807 lines
46 KiB
Markdown
807 lines
46 KiB
Markdown
---
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status: draft
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last_updated: 2026-10-08 (ADR-023 — fourth review round: numeric-argument domains pinned by kind, encode_payload typed, plain-path SQLite open, watcher cadence posture)
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---
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# Core contract
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The unified, engine-agnostic surface a `Store` exposes. This document
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specifies WHAT the contract is; the per-engine specs map it onto their
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machinery; ADRs carry the WHY. The starting artifact is the honker-rs
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surface (the Phase 0 §Interface finding) scoped to the
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inventory-confirmed features — [ADR-002](decisions/002-feature-scope.md)
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— and pinned against it. The base surface is pinned by
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[ADR-008](decisions/008-contract-v1-pinning.md) (contract v1 partition,
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`TxHandle` representation, wake type, reserved strings, error
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taxonomy, config split — amended in place, pre-implementation, by
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[ADR-014](decisions/014-outbox-tx-enqueue.md): `outbox_enqueue_tx`
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joins the `TxHandle` trait, and by
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[ADR-015](decisions/015-streams-depth.md): streams depth — key
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semantics, `StreamEvent` shape, the ordering row, `trim_to`,
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and `publish_with_key_tx`); ADR-009/ADR-010 add the first extensions
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beyond ADR-008's original v1 partition (scheduler collapse surface,
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`QueueOpts` depth — factually pre-release additions per ADR-017's
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class 1, shipped inside the initial contract v1 text; versioning
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discipline for the surface's changes is
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[ADR-017](decisions/017-contract-versioning.md)'s, resolved: the
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core crate's semver is the contract version);
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[ADR-016](decisions/016-deployment-honesty.md) decides the parked
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capability-surface question: **none, by default ever** — engine
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differences surface at compile time (engine-crate identity) and in
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the [deployment matrix](deployment.md), never as a runtime
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descriptor; the
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*obligations* are this document.
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## Concepts
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- **Store** — what a consumer opens from a connection string or file
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path ([ADR-001](decisions/001-crate-split.md)): one handle, the engine
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behind it chosen at open time. Consumer code never branches on
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engine type (guiding principle 4).
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- **Mechanism** — one of the surface's coordination families: notify,
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streams, queues (+outbox), locks, scheduler. Delivery guarantees are
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pinned per mechanism in [ADR-006](decisions/006-wake-and-delivery-contract.md)'s
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table (notify/streams/queues), extended with the locks row by
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[ADR-008](decisions/008-contract-v1-pinning.md), the scheduler row
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and collapse by [ADR-009](decisions/009-scheduler-collapse.md).
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*(Guiding principles are defined in `docs/research/phase-0.md`
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§Vision and cited by number throughout this directory.)*
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- **Wake** — the opaque "something changed, re-read" signal the wake
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contract delivers ([ADR-006](decisions/006-wake-and-delivery-contract.md)).
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The contract's central abstraction.
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- **TxHandle** — the caller-held transaction object whose `*_tx`
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methods make side effects commit-atomic with a business write
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([ADR-007](decisions/007-transactional-seam.md)). Contract shape:
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the `*_tx` methods live on the `TxHandle` trait itself — engines
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implement it for their concrete handle, no downcast
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([ADR-008](decisions/008-contract-v1-pinning.md) §2).
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## The seam
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Per [ADR-008](decisions/008-contract-v1-pinning.md) §6, the trait is
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constructed by engine crates (durability knobs, pool sizing, watcher
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cadence are engine options — [deployment.md](deployment.md) carries
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the facts); the contract is the trait surface it returns:
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```text
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Store::begin_tx() -> Box<dyn TxHandle + Send>
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trait TxHandle {
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enqueue_tx(name, opts, payload) -> job_id
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publish_tx(stream, payload) -> offset
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publish_with_key_tx(stream, key, payload) -> offset
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notify_tx(channel, payload)
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save_offset_tx(stream, consumer, offset)
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get_job_tx(queue, job_id) -> Option<Job> // ADR-021
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get_offset_tx(stream, consumer) -> i64 // ADR-021
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read_since_tx(stream, offset, limit) -> Vec<StreamEvent> // ADR-021
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read_from_consumer_tx(stream, consumer, limit) -> Vec<StreamEvent> // ADR-021
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outbox_enqueue_tx(outbox, opts, payload) -> job_id
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commit(self: Box<Self>) -> Result<()> // or rollback
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}
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```
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The tx read methods (`get_job_tx` / `get_offset_tx` / `read_since_tx`
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/ `read_from_consumer_tx`,
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[ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §1) make
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read-your-own-writes possible inside the business transaction — they
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take the mechanism name (mirroring `enqueue_tx`/`publish_tx`'s
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name-taking shape), read the caller's own transaction's rows, and are
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pure reads (no ops ride them). Reads and saves are tx-shaped;
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claim/maintenance ops never are (no `claim_tx` — a claim's visibility
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deadline must not be tied to a business transaction's lifetime;
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deliberate absence, not an omission). **Dropping a handle without
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`commit`/`rollback` rolls it back**
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([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §4) — the
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no-ghosts property holds through
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RAII paths, not only the explicit ones.
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`outbox_enqueue_tx` takes the **outbox name** and derives the backing
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queue engine-side (the reserved prefix makes the derived name
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unreachable by `enqueue_tx` by design —
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[ADR-014](decisions/014-outbox-tx-enqueue.md)).
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`publish_with_key_tx` validates the key like the non-tx form (a
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present key must be non-empty → `InvalidName`) and is
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`publish_tx`'s keyed twin — commit-atomic keyed publishes are the
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point ([ADR-015](decisions/015-streams-depth.md) §2).
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Mechanism handles come off the store (or, for transactional variants,
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off the handle). **Payload encoding** ([ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md)
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§4, signature typed by [ADR-023](decisions/023-fourth-review-round.md)
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§1): the trait crosses `serde_json::Value`; engines serialize it with
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serde_json via core's `encode_payload` (fallible — `Codec` on
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serialization failure, typed at the helper; never a silent fallback
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form) and store exactly those bytes — `payload_as<T>` decodes
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them, `Codec` on failure; round-trip (publish → read → decode →
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`Value` equality) is what the contract suite pins, on both engines.
