refactor(query): extract QueryEntry.supersede — one owner for the reset contract

[zzal]

Part II Wave 1 · #2 — the reset contract had already drifted

The "invalidate this entry's in-flight world" transition (force stale, generation bump, cancel in-flight, retry reset) was written longhand in two places — and they had already diverged:

• setQueryData cleared entry.error
• forceStaleAndRefetch did not — despite setQueryData's comment claiming to "mirror" it

So invalidating an entry that held an error kept the stale error visible in snapshots throughout the refetch, while the identical supersede via an optimistic write cleared it. Same sibling-inconsistency shape as Part I #1's diff arms — the dominant defect class per the pre-launch audit.

Change

Both sites now route through one owner, QueryEntry.supersede(clearError:) (QueryEntry.swift), so the transition can't drift apart again. The one real difference between the callers becomes a deliberate, documented, test-pinned decision:

Caller	clearError	Rationale
forceStaleAndRefetch (invalidate)	false	No new truth yet — keep the last-known error visible alongside the last-known data (SWR) until the refetch settles and overwrites both. Error persists until proven otherwise (TanStack-aligned).
setQueryData (optimistic write)	true	The written value IS the new truth; a lingering error would contradict it.

commitFetch's success path shares only the retry-reset half — it is the committing fetch, so there's nothing to bump or cancel — and now calls the extracted resetRetryCycle() (also used inside supersede).

Behavior-preserving, provably

The two policy tests were written and run GREEN against the longhand code first, then the extraction happened under them — they pin today's semantics, not the refactor's. A third test pins supersede's full field-by-field contract (generation bump, in-flight cancel, forced-stale, retry-ladder void, error policy both ways).

Verification

• New QueryEntry/supersede suite: 3/3
• SwiflowQuery suite (incl. the state-machine fuzz suite, which hammers invalidate/setQueryData): 123/123
• Full host suite: 1376 tests, 276 suites green
• QueryDemo wasm build clean

🤖 Generated with Claude Code

[github-actions]

📦 Bundle size

Artifact	Baseline	This PR	Δ
App.wasm	5.06 MB	5.15 MB	+1.91%
App.wasm (gzip)	1.80 MB	1.84 MB	+2.20%
JS runtime	54.5 KB	54.5 KB	+0.00%
JS runtime (gzip)	11.3 KB	11.3 KB	+0.00%
Total (gzip)	1.81 MB	1.85 MB	+2.19%

✅ Within budget (≤5% growth allowed).

_{Baseline: Swift 6.3, WASM SDK 6.3-RELEASE, measured 2026-06-18.}