fix(signals): an unread key written beside a held sibling publishes at flush (#4146)

.changeset/held-container-unread-key-4146.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/signals": patch
+---
+
+A write to a store key that nothing reads no longer waits for an unrelated action that is holding a sibling key on the same record (#4146). Before this fix, if a transaction held the record's container (an action wrote `card.version` and was still pending), a later setter outside that action writing `card.text` put the new value into the held staging. Plain reads of `card.text` then showed the old value until the action finished. With a live render effect reading `card.text`, the same write showed up at the next flush, because the effect's leaf node gave the key its own staging. Node existence is now unobservable here too (R1, #3706: a hold covers individual keys). The setter creates the key's leaf before writing, from the committed and staged values, so the leaf starts out unstaged and held by no transaction. The write then stages on that leaf and becomes visible at the flush (A28). A leaf on a held container is kept alive until the hold lands, so disposing a reader cannot pull the key back into the hold. A write to a key the hold itself changed still joins the hold (A34). Array elements follow the same per-key rule, so writing an index the hold left unchanged also shows at the flush. An added key, or an index appended to a held array, now behaves the same whether or not something reads it: its value shows at the flush, while the record's key list (or the array's length) still waits for the hold to land.

packages/signals/docs/RULES-INDEX.md

@@ -72,13 +72,13 @@ Status legend: **live** stated and standing · **ruled** carries an explicit rul
 | A25 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:309` | projection.ts×2 | derived-presence-async-3726.test.ts×2 seedless-derived-store.test.ts×1 uninitialized-visibility.test.ts×3 visibility-oracle-store.states.ts×7 visibility-oracle-store.test.ts×1 | [ruled 2026-07-16] A derived store's seed is a draft, never an observable value — (**ruled 2026-07-16**, #2897) **A derived store's seed is a draft, never an observable value.** The seed exists for th… |
 | A26 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:111` | — | action-await-contract.test.ts×2 fuzz-findings-l2.test.ts×1 posture-store-parity.test.ts×2 visibility-oracle-store.states.ts×2 visibility-oracle.states.ts×1 visibility-oracle.test.ts×1 | [ruled 2026-07-17] An ambient transaction window is one flush; parking is flush-driven — (**ruled 2026-07-17**, #2913; **enforcement hardened 2026-08-31**, #3141 — parking is flush-driven, and a trans… |
 | A27 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:301` | — | 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:95` | 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 issue-3800-repro.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… |
+| A28 | ruled, mechanism landed | `docs/SPEC-ASYNC-SEMANTICS.md:95` | constants.ts×1 core.ts×12 lanes.ts×2 scheduler.ts×3 types.ts×1 verdict.ts×2 store.ts×5 | continuation-sibling-reader-4146.test.ts×1 createOptimistic.test.ts×5 fuzz-findings-l2.test.ts×6 held-derivation-not-a-proposal-3612.test.ts×1 issue-3800-repro.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:119` | boundaries.ts×1 action.ts×1 constants.ts×1 core.ts×14 effect.ts×1 lanes.ts×1 scheduler.ts×4 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-branch-verdict-reader-4010.test.ts×1 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 loading-fallback-in-flush-3540.test.ts×6 loading-on-frame-following-3540.test.ts×1 mount-over-foreign-hold-3761.test.ts×1 optimistic-mount-nested-memo-3835.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 verdict-mount-first-pass-3851.test.ts×2 verdict-mount-loading-flush-loop.test.ts×2 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:257` | 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:131` | 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:139` | 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:273` | boundaries.ts×1 scheduler.ts×2 | async-chain-supersession.test.ts×2 boundary-not-born-held-3540.test.ts×2 create-deferred-3710.test.ts×1 fuzz-findings-l2.test.ts×4 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:283` | 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-guess-over-held-slot.test.ts×2 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… |
+| A34 | ruled | `docs/SPEC-ASYNC-SEMANTICS.md:283` | constants.ts×1 core.ts×6 lanes.ts×2 scheduler.ts×2 store.ts×6 | a34-writes-then-derivations.test.ts×2 continuation-sibling-reader-4146.test.ts×1 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-guess-over-held-slot.test.ts×2 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… |
 ## V — fixed violations
 
 | id | status | defined | cited in src | cited in tests | statement (at definition) |
@@ -141,7 +141,7 @@ Status legend: **live** stated and standing · **ruled** carries an explicit rul
 
