rivet/load/

reconcile.rs

//! End-to-end load integrity — reconcile **source → file → warehouse** row
//! counts before (and after) a load.
//!
//! The OSS engine records, in each run's `manifest.json`, two of the three legs
//! of the chain: how many rows the source held at extraction time
//! ([`ExtractionMetadata::source_row_count`](crate::manifest::ExtractionMetadata),
//! when cheaply probed) and how many rows were actually written to files
//! ([`RunManifest::row_count`]). The warehouse leg — how many rows the load
//! landed — is the loaders' post-load `COUNT(*)`, enforced by their
//! `expected_rows` gate.
//!
//! Until now that gate was dead in the production path: nothing read the
//! manifest, so `rivet load` trusted whatever Parquet happened to sit under
//! the prefix ("file in a bucket"). This module closes the loop:
//!
//! 1. read every `manifest.json` under the export's GCS prefix,
//! 2. **refuse** to load unless each is a self-consistent `Success` run whose
//!    source count (when known) matches what it extracted, and
//! 3. return the summed, authoritative `file_rows` the loader's count gate then
//!    checks against the warehouse.
//!
//! It is the value the OSS core deliberately stops short of — file-level
//! integrity is free (`rivet validate`); reconciling that the rows *arrived in
//! the warehouse* is the paid last mile.

use crate::destination::gcs::GcsStore;
use crate::manifest::{MANIFEST_FILENAME, ManifestStatus, RunManifest};
use crate::pipeline::validate_manifest::MANIFEST_MAX_BYTES;
use anyhow::{Context, Result, bail};

/// The reconciled row-count chain for one export's load, derived from the run
/// manifests under its GCS prefix. `file_rows` is what the warehouse must end
/// up holding; the loader's `expected_rows` gate enforces `warehouse == file`.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct LoadIntegrity {
    /// Rows the source held at extraction time, summed over the manifests that
    /// probed it. `None` when *no* contributing manifest carried a
    /// `source_row_count` — the source→file leg is then unverifiable from the
    /// manifest alone (e.g. a full snapshot that did not count the source).
    pub source_rows: Option<u64>,
    /// Rows written to files — the sum of the trustworthy manifests'
    /// `row_count`. This is the authoritative expected warehouse row count.
    pub file_rows: u64,
    /// How many run manifests contributed to the totals.
    pub manifests: usize,
}

impl LoadIntegrity {
    /// A one-line human summary of the chain, e.g.
    /// `source 1000 → files 1000 → (warehouse pending)`. The warehouse leg is
    /// filled in by the caller once the load's `COUNT(*)` is known.
    pub fn chain_prefix(&self) -> String {
        let src = self
            .source_rows
            .map_or_else(|| "?".to_string(), |n| n.to_string());
        format!("source {src} → files {}", self.file_rows)
    }
}

/// Fetch and parse every `manifest.json` under `gcs_prefix` (recursive), keeping
/// each manifest's bucket-relative storage key — needed to resolve a manifest's
/// (relative) part paths back to full object keys for per-run loading (see
/// [`select_load_uris`]).
///
/// A rivet export writes one manifest per `run_id`; a prefix that has
/// accumulated several incremental / CDC runs holds several. Transport is the
/// native opendal client the extraction destination already uses (`store`), so
/// auth is the export's own GCS credentials and this is offline-testable over a
/// filesystem-backed store.
///
/// `pub` (a public-API root the lib keeps alive) even though its only caller is
/// the binary-only `cli::dispatch`; `#[allow(private_interfaces)]` because the
/// injected `GcsStore` is deliberately an internal (`pub(crate)`) type — the
/// `destination` module stays crate-private. Same rationale as the `preflight`
/// module note in `lib.rs`.
#[allow(private_interfaces)]
pub fn fetch_manifests_keyed(
    store: &GcsStore,
    gcs_prefix: &str,
) -> Result<Vec<(String, RunManifest)>> {
    let (_, base) = crate::load::split_gs_uri(gcs_prefix)?;
    let keys = list_manifest_keys(store, base)?;
    keys.into_iter()
        .map(|key| {
            // Round-5 (CWE-400): cap the manifest body before reading it whole into
            // memory — a planted multi-GB manifest.json under the load prefix would
            // otherwise OOM the loader. Mirrors the V21 cap the export-side manifest
            // readers already enforce; this was the 4th, uncapped, read path.
            let sz = store.stat_size(&key)?;
            if sz > MANIFEST_MAX_BYTES {
                bail!(
                    "manifest {key} is {sz} bytes, over the {MANIFEST_MAX_BYTES}-byte cap — \
                     refusing to read a possibly-hostile manifest into memory (CWE-400)"
                );
            }
            let bytes = store.read(&key)?;
            let m = serde_json::from_slice::<RunManifest>(&bytes)
                .with_context(|| format!("parsing manifest {key}"))?;
            Ok((key, m))
        })
        .collect()
}

/// Full `gs://` URIs of the parquet to load for `new` (the not-yet-loaded run
/// manifests), preferring each manifest's own parts over a blanket listing.
/// See [`select_load_keys`] for the selection rule.
#[allow(private_interfaces)]
pub fn select_load_uris(
    store: &GcsStore,
    gcs_prefix: &str,
    new: &[(String, RunManifest)],
) -> Result<Vec<String>> {
    let (bucket, base) = crate::load::split_gs_uri(gcs_prefix)?;
    let all_parquet: Vec<String> = store
        .list_files(base)?
        .into_iter()
        .filter(|k| k.ends_with(".parquet"))
        .collect();
    Ok(select_load_keys(new, &all_parquet)
        .into_iter()
        .map(|k| format!("gs://{bucket}/{k}"))
        .collect())
}

/// The bucket-relative part keys a manifest declares, each resolved against the
/// manifest's own directory: `<dir(manifest_key)>/<part.path>`. Shared by
/// [`select_load_keys`] (which intersects them with what's present) and
/// [`gc_orphans`] (which treats them as the keep-set), so the two can't drift on
/// how a manifest maps to its files.
fn resolve_parts<'a>(
    manifest_key: &'a str,
    m: &'a RunManifest,
) -> impl Iterator<Item = String> + 'a {
    let dir = manifest_key.rsplit_once('/').map(|(d, _)| d).unwrap_or("");
    m.parts.iter().map(move |p| {
        if dir.is_empty() {
            p.path.clone()
        } else {
            format!("{dir}/{}", p.path)
        }
    })
}

/// Pure selection: which bucket-relative parquet keys to load for the given
/// (not-yet-loaded) run manifests.
///
/// Prefers each manifest's own parts (via [`resolve_parts`]) intersected with
/// `all_parquet` — so a load pulls exactly the new runs' files, not every object
/// under the prefix (the key to incremental loads once `cleanup_source` no
/// longer wipes the bucket). Falls back to the whole `all_parquet` listing when
/// ANY new manifest resolves to no present part (legacy/part-less manifests
/// still load, at the cost of not pruning); the row-count gate then still guards
/// correctness.
pub fn select_load_keys(new: &[(String, RunManifest)], all_parquet: &[String]) -> Vec<String> {
    use std::collections::BTreeSet;
    let present: std::collections::HashSet<&str> = all_parquet.iter().map(String::as_str).collect();
    let mut selected: BTreeSet<String> = BTreeSet::new();
    for (key, m) in new {
        let mut resolved_any = false;
        for full in resolve_parts(key, m) {
            if present.contains(full.as_str()) {
                selected.insert(full);
                resolved_any = true;
            }
        }
        if !resolved_any {
            // Can't resolve this run to files — don't risk a partial selection.
            return all_parquet.to_vec();
        }
    }
    selected.into_iter().collect()
}

