feat(vnext): add bounded browser parser executor (#181)

## Summary

Adds the private main-realm executor for the isolated parser worker
selected in
ADR 0004.

- Lazily creates at most one authoritative worker generation.
- Serializes requests through a bounded FIFO queue with independent
request-count
  and retained UTF-16 text limits.
- Enforces startup, queue-wait, and posted-execution safety deadlines.
- Settles caller cancellation promptly while draining already-posted
work.
- Retires crashed, timed-out, malformed, or poisoned generations without
  replaying posted work.
- Preserves never-posted queued work across eligible generation
replacement.
- Rejects reused worker identities and serializes retirement across
hostile
  cleanup/settlement reentrancy.
- Keeps the worker factory, executor, protocol, and implementation types
private;
  there is no root or `/vnext` public API change.

## Risk classification

Medium: concurrency, cancellation, worker lifecycle, resource
accounting, and
packaging boundaries.

The principal risks are double settlement, stale-generation authority,
physical
worker overlap, posted-work replay, unbounded retention, and browser
bundler
regressions. The implementation mutates ownership before every external
cleanup
or settlement boundary, uses an iterative pump trampoline, and tests
hostile
synchronous callbacks at each boundary.

## Evidence

- Full Node suite: 1,246 passed, 1 expected failure.
- Focused deterministic executor suite: 84 passed.
- Chromium: 4 files / 7 tests, including real worker, crash,
silent-worker
  deadline, recovery, and default static Worker URL behavior.
- Changed executor coverage:
  - Statements: 95.51%
  - Branches: 95.37%
  - Functions: 100%
  - Lines: 95.49%
- All TypeScript project checks, oxlint, test-integrity, and diff checks
pass.
- Packed-package smoke test passes and asserts the executor artifact.
- The post-rebase executor patch ID exactly matches the twice-reviewed
pre-rebase
  patch.

## Adversarial review ledger

The review loop found and fixed:

- cancellation and FIFO reentrancy during promotion;
- `preventDefault` running before generation retirement;
- listener installation continuing after synchronous retirement;
- recursive synchronous worker responses overflowing the stack;
- startup-failure queue transfer and ready-failure ownership errors;
- postMessage accessor disposal/forged-response races;
- a P1 physical-worker overlap during cleanup-triggered nested
submission; and
- same-worker identity reuse after termination.

Two independent reviewers approved the corrected pre-rebase patch. Two
fresh
independent audits also approved the exact rebased head after rerunning
Node,
Chromium, package, coverage, type, lint, integrity, placement, and demo
gates.

## API and rollout

This is implementation infrastructure only. It is not wired to sessions,
completion, diagnostics, or other public features. No compatibility or
migration
work is required in this slice. The next consuming coordinator must
preserve the
same bounded ownership and no-replay rules.

<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Adds a private, single-lane browser executor for the isolated SQL parser
worker with bounded queueing, strict deadlines, and safe lifecycle
handling. Internal only; no public or `/vnext` API changes. Hardened to
fail closed on retirement errors with explicit terminal states.

- **New Features**
- Lazily creates at most one worker generation; posts one request at a
time.
- Bounded FIFO queue with request-count and UTF‑16 text limits;
startup/queue/execution deadlines and prompt caller cancellation.
- Retires crashed/timed-out/poisoned generations without replay;
preserves never-posted queued work across replacement.
- Rejects reused worker identities; retirement is serialized and atomic
to avoid reentrancy races.
- Executor, worker factory, protocol, and types remain private; docs
updated and `scripts/package-smoke.mjs` asserts executor artifacts.

- **Bug Fixes**
- Fails closed if worker retirement throws to prevent accepting new work
in an unsafe state.
- Makes terminal states explicit to avoid resurrection and double
settlement.

<sup>Written for commit 1cb7105.
Summary will update on new commits.</sup>

<a
href="https://cubic.dev/pr/marimo-team/codemirror-sql/pull/181?utm_source=github"
target="_blank" rel="noopener noreferrer"
data-no-image-dialog="true"><picture><source
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srcset="https://www.cubic.dev/buttons/review-in-cubic-dark.svg"><source
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<!-- End of auto-generated description by cubic. -->

Author: Light2Dark

docs/adr/0004-isolated-parser-execution.md

@@ -55,21 +55,26 @@ Each `SqlLanguageService` will lazily own at most one dedicated parser worker.
 All sessions opened by that service share it. The worker is neither a
 `SharedWorker` nor a module-global singleton.
 
-The first executor is single-lane:
+The private browser executor is single-lane:
 
 - At most one request is posted at a time.
 - The host queue is bounded independently by request count and retained UTF-16
   text units.
-- A service owns construction, listeners, timers, termination, and disposal.
+- Worker construction is lazy and the executor owns listeners, timers,
+  termination, and disposal.
 - No worker pool or idle shutdown is introduced without profile evidence.
-- Service disposal terminates the worker and settles every pending consumer.
+- Executor disposal terminates the worker and settles every pending consumer.
+
+The executor and its worker factory remain package-private. No package export,
+`/vnext` export, language-service module, session ownership, or public
+configuration surface is introduced by this slice.
 
 Ordinary caller cancellation and supersession settle the consumer promptly
 without relying on a worker message that cannot run during synchronous
 parsing. The executor may drain and discard that active result. A hard
 wall-clock deadline, worker crash, malformed protocol, or service disposal
-terminates the generation. The placement benchmark must compare drain versus
-restart under rapid edits before the executor policy is frozen.
+terminates the generation. Never-posted queued requests may continue on a
+fresh generation, but a posted request is never replayed.
 