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**Numeric-argument domains** ([ADR-023](decisions/023-fourth-review-round.md)
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§2) — classified by argument kind, uniform on both engines (no engine
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may reinterpret a caller-supplied numeric argument via SQL-dialect
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semantics; validation happens at the trait-impl entry point, before
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the engine's storage layer):
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- **Extents** ("at most this many": `claim_batch(n)`,
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`read_since(limit)`, `read_from_consumer(limit)`) — non-positive
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values yield the **empty value result** (a value, not an error —
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the no-work vocabulary); the SQLite `LIMIT -1` dialect artifact
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(a negative extent reaching the whole queue/stream) is dead by
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this rule.
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- **Durations** (`try_lock(ttl)`, `renew(ttl)`) — non-positive values
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are rejections (`Err`, opaque `Database`, detail in the source
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chain); an exclusion mechanism must not silently hand back a lease
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the caller believes it holds.
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- **Boundaries/offsets** (`trim_to(horizon)`, enqueue `delay`/
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`run_at`/`expires`) — total: any `i64` is well-defined (a negative
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horizon deletes nothing; a negative delay resolves to a ready
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time in the past, i.e. ready now).
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```text
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store.notify(channel, payload) handle.notify_tx(channel, payload)
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store.stream(name) -> StreamHandle handle.publish_tx / publish_with_key_tx
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handle.save_offset_tx
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(the StreamHandle also carries
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trim_to — stream-side, outside the
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tx seam)
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store.queue(name, opts) -> Queue handle.enqueue_tx
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store.outbox(name) -> Outbox handle.outbox_enqueue_tx(outbox, opts, payload)
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store.try_lock(name, owner, ttl) -> Option<Lock>
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store.listen(channel) -> Box<dyn WakeReceiver>
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store.schedule(name, spec, queue, payload, opts) -> Result<Schedule>
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store.unschedule(name) -> bool
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store.run_schedules(stop: StopToken) -> Result<()>
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```
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The mechanism handles' full trait surfaces (`Queue { enqueue,
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claim_one, claim_batch, ack_batch, cancel, get_job, sweep_expired }`,
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`StreamHandle { publish, publish_with_key, read_since,
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read_from_consumer, save_offset, get_offset, trim_to, subscribe }`,
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`Outbox { enqueue, run_once }`, `Lock { renew, release }`, plus the
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boxed `JobHandle` a claim returns) are pinned by
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[ADR-019](decisions/019-mechanism-handle-surfaces.md); the
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`StopToken` parameter is a core-crate type (same ADR, §4).
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Payloads cross the trait as core value types (non-generic trait
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methods — object safety of the boxed handles,
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[ADR-008](decisions/008-contract-v1-pinning.md) §2); `payload_as<T>`
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decodes on concrete returned values (`Job`, `StreamEvent`). The
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`with_tx` closure wrapper ships over the handle shape (the POC-verified
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composition direction, [ADR-007](decisions/007-transactional-seam.md);
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signature pinned there 2026-10-07: `with_tx(f) -> Result<()>` with
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`f: FnOnce(&mut dyn TxHandle) -> BoxedFuture<Result<()>>` — `Ok` ⇒
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commit, `Err`/drop/panic ⇒ rollback; non-generic for object safety,
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values return through captured state, no handle escapes the closure).
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Mechanism handles (`Queue`, `StreamHandle`, `Outbox`, `Lock`) are
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core-owned trait objects like the tx handle — engine types never appear
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in consumer signatures. Their trait surfaces are pinned by
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[ADR-019](decisions/019-mechanism-handle-surfaces.md) (placement
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mirroring the honker-rs starting artifact: claim/maintenance ops on the
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`Queue` handle, publish/read/trim on the `StreamHandle`, the claim ops
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on the boxed `JobHandle`, `run_once` on the `Outbox`); trait-method
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additions on these traits post-release ride
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[ADR-017](decisions/017-contract-versioning.md) class 2 like any
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other trait surface.
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## Mechanism contracts
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### notify / listen
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Fire-and-forget signals, commit-atomic when sent in a transaction
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([ADR-007](decisions/007-transactional-seam.md)). No durability, no
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replay, no per-listener retry; a listener attached after a commit
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never sees it.
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- `notify(channel, payload)` — payload ≤ 8000 bytes on Postgres
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(client-side checked, typed `PayloadTooLarge` before the round
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trip, verified by POC #2; the measured quantity is the serde_json
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serialization of the payload `Value` — ADR-020 §4's stored-bytes
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form, so check and storage measure one thing); no limit on SQLite.
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The error variant is
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contract-wide (callers match it identically on both engines), the
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*occurrence* is the documented engine asymmetry
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([ADR-008](decisions/008-contract-v1-pinning.md) §5) — with no
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capability surface
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([ADR-016](decisions/016-deployment-honesty.md)), this variant is
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the one runtime carriage of an engine asymmetry; its occurrence
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asymmetry is pinned in the verification backlog below.
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- `listen(channel) -> Box<dyn WakeReceiver>` — starts from "now";
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delivers opaque `Wake { channel }` signals
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([ADR-006](decisions/006-wake-and-delivery-contract.md)), never
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payloads or ids ([ADR-008](decisions/008-contract-v1-pinning.md) §3).
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Wakes are **best-effort hints, not per-commit delivery promises**:
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possibly coalesced (SQLite) or per-notify (Postgres), possibly
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repeated after reconnect, possibly absent entirely (SQLite burst
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coalescing; the pg no-replay hole) — recovery is the consumer's
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re-read plus the engine's reconnect surface, never a guaranteed
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deliver. **Consumers must be idempotent on wake.**
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- Failure surfaces as channel events, never silence: watcher death
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closes the receiver (`recv() -> None`, SQLite); the synthetic
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reconnect-wake (a reserved channel
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([ADR-004](decisions/004-postgres-driver.md))) covers Postgres
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connection gaps.
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- Channel name is the one piece of semantic content a wake carries —
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the invalidation key for caching subscribers.
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### streams
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Durable pub/sub with per-consumer offsets
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([ADR-006](decisions/006-wake-and-delivery-contract.md)). The durable
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cousin of notify: publish is commit-atomic; every committed event is
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readable by every consumer whose offset hasn't passed it;
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replay-on-attach is the default; offsets are explicit and
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transaction-aware (`save_offset_tx` gives exactly-once-within-a-
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business-tx shape). Depth pinned by
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[ADR-015](decisions/015-streams-depth.md).
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- `publish` / `publish_tx` / `publish_with_key` / `publish_with_key_tx`
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— append to the stream's durable log; return the assigned offset.