/// Delete every `.parquet` under `gcs_prefix` that no **`Success`** manifest
/// references — crash leftovers from an interrupted extract that accumulate.
/// Keeps every manifest, `_SUCCESS`, and every manifested part (including a
/// `snapshot/` sub-prefix's, since `keyed` is fetched recursively). Strictly
/// gentler than `cleanup_source`, which wipes the whole prefix.
///
/// A candidate falls into three classes:
/// - referenced by a **`Success`** manifest → KEEP (live data).
/// - referenced by a **`Failed`/`Interrupted`** manifest → DELETE unconditionally.
///   A run that WROTE a manifest is terminal — no live extract is still streaming
///   it — so its leftovers are unambiguous crash debris.
/// - referenced by **NO manifest at all** → AMBIGUOUS: a crash-BEFORE-manifest
///   orphan (delete) OR a concurrent extract's committed-but-not-yet-manifested
///   part (must NOT delete). `active` decides — the caller's answer to "is a run
///   currently WRITING this prefix?", read from the central run-status ledger
///   (`StateStore::has_active_run_on_prefix`): authoritative and CLOCK-FREE.
///   `active` → spare every unmanifested part; `!active` → no run is live, so an
///   unmanifested part is dead crash debris → delete.
///
/// The ledger read is the SEAM. A co-located / shared-Postgres load gets a
/// precise `active`; a stateless or foreign-host load passes `active = true`
/// (conservative — spare rather than risk a live cross-host extract's parts),
/// which the bucket-manifest `running`-status projection later refines.
/// Returns `(removed, bytes)`.
#[allow(private_interfaces)]
pub fn gc_orphans(
    store: &GcsStore,
    gcs_prefix: &str,
    keyed: &[(String, RunManifest)],
    active: bool,
) -> Result<(usize, u64)> {
    let (_bucket, base) = crate::load::split_gs_uri(gcs_prefix)?;
    // Success parts → keep. Failed/Interrupted parts → terminal (their run is
    // done, so deletable regardless of `active`). A part in NEITHER set has no
    // manifest at all — the ambiguous case `active` gates.
    let mut keep: std::collections::HashSet<String> = std::collections::HashSet::new();
    let mut terminal: std::collections::HashSet<String> = std::collections::HashSet::new();
    for (key, m) in keyed {
        match m.status {
            ManifestStatus::Success => keep.extend(resolve_parts(key, m)),
            // A `running` manifest is a LIVE run's marker (schema-less, no parts).
            // Its parts (if any) must NOT be treated as terminal debris — its
            // activeness is what makes `active` true (see the callsite), which
            // spares the run's unmanifested in-flight parts below.
            ManifestStatus::Running => {}
            ManifestStatus::Failed | ManifestStatus::Interrupted => {
                terminal.extend(resolve_parts(key, m))
            }
        }
    }
    let mut removed = 0usize;
    let mut removed_bytes = 0u64;
    for key in store.list_files(base)? {
        if !key.ends_with(".parquet") || keep.contains(&key) {
            continue;
        }
        // A live run on this prefix + a part with NO manifest → maybe its
        // in-flight write → spare. A terminal-manifested part is deleted even
        // while a (different) run is active.
        if active && !terminal.contains(&key) {
            log::warn!(
                "gc_orphans: sparing unmanifested `{key}` — a run is active on this prefix \
                 (run-status ledger); it is GC'd once no run is active or it gets a manifest"
            );
            continue;
        }
        removed_bytes += store.stat_size(&key).unwrap_or(0);
        store.remove(&key)?;
        removed += 1;
    }
    // Second pass: a SUPERSEDED `running` MARKER manifest (its run was overtaken by
    // a newer run of the same export) is a dead crash marker — never the live
    // signal — so its lingering `.json` is safe to remove. gc otherwise never
    // touches it (the parquet pass above only lists `.parquet`), so a hard-crashed
    // run's marker would accumulate forever. A NON-superseded running manifest is
    // the ACTIVE signal and MUST survive — deletion here is gated on SUPERSESSION,
    // never on `active`.
    for (key, m) in keyed {
        if m.status == ManifestStatus::Running && is_superseded(m, keyed) {
            removed_bytes += store.stat_size(key).unwrap_or(0);
            store.remove(key)?;
            removed += 1;
        }
    }
    Ok((removed, removed_bytes))
}

/// Is a LIVE run's `running` MARKER manifest present under the prefix — the
/// bucket-side projection of the run-status ledger, for a cross-boundary load
/// (Airflow / a foreign-host `rivet load`) that cannot read the extract's state
/// DB? True iff some `running` manifest is NOT superseded by a NEWER manifest
/// (any status) of the SAME export — the same clock-free supersession the ledger
/// uses (a newer `started_at` means the old running run crashed and its successor
/// already re-ran). `gc_orphans`'s `active` is `ledger_active OR this`, so the two
/// signals are belt-and-suspenders: the ledger is precise co-located, the marker
/// covers cross-host.
pub fn has_active_running_manifest(keyed: &[(String, RunManifest)]) -> bool {
    keyed
        .iter()
        .any(|(_, m)| m.status == ManifestStatus::Running && !is_superseded(m, keyed))
}

/// A `running` manifest is SUPERSEDED when a NEWER run of the SAME export exists
/// (a higher `started_at`) — it crashed and its successor already re-ran, so it
/// no longer protects anything. The ONE clock-free staleness predicate, shared by
/// [`has_active_running_manifest`] (spare the non-superseded) and `gc_orphans`'s
/// marker-GC sweep (delete the superseded). The ledger enforces the same rule in
/// SQL — that copy cannot share this Rust.
fn is_superseded(m: &RunManifest, keyed: &[(String, RunManifest)]) -> bool {
    keyed
        .iter()
        .any(|(_, o)| o.export_name == m.export_name && o.started_at > m.started_at)
}

