Close the ambient transaction window when a transaction opens without writes (#3141) - #3145
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🦋 Changeset detectedLatest commit: 0d3e2d1 The changes in this PR will be included in the next version bump. This PR includes changesets to release 11 packages
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Coverage Report for CI Build 33370625606Warning Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes. Coverage remained the same at 71.652%Details
Uncovered ChangesNo uncovered changes found. Coverage RegressionsNo coverage regressions found. Coverage Stats
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Merging this PR will degrade performance by 18.34%
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| Benchmark | BASE |
HEAD |
Efficiency | |
|---|---|---|---|---|
| ❌ | merge |
225.1 µs | 329.2 µs | -31.63% |
| ❌ | merge |
265.2 µs | 366.5 µs | -27.65% |
| ⚡ | reconcile: deep tree, 10 of ~12k paths subscribed |
3.8 ms | 3.4 ms | +10.11% |
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Comparing fix/ambient-transaction-capture (0d3e2d1) with next (28a1eaf)
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… writes (#3141) Parking is flush-driven, but a transaction opened with no writes before its first suspension — an action whose first statements only await — scheduled nothing, so activeTransition and the adopted batch stayed armed across the async gap and captured the next unrelated work to arrive: an optimistic store's landing on a still-live lane was held until the stranger action settled, an unowned optimistic write rode that transaction instead of reverting, and deep()/per-key readers split-brained meanwhile. initTransition now guarantees a flush, enforcing the A26 containment ruling: the ambient window is one flush, period. Co-authored-by: Cursor <cursoragent@cursor.com>
… thread A source write entangled with downstream async that rejects must still commit — the error boundary handling the rejection is the transition resolving, not it failing. This pin came out of the router navigation investigation and was never landed; tests only, no changeset. Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
Fixes #3141.
actionwhose first statements only await — scheduled nothing.activeTransitionand the adopted batch stayed armed across the async gap, and the next unrelated work to arrive was adopted into a transaction it had nothing to do with. In 2.0.0-rc.4 | optimistic store, read in an effect, changes the visible rendering. and has inconsistent value when logged and when rendered. #3141's playground: the optimistic store's authoritative landing (on a still-live lane, since the generator keeps running past the yield) froze until the stranger 10s action settled; an unowned optimistic push rode that transaction instead of reverting at the flush; anddeep()/per-key readers split-brained — the DOM showed[1,2,3,1111](stale base + override) while the deep observer reported[3,2,1,1111].initTransitionends by scheduling a flush. The ambient window closes in one flush regardless of whether the transaction wrote anything. This is enforcement of the existing A26 containment ruling (SPEC-ASYNC-SEMANTICS, 2026-07-17, 2.0.0-beta.19: action(): writes after an internalawaitescape the transaction and commit mid-flight #2913), which explicitly rejected holdingactiveTransitionopen across await windows because "unrelated ambient writes… would be captured into the action's transaction and held until it settles" — pre-fix, that rejected behavior happened anyway through this gap. A26's accepted consequence (pre-await_transitionstamps rejoining) is untouched.optimistic-ambient-capture.test.ts) built on the two exact ingredients the capture needs — a bare-macrotask action open, and a store flight that stays pending past its yield (fails pre-fix on the captured landing, passes post-fix); a faithful web/jsdom port of the playground with real scaled timers and order-based assertions; and an observer-invariance suite. Spec + internals docs updated with the enforcement note.Follow-ups filed separately: the store's truth-flight owning its own transaction, and the
deep()-vs-per-key committed-read seam.Test plan
optimistic-ambient-capture.test.tsfails pre-fix (landing captured), passes post-fixMade with Cursor