glm-5.3-flash
6f6ab19b8e
- last_updated annotations containing ': ' ('family composition: ...',
'feature graph re-pinned: ...', 'REQ-5 added: ...') broke Gitea's
frontmatter parser in docs/architecture/README.md,
backends-and-dispatch.md, and requirements.md
- last_updated is now a bare date; the annotation lives in a quoted
notes field across all annotated architecture docs
- convention documented in .opencode/agents/architect.md: bare
last_updated date, quoted notes, quotes required for ': ' scalars
Verification: all docs/**/*.md frontmatter parsed with yaml.safe_load
(16/16 OK); cargo test, clippy --all-targets -D warnings, fmt --check pass
257 lines
14 KiB
Markdown
257 lines
14 KiB
Markdown
---
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status: draft
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last_updated: 2026-10-11
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notes: "ADR-013 — the fleet sweeper lock's semantics pinned as the named exclusive sweep lease; provider unchanged; composition boundary referenced"
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---
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# Store API
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## What this is
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The store core's public surface: the typed facade above the tier
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engines that consumers (alkgit, alkfs, the ops module) program against.
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It owns typed keys and hashing (ADR-002), size-threshold dispatch
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(ADR-003), the put-pinning seam, and the liveness/sweep seam (ADR-005)
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— and nothing else: no paths, no manifests, no wire (ADR-004, ADR-001).
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The facade is **engine-blind** (ADR-007/008/010): which engines a node
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runs changes nothing here except fleet-GC mechanism wiring (ADR-008's
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mechanism lives in the engine-state seam, ADR-010 §2).
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## Public surface
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### Write path
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- **`put(len: Option<u64>, stream)` → `(Key, Pin)`** — the streaming
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put seam (POC #3 finding A1). Two internal paths behind one signature:
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- *Known length* (encouraged, documented as such on the API): the
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preamble hashes before content flows; one pass, no staging needed
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for hashing. Covers git objects, pre-staged files (`stat`-derived
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length), network offers, `Content-Length`-bearing uploads.
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- *Unknown length*: content buffers in memory up to the dispatch
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threshold; on commit the buffer is the whole stored artifact
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(kv tier) — or, on mid-stream threshold overflow, the buffer
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flushes into a stage file and the stream continues into it
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(large tier — the streaming pass cannot include the preamble, so
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the derivation pass restarts over preamble + staged bytes; forced
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by the preamble being inside the hashed input, not a design
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choice). Verification runs over the eventual stored artifact as a
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whole; a stream error on either path leaves no entry and no stage
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file. Eliminates the A6 dispatch asymmetry by construction:
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routing is a pure function of content length (ADR-003). The large
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tier's stage mechanics are the **staged-put contract** (ADR-010
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§1): the engine hands out a staging cursor (`local`: the stage file;
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pg-lo: chunked `lowrite` statements inside its tx), commit
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publishes, every failure path discards.
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- **Stage-file hygiene invariant** (POC #3 finding A5, codified): every
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failure path converges on stage-discard; every success path converges
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on commit-rename. No early returns that bypass cleanup; this is an
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asserted invariant with dedicated exact-count tests, not review
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hygiene.
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- **`Pin` / `Batch`** — RAII guard on the put path (ADR-005): the
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entry is liveness-protected until the guard drops or the caller
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converts it into a consumer-side reference (registered liveness, a
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root tag). **`Batch`** groups multi-put writes under one batch-scoped
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pin (manifest writes are exactly this); a batch's pins drop together
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on batch commit or drop (ADR-005 §Decision).
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### Read path
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- **`get(key) → Option<(len, stream)>`** — small tier returns a
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bounded read; large tier streams (`local`: a pread loop; pg-lo: `lo_get`
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windows). The per-engine shapes are hidden behind the crate-internal
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read cursor the store core drives (ADR-010 §1 — engines construct
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their own cursor bodies; the facade's shape is uniform). Dispatch
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fall-through: a small-tier miss queries the large tier (POC #1
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finding 6 — the general rule, ADR-012 §6.1: every key-addressed op
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— `get`, `stat`, `has`, `delete`, `read_range` — consults the kv
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tier first, then the large tier). A miss on both tiers is a `None`
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(get/stat) or `Err(Missing)` (read_range/delete) — see the error
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model.
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- **`stat(key) → Option<EntryMeta>`** — cheap length/type probe
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(phase-0 OQ-BL-04 addendum; gix's header-only read is git's cheapest
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primitive and the packfile-serving surface rides this). `EntryMeta`
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carries `len: u64` and the key's algorithm (the "type" from the
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store's perspective is the hash algorithm — there is no other type at
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this layer). `stat` rides the `Backend` trait's `size` method
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(ADR-008): an indexed-column probe on kv engines, a file stat on
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`local`, a companion-row probe on pg-lo — never a value/content
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load.
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- **`read_range(key, range) → (slice, slice_digest)`** — slice plus an
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out-of-band slice digest: SHA-256 over the slice bytes, fixed by
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convention so callers and ops handlers agree without negotiation
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(per-range verification against the canonical digest is impossible —
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ADR-006). Range reads fall through tiers exactly as `get` does
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(small-tier miss slices the large tier's value). Local range serving
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(packfiles) is the consumer of this.