/// Full/chunked loads care only about the LATEST snapshot: from `keyed` (all run
/// manifests under the prefix) pick the newest by `finished_at`. Full loads
/// OVERWRITE, so exactly ONE snapshot may be loaded (loading every accumulated
/// run would duplicate rows). Deliberately **not** ledger-gated: full
/// re-materializes the latest snapshot on *every* load, so a re-load self-heals a
/// drifted target and stays resilient to hidden in-place source updates. An empty
/// input (no staged run — e.g. the staging was cleaned) yields an empty
/// selection, so the caller no-ops WITHOUT truncating the target.
///
/// Ordering parses `finished_at` as an instant — a lexical byte compare mis-picks
/// on mixed RFC3339 precision (`…00.5Z` sorts before `…00Z`) — and falls back to
/// lexical only if a timestamp fails to parse, so a malformed manifest can't panic.
pub fn latest_full(keyed: Vec<(String, RunManifest)>) -> Vec<(String, RunManifest)> {
    keyed
        .into_iter()
        .max_by(|a, b| {
            match (
                chrono::DateTime::parse_from_rfc3339(&a.1.finished_at).ok(),
                chrono::DateTime::parse_from_rfc3339(&b.1.finished_at).ok(),
            ) {
                (Some(x), Some(y)) => x.cmp(&y),
                _ => a.1.finished_at.cmp(&b.1.finished_at),
            }
        })
        .into_iter()
        .collect()
}

/// Which run manifests to load for `mode`, given the ledger's already-`loaded`
/// run_ids. The single mode→selection decision, pure and testable so the load's
/// central invariant isn't buried in dispatch I/O:
/// - `Full` → the single LATEST run ([`latest_full`]) — ledger-INDEPENDENT, so a
///   re-load re-materializes the snapshot (self-heal) and, crucially, the
///   STATELESS path (empty `loaded`) still picks the latest instead of blanket-
///   loading every accumulated snapshot (the duplicate-rows bug).
/// - `Incremental`/`Cdc` → every run not yet in `loaded` (append). Stateless →
///   `loaded` empty → load all; at-least-once, absorbed by the dedup view.
pub fn select_runs(
    keyed: Vec<(String, RunManifest)>,
    loaded: &std::collections::HashSet<String>,
    mode: crate::load::plan::LoadMode,
) -> Vec<(String, RunManifest)> {
    // A `running` manifest is a LIVE run's in-flight marker — never loadable (no
    // committed parts). Drop it BEFORE selection so it neither becomes the
    // "latest" full snapshot nor an incremental delta, either of which would
    // make `reconcile` refuse the whole load on a non-Success run.
    let keyed: Vec<(String, RunManifest)> = keyed
        .into_iter()
        .filter(|(_, m)| m.status != ManifestStatus::Running)
        .collect();
    match mode {
        crate::load::plan::LoadMode::Full => latest_full(keyed),
        _ => keyed
            .into_iter()
            .filter(|(_, m)| !loaded.contains(&m.run_id))
            .collect(),
    }
}

/// Bucket-relative keys of every run manifest under `base` (recursive).
fn list_manifest_keys(store: &GcsStore, base: &str) -> Result<Vec<String>> {
    let all: Vec<String> = store
        .list_files(base)?
        .into_iter()
        .filter(|k| is_manifest_key(k))
        .collect();
    // A run into a shared prefix leaves BOTH the canonical `manifest.json`
    // (last-writer-wins — a pointer to the LATEST run) and an immutable
    // `manifest-<run_id>.json` copy (one per run). Sum the per-run copies so a
    // prefix that accumulated several CDC/incremental cycles counts EVERY run;
    // counting the canonical pointer too would double-count the latest. Fall
    // back to the canonical name only when no per-run copy exists (a single
    // batch run, or a legacy prefix predating the run-unique copy).
    let run_unique: Vec<String> = all
        .iter()
        .filter(|k| is_run_unique_manifest(k.rsplit('/').next().unwrap_or("")))
        .cloned()
        .collect();
    Ok(if run_unique.is_empty() {
        all
    } else {
        run_unique
    })
}

/// A listed key is a run manifest iff its final path segment is the canonical
/// [`MANIFEST_FILENAME`] (`manifest.json`) or a run-unique copy
/// (`manifest-<run_id>.json`) — so a data file merely *named* like it (an
/// unlikely `…/x_manifest.json`) is not mistaken for one.
fn is_manifest_key(key: &str) -> bool {
    let base = key.rsplit('/').next().unwrap_or("");
    base == MANIFEST_FILENAME || is_run_unique_manifest(base)
}

/// A per-run manifest copy: `manifest-<token>.json` (the sidecar the OSS sink
/// writes alongside the canonical pointer so cross-run reconcile can sum it).
fn is_run_unique_manifest(base: &str) -> bool {
    // The sidecar naming scheme lives once, in `manifest.rs` (the writer's home).
    crate::manifest::is_run_unique_manifest_name(base)
}

/// Refuse a load whose prefix holds MORE THAN ONE export's manifests. The load
/// sums EVERY manifest under `gcs_prefix` (fetched recursively) and cleanup
/// removes the prefix recursively, so a shared base prefix — two `partition_by`
/// exports whose prefix-before-`{partition}` coincides — would silently cross-
/// contaminate the reconciled row count AND delete the sibling export's un-loaded
/// parts. The `LoadPlan` carries no source `export_name` to disambiguate which
/// export the operator meant, so fail LOUDLY rather than load-and-delete the
/// wrong data. Legacy manifests with no recorded `export_name` (pre-0.x) are
/// tolerated — an empty name matches any single named export, so a prefix that
/// mixes old and new runs of the SAME export still loads.
pub fn ensure_single_export(keyed: &[(String, RunManifest)]) -> Result<()> {
    let mut names: std::collections::BTreeSet<&str> = keyed
        .iter()
        .map(|(_, m)| m.export_name.as_str())
        .filter(|n| !n.is_empty())
        .collect();
    if names.len() > 1 {
        let listed: Vec<&str> = std::mem::take(&mut names).into_iter().collect();
        bail!(
            "the load prefix holds manifests from {} distinct exports ({}) — the load sums every \
             manifest under the prefix and cleanup wipes it recursively, so loading a shared \
             prefix would cross-contaminate the row count and could delete a sibling export's \
             parts. Give each export a DISTINCT destination prefix (or scope the load prefix to a \
             single export) and re-run.",
            listed.len(),
            listed.join(", ")
        );
    }
    Ok(())
}

/// Reconcile a run's manifests into the authoritative expected warehouse row
/// count, refusing to load anything that is not provably complete.
///
/// Every manifest must be a **`Success`** run (a `Failed` / `Interrupted`
/// manifest describes a partial, untrustworthy export) and **self-consistent**
/// (`row_count` == sum of committed parts — a mismatch is a writer bug). When a
/// manifest recorded a `source_row_count`, the **source→file** leg must
/// reconcile too: `source_row_count == row_count`, or the extract silently
/// dropped rows. `allow_source_drift` downgrades only that last check to a
/// warning (e.g. an incremental cursor window whose source moved under it);
/// the completeness and self-consistency gates never yield.
///
/// Returns [`LoadIntegrity`] with the summed `file_rows` the loader's
/// `expected_rows` gate then checks against the warehouse's `COUNT(*)`.
pub fn reconcile(manifests: &[RunManifest], allow_source_drift: bool) -> Result<LoadIntegrity> {
    if manifests.is_empty() {
        bail!(
            "no `{MANIFEST_FILENAME}` found under the export prefix — refusing to load \
             unverified files. A rivet export writes a manifest on success; its absence \
             means the run never completed (or points at the wrong prefix)."
        );
    }

    let mut file_rows: u64 = 0;
    let mut source_rows: u64 = 0;
    let mut any_source = false;

    for m in manifests {
        // Completeness: only a `Success` run may be loaded.
        if m.status != ManifestStatus::Success {
            bail!(
                "manifest for run `{}` (export `{}`) is {:?}, not Success — refusing to load a \
                 partial export",
                m.run_id,
                m.export_name,
                m.status
            );
        }
        // Self-consistency: the recorded aggregates must match the committed
        // parts (a divergence is a writer bug, per OSS `validate_self_consistency`).
        m.validate_self_consistency().map_err(|e| {
            anyhow::anyhow!(
                "manifest for run `{}` (export `{}`) is internally inconsistent: {e} — refusing \
                 to load",
                m.run_id,
                m.export_name
            )
        })?;

        let rows = u64::try_from(m.row_count).with_context(|| {
            format!(
                "manifest for run `{}` has a negative row_count ({})",
                m.run_id, m.row_count
            )
        })?;
        file_rows += rows;