 | id | status | defined | cited in src | cited in tests | statement (at definition) |
 |---|---|---|---|---|---|
-| CS-R1 | live | `docs/rules-mining/core-store.md:9` | store.ts×1 | flatten-async-iterable.test.ts×5 syncThenable.test.ts×14 visibility-oracle-store.states.ts×1 | Wrappable values are wrapped: reading a plain object/array child never returns the raw source (`state.data !== data`).** |
+| CS-R1 | live | `docs/rules-mining/core-store.md:9` | store.ts×2 | continuation-sibling-reader-4146.test.ts×2 flatten-async-iterable.test.ts×5 syncThenable.test.ts×14 visibility-oracle-store.states.ts×1 | Wrappable values are wrapped: reading a plain object/array child never returns the raw source (`state.data !== data`).** |
 | CS-R2 | live | `docs/rules-mining/core-store.md:13` | — | syncThenable.test.ts×12 visibility-oracle.states.ts×1 | Raw→proxy resolution is global and deduplicating: wrapping the same raw through two different stores yields the same proxy (`outer.list === inner`).** |
 | CS-R2a | live | `docs/INTERNALS-STORE-STATE.md:107` | — | — | Corollary R2a (Ryan, 2026-08-17): **take no responsibility for mutation |
 | CS-R3 | live | `docs/rules-mining/core-store.md:18` | — | — | A store proxy ingested into another store (deep or shallow) is re-wrapped in the ingesting store's own proxy family — never identity-passed, never raw-marked.** |

packages/signals/src/store/store.ts

@@ -342,11 +342,16 @@ function noteNode(target: StoreTarget, node: Signal<any>, key: PropertyKey): voi
 // dispatches CONFIG_SLOT_NODE nodes here (graph.ts) instead of holding a
 // per-node closure in a per-node NodeExtension. A dropped node is
 // unreachable through the store — a fresh read makes a fresh node.
+// A staged write — or a lane's value (a guess, S4) — is state only the node
+// holds: its release waits for the commit that resolves it. So does a leaf of
+// a held container (#4146): a mainline write it carried is in the held
+// staging too, where it would read as the hold's until the landing.
+const slotKept = (node: any): any =>
+  node._pendingValue !== NOT_PENDING ||
+  node._config & CONFIG_OVERRIDE ||
+  node._host.k?._config & CONFIG_HELD;
 setSlotUnobserved((node: any): void => {
-  // A staged write — or a lane's value (a guess, S4) — is state only the
-  // node holds: defer the release to the commit that resolves it.
-  if (node._pendingValue !== NOT_PENDING || node._config & CONFIG_OVERRIDE)
-    deferredReleases.add(node);
+  if (slotKept(node)) deferredReleases.add(node);
   else releaseSlot(node);
 });
 
@@ -898,11 +903,7 @@ function drainFolds(): void {
   }
   if (deferredReleases.size !== 0) {
     for (const node of deferredReleases) {
-      if (
-        node._pendingValue === NOT_PENDING &&
-        !(node._config & CONFIG_OVERRIDE) &&
-        node._subs === null
-      ) {
+      if (node._subs === null && !slotKept(node)) {
         deferredReleases.delete(node);
         releaseSlot(node);
       }
@@ -2179,6 +2180,18 @@ const traps: ProxyHandler<StoreTarget> = {
     if (key === "__proto__") return true; // pollution guard (core R30)
     const uv = target.s ? value : unwrapValue(value);
     const pb = ensurePB(target);
+    // #4146 (R1: node existence is unobservable; #3706: the hold's unit is
+    // the key): a user setter writing a key a HELD container's staging left
+    // unchanged would write it into the held staging — read as the hold's
+    // until its landing, while the same key with a leaf (a live reader)
+    // publishes at the flush. The key gets its leaf first, born from the two
+    // frames (`bornStaged`: a key the hold left unchanged — or added — is
+    // unstaged and held by no one; a key the hold changed is born held, A34
+    // (1)), and the write stages on it (A28; a write by the holder joins it,
+    // A34) — as it would with a reader's leaf. Kept while the container is
+    // held (`deferredReleases`).
+    if (userWrite && (target.k as any)?._config & CONFIG_HELD)
+      deferredReleases.add(getNode(target, key));
     if (Array.isArray(pb)) {
       touch(target, key);
       if (key === "length") target.wk = WK_ALL;