fix(signals): lane pass over a superseded override reads the displayed override (#3548)

[ryansolid]

Fixes #3548.

Symptom

Two overlapping optimistic moves in a kanban-style UI — three keyed <For> lists filtered from one createOptimisticStore over an async stream — rendered the same card in two lanes while the store itself held it once. Reproduced exactly from the reported playground (ported to a signals-level test, red on next):

lanes: [[], [0, 1], []]   store (tracked, same effect): [1, 1]
untracked view.cards.map(c => c.lane) outside the effect: [2, 1]

Cause

Not the provenance guard. The stream's landing runs mainline (origin = 0), so A18 correctly treats it as a fresh answer and supersedes the override on card0.lane; the lane memos re-derive as held transaction work and no frame publishes.

The tear comes one step later. A fresh action's write to card1.order creates a new lane that reaches lane 1's mapArray memo — a reader shared between card0.lane and card1.order. That memo now runs as a lane pass, and overrideRead had no lane arm: it fell through to the superseded branch and was served the staged truth (lane = 1). The lane pass published via laneOverride and runEffect(LANE_RUN) applied it immediately. Lane 2's memo was not on the new lane, its plain recompute stayed held, and it kept displaying the override. Two readers, two paths, one torn frame.

Fix

overrideRead (packages/signals/src/core/optimistic.ts): a lane pass reading a superseded override gets the displayed override — A18 (c), the applied screen keeps the override until the owning transaction commits — and the reader is recorded in the owner's _gatedSubs for replay at that commit, under the same contract as laneReadsCommitted / gatedRead. The replay is load-bearing: resolveOptimisticNodes deliberately does not notify a superseded node's subscribers at the drop, so without it the lane-pass reader would never see the reveal. The test pins the post-settle reveal ([[1],[0],[]]) as well as the whole frame at every step.

A17's "lane recomputes see the arrived truth" is read here as the demoted pass at supersession time, not a later lane's pass whose frame is applied pre-commit. The alternative — demoting such a pass off the lane entirely — also removes the tear but hides the newest action's optimistic write until the merged transaction commits; this fix keeps the newest write optimistic and the screen whole.

Verification

• New packages/signals/tests/optimistic-move-duplicate-3548.test.ts (red on next, green here); a temporary web-level <For> spec reproduced the report's exact DOM on next and passed with the fix.
• @solidjs/signals: 205 files, 3465 passed, 1 skipped. @solidjs/web jsdom suite: 96 files / 834 passed against rebuilt dists.
• Size budget: all scenarios within caps, no cap bumps (a redundant activeTransition ?? fallback was trimmed to stay under).
• RULES-INDEX.md regenerated (A18 citation count).

Changeset: .changeset/fix-optimistic-move-duplicate-3548.md (@solidjs/signals: patch).

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Diagnosed and implemented by Claude via Cursor.

[changeset-bot]

🦋 Changeset detected

Latest commit: 739404d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 11 packages

Name	Type
@solidjs/signals	Patch
test-integration	Patch
@solidjs/web	Patch
@solidjs/babel-plugin	Patch
@solidjs/compiler	Patch
@solidjs/diagnostics	Patch
@solidjs/element	Patch
@solidjs/h	Patch
@solidjs/html	Patch
solid-js	Patch
@solidjs/universal	Patch

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[codspeed]

Merging this PR will not alter performance

✅ 172 untouched benchmarks
⏩ 3 skipped benchmarks¹

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_{Comparing fix/optimistic-move-duplicate-3548 (739404d) with next (be46a04)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[coveralls]

Coverage Report for CI Build 35503195443

Coverage remained the same at 72.722%

Details

• Coverage remained the same as the base build.
• Patch coverage: No coverable lines changed in this PR.
• No coverage regressions found.

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