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**Key semantics ([ADR-015](decisions/015-streams-depth.md) §1): the
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key is carried metadata** — stored on the event row, round-tripped
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on every read, `Option<String>`-shaped on `StreamEvent` — with no
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engine-enforced behavioral role: **the ordering guarantee stays
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global FIFO by offset within the stream**; per-key in-order reading
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is the documented emergent pattern (filter by key, read in offset
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order), not a server promise. A present key must be non-empty
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(`InvalidName`). Server-enforced per-key ordering re-enters only
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via a consumer-inventory row naming it.
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- **`StreamEvent` shape** ([ADR-015](decisions/015-streams-depth.md)
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§3): `{ offset: i64, stream: String, key: Option<String>, payload:
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Vec<u8>, created_at: i64 }` — `stream` renames honker's `topic`
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(one term everywhere, the ADR-008 §4 kinds list); `offset` is
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engine-assigned, monotone per stream, **immutable, never renumbered**
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(gaps after a trim are legal); `created_at` is unix-seconds-at-
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publish, informational, **not an ordering field** (offset is the
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only one); `payload_as<T>` decodes (the error is `Codec`).
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- **Ordering guarantee row** ([ADR-015](decisions/015-streams-depth.md)
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§4, extending [ADR-006](decisions/006-wake-and-delivery-contract.md)
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§2's streams row): `read_since`/`subscribe` yield `offset ASC` —
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global FIFO per stream; committed-event visibility and
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replay-on-attach as already pinned; offsets immutable. The
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contract suite pins cross-engine equivalence against this row
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(same publish sequence → same offset sequence → same read order).
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- `read_since` / `read_from_consumer(offset)` — cursor-based reads;
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`get_offset(consumer)` — checkpoint inspection. A read from a
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trimmed-away offset region (below) resumes at the trim horizon's
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first remaining row.
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- `save_offset` / `save_offset_tx` — consumer checkpoint, explicit;
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**the contract's save is always explicit** (no auto-checkpoint
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cadence — honker's per-binding ambiguity is not inherited). The
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subscription handle exposes no `save_every` / auto-save-on-drop
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([ADR-008](decisions/008-contract-v1-pinning.md) §8). Saves are
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monotone — a save below the stored checkpoint is a silent no-op —
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so the direct form and the receiver's no-arg form
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(`EventReceiver::save_offset(&mut self)`, which saves the
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last-yielded event's offset through the same op,
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[ADR-019](decisions/019-mechanism-handle-surfaces.md) §6)
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interleave freely and cannot regress one another. Both save
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forms' `Err` arm carries `Database` only
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([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §5) —
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regression refusal is a silent no-op, so a save result errs only
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on storage failure. A saved offset
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below the trim horizon
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([ADR-015](decisions/015-streams-depth.md) §5) stays a valid
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position marker.
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- `trim_to(horizon) -> count` — delete events with `offset <= horizon`
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(exact-boundary; the horizon is a boundary argument, total per
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[ADR-023](decisions/023-fourth-review-round.md) §2 — a negative
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horizon deletes nothing, idempotently)
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([ADR-015](decisions/015-streams-depth.md) §5; the return is the
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deleted-row count, [ADR-019](decisions/019-mechanism-handle-surfaces.md)). The stream-side
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bounded-growth op, consumer-invoked, no engine-default
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retention and no ambient sweeper (the ADR-010 §6 posture; the
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replay-forever default is the mechanism's purpose — growth is
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documented with the tool in-contract to bound it). Trim emits no
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dedicated wake and no notify — on SQLite the `data_version`
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watcher may still fire (any committed write bumps it; a spurious
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hint, contract-legal); surviving events keep their offsets.
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- `subscribe(consumer) -> Box<dyn EventReceiver>` — durable
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consumption: attach, read to current tail, resume after restart
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from the stored offset; explicit `save_offset` on the receiver
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(shape in [ADR-008](decisions/008-contract-v1-pinning.md) §8).
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**Error and close arms pinned**
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([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §5):
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`recv()`'s `Err` arm carries `Database` only (payloads cross raw;
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`Codec` lives at `payload_as<T>`; `Closed` is the `None` arm);
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close is terminal and its *cause* is the documented engine
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asymmetry — SQLite's receiver closes on watcher death (POC-pinned),
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the pg receiver stays open across forwarder reconnects (reconnect
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wakes arrive on it) and closes only at engine shutdown. A closed
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receiver never reopens; recovery is a fresh `subscribe(consumer)`
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resuming from the saved offset.
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Consumption is wake-driven with table re-read — the same
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mechanism split as queues (durable row, LISTEN/watcher wake,
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[ADR-006](decisions/006-wake-and-delivery-contract.md)); the
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receiver's engine-side trigger is engine-internal, but events
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never require polling to become visible (the queues row's pg
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re-poll safety net is an admission of LISTEN loss, not the
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posture).
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### queues
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Durable at-least-once work
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([ADR-002](decisions/002-feature-scope.md)). Depth pinned by
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[ADR-010](decisions/010-queue-semantics-depth.md); contract-level
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obligations:
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- `enqueue` / `enqueue_tx` — commit-atomic; `EnqueueOpts { delay,
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run_at, priority, max_attempts, expires }`; **field types pinned
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(2026-10-07, third review round follow-through)**: `delay`,
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`run_at`, `expires` are `Option<i64>` (honker-rs parity,
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`packages/honker-rs/src/lib.rs:439-447` — unset is distinguishable
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from zero, and the resolution rules below are the unset behavior),
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`priority` is a plain `i64` with default **0** (the claim-order
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key; the row schema's `DEFAULT 0`), and `max_attempts` is
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`Option<i64>` with `None` = the queue-level stamp decides (the
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§3a override; no honker counterpart — our field). Every field has
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a default-resolved meaning, so all are constructor-settable with
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`..Default::default()`. Queue-level
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`QueueOpts { visibility_timeout_s, max_attempts, backoff_base_s,
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dead_letter_retention_s }` ([ADR-010](decisions/010-queue-semantics-depth.md)
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§3/§3a): plain `i64` fields (`dead_letter_retention_s:
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Option<i64>`, `None` = forever) with a `Default` providing the
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pinned defaults 300/3/5/none (honker parities except retention,
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which is ours); `ScheduleOpts { priority, max_attempts, expires }`
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types identical to their `EnqueueOpts` twins. **Option semantics
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([ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md))**:
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ready time resolves `delay` → `now + delay` (wins) over `run_at` →
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literal absolute over neither → now; `expires` is relative seconds
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from enqueue resolved to an absolute row `expires_at` (`None` =
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never); the resolved values — not the raw fields — are what
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`get_job` shows. The `QueueOpts` stamps land on each job row at
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enqueue (§3a), resolved per
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[ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md) §3 by
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call shape: the auto-commit `Queue::enqueue` (the one handle-carrying
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shape) resolves over that handle's opts; `enqueue_tx` (a
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`TxHandle` carries no queue opts) and every other no-handle-open
|
|
path — outbox backing queues, scheduler boundary fires — stamp the
|
|
engine's derived defaults (plain 300/3/5/none; the outbox's
|
|
60/5/5 set).