        // Source→file: reconcile the extract against the source when the run
        // probed it. `None` = not probed (unverifiable, not a failure).
        if let Some(src) = m
            .source
            .extraction
            .as_ref()
            .and_then(|x| x.source_row_count)
        {
            let src = u64::try_from(src).with_context(|| {
                format!(
                    "manifest for run `{}` has a negative source_row_count ({src})",
                    m.run_id
                )
            })?;
            any_source = true;
            source_rows += src;
            if src != rows {
                if allow_source_drift {
                    eprintln!(
                        "warning: source→file drift for run `{}` (export `{}`): source had {src} \
                         rows, extracted {rows} (--allow-source-drift)",
                        m.run_id, m.export_name
                    );
                } else {
                    bail!(
                        "source→file mismatch for run `{}` (export `{}`): source had {src} rows \
                         but {rows} were extracted — the extract dropped {} row(s). Investigate \
                         before loading, or pass --allow-source-drift to override.",
                        m.run_id,
                        m.export_name,
                        src.abs_diff(rows)
                    );
                }
            }
        }
    }

    Ok(LoadIntegrity {
        source_rows: any_source.then_some(source_rows),
        file_rows,
        manifests: manifests.len(),
    })
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::manifest::{
        ExtractionMetadata, ManifestDestination, ManifestPart, ManifestSource, PartStatus,
    };

    /// A minimal `Success` manifest with one committed part of `rows` rows and,
    /// optionally, a probed `source_row_count`.
    fn manifest(run: &str, rows: i64, source: Option<i64>) -> RunManifest {
        RunManifest {
            manifest_version: crate::manifest::MANIFEST_VERSION,
            run_id: run.into(),
            export_name: "orders".into(),
            mode: "batch".into(),
            started_at: "t".into(),
            finished_at: "t".into(),
            status: ManifestStatus::Success,
            source: ManifestSource {
                engine: "pg".into(),
                schema: None,
                table: None,
                extraction: source.map(|n| ExtractionMetadata {
                    strategy: "full".into(),
                    cursor_column: None,
                    cursor_type: None,
                    cursor_low: None,
                    cursor_high: None,
                    source_row_count: Some(n),
                }),
            },
            destination: ManifestDestination {
                kind: "gcs".into(),
                uri: "gs://b/p".into(),
            },
            format: "parquet".into(),
            compression: "zstd".into(),
            schema_fingerprint: "xxh3:0".into(),
            row_count: rows,
            part_count: 1,
            parts: vec![ManifestPart {
                part_id: 0,
                path: "part-000000.parquet".into(),
                rows,
                size_bytes: 1,
                content_fingerprint: "xxh3:0".into(),
                content_md5: String::new(),
                status: PartStatus::Committed,
            }],
            column_checksums: None,
            checksum_key_column: None,
        }
    }

    #[test]
    fn sums_file_and_source_rows_across_manifests() {
        let ms = vec![manifest("r1", 100, Some(100)), manifest("r2", 40, Some(40))];
        let got = reconcile(&ms, false).unwrap();
        assert_eq!(got.file_rows, 140);
        assert_eq!(got.source_rows, Some(140));
        assert_eq!(got.manifests, 2);
    }

    #[test]
    fn ensure_single_export_refuses_a_prefix_shared_by_two_exports() {
        let keyed = |m: RunManifest| ("gs://b/p/manifest-x.json".to_string(), m);
        let orders = keyed(manifest("r1", 10, None)); // export_name "orders"
        let mut cust_m = manifest("r2", 10, None);
        cust_m.export_name = "customers".into();
        // Two DISTINCT exports under one load prefix → loud refusal (else the load
        // sums both and cleanup deletes the sibling's parts).
        assert!(ensure_single_export(&[orders.clone(), keyed(cust_m)]).is_err());
        // Many runs of ONE export → fine.
        assert!(ensure_single_export(&[orders.clone(), keyed(manifest("r3", 5, None))]).is_ok());
        // A legacy (no export_name) run mixed with the SAME named export → still
        // one logical export, tolerated (an upgrade mid-prefix must not brick load).
        let mut legacy = manifest("r0", 3, None);
        legacy.export_name = String::new();
        assert!(ensure_single_export(&[orders, keyed(legacy)]).is_ok());
    }

    #[test]
    fn source_rows_is_none_when_no_manifest_probed_the_source() {
        let ms = vec![manifest("r1", 100, None), manifest("r2", 40, None)];
        let got = reconcile(&ms, false).unwrap();
        assert_eq!(got.file_rows, 140);
        assert_eq!(
            got.source_rows, None,
            "unprobed source is unknown, not zero"
        );
    }

    #[test]
    fn source_rows_present_even_if_only_some_manifests_probed() {
        let ms = vec![manifest("r1", 100, Some(100)), manifest("r2", 40, None)];
        let got = reconcile(&ms, false).unwrap();
        assert_eq!(got.source_rows, Some(100));
    }

    #[test]
    fn empty_manifests_refuses_to_load() {
        let err = reconcile(&[], false).unwrap_err().to_string();
        assert!(err.contains("refusing to load"), "{err}");
    }

    #[test]
    fn non_success_manifest_refuses_to_load() {
        let mut m = manifest("r1", 100, Some(100));
        m.status = ManifestStatus::Interrupted;
        let err = reconcile(&[m], false).unwrap_err().to_string();
        assert!(err.contains("not Success"), "{err}");
    }

    #[test]
    fn self_inconsistent_manifest_refuses_to_load() {
        // row_count claims 100 but the only committed part holds 100 → make the
        // aggregate lie by bumping the recorded row_count only.
        let mut m = manifest("r1", 100, Some(100));
        m.row_count = 999; // no longer equals committed parts' sum (100)
        let err = reconcile(&[m], false).unwrap_err().to_string();
        assert!(err.contains("inconsistent"), "{err}");
    }

    #[test]
    fn source_file_mismatch_hard_fails_by_default() {
        // Source had 120, only 100 extracted → 20 rows silently dropped.
        let m = manifest("r1", 100, Some(120));
        let err = reconcile(&[m], false).unwrap_err().to_string();
        assert!(err.contains("source→file mismatch"), "{err}");
        assert!(err.contains("dropped 20"), "{err}");
    }

