fix(signals): L2 lane takeover of held effects (#3766) and optimistic writes over a held row (#3796)

.changeset/lane-takeover-held-effect.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/signals": patch
+---
+
+Fix a render effect a lane took over from a held transaction: it keeps running as the lane's work while it waits on the lane's flight, and drops the hold when it leaves the lane (#3766).

.changeset/optimistic-over-held-row.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/signals": patch
+---
+
+Fix an optimistic store over a derived store hiding its update after an action's local write to the same row: the row a held write staged is no longer guessed over the container's slot (#3796).

packages/signals/docs/RULES-INDEX.md

@@ -61,7 +61,7 @@ Status legend: **live** stated and standing · **ruled** carries an explicit rul
 | A14 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:201` | — | spec-async-semantics.test.ts×1 | [ruled, amended in place 2026-07-06 (promoted from B2)] Companion nodes get child lanes that do not merge with the owner — (was B2) `isPending`/`latest` companion nodes get child lanes that do not mer… |
 | A15 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:237` | async.ts×2 constants.ts×1 core.ts×3 lanes.ts×4 scheduler.ts×14 verdict.ts×3 | async-chain-supersession.test.ts×1 first-observer-stale-reader.test.ts×1 fuzz-findings-l2.test.ts×17 held-restore.test.ts×1 l2-contract.test.ts×7 lane-contract.test.ts×1 lane-hold-on-observation.test.ts×1 lane-outside-view.test.ts×1 lane-pass-stamped-effect-3662.test.ts×1 mount-over-foreign-hold-3761.test.ts×2 overlapping-flights.test.ts×3 posture-born-held-and-observation.test.ts×4 posture-store-parity.test.ts×2 reveal-carve-out.test.ts×2 shared-effect-no-entangle.test.ts×1 spec-async-semantics.test.ts×2 stale-read-uninitialized-cross-transition.test.ts×1 superseded-source-blocks-3462.test.ts×2 tick-scoped-pass-transaction.test.ts×1 treeshake.test.ts×4 visibility-oracle-store.states.ts×6 visibility-oracle.states.ts×7 visibility-oracle.test.ts×1 write-proposals-3494.test.ts×1 | [ruled, amended in place 2026-07-06 (promoted from B3)] Transition entanglement is graph-driven; lanes settle as one reveal — (was B3) Transition entanglement is graph-driven: writes whose async work … |
 | A16 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:209` | scheduler.ts×1 | spec-async-semantics.test.ts×1 strict-read-pending-store.test.ts×2 uninitialized-visibility.test.ts×1 visibility-oracle-store.states.ts×2 visibility-oracle.states.ts×2 visibility-oracle.test.ts×1 | [ruled, amended in place 2026-07-06 (promoted from B5)] `isPending` never throws in untracked contexts — (was B5) `isPending` never throws in untracked contexts — thunks that throw real errors or read… |
-| A17 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:67` | async.ts×3 constants.ts×1 lanes.ts×5 scheduler.ts×2 verdict.ts×1 map.ts×1 store.ts×3 | fuzz-findings-l2.test.ts×4 lane-uninitialized-landing-3648.test.ts×5 optimistic-read-lane-not-transaction-3698.test.ts×2 optimistic-undefined-override.test.ts×1 posture-store-parity.test.ts×1 refresh-await.test.ts×1 reveal-gating-contract.test.ts×3 spec-async-semantics.test.ts×10 createOptimisticStore.test.ts×2 kanban-a17-fixture.test.ts×3 optimistic-list-mutation-matrix.test.ts×1 optimistic-maparray-index-frame-f1.test.ts×1 optimistic-untracked-reads-f3-f5.test.ts×1 signal-store-twins-qd.test.ts×1 treeshake.test.ts×1 until.test.ts×1 visibility-oracle-store.states.ts×24 visibility-oracle-store.test.ts×1 visibility-oracle.states.ts×20 visibility-oracle.test.ts×1 | [ruled, amended in place 2026-07-06 (promoted from C4)] An active override is the displayed value until its transaction commits, and the graph's value until its own source answers — **Statement (curre… |