|
|
- `claim_one` / `claim_batch` — exactly-once handout under concurrency
|
|
(POC-pinned on both engines); take a caller-supplied `worker_id`
|
|
(claimant identity — consumer-local, no reserved rule, non-empty;
|
|
[ADR-019](decisions/019-mechanism-handle-surfaces.md) §2); claim
|
|
ordering: priority DESC, then
|
|
ready-time, then enqueue order (FIFO under equal priority). Claims
|
|
return boxed `JobHandle`s — ops + row value (same ADR, §3).
|
|
`claim_batch(n)`'s `n` is an extent
|
|
([ADR-023](decisions/023-fourth-review-round.md) §2): `n <= 0`
|
|
claims nothing (the empty `Vec`, a value — never an error, never
|
|
the whole queue).
|
|
- Job handle: `ack / retry / fail / heartbeat` on the boxed
|
|
`JobHandle` a claim returns ([ADR-019](decisions/019-mechanism-handle-surfaces.md)
|
|
§3 — `job(&self) -> &Job` beside the ops; one-shot `self: Box<Self>`
|
|
ops like the tx commit). The one-shot/repeatable split is
|
|
deliberate: `ack`/`retry`/`fail` consume the handle (each is a
|
|
terminal transition of the claim); **`heartbeat(self, extend)`
|
|
takes `&self` and is repeatable** — renewal is inherently repeated
|
|
within one claim; do not "fix" this asymmetry at implementation
|
|
([ADR-019](decisions/019-mechanism-handle-surfaces.md) §3). `ack`
|
|
deletes the row;
|
|
`heartbeat(extend)` is *renewal* — an absolute reset of the claim
|
|
deadline (extend is the new full deadline from now, **not additive**
|
|
to elapsed time); late heartbeat refused; **a reclaim consumes an
|
|
attempt**; `retry(err, None)` computes the queue's equal-jitter
|
|
exponential delay (range pinned by
|
|
[ADR-010](decisions/010-queue-semantics-depth.md) §3), `retry(err,
|
|
Some(d))` overrides; `fail` = immediate dead-letter. Handle-op
|
|
validity (uniform predicate): an op succeeds only while the row is
|
|
`processing` and the caller's claim deadline is unexpired — deadline
|
|
lapse refuses all handle ops (heartbeats, acks included) and a
|
|
reclaim does too; the dual-execution window's worker may still
|
|
complete its work but its ack will not land (at-least-once, as
|
|
documented); false, not error
|
|
([ADR-010](decisions/010-queue-semantics-depth.md) §2). Dead letters:
|
|
move-to-dead storage, `get_job` sees dead rows (with
|
|
`last_error`/`died_at`), retention via `dead_letter_retention_s`
|
|
(default forever), no redrive API
|
|
([ADR-010](decisions/010-queue-semantics-depth.md) §1–§4).
|
|
`QueueOpts` stamp onto the job row at enqueue (§3a) — queues are
|
|
names, not config owners. The remaining v1-skeleton ops (`ack_batch`
|
|
— the batch ack applies the uniform predicate per id, lapsed or
|
|
non-claimed ids silently not counted; `cancel` — unconditional
|
|
delete, not an interrupt) pin in
|
|
[ADR-010](decisions/010-queue-semantics-depth.md) §1.
|
|
- `sweep_expired()` — moves *every* past-expiry row (any state) to
|
|
dead + enforces dead-letter retention — the no-stranded-rows
|
|
property ([ADR-010](decisions/010-queue-semantics-depth.md) §5);
|
|
the queue-scoped handle form ([ADR-019](decisions/019-mechanism-handle-surfaces.md)
|
|
§1 — the name rides the handle); cadence recipe in
|
|
[queues.md](queues.md) (no ambient sweeper).
|
|
|
|
### named locks
|
|
|
|
TTL-bounded coordination locks. Lock rows live in the same database
|
|
as the caller's business data — coordination and data co-locate —
|
|
but lock ops are **not** part of the tx seam: there is no `lock_tx`;
|
|
a lock held across a business transaction is held by explicit
|
|
acquisition before/inside it, not transaction-scoped (acquisition is
|
|
a separate auto-commit op; rollback of the business tx does not
|
|
release it — the TTL discipline governs).
|
|
|
|
- `try_lock(name, owner, ttl)` — acquire or fail (`Option<Lock>` —
|
|
no-work is a value, not an error); `renew` and `release` on the
|
|
lock handle. Release on explicit unlock or TTL expiry.
|
|
Re-acquirable after expiry (POC-pinned on Postgres; on SQLite it
|
|
rests on the forked substrate's lock machinery — the SQLite-side pin
|
|
is in the verification backlog below). `ttl <= 0` is a rejection
|
|
(duration kind, [ADR-023](decisions/023-fourth-review-round.md) §2)
|
|
— opaque `Err`, never a silent immediately-expired lease.
|
|
- **Guarantee row** ([ADR-008](decisions/008-contract-v1-pinning.md)
|
|
§7): mutual exclusion bounded by TTL + renewal — after TTL expiry
|
|
exclusion lapses *silently* (no revocation event); holders must
|
|
`renew` within TTL; expiry is a loss of exclusivity, not an error.
|
|
- Lock names are shared-namespace (reserved-prefix rules below,
|
|
[ADR-008](decisions/008-contract-v1-pinning.md) §4).
|
|
|
|
### outbox
|
|
|
|
A helper over queues, not a separate mechanism: enqueue inside the
|
|
business transaction + the delivery/consumption worker entry points.