 The execution deadline belongs to the posted worker job, not to any attached
 consumer. Consumer cancellation never clears it. A draining operation retains
@@ -154,16 +159,20 @@ Messages do not contain:
 
 The wire does not transport an independently supplied retryability boolean.
 The host treats only `module-load` as retryable; `backend` and
-`malformed-output` are terminal. A module-load failure closes the current
-worker generation so a retry cannot reuse a rejected dynamic-import realm.
+`malformed-output` are terminal. Every worker-reported failure retires the
+current generation. In particular, `backend` cannot distinguish an ordinary
+parse failure from descriptor-cleanup poisoning that closes the endpoint, and
+`module-load` must not reuse a rejected dynamic-import realm. Never-posted
+queued requests may continue on a fresh generation; the failed posted request
+is never replayed.
 
 The host requires the current protocol version and correlation ID, validates
 all keys and closed values, and copies accepted data into new frozen objects.
-It then constructs an authentic `SqlParserAnalysis` with the exact pending
-request text and the host-owned authority. PostgreSQL and BigQuery rejection
-remain uncovered constructs; DuckDB rejection remains compatibility rejection.
-Worker isolation does not strengthen the compatibility-only evidence recorded
-by ADR 0003.
+A future statement coordinator will construct an authentic
+`SqlParserAnalysis` with the exact pending request text and the host-owned
+authority. PostgreSQL and BigQuery rejection remain uncovered constructs;
+DuckDB rejection remains compatibility rejection. Worker isolation does not
+strengthen the compatibility-only evidence recorded by ADR 0003.
 
 Old-generation events are ignored by generation-owned listeners. A malformed,
 duplicate, unsolicited, or mismatched response kills the generation and
@@ -211,7 +220,7 @@ prove:
   recorded.
 - Raw and gzip worker sizes are recorded.
 
-The executor and semantic slices additionally require:
+The semantic and session-integration slices additionally require:
 
 - Main-thread long-task and event-loop responsiveness evidence.
 - Malformed message, crash, timeout, late-event, and restart tests.
@@ -280,7 +289,7 @@ optional-integration bundle budget.
 
 1. Add this ADR and the packed-consumer browser placement harness.
 2. Extract a realm-neutral backend engine and add strict protocol codecs.
-3. Add the minimal browser worker and single-lane executor.
+3. Add the minimal browser worker and private bounded single-lane executor.
 4. Add in-worker normalized relation extraction.
 5. Add the pure statement coordinator, bounded cache, in-flight sharing, and
    atomic session ownership.

docs/vnext/node-sql-parser-adapter.md

@@ -69,7 +69,7 @@ parsing, and output normalization.
 The package contains a production-shaped but private module-worker endpoint.
 It is not exported from the package and is not reachable through `/vnext`.
 There is no public worker constructor, executor, queue, language-service
-module, or session integration yet.
+module, or session integration.
 
 The endpoint:
 
@@ -88,16 +88,27 @@ The endpoint:
   exact.
 
 The endpoint accepts only one request at a time. Overlap and malformed messages
-fail closed instead of creating an implicit worker-side queue. The future
-service-owned executor is responsible for serialization, correlation,
-deadlines, cancellation, generation replacement, and disposal.
+fail closed instead of creating an implicit worker-side queue. A private
+main-realm executor now provides bounded FIFO admission, serialization,
+correlation, startup/queue/execution deadlines, prompt consumer cancellation,
+generation replacement, and disposal. It creates the production module worker
+lazily and keeps cancelled posted work in a draining lane until the worker
+responds or its safety deadline retires that generation. Posted work is never
+replayed. Every worker-reported failure retires the generation because a
+`backend` failure may be indistinguishable from endpoint cleanup poisoning;
+never-posted queued work retains its original deadline on the replacement.
+
+The executor remains implementation infrastructure only. It is not exported
+from the root package or `/vnext`, is not owned by `SqlLanguageService`, and
+does not yet create authenticated syntax analyses or relation facts for a
+session.
 
 Direct Chromium tests construct this source module worker and exercise both
-real grammar builds. The separate worker-placement fixture remains
-diagnostic packaging evidence: it records resource timing, emitted chunk
-reachability, and bundle sizes with a fixture-owned protocol. It is not the
-public integration boundary and must not be read as evidence that an executor
-or session API already exists.
+real grammar builds, including the private executor's production worker path.
+The separate worker-placement fixture remains diagnostic packaging evidence:
+it records resource timing, emitted chunk reachability, and bundle sizes with
+a fixture-owned protocol. It is not the public integration boundary and must
+not be read as evidence that a session API already exists.
 
 Approximate local Node 24 arm64 measurements for the installed package were:
 

scripts/package-smoke.mjs

@@ -170,6 +170,8 @@ try {
     throw new Error("Packed manifest does not declare node-sql-parser");
   }
   const privateWorkerArtifacts = [
+    "dist/vnext/node-sql-parser-browser-executor.d.ts",
+    "dist/vnext/node-sql-parser-browser-executor.js",
     "dist/vnext/node-sql-parser-browser-worker.d.ts",
     "dist/vnext/node-sql-parser-browser-worker.js",
     "dist/vnext/node-sql-parser-browser-worker-endpoint.d.ts",