+| A17 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:67` | async.ts×3 constants.ts×1 lanes.ts×6 scheduler.ts×2 verdict.ts×1 map.ts×1 store.ts×3 | fuzz-findings-l2.test.ts×6 lane-uninitialized-landing-3648.test.ts×5 optimistic-over-held-row-3796.test.ts×1 optimistic-read-lane-not-transaction-3698.test.ts×2 optimistic-undefined-override.test.ts×1 posture-store-parity.test.ts×1 refresh-await.test.ts×1 reveal-gating-contract.test.ts×3 spec-async-semantics.test.ts×10 createOptimisticStore.test.ts×2 kanban-a17-fixture.test.ts×3 optimistic-list-mutation-matrix.test.ts×1 optimistic-maparray-index-frame-f1.test.ts×1 optimistic-untracked-reads-f3-f5.test.ts×1 signal-store-twins-qd.test.ts×1 treeshake.test.ts×1 until.test.ts×1 visibility-oracle-store.states.ts×24 visibility-oracle-store.test.ts×1 visibility-oracle.states.ts×20 visibility-oracle.test.ts×1 | [ruled, amended in place 2026-07-06 (promoted from C4)] An active override is the displayed value until its transaction commits, and the graph's value until its own source answers — **Statement (curre… |
 | A18 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:77` | action.ts×1 async.ts×2 core.ts×3 lanes.ts×8 scheduler.ts×2 types.ts×1 verdict.ts×1 map.ts×1 optimistic.ts×1 projection.ts×1 | body-end-supersession-visibility.test.ts×4 createOptimistic.test.ts×3 lane-contract.test.ts×1 lane-frame-deferred-run-3662.test.ts×1 lane-outside-view.test.ts×1 lane-uninitialized-landing-3648.test.ts×5 optimistic-move-duplicate-3548.test.ts×2 optimistic-read-lane-not-transaction-3698.test.ts×4 posture-store-parity.test.ts×5 spec-async-semantics.test.ts×3 flight-owned-transaction.test.ts×1 optimistic-list-mutation-matrix.test.ts×1 optimistic-untracked-reads-f3-f5.test.ts×1 signal-store-twins-qd.test.ts×1 unchanged-presence-no-hold-3743.test.ts×2 superseded-before-first-commit.test.ts×4 visibility-oracle-store.states.ts×8 visibility-oracle-store.test.ts×1 visibility-oracle.states.ts×19 visibility-oracle.test.ts×1 | [ruled, amended in place 2026-07-07 (promoted from B4)] An override lives exactly as long as its own transaction; a newer truth from the source supersedes it in the graph immediately, on screen at com… |
 | A19 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:137` | async.ts×1 constants.ts×1 core.ts×6 scheduler.ts×2 types.ts×1 verdict.ts×4 store.ts×1 | fuzz-findings-l2.test.ts×4 lane-uninitialized-landing-3648.test.ts×2 mount-over-foreign-hold-3761.test.ts×2 spec-async-semantics.test.ts×3 derived-presence-async-3726.test.ts×2 superseded-before-first-commit.test.ts×3 uninitialized-visibility.test.ts×1 visibility-oracle-store.states.ts×8 visibility-oracle-store.test.ts×1 visibility-oracle.states.ts×14 visibility-oracle.test.ts×1 write-proposals-3494.test.ts×1 | [ruled, amended in place 2026-07-07 (promoted from C1)] `isPending(x)` ≡ the observable value is not final (three causes) — (was C1 — **partially reverses an earlier decision**) **Definition: `isPendi… |