    #[test]
    fn source_file_mismatch_is_allowed_under_the_override() {
        let m = manifest("r1", 100, Some(120));
        let got = reconcile(&[m], true).expect("--allow-source-drift proceeds");
        assert_eq!(got.file_rows, 100);
        assert_eq!(
            got.source_rows,
            Some(120),
            "the probed source count is still surfaced"
        );
    }

    /// A `(manifest_key, manifest)` pair with a single part named `part`.
    fn keyed(key: &str, run: &str, part: &str) -> (String, RunManifest) {
        let mut m = manifest(run, 10, Some(10));
        m.parts[0].path = part.into();
        (key.to_string(), m)
    }

    #[test]
    fn select_load_keys_picks_only_the_new_runs_parts() {
        // Two runs' files sit under the prefix; only r2 is "new".
        let all = vec![
            "base/r1-000.parquet".to_string(),
            "base/r2-000.parquet".to_string(),
        ];
        let new = vec![keyed("base/manifest-r2.json", "r2", "r2-000.parquet")];
        assert_eq!(
            select_load_keys(&new, &all),
            vec!["base/r2-000.parquet".to_string()],
            "loads r2's part only — not r1's already-loaded file"
        );
    }

    #[test]
    fn select_load_uris_lists_and_re_prefixes_selected_keys_with_the_source_bucket() {
        // select_load_keys (the pure selection) is unit-tested throughout; this
        // pins the store WRAPPER around it — list `.parquet` under the base, then
        // reconstruct each `gs://<bucket>/<key>` the loader COPYs from. A mangled
        // wrapper (empty/garbage URIs) would send the warehouse load at nothing,
        // or the wrong object — invisible to the pure-selection tests.
        let (store, _g) = fs_store(&[
            ("base/r1-000.parquet", b"a".to_vec()),
            ("base/manifest-r1.json", b"{}".to_vec()), // not .parquet — must be skipped
        ]);
        let new = vec![keyed("base/manifest-r1.json", "r1", "r1-000.parquet")];
        assert_eq!(
            select_load_uris(&store, "gs://my-bucket/base", &new).unwrap(),
            vec!["gs://my-bucket/base/r1-000.parquet".to_string()],
            "the selected key, re-prefixed with the source bucket — never the manifest"
        );
    }

    #[test]
    fn select_load_keys_resolves_a_snapshot_subprefix_manifest() {
        // A snapshot manifest lives under `base/snapshot/`; its part is relative
        // to that dir. Resolution must reconstruct the full key.
        let all = vec!["base/snapshot/snap-000.parquet".to_string()];
        let new = vec![keyed(
            "base/snapshot/manifest-r1.json",
            "r1",
            "snap-000.parquet",
        )];
        assert_eq!(
            select_load_keys(&new, &all),
            vec!["base/snapshot/snap-000.parquet".to_string()]
        );
    }

    #[test]
    fn select_load_keys_falls_back_to_full_listing_when_a_manifest_has_no_present_part() {
        // A manifest whose part isn't in the listing (legacy / renamed) → don't
        // risk a partial selection; load everything under the prefix.
        let all = vec!["base/a.parquet".to_string(), "base/b.parquet".to_string()];
        let new = vec![keyed("base/manifest-r1.json", "r1", "missing.parquet")];
        assert_eq!(
            select_load_keys(&new, &all),
            all,
            "unresolvable part → blanket fallback"
        );
    }

    #[test]
    fn select_load_keys_empty_new_set_selects_nothing_never_the_full_listing() {
        // When every run is already in the ledger the "new" set is empty. That
        // must resolve to ZERO uris — NOT the blanket fallback, which would
        // re-load the whole prefix on every up-to-date run (double-load). The
        // fallback fires only for an unresolvable NON-empty manifest.
        let all = vec![
            "base/r1-000.parquet".to_string(),
            "base/r2-000.parquet".to_string(),
        ];
        assert!(
            select_load_keys(&[], &all).is_empty(),
            "no new runs ⇒ load nothing, not everything"
        );
    }

    #[test]
    fn gc_orphans_removes_unmanifested_parquet_only() {
        let (store, _g) = fs_store(&[
            ("base/r1-000.parquet", b"aa".to_vec()),   // manifested
            ("base/orphan.parquet", b"junk".to_vec()), // crash leftover — no manifest
            ("base/manifest.json", b"{}".to_vec()),    // kept — not a .parquet
            ("base/_SUCCESS", b"".to_vec()),           // kept — not a .parquet
        ]);
        let keyed = vec![keyed("base/manifest-r1.json", "r1", "r1-000.parquet")];
        // No run is active on this prefix → the unmanifested part is dead debris.
        let (removed, bytes) = gc_orphans(&store, "gs://b/base", &keyed, false).unwrap();
        assert_eq!(removed, 1, "only the unmanifested part is removed");
        assert_eq!(bytes, 4, "'junk' is 4 bytes");
        let mut left = store.list_files("base").unwrap();
        left.sort();
        assert_eq!(
            left,
            vec![
                "base/_SUCCESS".to_string(),
                "base/manifest.json".to_string(),
                "base/r1-000.parquet".to_string(),
            ],
            "the manifested part, the manifest, and _SUCCESS all survive"
        );
    }

    #[test]
    fn gc_orphans_of_an_all_manifested_prefix_removes_nothing() {
        let (store, _g) = fs_store(&[("base/r1-000.parquet", b"a".to_vec())]);
        let keyed = vec![keyed("base/manifest-r1.json", "r1", "r1-000.parquet")];
        assert_eq!(
            gc_orphans(&store, "gs://b/base", &keyed, false).unwrap().0,
            0
        );
    }

    #[test]
    fn gc_orphans_keeps_a_snapshot_subprefix_manifested_part() {
        let (store, _g) = fs_store(&[
            ("base/snapshot/s-000.parquet", b"a".to_vec()), // manifested under snapshot/
            ("base/orphan.parquet", b"x".to_vec()),         // top-level orphan
        ]);
        let keyed = vec![keyed("base/snapshot/manifest-s.json", "s", "s-000.parquet")];
        let (removed, _) = gc_orphans(&store, "gs://b/base", &keyed, false).unwrap();
        assert_eq!(removed, 1, "the top-level orphan goes");
        assert_eq!(
            store.list_files("base/snapshot").unwrap(),
            vec!["base/snapshot/s-000.parquet".to_string()],
            "the snapshot-subprefix manifested part is kept"
        );
    }

    #[test]
    fn gc_orphans_deletes_a_terminal_runs_parts_even_while_a_run_is_active() {
        // A Failed/Interrupted run's parts are terminal crash debris — deleted
        // regardless of `active`, since no LIVE run is streaming THEM. Passing
        // active=true proves the `active` gate applies only to UNmanifested parts.
        let (store, _g) = fs_store(&[("base/f-000.parquet", b"x".to_vec())]);
        let mut kv = keyed("base/manifest-f.json", "f", "f-000.parquet");
        kv.1.status = ManifestStatus::Failed;
        assert_eq!(gc_orphans(&store, "gs://b/base", &[kv], true).unwrap().0, 1);
    }

