--- id: sqlite-commit-error-arm name: SQLite engine — commit-error-arm coverage (wave-3 review's deferred test) status: completed depends_on: [] scope: narrow risk: medium impact: isolated level: implementation tags: [wave-5, sqlite-engine, tests] --- ## Description Land the wave-3 review gate's deferred coverage item (`tasks/review-wave-3.md` Notes: "Coverage of the commit-error arm — no test induces a failing `COMMIT` ... natural home is wave 5's suite hardening"): a test that drives a failing `COMMIT` through the SQLite engine's `commit` path and pins the fix the review verified by code-read — the writer slot is replenished via the `reopen` closure on the failed `COMMIT` (no stranding), the error surfaces as the opaque `Database`, and the store remains fully usable afterward (subsequent `begin_tx`/auto-commit ops work). The injection mechanism is this task's to find — candidates: a `PRAGMA max_page_count` squeeze forcing `SQLITE_FULL` on a space-consuming commit, or a `cfg(test)` fault seam in the seam layer if the PRAGMA route cannot hit the COMMIT arm deterministically. The wave-4 fix batch's `cfg(test)` config-seam precedent (`pg-fix-forwarder-reconnect`) is the house pattern if a seam is needed. Prefer the least-invasive mechanism that deterministically reaches the arm; document the choice. If the same session has cheap room for it, the waves-1–2 review's optional add — the watcher reconnect-*success* path test (upstream's W-1 test drives only the failure path; "a reconnect success test would require a file appearing mid-run") — rides here **only if** the engine kept the current watcher shape and the test is genuinely cheap; otherwise leave it recorded as not-taken in Notes (it was a suggestion, not an order). ## Acceptance Criteria - [ ] A test induces a failing `COMMIT` on the SQLite engine and pins: error surfaces (`Database`), writer slot replenished (a subsequent `begin_tx` succeeds), no partial-commit residue - [ ] The injection mechanism documented in Notes (PRAGMA vs seam, and why) - [ ] The watcher reconnect-success test either landed or explicitly recorded as not-taken with the reason - [ ] `cargo test -p alkstore-sqlite` green server-less; clippy `-D warnings`; fmt clean ## References - tasks/review-wave-3.md (Notes: the deferred commit-error-arm coverage) - tasks/sqlite-engine-seam-tx.md (the `commit` replenish fix the test pins) - tasks/pg-fix-forwarder-reconnect.md (the `cfg(test)` seam precedent) - docs/reviews/001-waves-1-2-general-review.md §2 (the watcher reconnect-success suggestion) ## Notes > Decisions of record the implementation made that the description > didn't pin: - **Injection mechanism: the `cfg(test)` commit-fault seam, not the PRAGMA route — decided by live probe.** Both PRAGMA candidates were tested against real SQLite before choosing: in *both* WAL and DELETE journal modes, `PRAGMA max_page_count` squeezed to the current page count fails the first growth statement (`SQLITE_FULL` / `DiskFull` at page-allocation time), leaving "no transaction is active" for the subsequent `COMMIT` — the commit arm is unreachable through PRAGMA-space. (Also probed: `max_page_count` is per-connection, so arming on the writer conn pre-`begin_tx` would have ridden into the tx connection — the route failed on placement of the error, not on delivery.) The seam substitutes a `SQLITE_FULL`-shaped `rusqlite::Error` for **one** commit and feeds it into the *production* commit error arm — the test pins the real drop + `reopen` replenish code, not a replica. - **Scoping design** (the seam's cross-test-safety shape): the fault flag is a per-`SqliteStore` `Arc` (born disarmed, armed via the `#[cfg(test)]` `arm_commit_fault`, disarmed on first consumption — exactly one commit faults and every later commit is real, which the test also pins). Parallel test stores can never interfere. Plumbing follows the `pg-fix-forwarder-reconnect` precedent exactly: `#[cfg(test)]` field on `SqliteStore` and on `SqliteTxHandle`, `#[cfg(test)]` param on `SqliteTxHandle::begin`, cfg'd statement branches in `store.rs::begin_tx` and `src/tx.rs::commit` — production builds compile the plain path. - **Replay-proofed live**: with the commit error arm's `writer_reopen` replenish temporarily removed, the new test fails (the next `begin_tx` parks past its 5 s timeout — the stranding the review identified by code-read); reverted, it passes. - **The watcher reconnect-success add rides here — taken.** The vanished-file route the waves-1–2 review sketched could not reach the success body (on file reappearance the identity check reads a fresh `(dev, ino)` and the watcher dies through the dead-man's switch before the reconnect would matter). Instead the test drives `run_poll_loop` directly through the `open_conn_fn` seam the loop already takes — the same instrument as the W-1 failure test — with the db file present throughout (identity stable): initial open and first two reconnects injected as failures, third reconnect succeeds, and a commit from a writer connection then wakes `on_change` (proving the success arm re-baselines `data_version` and restores delivery). Watcher shape untouched. - `cargo build`; `cargo test -p alkstore-sqlite` green server-less (191 lib + 25 suite, both new tests included); workspace `cargo test` 399 passed / 0 failed (core 25 + harness 3; postgres 121 + 25 suite + 9 schema; sqlite 191 + 25 suite); `cargo clippy --all-targets -- -D warnings`; `cargo fmt --check` — all green. ## Summary > What landed, verified how: - **`alkstore-sqlite/src/seam.rs`**: the `#[cfg(test)]` `commit_fault` module — per-store `Flag` (`Arc`), `disarmed`/`arm`/`take` (disarm-on-consume), and the `SQLITE_FULL`-shaped fabricated `rusqlite::Error` — with the mechanism-choice rationale (the PRAGMA probes) in its doc comment. - **`alkstore-sqlite/src/tx.rs`**: `#[cfg(test)]` fault field on `SqliteTxHandle` + `begin` param; `commit`'s blocking body gains a cfg'd branch that feeds the fault into the existing production match — the error arm (drop + `reopen` replenish, `sqlite_error` mapping) runs unmodified. - **`alkstore-sqlite/src/store.rs`**: `#[cfg(test)]` `commit_fault` field on `SqliteStore`, the `arm_commit_fault` surface, and the cfg-branched `begin_tx` call. - **`alkstore-sqlite/src/store/tx_tests.rs`**: `failed_commit_replenishes_the_writer_slot` — failed `COMMIT` errs opaque `Database` with the SQLITE_FULL source chain; the next `begin_tx` proceeds (slot replenished, no stranding); no partial-commit residue; the post-failure commit is real and clean (fault disarmed); auto-commit `notify` works afterward. - **`alkstore-sqlite/src/substrate/watcher.rs`**: `reconnect_success_resumes_wake_delivery` — the waves-1–2 review's optional reconnect-success add, driven through the loop's `open_conn_fn` seam (injected failed opens, then a successful reconnect; wake delivery resumes and is pinned). Recorded as *taken* per the task's optional clause. - **Gates**: `cargo build`, `cargo test` (server-less: core 25 + core suite 25 + sqlite 191 + postgres 121 + 9 schema — 399 passed / 0 failed, postgres harness skipped server-less), `cargo clippy --all-targets -- -D warnings`, `cargo fmt --check` — all green.