 | A20 | superseded | `docs/SPEC-ASYNC-SEMANTICS.md:396` | — | question-scoped-pending.test.ts×2 spec-async-semantics.test.ts×3 createOptimisticStore.test.ts×1 | [superseded 2026-07-13 by A24] (superseded) Optimistic writes announce a store-wide pending — (**SUPERSEDED 2026-07-13 by A24** — the mask is deleted; optimistic writes are verdict-inert. Kept for the… |
@@ -74,8 +74,8 @@ Status legend: **live** stated and standing · **ruled** carries an explicit rul
 | A27 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:289` | — | loading-value.test.ts×2 visibility-oracle.states.ts×18 visibility-oracle.test.ts×1 | [ruled 2026-08-10] The commit-#0 loading window is loading-class and verdict-quiet — (**ruled 2026-08-10**) **The commit-#0 loading window is loading-class and verdict-quiet.** A node born committed v… |
 | A28 | ruled, mechanism landed | `docs/SPEC-ASYNC-SEMANTICS.md:87` | constants.ts×1 core.ts×12 lanes.ts×2 scheduler.ts×3 types.ts×1 verdict.ts×2 store.ts×4 | createOptimistic.test.ts×5 fuzz-findings-l2.test.ts×6 held-derivation-not-a-proposal-3612.test.ts×1 latest-held-till-flush.test.ts×1 posture-store-parity.test.ts×5 question-scoped-pending.test.ts×3 snapshot-derived-store-rows.test.ts×1 createOptimisticStore.test.ts×10 optimistic-draft-visibility-3665.test.ts×5 optimistic-list-mutation-matrix.harness.ts×1 optimistic-list-mutation-matrix.test.ts×2 shallow.test.ts×1 woken-transaction-adopts-staged-bump.test.ts×1 treeshake.test.ts×2 verdict-contract.test.ts×1 visibility-oracle-store.states.ts×8 visibility-oracle.states.ts×8 | [ruled, mechanism landed 2026-09-15] A write becomes visible at flush — to every channel — (**ruled 2026-09-08**; supersedes the #2922 mid-tick pull) **A write becomes visible at flush — to every chan… |
 | A29 | amended | `docs/SPEC-ASYNC-SEMANTICS.md:111` | boundaries.ts×1 action.ts×1 constants.ts×1 core.ts×9 effect.ts×1 scheduler.ts×3 signals.ts×1 store.ts×1 | adoption-unchanged-key-read-3706.test.ts×9 body-end-supersession-visibility.test.ts×1 born-held.test.ts×3 boundary-not-born-held-3540.test.ts×4 createProjection.draft-lifetime-3585.test.ts×1 direct-commit-readers-posture.test.ts×1 fuzz-findings-l2.test.ts×6 held-conditional-memo.test.ts×1 held-frame-dependencies.test.ts×2 held-truth-lane-only.test.ts×3 l2-contract.test.ts×1 latest-held-till-flush.test.ts×2 mount-over-foreign-hold-3761.test.ts×1 optimistic-read-lane-not-transaction-3698.test.ts×3 posture-born-held-and-observation.test.ts×1 posture-store-parity.test.ts×6 derived-presence-async-3726.test.ts×3 optimistic-untracked-reads-f3-f5.test.ts×1 store-unchanged-read-independent-write-3688.test.ts×1 tick-scoped-pass-transaction.test.ts×2 treeshake.test.ts×3 visibility-oracle-store.states.ts×5 visibility-oracle-store.test.ts×1 visibility-oracle.states.ts×9 visibility-oracle.test.ts×1 write-proposals-3494.test.ts×1 | [ruled, amended in place 2026-09-13 (#3408)] A tracked read served a live transaction's staged value enters that transaction — A tracked computation served a node's staged `_pendingValue` — a value a … |
-| A30 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:245` | async.ts×3 attribution.ts×1 constants.ts×1 core.ts×1 effect.ts×1 scheduler.ts×5 | async-landing-deps-3461.test.ts×3 fuzz-findings-l2.test.ts×2 held-conditional-effect.test.ts×1 held-conditional-memo.test.ts×1 held-frame-dependencies.test.ts×2 ispending-in-boundary-on-3528.test.ts×1 lane-frame-deferred-run-3662.test.ts×1 lane-frame-held-lane-3662.test.ts×1 posture-born-held-and-observation.test.ts×1 treeshake.test.ts×2 write-proposals-3494.test.ts×2 zombie-rerun-after-commit-3546.test.ts×2 | [ruled 2026-09-13 (#3410)] A memo's dependencies are the committed frame's until the frame is replaced — A pass that _staged_ its value has not replaced the committed frame, so the committed value sti… |