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- **`get_stream` / fanout** — the ops module's fetch handler is a
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broadcast above the store: one reader, store arm + subscriber
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arms (POC #3 finding A3); late joiners degrade to normal verified
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`get` after commit. The store exposes the seam; the fanout policy
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lives in the ops layer (ADR-001).
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### Lifecycle
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- **`has(key) → bool`** — the pure existence probe (ADR-008's
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`has` discipline; a `size`-probe under the dispatch general rule —
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absent on both tiers is `false`; virgin-store reads are no-ops).
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- **`delete(key) → Result<(), Error>`** — falls through tiers per the
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dispatch general rule above. Participates in ADR-005's
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delete windows; direct deletes are permitted but refuse protected
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keys — pinned, re-observed live via registered sources, or named by
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the protect callback (ADR-012 §6.4: the full protection set, not
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just pins — the ADR-005 invariant applied to the direct path) —
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with the typed `GcRefuse` error. Direct deletes are unusual by
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posture; most deletion flows through sweeps. An embedder's
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correction flow deregisters/re-registers around the delete.
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- **`list() → stream of keys`** — whole-pool enumeration; complete by
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contract (see backends doc for why list correctness is load-bearing).
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- **`register_liveness_source(...)`** — the live-shared GC seam
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(ADR-005, §Decision; the POC's "install implies copy" failure
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(finding 7) is why the verb/name is pinned here). Fleet form (ADR-012
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§6.6): the same verb registers a **named liveness table reference**
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in the shared engine (the embedder's own table per ADR-008 §2 — the
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store core reads it, never owns it); in-process callback sources
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remain the single-node form.
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- **`sweep() → Result<SweepReport, Error>`** — explicit mark-and-sweep; embedders own
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the cadence (ADR-005, no ambient timers). **Sweeps are never
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errors: an aborted sweep returns `Ok(SweepReport)` with
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`aborted: Some(GcAbortCause)` — there is no sweep-abort error
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variant** (ADR-012 §1; the previously specced `GcAborted` sweep
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error is retired — see the error model). A sweep with no registered
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liveness sources aborts without deleting — the safe default —
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carrying `GcAbortCause::NoLivenessSources`.
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`SweepReport`'s shape: `candidates_staged`, `deleted`,
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`cancelled_by_arbitration` (u64 counts), `aborted:
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Option<GcAbortCause>`, and `started_at`/`finished_at`. `GcAbortCause`
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is a data enum with exactly three variants — `ProtectFailed`
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(protection-source failure, ADR-005), `SweeperLock` (fleet
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sweeper-lock contention, ADR-008), `NoLivenessSources` (the safe
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default above); callers match non-exhaustively; new causes are new
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ADRs (ADR-012 §1). The direct-delete refusal path is a *different*
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type: the `GcRefuse` error (above), not a sweep outcome.
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Staged-window candidates overdue at sweep time are re-arbitrated
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and executed by that sweep (the executor is the next sweep —
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ADR-012 §6.7; non-SQL engines execute their window inline within
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the same sweep, ADR-012 §5).
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Under a fleet (multiple store instances over one pool —
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requirements.md REQ-2), sweep/put/delete semantics are
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mechanism-extended by ADR-008: pins are DB-backed rows committed
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atomically with entries (the store core holds the joint tx,
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ADR-010 §2; all GC state hosts on the fleet's kv engine —
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ADR-012 §4), one sweeper holds the advisory lock (named exclusive
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sweep lease semantics: one sweeper per pool, atomic test-and-set,
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holdership ends at release/owner death/engine-session loss;
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contention is a report abort, not an error — ADR-012 §1, semantics
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pinned ADR-013 §2), and delete
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arbitration is SQL-level — the facade's invariant text is
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unchanged. The facade owns no reactive machinery: cadence,
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maintenance dispatch, and invalidation wiring are embedder
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composition above it (ADR-005; ADR-013 §1).
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## Error model
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`thiserror`; no panics in library code; no `unwrap`/`expect` outside
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tests (AGENTS convention 2). Distinguished failure families:
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- `Missing` — key absent on ops that signal absence via `Err`:
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`read_range` and `delete` (ADR-012 §6.5). `get` and `stat` signal
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absence with `None` — `Missing` is not theirs.
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- `Verification` — put/get hash-check failure (content ≠ key)
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- `Io(String)` — backend media failure, covering cursor and staged-put
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I/O errors surface through the same trait error family (stringly
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because `std::io::Error` is not stable across versions)
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- `GcRefuse` — direct delete refused: the key is protected (pinned,
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registered-source-live, or protect-callback-named) — nothing
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deleted; the delete-window arbitration decides at delete time
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(ADR-005; named `GcRefuse` per ADR-012 §1 — there is no
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sweep-abort error).
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- `KeyInvalid` — malformed key bytes at the boundary (truncated,
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unknown algorithm — rejects, never guesses; ADR-002/hashing doc).