|
|
Same evidence base and guarantee as queues
|
|
([ADR-002](decisions/002-feature-scope.md)). Worker semantics
|
|
(honker's `run_once` shape, inherited as the pinned posture; the
|
|
delivery callable's shape pinned by
|
|
[ADR-019](decisions/019-mechanism-handle-surfaces.md) §5):
|
|
`run_once(worker_id, delivery) -> bool` is a *pull* op — claim one
|
|
job, run
|
|
the delivery closure, `ack` on `Ok`, `retry(err, None)` (the queue's
|
|
curve) on `Err`; the consumer calls it in its own loop. **No
|
|
engine-issued heartbeat inside delivery** (honker parity, inherited
|
|
deliberately — the helper does not auto-heartbeat on the caller's
|
|
behalf; the boxed `JobHandle`'s own `heartbeat` remains available to
|
|
the delivery closure, and renewal inside the deadline is the
|
|
consumer's obligation):
|
|
delivery slower than the backing queue's stamped visibility timeout
|
|
(default 60 s for outbox-backed queues) can have its claim expire
|
|
mid-delivery and be redelivered — the dual-execution window;
|
|
idempotent delivery is the consumer's obligation, same as queues.
|
|
|
|
The transactional enqueue side is `outbox_enqueue_tx(outbox, opts,
|
|
payload)` on the `TxHandle` trait
|
|
([ADR-014](decisions/014-outbox-tx-enqueue.md)): it takes the outbox
|
|
name (validated like `store.outbox(name)` — empty → `InvalidName`,
|
|
reserved-prefixed → `ReservedName`), derives the backing queue name
|
|
engine-side, and lands the job row in the caller's transaction with
|
|
`EnqueueOpts` stamped per
|
|
[ADR-010](decisions/010-queue-semantics-depth.md) §3a over the backing
|
|
queue's derived `QueueOpts`. Commit
|
|
makes the job visible to `run_once` exactly when the business write
|
|
commits; rollback drops both (the no-ghosts property,
|
|
[ADR-007](decisions/007-transactional-seam.md)). The derived backing
|
|
queue name is not expressible through `enqueue_tx` (the reserved
|
|
prefix is rejected on directly-supplied names) —
|
|
`outbox_enqueue_tx` is the only transactional path into it, which is
|
|
itself the guarantee that the derivation cannot be collided with.
|
|
|
|
### scheduler
|
|
|
|
Collapsed into queues per [ADR-009](decisions/009-scheduler-collapse.md):
|
|
`schedule(name, spec, queue, payload, opts)` (upsert by name),
|
|
`unschedule(name)`, and the opt-in `run_schedules(stop: StopToken)`
|
|
runner (`StopToken` is a core-crate cloneable cancel handle —
|
|
[ADR-019](decisions/019-mechanism-handle-surfaces.md) §4; the
|
|
leader-elected leadership lock is the reserved name
|
|
`__alkstore_scheduler`). Both name-bearing arguments validate at the
|
|
entry point: the schedule *name* like a queue name (non-empty,
|
|
reserved-prefix rejected —
|
|
[ADR-009](decisions/009-scheduler-collapse.md) §1) and, since
|
|
[ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §3, the
|
|
**queue argument** identically (`InvalidName`/`ReservedName`) — a
|
|
schedule cannot target a reserved name, so the outbox backing queue
|
|
stays reachable only through the outbox surface
|
|
([ADR-014](decisions/014-outbox-tx-enqueue.md)). Schedules never fire
|
|
without a runner (no ambient timers). v1 spec grammar:
|
|
`@every <n><unit>` only (`s|m|h|d`); cron strings are rejected
|
|
(`InvalidSpec`) pending a consumer-inventory row naming wall-clock
|
|
cron. Each boundary fire enqueues ordinary work stamped with
|
|
`ScheduleOpts { priority, max_attempts, expires }`
|
|
([ADR-009](decisions/009-scheduler-collapse.md) §3) — resolved over
|
|
the target queue's *derived engine defaults* (visibility/backoff/
|
|
retention; no handle is open), per
|
|
[ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md) §3.
|
|
Boundary
|
|
guarantee: [ADR-009](decisions/009-scheduler-collapse.md) §4
|
|
(at-least-once per elapsed boundary, bounded catch-up with
|
|
skip-forward past the cap).
|
|
|
|
## Cross-cutting contracts
|
|
|
|
### Delivery-guarantee table
|
|
|
|
The per-mechanism table in
|
|
[ADR-006](decisions/006-wake-and-delivery-contract.md) is the contract
|
|
of record for notify/streams/queues; the locks row is
|
|
[ADR-008](decisions/008-contract-v1-pinning.md) §7's and the scheduler
|
|
row is [ADR-009](decisions/009-scheduler-collapse.md) §4's. This spec
|
|
inherits them and adds the consumer obligations:
|
|
|
|
- wake idempotence (notify's best-effort, coalescing behavior);
|
|
- explicit offset saves (streams);
|
|
- visibility-timeout budgeting — heartbeat inside the deadline for
|
|
long work; the dual-execution window and reclaim-eats-attempt rules
|
|
are documented consumer obligations
|
|
([ADR-010](decisions/010-queue-semantics-depth.md) §2);
|
|
- running `run_schedules` for schedules to fire at all, and scheduling
|
|
sweep cadences via the collapse recipe — timeliness is the
|
|
consumer's, correctness-of-transition the engine's
|
|
([ADR-010](decisions/010-queue-semantics-depth.md) §6);
|
|
- `*_tx` operations are *only* durable after the caller's commit —
|
|
rollback drops job rows, event rows (keyed and unkeyed alike),
|
|
notifications, and offset saves together (the no-ghosts property,
|
|
POC-pinned on both engines).
|
|
|
|
### Errors
|
|
|
|
`thiserror`-typed, per the family standard. Pinned by
|
|
[ADR-008](decisions/008-contract-v1-pinning.md) §5: one top-level
|
|
`Error`, with v1 variants `PayloadTooLarge` (universal; produced
|
|
pg-side, contract-wide matchable), `ReservedName`, `InvalidName`,
|
|
`Closed`, `Codec`, and the opaque `Database` fallback (engine detail
|
|
preserved via the source chain). `InvalidSpec` (schedule spec grammar)
|
|
and `LeadershipLost` (`run_schedules` return on leadership loss) —
|
|
both from [ADR-009](decisions/009-scheduler-collapse.md) §6 — are
|
|
part of contract v1's initial text (pre-release additions per
|
|
[ADR-017](decisions/017-contract-versioning.md) class 1; the
|
|
"post-v1 additions" framing an earlier draft used is retired). Pinning rule: a variant exists only when
|
|
callers can act differently on it. Queue claim "no work" and job/lock
|
|
boolean results are values, not errors; dead-letter is observable
|
|
state (`get_job`), not an error.