-| A31 | live | `docs/SPEC-ASYNC-SEMANTICS.md:119` | boundaries.ts×1 core.ts×1 verdict.ts×2 | fuzz-findings-l2.test.ts×5 ispending-combined-atomic-3442.test.ts×1 | [live 2026-09-14 (#3442)] A memo computes under its own lane posture, never its puller's — A memo's value is one shared slot every reader sees, so its pass runs under the lane posture the memo itself … |
+| A30 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:245` | async.ts×3 attribution.ts×1 constants.ts×1 core.ts×1 effect.ts×1 lanes.ts×1 scheduler.ts×5 | async-landing-deps-3461.test.ts×3 fuzz-findings-l2.test.ts×3 held-conditional-effect.test.ts×1 held-conditional-memo.test.ts×1 held-frame-dependencies.test.ts×2 ispending-in-boundary-on-3528.test.ts×1 lane-frame-deferred-run-3662.test.ts×1 lane-frame-held-lane-3662.test.ts×1 posture-born-held-and-observation.test.ts×1 treeshake.test.ts×2 write-proposals-3494.test.ts×2 zombie-rerun-after-commit-3546.test.ts×2 | [ruled 2026-09-13 (#3410)] A memo's dependencies are the committed frame's until the frame is replaced — A pass that _staged_ its value has not replaced the committed frame, so the committed value sti… |
+| A31 | live | `docs/SPEC-ASYNC-SEMANTICS.md:119` | boundaries.ts×1 core.ts×1 lanes.ts×1 verdict.ts×2 | fuzz-findings-l2.test.ts×6 ispending-combined-atomic-3442.test.ts×1 | [live 2026-09-14 (#3442)] A memo computes under its own lane posture, never its puller's — A memo's value is one shared slot every reader sees, so its pass runs under the lane posture the memo itself … |
 | A32 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:127` | core.ts×4 lanes.ts×1 store.ts×1 | visibility-oracle-store.states.ts×8 visibility-oracle-store.test.ts×1 visibility-oracle.states.ts×9 visibility-oracle.test.ts×1 | [ruled 2026-09-14] Children-forbidden readers see the frame, not the graph — `createTrackedEffect` and `onSettled` callbacks are effect-phase code that runs after the frame is decided. They read the f… |
 | A33 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:261` | boundaries.ts×1 scheduler.ts×1 | async-chain-supersession.test.ts×2 boundary-not-born-held-3540.test.ts×2 fuzz-findings-l2.test.ts×2 ispending-in-boundary-on-3528.test.ts×2 loading-reset-collects-forwarded-3459.test.ts×3 | [ruled 2026-09-12 (#3375)] A fallback-caught flight holds no transaction; a Loading reset moves the hold onto the boundary — A `<Loading>` boundary showing its fallback is the display of everything un… |
 | A34 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:271` | constants.ts×1 core.ts×6 lanes.ts×2 scheduler.ts×2 store.ts×4 | a34-writes-then-derivations.test.ts×2 createMemo.test.ts×1 derived-write-then-derivation-3733.test.ts×1 finalize-reentry.test.ts×2 fuzz-findings-l2.test.ts×5 held-derivation-not-a-proposal-3612.test.ts×6 optimistic-list-mutation-matrix.test.ts×1 unchanged-presence-no-hold-3743.test.ts×3 woken-transaction-adopts-staged-bump.test.ts×1 transition-corpse-revival.test.ts×1 treeshake.test.ts×2 visibility-oracle.states.ts×2 write-proposals-3494.test.ts×5 | [ruled 2026-09-16 (#3494)] A write is a proposal: one on a held node entangles its tick; one that nets to the committed value is none — A write proposes a value for a node. **Held, both are suggestion… |