    #[test]
    fn gc_orphans_spares_an_unmanifested_part_while_a_run_is_active() {
        // The concurrent-extract guard. A part with NO manifest, while a run is
        // ACTIVE on this prefix (the run-status ledger says so), is probably that
        // run's committed-but-not-yet-manifested write — deleting it would be
        // silent data loss on the live extract. RED against a mutant that ignores
        // `active` (deletes every non-Success-manifested `.parquet`).
        let (store, _g) = fs_store(&[
            ("base/r1-000.parquet", b"aa".to_vec()),  // manifested (kept)
            ("base/inflight.parquet", b"x".to_vec()), // unmanifested, a live run's part
        ]);
        let keyed = vec![keyed("base/manifest-r1.json", "r1", "r1-000.parquet")];
        let (removed, _) = gc_orphans(&store, "gs://b/base", &keyed, true).unwrap();
        assert_eq!(
            removed, 0,
            "an unmanifested part is spared while a run is active"
        );
        assert!(
            store
                .list_files("base")
                .unwrap()
                .iter()
                .any(|k| k.ends_with("inflight.parquet")),
            "the live run's in-flight part must survive gc_orphans"
        );
    }

    #[test]
    fn gc_orphans_collects_an_unmanifested_part_when_no_run_is_active() {
        // The other half: with NO run active, an unmanifested part is a dead
        // crash orphan and IS collected — the gate DEFERS cleanup, never abandons.
        let (store, _g) = fs_store(&[
            ("base/r1-000.parquet", b"aa".to_vec()),
            ("base/dead-orphan.parquet", b"x".to_vec()),
        ]);
        let keyed = vec![keyed("base/manifest-r1.json", "r1", "r1-000.parquet")];
        assert_eq!(
            gc_orphans(&store, "gs://b/base", &keyed, false).unwrap().0,
            1,
            "with no active run, an unmanifested orphan is collected"
        );
    }

    /// A `running` MARKER manifest (schema-less, no parts) started at `started_at`.
    fn running(run: &str, started_at: &str) -> (String, RunManifest) {
        let mut m = manifest(run, 0, None);
        m.status = ManifestStatus::Running;
        m.started_at = started_at.into();
        m.finished_at = String::new();
        m.parts.clear();
        (format!("base/manifest-{run}.json"), m)
    }

    #[test]
    fn has_active_running_manifest_true_for_a_lone_running_marker() {
        assert!(has_active_running_manifest(&[running(
            "r1",
            "2026-01-01T00:00:00Z"
        )]));
    }

    #[test]
    fn has_active_running_manifest_false_when_none_is_running() {
        // A Success manifest is not a live-run marker.
        assert!(!has_active_running_manifest(&[keyed(
            "k",
            "r1",
            "p.parquet"
        )]));
    }

    #[test]
    fn has_active_running_manifest_false_for_a_superseded_running_marker() {
        // r1 crashed leaving a `running` marker; r2 (newer started_at, SAME
        // export) already ran → r1 is stale and must NOT count as active. Same
        // clock-free supersession the ledger uses.
        let r1 = running("r1", "2026-01-01T00:00:00Z");
        let mut r2 = manifest("r2", 10, Some(10)); // Success, same export ("orders")
        r2.started_at = "2026-01-02T00:00:00Z".into();
        assert!(!has_active_running_manifest(&[
            r1,
            ("base/manifest-r2.json".into(), r2)
        ]));
    }

    #[test]
    fn select_runs_drops_a_running_manifest() {
        // A `running` (in-flight) manifest must NEVER be selected for load — else
        // reconcile would refuse the whole load on a non-Success run. Incremental
        // mode would otherwise include it (not yet loaded).
        let run_marker = running("r_running", "2026-01-02T00:00:00Z");
        let ok = keyed("base/manifest-r_ok.json", "r_ok", "r_ok-000.parquet"); // Success
        let sel = select_runs(
            vec![run_marker, ok],
            &std::collections::HashSet::new(),
            crate::load::plan::LoadMode::Incremental,
        );
        assert_eq!(sel.len(), 1, "only the Success run is selected");
        assert_eq!(sel[0].1.run_id, "r_ok");
        assert!(sel.iter().all(|(_, m)| m.status != ManifestStatus::Running));
    }

    #[test]
    fn gc_orphans_removes_a_superseded_running_marker_but_spares_a_live_one() {
        // r1 crashed leaving a `running` marker; r2 (newer, same export) is the
        // live run. The DEAD superseded marker must be GC'd (else it accumulates
        // forever — gc otherwise only lists `.parquet`); the LIVE one must survive
        // (it is the active signal). Gated on supersession, so `active=true`.
        let (store, _g) = fs_store(&[
            ("base/manifest-r1.json", b"{}".to_vec()), // superseded running marker
            ("base/manifest-r2.json", b"{}".to_vec()), // live running marker (newest)
        ]);
        let r1 = running("r1", "2026-01-01T00:00:01Z");
        let r2 = running("r2", "2026-01-01T00:00:02Z");
        let (removed, _) = gc_orphans(&store, "gs://b/base", &[r1, r2], true).unwrap();
        assert_eq!(removed, 1, "only the superseded running marker is removed");
        let left = store.list_files("base").unwrap();
        assert!(
            !left.iter().any(|k| k.ends_with("manifest-r1.json")),
            "the superseded (dead) running marker is deleted"
        );
        assert!(
            left.iter().any(|k| k.ends_with("manifest-r2.json")),
            "the live (non-superseded) running marker survives — it is the active signal"
        );
    }

    fn keyed_at(run: &str, finished_at: &str) -> (String, RunManifest) {
        let mut m = manifest(run, 100, None);
        m.finished_at = finished_at.into();
        (format!("base/manifest-{run}.json"), m)
    }

    #[test]
    fn latest_full_picks_the_newest_snapshot_not_all() {
        // Full loads OVERWRITE, so only the LATEST snapshot may be loaded —
        // selecting all accumulated runs would load duplicate snapshots.
        let keyed = vec![
            keyed_at("r1", "2026-01-01T00:00:00Z"),
            keyed_at("r3", "2026-01-03T00:00:00Z"),
            keyed_at("r2", "2026-01-02T00:00:00Z"),
        ];
        let sel = latest_full(keyed);
        assert_eq!(sel.len(), 1, "exactly one snapshot, never all");
        assert_eq!(sel[0].1.run_id, "r3", "the newest by finished_at");
    }

    #[test]
    fn latest_full_re_materializes_even_when_the_latest_is_already_loaded() {
        // Full is NOT ledger-skipped: a re-load re-OVERWRITEs from the latest
        // snapshot, self-healing a drifted target and staying resilient to hidden
        // in-place updates. The ledger must NOT suppress the re-materialization —
        // full has to stay full (the old `latest_unloaded_full` skip was the bug).
        let keyed = vec![
            keyed_at("r1", "2026-01-01T00:00:00Z"),
            keyed_at("r2", "2026-01-02T00:00:00Z"),
        ];
        // r2 is "already loaded" in the caller's ledger, yet full still selects it.
        let sel = latest_full(keyed);
        assert_eq!(sel.len(), 1);
        assert_eq!(sel[0].1.run_id, "r2", "always the latest, loaded or not");
    }