|
|
|
|
### Capability surface
|
|
|
|
None — decided by
|
|
[ADR-016](decisions/016-deployment-honesty.md) (2026-10-06): `Store`
|
|
carries no capabilities accessor, in v1 and by default ever. The
|
|
honest single-host/multi-host boundary lives at compile time (the
|
|
engine-crate dependency *is* the deployment statement —
|
|
[ADR-001](decisions/001-crate-split.md)'s single-driver binaries) and
|
|
in [deployment.md](deployment.md)'s matrix. Runtime carriage of the
|
|
one caller-actionable engine asymmetry is the contract-wide
|
|
matchable `PayloadTooLarge` variant (Errors above); re-entry requires
|
|
a consumer-inventory row naming a runtime-adapt need.
|
|
|
|
### Naming / reserved namespace
|
|
|
|
Consumer-visible names (channels, streams, queues, outboxes, locks,
|
|
and schedule names) share engine-visible namespaces on Postgres (LISTEN
|
|
channel names are server-global per database). The canonical kinds
|
|
list is exactly these six (notify/stream/queue/outbox/lock/schedule;
|
|
pinned by [ADR-008](decisions/008-contract-v1-pinning.md) §4, outbox
|
|
added by [ADR-014](decisions/014-outbox-tx-enqueue.md), schedule names
|
|
by [ADR-009](decisions/009-scheduler-collapse.md) §1):
|
|
|
|
- Reserved prefix **`__alkstore_`**, engine-independent, applies
|
|
across all name kinds; the one v1-reserved string is
|
|
`__alkstore_listener_reconnected__` (the Postgres reconnect-wake
|
|
channel, [ADR-004](decisions/004-postgres-driver.md)).
|
|
- Reserved-prefix names are rejected at every entry point — the
|
|
name-bearing methods *and their `*_tx` counterparts* — with the
|
|
typed `ReservedName` error; empty names with `InvalidName`
|
|
([ADR-008](decisions/008-contract-v1-pinning.md) §4 — enforced as
|
|
non-empty-after-whitespace-exclusion per that ADR's wave-1 review
|
|
annotation: whitespace-only names are `InvalidName` on both name
|
|
classes; names are not trimmed). Stream-consumer
|
|
names are consumer-local identifiers, not a reserved-namespace kind.
|
|
- Engine-derived names in consumer namespaces carry the reserved
|
|
prefix (the outbox's backing queue is derived under the prefix —
|
|
honker's `_outbox:{name}` scheme is not inherited verbatim).
|
|
- SQLite: the substrate's `__alkstore_*` internal table family is
|
|
storage-internal (not consumer namespace) — re-owned from upstream's
|
|
`_honker_*` by the fork ([ADR-011](decisions/011-sqlite-substrate-fork.md),
|
|
designed per [ADR-012](decisions/012-forked-substrate-design.md)).
|
|
Postgres: engine tables are
|
|
schema-scoped — one engine-owned schema
|
|
([ADR-010](decisions/010-queue-semantics-depth.md) §8) — the
|
|
*channel* namespace is this section's.
|
|
|
|
## Verification backlog
|
|
|
|
Contract properties POC-pinned on one engine only (or sketched rather
|
|
than surface-verified) — the contract test suite must pin both engines
|
|
before the engine specs are called `stable`:
|
|
|
|
- **Named-lock TTL/expiry re-acquisition on SQLite** — pinned on
|
|
Postgres (pg POC's lock probe); on SQLite it rests on the forked
|
|
substrate's lock machinery (its `lock_renew` verified in the quality
|
|
read; the re-acquire-does-not-refresh-TTL behavior is upstream's,
|
|
inherited deliberately) — pin it in the contract suite.
|
|
- **Wake semantics under `WakeReceiver` shapes** — POCs verified
|
|
wake delivery/coalescing through their own probe types; the pinned
|
|
`Wake { channel }` / recv forms (§3 of
|
|
[ADR-008](decisions/008-contract-v1-pinning.md)) need the contract
|
|
suite's own property tests on both engines.
|
|
- **`save_offset_tx` exactly-once-within-a-business-tx shape** — both
|
|
POCs verified it through their *sketch* implementations (SQLite's
|
|
offset-save was a plain SQL upsert, not the forked substrate's full
|
|
surface;
|
|
the pg side likewise through its probe), so the property must be
|
|
re-pinned against the real engines' `save_offset_tx` in the
|
|
contract suite.
|
|
- **Concurrent `try_lock` loser/error behavior** on SQLite (the pg
|
|
side returns cleanly; the substrate's busy-path under lock
|
|
contention is the thing to pin).
|
|
- **Scheduler + depth properties on Postgres** — the SQLite side's
|
|
tick/leader/catch-up machinery inherits the forked substrate's
|
|
test-pinned implementation; the pg engine's re-derived tick (boundary
|
|
advance,
|
|
64-cap skip-forward, leadership-loss discipline) and the
|
|
[ADR-010](decisions/010-queue-semantics-depth.md) depth properties
|
|
(visibility reclaim consuming attempts, dead-letter moves, the
|
|
no-stranded-rows sweep) pin in the contract suite at
|
|
implementation.
|
|
- **Backoff-curve and stamp-resolution equivalence across engines** —
|
|
the equal-jitter curve ([ADR-010](decisions/010-queue-semantics-depth.md)
|
|
§3) and the opts-stamping resolution (§3a) are computed engine-side
|
|
per [ADR-012](decisions/012-forked-substrate-design.md) §2's
|
|
contract-blind boundary; the contract suite must pin both engines'
|
|
arithmetic to identical outputs.
|
|
- **Job-handle validity predicate on both engines** — the uniform
|
|
processing-state + unexpired-deadline rule
|
|
([ADR-010](decisions/010-queue-semantics-depth.md) §2): the
|
|
late-heartbeat boundary (refused exactly when the deadline has
|
|
lapsed), the post-lapse-ack-refusal (at-least-once), and the
|
|
ack-vs-reclaim race (one wins atomically); `ack_batch` applies the
|
|
predicate per id (lapsed or non-claimed ids silently not counted);
|
|
`retry`'s refusal is `false` with the row untouched; the
|
|
engine-default strings land identically (`fail(None)` →
|
|
`"failed"`, exhaustion → `"max attempts exceeded"`); both engines'
|
|
SQL pin identical outcomes in the contract suite.
