is readable after reusing the section.
            let entry = oversized.get(1, 0).await.expect("Failed to get");
            assert_eq!(entry.id, 99);
            let value = oversized
                .get_value(1, offset, size)
                .await
                .expect("Failed to get value");
            assert_eq!(value, new_value);

            drop(oversized);

            // Second restart - verify persistence
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("third"), cfg.clone())
                    .await
                    .expect("Failed to reinit again");

            // Section 1's new entry should be valid
            let entry = oversized.get(1, 0).await.expect("Failed to get");
            assert_eq!(entry.id, 99);

            // Section 2 should still be valid
            let entry = oversized.get(2, 0).await.expect("Failed to get section 2");
            assert_eq!(entry.id, 10);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_get_value_size_equals_crc_size() {
        // Tests the boundary condition where size = 4 (just CRC, no data).
        // This should fail because there's no actual data to decode.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            let offset;
            (oversized, _, offset, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Size = 4 (exactly CRC_SIZE) means 0 bytes of actual data
            // This should fail with ChecksumMismatch or decode error
            let result = oversized.get_value(1, offset, 4).await;
            assert!(result.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_get_value_size_just_over_crc() {
        // Tests size = 5 (CRC + 1 byte of data).
        // This should fail because the data is too short to decode.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let value: TestValue = [42; 16];
            let entry = TestEntry::new(1, 0, 0);
            let offset;
            (oversized, _, offset, _) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");

            // Size = 5 means 1 byte of actual data (after stripping CRC)
            // This should fail with checksum mismatch since we're reading wrong bytes
            let result = oversized.get_value(1, offset, 5).await;
            assert!(result.is_err());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_maximum_section_numbers() {
        // Test recovery with very large section numbers near u64::MAX to check
        // for overflow edge cases in section arithmetic.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Use section numbers near u64::MAX
            let large_sections = [u64::MAX - 3, u64::MAX - 2, u64::MAX - 1];

            // Create and populate with large section numbers
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let mut locations = Vec::new();
            for &section in &large_sections {
                let value: TestValue = [(section & 0xFF) as u8; 16];
                let entry = TestEntry::new(section, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(section, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((section, (position, offset, size)));
                oversized = oversized.sync(section).await.expect("Failed to sync");
            }
            drop(oversized);

            // Simulate crash: truncate glob for middle section
            let middle_section = large_sections[1];
            let (blob, size) = context
                .open(&cfg.value_partition, &middle_section.to_be_bytes())
                .await
                .expect("Failed to open blob");
            blob.resize(size / 2).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Reinitialize - should recover without overflow panics
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // First and last sections should still be valid
            let entry = oversized
                .get(large_sections[0], 0)
                .await
                .expect("Failed to get first section");
            assert_eq!(entry.id, large_sections[0]);

            let entry = oversized
                .get(large_sections[2], 0)
                .await
                .expect("Failed to get last section");
            assert_eq!(entry.id, large_sections[2]);

            // Middle section should have been rewound (no entries)
            assert!(oversized.get(middle_section, 0).await.is_err());

            // Verify we can still append to these large sections
            let new_value: TestValue = [0xAB; 16];
            let new_entry = TestEntry::new(999, 0, 0);
            (oversized, _, _, _) = oversized
                .append(middle_section, new_entry, &new_value)
                .await
                .expect("Failed to append after recovery");

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_crash_during_recovery_rewind() {
        // Tests a nested crash scenario: initial crash leaves inconsistent state,
        // then a second crash occurs during recovery's rewind operation.
        // This simulates the worst-case where recovery itself is interrupted.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Phase 1: Create valid data with 5 entries
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let mut locations = Vec::new();
            for i in 0..5u8 {
                let value: TestValue = [i; 16];
                let entry = TestEntry::new(i as u64, 0, 0);
                let (position, offset, size);
                (oversized, position, offset, size) = oversized
                    .append(1, entry, &value)
                    .await
                    .expect("Failed to append");
                locations.push((position, offset, size));
            }
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Phase 2: Simulate first crash - truncate glob to lose last 2 entries
            let (blob, _) = context
                .open(&cfg.value_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open blob");
            let keep_size = byte_end(locations[2].1, locations[2].2);
            blob.resize(keep_size).await.expect("Failed to truncate");
            blob.sync().await.expect("Failed to sync");
            drop(blob);

            // Phase 3: Simulate crash during recovery's rewind
            // Recovery would try to rewind index from 5 entries to 3 entries.
            // Simulate partial rewind by manually truncating index to 4 entries
            // (as if crash occurred mid-rewind).
            let chunk_size = FixedJournal::<deterministic::Context, TestEntry>::CHUNK_SIZE as u64;
            let (index_blob, _) = context
                .open(&cfg.index_partition, &1u64.to_be_bytes())
                .await
                .expect("Failed to open index blob");
            let partial_rewind_size = 4 * chunk_size; // 4 entries instead of 3
            index_blob
                .resize(partial_rewind_size)
                .await
                .expect("Failed to resize");
            index_blob.sync().await.expect("Failed to sync");
            drop(index_blob);

            // Phase 4: Second recovery attempt should handle the inconsistent state
            // Index has 4 entries, but glob only supports 3.
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit after nested crash");

            // Only first 3 entries should be valid (recovery should rewind again)
            for i in 0..3u8 {
                let entry = oversized.get(1, i as u64).await.expect("Failed to get");
                assert_eq!(entry.id, i as u64);

                let (_, offset, size) = locations[i as usize];
                let value = oversized
                    .get_value(1, offset, size)
                    .await
                    .expect("Failed to get value");
                assert_eq!(value, [i; 16]);
            }

            // Entry 3 should not exist (index was rewound to match glob)
            assert!(oversized.get(1, 3).await.is_err());