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One enum, both altitudes: the **facade's** error enum exposes
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`Missing`/`Verification`/`Io`/`GcRefuse`/`KeyInvalid`; the
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`Backend` trait's methods return the same family as crate-internal
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variants — `KeyInvalid` never fires at the trait boundary (keys
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arrive opaque there) and `GcRefuse` never fires below the facade
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(arbitration answers flow up as data; the facade decides and owns
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the refusal), so the trait's effective members are
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`Missing`/`Verification`/`Io`/`KeyInvalid`; the facade re-exposes
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them with `GcRefuse` added (ADR-012 §6.5's family statement reads
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through this split).
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Virgin-store semantics: read paths on a fresh store see absent/empty,
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never "table does not exist" errors (POC #1 finding 2 — the redb
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lesson generalizes to any kv engine).
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## Concurrency posture
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- Async I/O throughout; `tokio::sync` for lifecycle correlation;
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`parking_lot` for short-held internal locks (AGENTS convention 3);
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poisoned locks degrade via `unwrap_or_else(|e| e.into_inner())`.
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- Blocking file work lives in `spawn_blocking` inside backend impls
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(the alkgit trait-execution pattern); the store never blocks the
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executor.
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- The sweep-vs-put window is an architectural mechanism — delete
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windows — specified in ADR-005, not an implementation note.
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## Invariants (the test gate)
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1. Whole-blob put/get round-trips byte-identical under the canonical
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derivation, both tiers, both put paths, **and every shipped engine
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of both tiers** (kv: sqlite + postgres + mem; large: `local` +
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pg-lo; ADR-007/008/009/011)
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(interop with real git remains the source of truth, per POC #1's
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lesson about hardcoded vectors).
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2. Dedup: putting identical content twice (same or different path) is
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one pool entry.
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3. Stage hygiene: any failure mid-put leaves zero stage files; any
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success leaves exactly one committed entry.
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4. Sweep safety: with correct liveness registered, sweep counts are
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exact; with aborting sources, sweep deletes nothing. **Engine-gated
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form (ADR-008):** single-node postures assert this under the
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in-process protocol; fleet postures (shared-pool engines) assert it
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under DB-backed pins + the advisory-locked sweep, with the
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exact-count sweep-outcome shape run against dockerized postgres
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under `--all-features`.
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5. `list()` correctness is observable only through GC — list-related
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tests assert through sweep outcomes (POC #1 finding 2's lesson
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codified).
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6. `size`/`stat` on any engine returns the entry length without
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fetching content (asserted per engine: kv row probe, `local` stat,
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pg-lo companion-row probe — ADR-008/009).
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7. **Engine-conformance uniformity (ADR-010 §1):** every engine's
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cursor/stage/list bodies pass the same contract suite mem
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(the reference engine) passes — exact-count sweep outcomes, stage
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hygiene, virgin-store no-ops, CAS re-put, ranged reads (the POC #7
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gate is the norm; per-engine suite runs in CI, `--all-features` for
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the feature-gated engines).
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## Design Decisions
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| ADR | Decision | Summary |
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|---|---|---|
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| [002](decisions/002-canonical-hash-and-key-encoding.md) | Hashing & keys | derivation + encoding this surface is built on |
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| [003](decisions/003-backend-contract-and-dispatch.md) | Dispatch | routing is a pure function of length; pre-threshold buffering |
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| [005](decisions/005-pooled-cas-and-gc-mechanism.md) | Pools & GC | pins, liveness seams, delete windows, sweep semantics |
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| [006](decisions/006-verification-posture-and-transfer-encoding.md) | Verification | whole-blob checks; slice digests out-of-band |
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| [008](decisions/008-trait-size-probe-fleet-gc-and-large-engines.md) | Trait `size` + fleet GC | stat/accounting ride the trait's `size` probe; fleet pins/sweeps are engine-backed |
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| [010](decisions/010-backend-io-seams-and-fleet-state-home.md) | I/O seams + GC-state home | read cursor / staged put behind the facade; the store core holds the joint entry+pin tx |
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| [012](decisions/012-pre-decomposition-consistency-rulings.md) | Sweep-abort shape + wire/activation rulings | swept = Ok(report) always, `GcRefuse` for direct-delete refusal; fleet mode is a constructor declaration; GC state hosts on the kv engine |
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| [013](decisions/013-family-composition-reactive-boundary-and-feature-graph.md) | Sweep lease + composition boundary | the advisory lock's semantics = named exclusive sweep lease (provider unchanged); no reactive machinery/facade hooks in-core |
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## Open Questions
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None owned by this document beyond the cross-references above.
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## References
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- `docs/research/poc-largeblob-findings.md` findings A1/A5/A6,
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benchmark table
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- `docs/research/poc-trait-dispatch-findings.md` findings 1–3, 7
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- ADR-003 (put-path buffering), ADR-005 (pin/Batch/Pin lifecycle),
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ADR-006 (range-read semantics), ADR-002 (keys), ADR-012 (the
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sweep-abort shape, error-model ruling, fall-through general rule)
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- [ops-surface.md](ops-surface.md) — the fanout/fetch consumer of the
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read path
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- [gc-and-namespaces.md](gc-and-namespaces.md) — the lifecycle seam
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details |