|
|
- **`outbox_enqueue_tx` commit-atomicity on both engines**
|
|
([ADR-014](decisions/014-outbox-tx-enqueue.md)) — rollback drops
|
|
the backing-queue job row together with the business write (no
|
|
ghost job); commit makes it claimable by `run_once`; reserved/empty
|
|
outbox names rejected identically on the tx path
|
|
(`ReservedName`/`InvalidName`); stamped opts visible via `get_job`
|
|
equal for both engines.
|
|
- **Cross-engine stream equivalence** ([ADR-015](decisions/015-streams-depth.md)
|
|
§3/§4) — publish sequence → identical *(per-stream)* offset
|
|
sequence → identical
|
|
`read_since` output order on both engines, direct and subscriber
|
|
reads alike (offsets are global counters engine-side — pg
|
|
bigserial, SQLite AUTOINCREMENT — so equivalence is per-stream
|
|
relative order, never absolute offset values); keyed/unkeyed
|
|
interleavings preserve global FIFO;
|
|
`key` round-trips exactly (`None` vs `Some`), `stream`/`created_at`
|
|
fields equal.
|
|
- **`publish_with_key_tx` commit-atomicity on both engines**
|
|
([ADR-015](decisions/015-streams-depth.md) §2) — rollback drops the
|
|
keyed event row with the business write (no ghost event); commit
|
|
makes it visible to `read_since`/`subscribe`; empty-`Some`-key
|
|
`InvalidName` on both engines' tx paths.
|
|
- **`PayloadTooLarge` occurrence asymmetry** ([ADR-016](decisions/016-deployment-honesty.md)
|
|
§5) — with no capability surface, `PayloadTooLarge` is the one
|
|
runtime carriage of an engine asymmetry, so its matchability pins
|
|
in the suite: an oversized `notify`/`notify_tx` payload is rejected
|
|
client-side by the Postgres engine before any round trip (the
|
|
limit in the variant), and the SQLite engine never produces the
|
|
variant at any size — engine-agnostic code writes the same match
|
|
on both engines and the non-occurring arm simply never fires.
|
|
- **`trim_to` semantics on both engines** ([ADR-015](decisions/015-streams-depth.md)
|
|
§5) — exact-boundary trim (`<=`), surviving rows keep their offsets
|
|
(gaps legal, never renumbered), reads resume at the trim horizon's
|
|
first remaining row, saved offsets below the horizon stay valid,
|
|
trim wakes nothing, and a concurrent subscriber never loses its
|
|
place.
|
|
- **Save-offset monotone composition** ([ADR-019](decisions/019-mechanism-handle-surfaces.md)
|
|
§6) — direct-form and receiver-form saves interleave without
|
|
regression on both engines; a lower-offset save is a silent no-op;
|
|
receiver saves land the last-yielded event's offset exactly.
|
|
- **Payload encode/decode round-trip on both engines**
|
|
([ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md) §4) —
|
|
same `Value` published/enqueued on both engines stores byte-identical
|
|
rows and decodes back to `Value` equality (`Codec` only on
|
|
non-serializable target types).
|
|
- **Enqueue-opts resolution equivalence** ([ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md)
|
|
§1/§2/§3) — delay-over-run_at precedence, relative-expires
|
|
resolution, and the scheduler-fired jobs' derived-default stamps
|
|
(`get_job`-visible via the row) are identical on both engines;
|
|
plain `enqueue_tx` stamps the same plain-queue derived defaults
|
|
(300/3/5/none) on both engines — auto-commit-handle enqueues stamp
|
|
the handle's opts, no-handle-open shapes stamp derived defaults
|
|
(the outbox's 60/5/5 set being the one exception, ADR-014 §1).
|
|
- **In-tx read-your-own-writes on both engines**
|
|
([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §1) —
|
|
reads issued on the tx handle see the transaction's own writes
|
|
(`get_job_tx` a row the same tx enqueued; `read_since_tx` an event
|
|
the same tx published); another engine connection sees none of it
|
|
pre-commit; post-rollback the reads' subjects are gone (no-ghosts
|
|
for reads).
|
|
- **Drop = rollback on both engines**
|
|
([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §4) —
|
|
a handle dropped before commit leaves no job/event/notify/offset
|
|
residue (no-ghosts via RAII); afterward the SQLite writer slot is
|
|
reusable and the pg client re-poolable.
|
|
- **`schedule()` queue-argument validation on both engines**
|
|
([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §3) —
|
|
reserved-prefix and empty queue arguments rejected at registration
|
|
with `ReservedName`/`InvalidName`; stored schedules fire only into
|
|
non-reserved queue names.
|
|
- **Receiver error/close arms on both engines**
|
|
([ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) §5) —
|
|
`recv()`'s `Err` carries `Database` only; `save_offset`'s `Err`
|
|
carries `Database` only; regression saves are silent no-ops;
|
|
SQLite's receiver closes on watcher death (terminal `None`); the
|
|
pg receiver stays open across forwarder reconnects (reconnect-wakes
|
|
arrive; no close) and closes only at engine shutdown.
|
|
- **Numeric-domain semantics on both engines**
|
|
([ADR-023](decisions/023-fourth-review-round.md) §2) — extents
|
|
clamp to empty (`claim_batch(n <= 0)` claims nothing; stream reads
|
|
with `limit <= 0` read nothing, never the whole queue/stream), so
|
|
the SQLite `LIMIT -1` dialect artifact is dead on both engines;
|
|
durations reject (`try_lock`/`renew` with `ttl <= 0` are opaque
|
|
`Err`s on both engines); boundaries are total (a negative
|
|
`trim_to` horizon deletes nothing, idempotently).
|
|
- **`encode_payload` typed failure**
|
|
([ADR-023](decisions/023-fourth-review-round.md) §1) — the helper
|
|
returns `Result<Vec<u8>, Error::Codec>`; enqueue/publish store and
|
|
decode the exact serialization of the input `Value` (byte-identical
|
|
rows cross-engine, the §4 round-trip unchanged), and the failure
|
|
arm is typed at the helper — no silent empty-byte fallback exists.
|
|
- **Plain-path SQLite open** ([ADR-023](decisions/023-fourth-review-round.md)
|
|
§3) — the SQLite engine's `open` path argument is a plain
|
|
filesystem path: a string carrying a `?name=value` suffix is
|
|
treated as a filename, no URI interpretation, no connection-
|
|
semantics mutation outside the constructor's opts.