    #[test]
    fn latest_full_of_no_staged_runs_is_empty_so_the_caller_no_ops_without_truncating() {
        // Empty staging (e.g. cleaned, no fresh extract) → empty selection → the
        // caller returns None and never truncates the target to empty.
        assert!(latest_full(Vec::new()).is_empty());
    }

    #[test]
    fn latest_full_orders_by_parsed_instant_not_lexical_bytes() {
        // `…00.500Z` is LATER than `…00Z` but sorts EARLIER lexically ('.' < 'Z').
        // Parsing to an instant picks the truly-newest run, not the lexical max.
        let keyed = vec![
            keyed_at("older", "2026-01-01T00:00:00Z"),
            keyed_at("newer", "2026-01-01T00:00:00.500Z"),
        ];
        let sel = latest_full(keyed);
        assert_eq!(sel.len(), 1);
        assert_eq!(
            sel[0].1.run_id, "newer",
            "the fractional-second run is the newer instant"
        );
    }

    #[test]
    fn select_runs_full_picks_the_latest_even_when_loaded_and_even_when_stateless() {
        use crate::load::plan::LoadMode;
        use std::collections::HashSet;
        let keyed = vec![
            keyed_at("r1", "2026-01-01T00:00:00Z"),
            keyed_at("r2", "2026-01-02T00:00:00Z"),
        ];
        // Stateful, r2 already loaded → still selects r2 (re-materialize/self-heal).
        let loaded = HashSet::from(["r2".to_string()]);
        let sel = select_runs(keyed.clone(), &loaded, LoadMode::Full);
        assert_eq!(sel.len(), 1);
        assert_eq!(sel[0].1.run_id, "r2", "Full picks latest, loaded or not");
        // STATELESS (empty loaded) → the latest, NEVER a blanket load of both
        // snapshots (the duplicate-rows bug this fix closes).
        let sel = select_runs(keyed, &HashSet::new(), LoadMode::Full);
        assert_eq!(sel.len(), 1, "stateless Full is not a blanket load");
        assert_eq!(sel[0].1.run_id, "r2");
    }

    #[test]
    fn select_runs_append_modes_filter_loaded_and_load_all_when_stateless() {
        use crate::load::plan::LoadMode;
        use std::collections::HashSet;
        let keyed = vec![
            keyed_at("r1", "2026-01-01T00:00:00Z"),
            keyed_at("r2", "2026-01-02T00:00:00Z"),
        ];
        let loaded = HashSet::from(["r1".to_string()]);
        for mode in [LoadMode::Incremental, LoadMode::Cdc] {
            let sel = select_runs(keyed.clone(), &loaded, mode);
            assert_eq!(sel.len(), 1, "{mode:?}: only the unloaded run");
            assert_eq!(sel[0].1.run_id, "r2");
            // Stateless → empty loaded → load all (at-least-once, dedup absorbs).
            assert_eq!(
                select_runs(keyed.clone(), &HashSet::new(), mode).len(),
                2,
                "{mode:?}: stateless loads every run"
            );
        }
    }

    #[test]
    fn is_run_unique_manifest_needs_both_prefix_and_json() {
        assert!(is_run_unique_manifest("manifest-20260101T000000.json"));
        assert!(!is_run_unique_manifest("manifest.json")); // no `-` after manifest
        assert!(!is_run_unique_manifest("manifest-abc.txt")); // not .json
        assert!(!is_run_unique_manifest("data.json")); // wrong prefix
    }

    #[test]
    fn chain_prefix_renders_source_and_files() {
        let known = LoadIntegrity {
            source_rows: Some(100),
            file_rows: 100,
            manifests: 1,
        };
        assert_eq!(known.chain_prefix(), "source 100 → files 100");
        let unknown = LoadIntegrity {
            source_rows: None,
            file_rows: 40,
            manifests: 1,
        };
        assert_eq!(unknown.chain_prefix(), "source ? → files 40");
    }

    #[test]
    fn is_manifest_key_matches_only_the_final_segment() {
        assert!(is_manifest_key("gs://b/p/manifest.json"));
        assert!(is_manifest_key("manifest.json"));
        assert!(!is_manifest_key("gs://b/p/part-0.parquet"));
        assert!(!is_manifest_key("gs://b/p/x_manifest.json"));
    }

    // ---- offline (filesystem-backed store) transport tests ----

    /// Build an fs-backed [`GcsStore`] over a fresh tempdir seeded with
    /// `(bucket-relative-key, bytes)` objects. Returns the store and the guard —
    /// hold the `TempDir` for the store's lifetime.
    fn fs_store(files: &[(&str, Vec<u8>)]) -> (GcsStore, tempfile::TempDir) {
        let dir = tempfile::tempdir().unwrap();
        for (rel, bytes) in files {
            let p = dir.path().join(rel);
            std::fs::create_dir_all(p.parent().unwrap()).unwrap();
            std::fs::write(p, bytes).unwrap();
        }
        let store = GcsStore::open_fs(dir.path().to_str().unwrap()).unwrap();
        (store, dir)
    }

    fn manifest_bytes(run: &str, rows: i64, source: Option<i64>) -> Vec<u8> {
        serde_json::to_vec(&manifest(run, rows, source)).unwrap()
    }

    #[test]
    fn list_manifest_keys_prefers_run_unique_copies_over_the_canonical_pointer() {
        // A shared prefix that accumulated two runs holds the last-writer-wins
        // `manifest.json` pointer AND one immutable per-run copy each. Summing
        // must count the two run copies, never the pointer (double-count guard).
        let (store, _g) = fs_store(&[
            ("base/manifest.json", b"{}".to_vec()),
            ("base/manifest-r1.json", b"{}".to_vec()),
            ("base/manifest-r2.json", b"{}".to_vec()),
            ("base/part-0.parquet", b"x".to_vec()), // data file: not a manifest
        ]);
        let mut keys = list_manifest_keys(&store, "base").unwrap();
        keys.sort();
        assert_eq!(
            keys,
            vec![
                "base/manifest-r1.json".to_string(),
                "base/manifest-r2.json".to_string(),
            ]
        );
    }

    #[test]
    fn list_manifest_keys_falls_back_to_the_canonical_name_for_a_single_run() {
        // A single batch run (or a legacy prefix) has only the canonical name —
        // with no per-run copy, it must still be found.
        let (store, _g) = fs_store(&[("base/manifest.json", b"{}".to_vec())]);
        assert_eq!(
            list_manifest_keys(&store, "base").unwrap(),
            vec!["base/manifest.json".to_string()]
        );
    }