packages/signals/src/core/lanes.ts

@@ -46,6 +46,7 @@ import {
   REACTIVE_FRAME_READ,
   REACTIVE_IN_HEAP,
   REACTIVE_JOINED,
+  REACTIVE_LANE_DIRTY,
   REACTIVE_LANE_READ,
   REACTIVE_PROBE_UNANSWERED,
   REACTIVE_SCREEN_READ,
@@ -294,21 +295,25 @@ export function verdictLane(t: Transaction): Transaction {
  * pass's answer replaces it, and the frame's hold on it is over. An
  * effect's value slot is private (no lane value). A pass in a lane's seat
  * that read none of the lane's world has left it (false): its result is the
- * frame's — a derivation whose branch no longer reaches the guess. A first
- * pass under a lane is the lane's (ruling A); a guess is written, not
- * derived — it never leaves this way. */
+ * frame's — a derivation whose branch no longer reaches the guess — and no
+ * hold the lane took over from a transaction stays on it (#3698: lane work
+ * never makes its node transaction work; a born-held effect's hold went to
+ * the lane). A pass interrupted before it got there (pending, errored) did
+ * not leave (A30: it never got there). A first pass under a lane is the
+ * lane's (ruling A); a guess is written, not derived — it never leaves this
+ * way. */
 export function laneStage(
   el: Computed<any>,
   l: Transaction,
   create: boolean,
   errored: boolean
 ): boolean {
-  if (!create && !(el._flags & REACTIVE_LANE_READ) && !(el._config & CONFIG_GUESS)) {
+  if (!(create || errored || el._flags & REACTIVE_LANE_READ || el._config & CONFIG_GUESS)) {
     if (el._x !== null) {
       if (el._x._transaction?._lane) el._x._transaction = null;
       el._x._lane = NOT_PENDING;
     }
-    el._config &= ~CONFIG_OVERRIDE;
+    el._config &= ~(CONFIG_OVERRIDE | CONFIG_HELD);
     return false;
   }
   if (!(el as any)._type) {
@@ -325,6 +330,11 @@ export function laneStage(
     // leaves the guess.
     if (!errored) el._config &= ~CONFIG_GUESS;
   }
+  // A leaf has no lane value to seat it (`recompute`): one left waiting on
+  // the lane's flight runs its next pass as the lane's — the landing that
+  // wakes it is the lane's re-staging (A31), and the lane holds its render
+  // effects until its derivations land (A17; #3766, F5).
+  else if (errored) el._flags |= REACTIVE_LANE_DIRTY;
   list(el, l);
   return true;
 }

packages/signals/src/store/optimistic.ts

@@ -53,6 +53,7 @@ import {
   installOptHooks,
   LaneView,
   nameStore,
+  resolveChainedRaw,
   sameKey,
   storeSetter,
   targetsEqual,
@@ -115,7 +116,11 @@ export function notifyOptimisticWrites(
   let structural = false;
   for (const key of Reflect.ownKeys(pb)) {
     if ((isArr && key === "length") || key === $OWNER) continue;
-    const nv = unwrapValue(pb[key as any]);
+    // A chained draft holds the inner store's raws; a raw is the inner slot it
+    // resolves to (as a read of it serves) — the row a held write staged is
+    // the same row, not a guess over the slot (#3796).
+    const raw = pb[key as any];
+    const nv = unwrapValue(inner && raw ? resolveChainedRaw(t, key, raw) : raw);
     if (!(key in old)) {
       guess(getNode(t, key), key, false, nv);
       guess(getHasNode(t, key), key, true, true);

packages/signals/src/store/store.ts

@@ -1816,7 +1816,7 @@ function holdWithDerive(target: StoreTarget, node: Signal<any>): void {
  * at this key, is served as the inner store's wrapper — never a fresh
  * raw-keyed one — so the chained targets are the same objects across
  * settled and pending views. */
-function resolveChainedRaw(target: StoreTarget, key: PropertyKey, v: object): any {
+export function resolveChainedRaw(target: StoreTarget, key: PropertyKey, v: object): any {
   const innerT: StoreTarget = (target.v as any)[$TARGET];
   if (innerT.ch) {
     const iv = resolveChainedRaw(innerT, key, v);