            // Verify append works after nested crash recovery
            let new_value: TestValue = [0xFF; 16];
            let new_entry = TestEntry::new(100, 0, 0);
            let (pos, offset, _size);
            (oversized, pos, offset, _size) = oversized
                .append(1, new_entry, &new_value)
                .await
                .expect("Failed to append");
            assert_eq!(pos, 3); // Should be position 3 (after the 3 valid entries)

            // Verify the offset starts where entry 2 ended (no gaps)
            assert_eq!(offset, byte_end(locations[2].1, locations[2].2));

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_recovery_crash_during_orphan_cleanup() {
        // Tests crash during orphan section cleanup: recovery starts removing
        // orphan value sections, but crashes mid-cleanup.
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);

            // Phase 1: Create valid data in section 1
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("first"), cfg.clone())
                    .await
                    .expect("Failed to init");

            let value: TestValue = [1; 16];
            let entry = TestEntry::new(1, 0, 0);
            let (offset1, size1);
            (oversized, _, offset1, size1) = oversized
                .append(1, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(1).await.expect("Failed to sync");
            drop(oversized);

            // Phase 2: Create orphan value sections 2, 3, 4 (no index entries)
            let glob_cfg = GlobConfig {
                partition: cfg.value_partition.clone(),
                compression: cfg.compression,
                codec_config: (),
                write_buffer: cfg.value_write_buffer,
            };
            let mut glob: Glob<_, TestValue> = Glob::init(context.child("glob"), glob_cfg)
                .await
                .expect("Failed to init glob");

            for section in 2u64..=4 {
                let orphan_value: TestValue = [section as u8; 16];
                (glob, _, _) = glob
                    .append(section, &orphan_value)
                    .await
                    .expect("Failed to append orphan");
                glob = glob.sync(section).await.expect("Failed to sync glob");
            }
            drop(glob);

            // Phase 3: Simulate partial orphan cleanup (section 2 removed, 3 and 4 remain)
            // This simulates a crash during cleanup_orphan_value_sections()
            context
                .remove(&cfg.value_partition, Some(&2u64.to_be_bytes()))
                .await
                .expect("Failed to remove section 2");

            // Phase 4: Recovery should complete the cleanup
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context.child("second"), cfg.clone())
                    .await
                    .expect("Failed to reinit");

            // Section 1 should still be valid
            let entry = oversized.get(1, 0).await.expect("Failed to get");
            assert_eq!(entry.id, 1);
            let value = oversized
                .get_value(1, offset1, size1)
                .await
                .expect("Failed to get value");
            assert_eq!(value, [1; 16]);

            // No orphan sections should remain
            assert_eq!(oversized.oldest_section(), Some(1));
            assert_eq!(oversized.newest_section(), Some(1));

            // Should be able to append to section 2 (now clean)
            let new_value: TestValue = [42; 16];
            let new_entry = TestEntry::new(42, 0, 0);
            let pos;
            (oversized, pos, _, _) = oversized
                .append(2, new_entry, &new_value)
                .await
                .expect("Failed to append to section 2");
            assert_eq!(pos, 0); // First entry in new section

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_rewind_to_zero_index_size() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let value: TestValue = [1; 16];
            let entry = TestEntry::new(1, 0, 0);
            (oversized, _, _, _) = oversized
                .append(0, entry, &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync(0).await.expect("Failed to sync");

            oversized = oversized
                .rewind(0, 0)
                .await
                .expect("rewind to zero index_size must not fail");

            assert_eq!(oversized.last(0).await.unwrap(), None);
            assert_eq!(oversized.size(0).unwrap(), 0);
            assert_eq!(oversized.value_size(0).await.unwrap(), 0);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_rewind_to_zero_on_missing_section() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            oversized = oversized
                .rewind(0, 0)
                .await
                .expect("rewind on missing section must not fail");

            assert!(matches!(
                oversized.last(0).await,
                Err(Error::SectionOutOfRange(0))
            ));
            assert_eq!(oversized.value_size(0).await.unwrap(), 0);

            oversized.destroy().await.expect("Failed to destroy");
        });
    }

    #[test_traced]
    fn test_rewind_nonzero_on_missing_section_errors() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let result = oversized.rewind(0, 1).await;
            assert!(
                matches!(result, Err(Error::SectionOutOfRange(0))),
                "nonzero index_size on missing section must fail, got: {result:?}"
            );
        });
    }

    #[test_traced]
    fn test_rewind_section_nonzero_on_missing_section_errors() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let result = oversized.rewind_section(0, 1).await;
            assert!(
                matches!(result, Err(Error::SectionOutOfRange(0))),
                "nonzero index_size on missing section must fail, got: {result:?}"
            );
        });
    }

    #[test_traced]
    fn test_last_pruned_section_returns_error() {
        let executor = deterministic::Runner::default();
        executor.start(|context| async move {
            let cfg = test_cfg(&context);
            let mut oversized: Oversized<_, TestEntry, TestValue> =
                Oversized::init(context, cfg).await.expect("Failed to init");

            let value: TestValue = [1; 16];
            (oversized, _, _, _) = oversized
                .append(0, TestEntry::new(1, 0, 0), &value)
                .await
                .expect("Failed to append");
            (oversized, _, _, _) = oversized
                .append(1, TestEntry::new(2, 0, 0), &value)
                .await
                .expect("Failed to append");
            oversized = oversized.sync_all().await.expect("Failed to sync");

            (oversized, _) = oversized.prune(1).await.expect("Failed to prune");

            assert!(matches!(
                oversized.last(0).await,
                Err(Error::AlreadyPrunedToSection(1))
            ));
            assert!(oversized.last(1).await.unwrap().is_some());

            oversized.destroy().await.expect("Failed to destroy");
        });
    }
}