|
|
- **Watcher cadence default + knob** ([ADR-023](decisions/023-fourth-review-round.md)
|
|
§4) — the SQLite store's watcher runs at the inherited 1 ms
|
|
default; `SqliteOpts::poll_interval` changes the configured
|
|
cadence (config-surface accounting — wall-clock cadence
|
|
measurements stay out of the contract suite's deterministic
|
|
posture).
|
|
|
|
## Design Decisions
|
|
|
|
| ADR | Decision | Summary |
|
|
|---|---|---|
|
|
| [001](decisions/001-crate-split.md) | Crate split | core + per-engine crates; single-driver binaries |
|
|
| [002](decisions/002-feature-scope.md) | Feature scope | inventory-confirmed features only; cut-flags explicit |
|
|
| [006](decisions/006-wake-and-delivery-contract.md) | Wake contract | opaque wake + re-read; notify-vs-streams guarantee split |
|
|
| [007](decisions/007-transactional-seam.md) | Tx seam | caller-held handle, `*_tx` methods, native commit-atomicity |
|
|
| [008](decisions/008-contract-v1-pinning.md) | Contract v1 pinning | surface partition, `TxHandle` trait shape, `Wake` type, reserved strings, error taxonomy, config split, locks guarantee row |
|
|
| [009](decisions/009-scheduler-collapse.md) | Scheduler collapse (pre-release extension) | queues + `schedule()`/`run_schedules`, `@every`-only v1, boundary guarantee row |
|
|
| [010](decisions/010-queue-semantics-depth.md) | Queue depth (pre-release extension) | visibility/renewal, opts stamping, backoff curve, dead-letter, sweep, layout |
|
|
| [011](decisions/011-sqlite-substrate-fork.md) | Substrate fork | SQLite substrate owned (`__alkstore_*` naming); queue ops re-derived on contract v1 |
|
|
| [012](decisions/012-forked-substrate-design.md) | Fork design | contract-blind substrate boundary; engine-side formula arithmetic pinned equivalent by the contract suite |
|
|
| [014](decisions/014-outbox-tx-enqueue.md) | Outbox tx enqueue (amends 008) | `outbox_enqueue_tx` on `TxHandle`; outbox-name validation; derived backing queue reached only through the outbox surface |
|
|
| [015](decisions/015-streams-depth.md) | Streams depth (amends 006/008) | key = carried metadata, global-FIFO ordering row, `StreamEvent` shape, `publish_with_key_tx`, `trim_to` |
|
|
| [016](decisions/016-deployment-honesty.md) | Deployment honesty (decides 008's parked question) | no runtime capability surface — compile-time engine identity + documented matrix; `PayloadTooLarge` occurrence asymmetry pinned |
|
|
| [017](decisions/017-contract-versioning.md) | Contract versioning (governs this surface's changes) | core crate's semver *is* the contract version; four change classes; amend-in-place ends at first release; pairing = manifest pin + version-stamped contract suite + docs |
|
|
| [019](decisions/019-mechanism-handle-surfaces.md) | Mechanism handles (amends 008 §1/§2/§8) | handle traits pinned (`Queue`/`StreamHandle`/`Outbox`/`Lock`/`JobHandle`); `worker_id` claimant identity; `Job`/`Schedule` struct shapes; core-owned `StopToken`; save-offset composition |
|
|
| [020](decisions/020-enqueue-opt-semantics-and-bridges.md) | Enqueue options + bridges (amends 008 §1/§2, 009 §3) | `delay` wins over `run_at`; `expires` = relative seconds; scheduler stamps from derived queue defaults; serde_json byte-level payload encoding |
|
|
| [021](decisions/021-tx-reads-and-value-shape-fixes.md) | Third review round (amends 008 §2/§8, 019 §1/§3, 009 §1) | tx-side read methods on `TxHandle` (read-your-own-writes); `Job.claimed_at` restored; `schedule()` queue argument validated; drop = rollback; receiver close/error arms pinned |
|
|
| [023](decisions/023-fourth-review-round.md) | Fourth review round (amends 020 §4, 008 §5, 012 §4) | numeric-argument domains by kind (extents clamp empty, durations reject, boundaries total); `encode_payload` typed (`Codec`); plain-path SQLite open (URI flag dropped); watcher cadence 1 ms default + `SqliteOpts` knob |
|
|
|
|
## Open Questions
|
|
|
|
Open questions are tracked in
|
|
[open-questions.md](open-questions.md). Key
|
|
questions affecting this document:
|
|
|
|
- **OQ-10**: contract versioning discipline across engine crates —
|
|
**resolved** ([ADR-017](decisions/017-contract-versioning.md)):
|
|
the core crate's semver is the contract version; change classes
|
|
pinned; the verification backlog below matures into the
|
|
version-stamped contract suite (the pairing instrument).
|
|
|
|
Resolved on this document's surface: **OQ-09** (scheduler collapse —
|
|
[ADR-009](decisions/009-scheduler-collapse.md)), **OQ-05** (queue
|
|
semantics depth — [ADR-010](decisions/010-queue-semantics-depth.md)),
|
|
**OQ-13** (transactional outbox enqueue shape —
|
|
[ADR-014](decisions/014-outbox-tx-enqueue.md)), **OQ-12** (streams
|
|
depth — [ADR-015](decisions/015-streams-depth.md)), **OQ-08**
|
|
(capability-surface shape — none, by default ever;
|
|
[ADR-016](decisions/016-deployment-honesty.md)), and **OQ-10**
|
|
(the versioning discipline this document's surface is governed by —
|
|
[ADR-017](decisions/017-contract-versioning.md)), 2026-10-05/06.
|
|
The second review round (2026-10-06) found no new open questions —
|
|
its findings resolved directly as
|
|
[ADR-019](decisions/019-mechanism-handle-surfaces.md) (handle
|
|
surfaces, value shapes, stop token) and
|
|
[ADR-020](decisions/020-enqueue-opt-semantics-and-bridges.md)
|
|
(enqueue-option semantics, scheduler stamp source, payload encoding).
|
|
The third review round (2026-10-07, pre-decomposition) likewise found
|
|
no new open questions — its five findings resolved directly as
|
|
[ADR-021](decisions/021-tx-reads-and-value-shape-fixes.md) (tx-side
|
|
reads, `Job.claimed_at`, `schedule()` queue-validation, drop =
|
|
rollback, receiver close/error arms).
|