    #[test]
    fn fetch_manifests_keyed_reads_and_parses_every_run_copy_under_the_prefix() {
        // Two runs' copies plus a canonical pointer to the latest: fetch returns
        // exactly the two run copies, parsed — so reconcile sums 100 + 40 = 140
        // without double-counting the pointer.
        let (store, _g) = fs_store(&[
            ("base/manifest.json", manifest_bytes("r2", 40, Some(40))),
            (
                "base/manifest-r1.json",
                manifest_bytes("r1", 100, Some(100)),
            ),
            ("base/manifest-r2.json", manifest_bytes("r2", 40, Some(40))),
        ]);
        let manifests: Vec<_> = fetch_manifests_keyed(&store, "gs://my-bucket/base")
            .unwrap()
            .into_iter()
            .map(|(_, m)| m)
            .collect();
        assert_eq!(manifests.len(), 2);
        let integrity = reconcile(&manifests, false).unwrap();
        assert_eq!(integrity.file_rows, 140);
        assert_eq!(integrity.manifests, 2);
    }

    #[test]
    fn fetch_manifests_keyed_names_the_key_when_a_manifest_is_unparseable() {
        let (store, _g) = fs_store(&[("base/manifest.json", b"{ not json".to_vec())]);
        let err = fetch_manifests_keyed(&store, "gs://my-bucket/base")
            .unwrap_err()
            .to_string();
        assert!(
            err.contains("parsing manifest") && err.contains("base/manifest.json"),
            "error should name the offending key: {err}"
        );
    }

    // ── fake-gcs-server: the storage contract over the REAL opendal-GCS transport
    //
    // Every test above runs the storage-contract fns over an Fs-backed GcsStore —
    // proving the LOGIC, but not that opendal's GCS client speaks the same
    // list/read/remove semantics a real bucket answers with. This cell closes that
    // gap against fsouza/fake-gcs-server (the GCS JSON API emulator the extract
    // side already uses), so a GCS-only regression — listing pagination, prefix
    // handling, `remove_all` recursion — fails HERE, not in production. The
    // warehouse half (bq/snow COPY) can't be emulated; it stays the live BigQuery
    // matrix (`smoke_batch_mysql` / `StagingWiped`). This owns the BUCKET half.
    const FAKE_GCS_ENDPOINT: &str = "http://127.0.0.1:4443";
    const FAKE_GCS_BUCKET: &str = "rivet-load-emulator";

    /// A real GCS-transport [`GcsStore`] against the local emulator, scoped to
    /// `FAKE_GCS_BUCKET`. Ensures the bucket first via the emulator's JSON API
    /// (fake-gcs does not auto-create on write) — an idempotent POST, so a re-run
    /// needs no teardown. curl, not a new HTTP dep: this is a dev-only cell.
    fn fake_gcs_store() -> GcsStore {
        let created = std::process::Command::new("curl")
            .args([
                "-s",
                "-X",
                "POST",
                &format!("{FAKE_GCS_ENDPOINT}/storage/v1/b?project=rivet-test"),
                "-H",
                "Content-Type: application/json",
                "-d",
                &format!("{{\"name\":\"{FAKE_GCS_BUCKET}\"}}"),
            ])
            .output();
        assert!(
            created.is_ok_and(|o| o.status.success()),
            "could not reach fake-gcs to create the bucket — is `docker compose up -d fake-gcs` running on :4443?"
        );
        let cfg = crate::config::DestinationConfig {
            destination_type: crate::config::DestinationType::Gcs,
            bucket: Some(FAKE_GCS_BUCKET.into()),
            endpoint: Some(FAKE_GCS_ENDPOINT.into()),
            allow_anonymous: true,
            ..Default::default()
        };
        GcsStore::new(&cfg).expect("build GcsStore against fake-gcs")
    }

    /// Per-object drain of `prefix` — list + single `remove` each. fake-gcs
    /// implements single-object DELETE but NOT the GCS batch-delete endpoint that
    /// opendal's `remove_all` issues for 2+ objects (that 400s with `deleted: 0`),
    /// so the emulator can't run the `cleanup_source` batch wipe. That wipe
    /// (`delete_under` → `remove_all`) is verified against a REAL bucket by the
    /// live BigQuery `StagingWiped` matrix, and over the Fs seam above; here we
    /// drain per-object for idempotent setup/teardown.
    fn drain(store: &GcsStore, prefix: &str) {
        for key in store.list_files(prefix).unwrap() {
            store.remove(&key).unwrap();
        }
    }

    #[test]
    #[ignore = "emulator: needs `docker compose up -d fake-gcs` (fsouza/fake-gcs-server :4443)"]
    fn storage_contract_over_fake_gcs() {
        let store = fake_gcs_store();
        // Test-owned prefix, drained first so a re-run starts clean even though the
        // emulator bucket persists (no cross-run bleed).
        let prefix = "load-contract/orders";
        drain(&store, prefix);
        let gs = format!("gs://{FAKE_GCS_BUCKET}/{prefix}");

        // Seed one Success run (its manifest + committed part) plus a crash orphan
        // — an unmanifested `.parquet` an interrupted extract would leave behind.
        store
            .put(
                &format!("{prefix}/manifest-r1.json"),
                &manifest_bytes("r1", 100, Some(100)),
            )
            .unwrap();
        store
            .put(&format!("{prefix}/part-000000.parquet"), b"rows-of-r1")
            .unwrap();
        store
            .put(&format!("{prefix}/orphan.parquet"), b"crash-leftover")
            .unwrap();

        // 1. fetch + parse the manifest back over real GCS list+read.
        let keyed = fetch_manifests_keyed(&store, &gs).unwrap();
        assert_eq!(keyed.len(), 1, "the run's manifest, read back over GCS");

        // 2. reconcile → file_rows, the value the warehouse COUNT(*) gate enforces.
        let manifests: Vec<_> = keyed.iter().map(|(_, m)| m.clone()).collect();
        assert_eq!(
            reconcile(&manifests, false).unwrap().file_rows,
            100,
            "file_rows drives the count-gate; a bad GCS read would corrupt it"
        );

        // 3. select_load_uris resolves the MANIFESTED part only — never the orphan.
        assert_eq!(
            select_load_uris(&store, &gs, &keyed).unwrap(),
            vec![format!(
                "gs://{FAKE_GCS_BUCKET}/{prefix}/part-000000.parquet"
            )],
            "load pulls the manifested part, not the unmanifested crash orphan"
        );

        // 4. gc_orphans deletes the orphan over real GCS — a REAL single-object
        // DELETE against the emulator — keeping the manifested part + manifest.
        let (removed, _bytes) = gc_orphans(&store, &gs, &keyed, false).unwrap();
        assert_eq!(
            removed, 1,
            "exactly the orphan parquet is GC'd over real GCS"
        );
        let mut left = store.list_files(prefix).unwrap();
        left.sort();
        assert_eq!(
            left,
            vec![
                format!("{prefix}/manifest-r1.json"),
                format!("{prefix}/part-000000.parquet"),
            ],
            "the manifested part + its manifest survive the orphan GC"
        );

        // cleanup_source's batch wipe (`remove_all`) is NOT emulatable here — see
        // `drain`. Teardown per-object; the empty listing confirms the deletes
        // landed over real GCS transport.
        drain(&store, prefix);
        assert!(
            store.list_files(prefix).unwrap().is_empty(),
            "teardown left the prefix clean over real GCS"
        );
    }
}