UI rebuild (desktop):
- TraceSession: replace 3-column layout with two panes — turn-grouped
timeline tree (draggable splitter, search/filter, keyboard nav) and a
section-flow detail panel (Response / Messages / System Prompt /
Tools / Parameters / Raw), collapse state persists across spans
- Render LLM requests/responses semantically: messages as role-colored
conversation with tool_use/tool_result pairing instead of raw JSON
dumps; Raw fallback via CodeViewer for legacy truncated records
- TraceList: row-style list with model chips, mono metrics, hover
actions; content-visibility rows (no virtualization, WebKit-safe)
- i18n synced across zh/en/jp/kr/zh-TW (+25/-55 keys)
Data & capture (server):
- Capture full bodies: preview cap 2048 -> 240k chars, stream cap
256KB -> 1MB; list API trims previews to keep polling light; new
GET /api/sessions/:id/trace/calls/:callId returns the full record
- Extract per-call token usage at read time (SSE + JSON + proxy
wrapped); mtime-keyed read cache for the polling path
- Fix sensitive-key regex redacting *_tokens count fields, which made
token stats always report 0
Frontend data layer:
- SSE stream reassembly (Anthropic + OpenAI chat) adapted from
claude-tap (MIT, attribution in THIRD_PARTY_LICENSES.md), request/
response body parsers, shared formatters, on-demand call detail
cache; traceViewModel gains tokenUsage/isLifecycleNoise, drops
fullRaw
Tested:
- bun run check:server (1201 pass)
- bun run check:desktop (lint + 1358 tests + build)
- Chromium walkthrough against real local traces: list, session tree,
LLM semantic detail (new format), legacy fallback, tool detail
Desktop users need the same branch-from-here workflow that the CLI already exposed, so the branch creation logic now lives in a shared transcript utility and the desktop app routes completed message actions through the server API. The UI hydrates transcript ids after live completions so newly generated turns can be branched immediately without a refresh.
Constraint: Source sessions must remain unmodified while branch sessions inherit the active transcript chain and persistence metadata.
Rejected: Keep a desktop-only branch implementation | it would drift from CLI /branch semantics and duplicate transcript filtering rules
Confidence: high
Scope-risk: moderate
Directive: Do not remove the post-completion transcript hydration without a real-model desktop E2E for just-finished messages
Tested: bun run verify; Chrome Web UI E2E with real gpt-5.5 provider on ports 45678/45679
Not-tested: Provider-specific behavior beyond the configured Sub2API-ChatGPT route
