Renderer V2 Chat UI — Reviewer Cluster

Scope

Subpath	Files (~)	Role
src/renderer/src/pages/home/V2*	V2ChatContent.tsx, V2Inputbar.tsx, …	Page-level chat shell — wires up transport, overlay, history
pages/home/Messages/Blocks/	PartsRenderer.tsx, ToolBlock*.tsx, MainTextBlock.tsx, ThinkingBlock.tsx, V2Contexts.ts, …	Parts → React tree
pages/home/Messages/Tools/	approval cards, useToolApproval, defer hints	Tool-call rendering + approval UX
pages/home/Messages/ (page-level)	Message.tsx, MessageGroup.tsx, ChatVirtualList.tsx, MessageMenubar.tsx, branch nav (ChatNavigation.tsx, ChatFlowHistory.tsx), SiblingNavigator, MessageEditor.tsx	Composition of blocks into messages
pages/home/Messages/Blocks/__tests__/	snapshots + interaction tests	Per-block coverage

About 68 files in this cluster — the largest by file count.

Intent

v1 rendered out of a Redux messages slice and an ad-hoc blocks field on each message; streaming wrote into Redux through ChatSessionManager.handleFinish (440 lines). v2 reads from:

• useTopicMessagesV2(topicId) — DataApi query for the topic tree.
• useExecutionOverlay(topicId) — in-memory parts during streaming.
• useTopicStreamStatus(topicId) — pending / streaming / awaiting-approval / terminal status from the shared cache.

The blocks field is gone (commit 78a02662b refactor(agent-message): remove deprecated blocks field); rendering reads parts: CherryMessagePart[] directly.

Key changes

PartsRenderer

Renders CherryMessagePart[] by dispatching on part.type. The per- type renderers live in Blocks/ (one component per type). Adding a new part type means adding one switch arm + one renderer component.

Beat-loader visibility uses useIsActiveTurnTarget(message) — the single predicate covering "DB status says streaming AND this is the turn-target message AND nothing else has rendered yet". See Renderer Transport for the classifier consolidation.

Commit 6ba5cd20c refactor(v2-chat): extract useIsActiveTurnTarget.

V2Contexts.ts

Two contexts:

• PartsContext — Record<messageId, CherryMessagePart[]> | null. null means "v1 mode" (no provider mounted) — handlers in Blocks/ branch on this.
• TranslationOverlayContext + TranslationOverlaySetterContext — separate reader/writer contexts so writers don't re-render on every setter call. The setter context has a strict variant (useTranslationOverlaySetter — throws when no provider) and a non-strict variant (useOptionalTranslationOverlaySetter — returns null for scopes that intentionally don't mount the provider, e.g. agent sessions / quick assistant).

Branch navigation

SiblingNavigator shows < i/N > arrows. For deep forks (subtree size

5 OR last activity > 1h ago) it shows the extended form (< 2/3 · 47 msgs · 3d ago >). See branch-navigation.md.

ChatFlowHistory.tsx is the modal tree view. Reads MessageService.getTree(topicId, opts) from DataApi — no Redux, no state.messages.

Approval cards

Tool blocks with state === 'approval-requested' render an approval card (Blocks/ToolBlock.tsx switching on state). The card:

• Reads the approval id from part.approval.id.
• On click, calls useToolApprovalBridge(topicId)(match, approved, ...).
• Optionally calls useToolApproval to remember the per-server / per-tool decision for future calls (commit a87a8cc65 refactor(tool-approval): enhance useToolApproval to support MCP tool persistence).

Translation overlay

MessageTranslate.tsx + TranslationBlock.tsx: when the user translates a message, the translation appears as an overlay layer above the original parts. Persists into the translate_history table via the translate-on-main flow.

MessageMenubar.tsx was hardened against missing translation overlay in agent sessions (commit 6f2cb19c3 fix(message-menubar): don't crash agent sessions on missing translation overlay).

Streaming smoothness

Two perf-driven changes shipped in this cluster:

• baa1a66f6 perf(markdown): block-split streaming render to remove O(n²) re-parse — incremental markdown re-parse.
• 20d330b18 fix(smooth-stream): adaptive jitter-buffer playout to kill burst-pause sawtooth + e427bae44 fix(smooth-stream): keep render loop alive across mid-stream queue drains + 1461b461c fix(stream-listener): bound delta coalescing by wall-clock and size — smoothing the visual pacing of text-delta playback.

useScrollAnchor

New hook that anchors the virtual list on the active message rather than the bottom — keeps the user's reading position stable as the assistant streams in.

Invariants

• The renderer never PATCHes approval state directly. Decisions go through useToolApprovalBridge.
• Streaming parts come from the execution overlay, NOT from SWR. Writing streamed parts to SWR would race the DB-authoritative refresh and cause visible flicker; see commit cd5560f26 feat(pending-messages): move optimistic turn out of the authoritative cache.
• Overlay is disposed only after DB refresh resolves (.finally).
• The classification of "is this message the active turn target" lives exclusively in useIsActiveTurnTarget — duplicating that logic in consumers caused the Phase-2 regression.

Validation

• Blocks/__tests__/ — per-block snapshots + interaction
• agents/__tests__/ for agent-session-specific UI
• Commit chain 3b2fb0752 → 6ba5cd20c → ed905ca45 consolidated the turn-state plumbing; each commit is small enough to review individually.

Follow-ups (out of scope)

• The ChatFlowHistory modal is still functional but the design is pending UX iteration — see branch-navigation.md.
• Some v1 → v2 bridge code still lives in bridge.ts / legacy: only present in v1 settings annotations on types; deletion is gated on the renderer cleanup chain (see memory: v1→v2 renderer cleanup blockers).