PR #182 review (post-fix pass) surfaced two latent correctness risks in the
new MessageItem memo: the per-message signature tracks only [type, text length,
state, error/output presence] + metadata, so a part kind whose VISIBLE content
can change WITHOUT changing those fields would silently freeze a stale row.
Neither is reachable with the current toolset (tool output is set once;
streaming is append-only with a fixed id), so the correct fix is to harden the
documented invariant rather than hash output content on every delta (getPage
returns full page content — hashing it per-delta would tax the hot path this
PR optimizes).
Add a WARNING in messageSignature naming the two future triggers (a tool that
streams `preliminary` output; a client-side regenerate/edit that mutates a
finalized row in place) and the required action (extend the signature).
No behavior change (comment only). vitest src/features/ai-chat 189/189 pass,
tsc clean for the touched files.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Resolve the PR #182 code-review (Request changes) on top of the already-merged
develop (the merge commit preserves both the markdown useMemo and the
collapseBlankLines fix in reasoning-block.tsx).
- Extract messageSignature from message-item.tsx into utils/message-signature.ts
(matches the feature's "pure UIMessage helper + colocated test" convention) and
export arePropsEqual so the memo seam is unit-testable. No logic change.
- Add utils/message-signature.test.ts covering every change signal (text grows,
part appended, state flip, output appears, errorText appears, usage.reasoningTokens
arriving on finish-step, metadata error/finishReason) plus the negative
content-identical-clone case.
- Add components/message-item.test.ts for arePropsEqual (each prop diff -> false,
identity fast-path -> true, same-content-different-object -> true, changed -> false).
- Add components/message-item-memo.test.tsx: render-level proof that finalized text
parts are not re-parsed when only a tail part grows (MarkdownPart memo).
- CHANGELOG: add the user-facing 100% CPU freeze fix under [Unreleased] / Fixed.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
