feat(core,cli): two-phase session listing for instant /resume first frame - #3988
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feat(core,cli): two-phase session listing for instant /resume first frame#3988qqqys wants to merge 12 commits into
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`listSessions` previously called `countSessionMessages` per file, which streamed the entire JSONL through `readline` to count unique user/assistant UUIDs. For a project with N sessions averaging M bytes each, every /resume open paid O(N · M) wall time before showing the picker — by far the dominant cost once a project accumulated many multi-MB sessions. This change: - Drops the per-file count from listSessions / findSessionsByTitle. `SessionListItem.messageCount` is now optional. Callers that need a count call the new public `SessionService.countSessionMessages (sessionId)` lazily — typically only when a SessionPreview panel is about to display the badge. - Pools a single 64KB tail-read buffer across the per-file metadata reads in listSessions / findSessionsByTitle, mirroring the pattern in claude-code's `enrichLogs`. The two helpers in `sessionStorageUtils` (`readLastJsonStringFieldSync` and `readLastJsonStringFieldsSync`) accept an optional caller-owned scratch buffer; one-off callers (rename, single-session lookup) pass nothing and keep the original alloc behaviour. - Updates SessionPicker's row metadata to omit the "N messages" segment when `messageCount` isn't available, keeping the visual layout intact. Tests: - Pin that listSessions does not populate messageCount (regression guard against silently re-introducing the per-file scan). - Smoke test the buffer-pool plumbing — same caller-owned buffer handed to two reads of different file sizes returns both correct values without state bleed. Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>
Tightens the title-write / title-read invariant so the picker's
metadata read is bounded to a fixed 2 × 64KB per file, regardless
of session length, with no fallback that scales with file size.
Writer (`ChatRecordingService`):
- New `bytesSinceTitleAnchor` counter and `TITLE_REANCHOR_BYTES`
threshold (32 KB, half of LITE_READ_BUF_SIZE).
- `appendRecord` now updates the counter and, once it crosses the
threshold while a title is set, re-appends a fresh `custom_title`
record to EOF (`reanchorTitle`). The recursive append routes
back through the same tracking path, which sees the title
record and resets the counter to zero.
- Sessions that never set a title pay zero overhead — the early
return in `updateTitleAnchorTracking` short-circuits.
Reader (`sessionStorageUtils`):
- `readLastJsonStringFieldSync` / `readLastJsonStringFieldsSync`
now read the file's last 64 KB, fall back to the first 64 KB
on miss, and return `undefined` if neither contains the field.
The previous Phase-2 streaming full-file scan (capped at 64 MB)
is removed entirely.
- The pooled scratch buffer (already optional) now backs both the
tail and head reads — only one allocation per `listSessions`
page even with the head fallback firing.
- `MAX_FULL_SCAN_BYTES` constant deleted (unused).
The two changes are coupled: the reader's tighter bound only works
because the writer guarantees the title stays in tail. A title
buried mid-file is now intentionally `undefined` (the picker
falls back to `firstPrompt` for display) rather than triggering a
full-file scan that would freeze the UI on long agent transcripts.
Tests:
- `chatRecordingService.customTitle.test.ts` — three scenarios
pinning the re-anchor invariant: threshold trigger, no-spurious
on no-title sessions, no-trigger on small write bursts.
- `sessionStorageUtils.test.ts` — replaces Phase-2 tests with
head-window fallback tests; pins the new "buried beyond both
windows returns undefined" contract; updates buffer-pool reuse
test to cover both tail and head reads with the same scratch.
E2E coverage (35/35 scenarios on a separate harness against real
fs): R1–R10 reader contract, M1–M4 multi-field, W1–W7 writer
re-anchor, L1–L6 listing latency + regression pins, S1 stress
(200 × 3 MB), C1 concurrency, I1–I5 writer/reader integration.
Measured 2.6× speedup on listSessions(50) over 50 × 4 MB
sessions vs the legacy `countSessionMessages` baseline; speedup
scales linearly with average file size.
Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>
- countSessionMessages: valid id counts unique user/assistant uuids and ignores other types/malformed lines; invalid id short-circuits without filesystem access; ENOENT degrades to 0 instead of bubbling. - readLastJsonStringFieldsSync: mirror the single-field variant's scratch-buffer reuse test across a tail-hit then head-fallback to catch any decode that ignores bytesRead. - ChatRecordingService re-anchor: legacy resumed session (source undefined) must omit titleSource on threshold-triggered re-anchor, not silently reclassify as 'manual'. Co-authored-by: Qwen-Coder <noreply@alibabacloud.com>
`String.length` undercounts the on-disk size of multi-byte payloads (CJK, emoji are 1 UTF-16 unit but 3 UTF-8 bytes), so a session full of CJK content could push >96KB of writes past the last anchor before the 32KB threshold thinks it has — silently drifting the title past the 64KB tail window the picker scans. Switch the byte counter to `Buffer.byteLength(..., 'utf8')` for parity with `jsonl.writeLine`. Also reset `bytesSinceTitleAnchor` to 0 in the reanchor catch: without it, a failing reanchor pins the counter at the threshold and turns a single transient I/O fault into a per-record retry storm. One missed anchor is the right tradeoff — finalize() will re-emit on the next lifecycle event. Co-authored-by: Qwen-Coder <noreply@alibabacloud.com>
The 64KB head-window fallback in `readLastJsonStringFieldSync` / `readLastJsonStringFieldsSync` reads a fixed slice and hands it straight to the extractor — its trailing bytes can fall mid-record. A partial line whose `customTitle` value happens to close inside the buffer but whose body extends past 64KB would otherwise win the latest-match race and surface as the picker's title. Drop everything past the last `\n` before extracting (only when the buffer is shorter than the file — a small file is necessarily whole- line). Honors the original Phase-2 contract that only complete lines get a vote, without paying for the deleted full-file scan. Co-authored-by: Qwen-Coder <noreply@alibabacloud.com>
…ession-list-perf # Conflicts: # packages/core/src/services/sessionService.ts
…, pin perf contract Address QwenLM#3897 follow-up review findings: - SessionPreview footer no longer drops the message count when listSessions omits it. The prop is the override path; default falls back to a unique user/assistant uuid count derived from the already-loaded conversation, matching countSessionMessages semantics with zero extra disk I/O. - countSessionMessages now scopes to the current project, mirroring the first-record cwd check in deleteSession/renameSession/loadSession. A valid sessionId from another project sharing the chats dir no longer bypasses project boundaries on lazy count. - New regression tests: - SessionPicker row renders cleanly with messageCount === undefined (no "messages"/"undefined"/dangling separator) - findSessionsByTitle perf contract: matches have messageCount undefined and fs.createReadStream is never called - countSessionMessages: cross-project sessions return 0 without streaming, empty file returns 0 - Update corruption-recovery tests to call private countSessionMessagesFromPath (the streaming entry point) instead of the public sessionId-shaped API the merge from main pointed them at. Co-Authored-By: Qwen-Coder <noreply@qwen.com>
The session metadata reader uses two bounded 64KB windows (tail + head) since the perf rework on this branch — never a full-file scan. Two comments still described the prior behavior. Reported in MR review. Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>
ACP renameSession constructed a fresh SessionService and wrote the custom_title record straight to disk. When the same session was live in this process, ChatRecordingService.currentCustomTitle stayed at the old value, so the next title re-anchor (every 32KB) or finalize() re-emitted the stale title at EOF and silently reverted the rename. Now we look up the live ChatRecordingService first and route through recordCustomTitle, which keeps the in-memory cache and the on-disk record in sync. The SessionService path remains for the non-live case (e.g., another client renaming a backgrounded session). Reported in MR review. Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>
…rame `SessionService.listSessions` is split into a stat-only `listSessionsLite` (readdir + stat, no JSONL IO) and an `enrichSessions` step that does the head + tail reads and applies the project-hash filter. The picker hook now drives both: the lite phase paints the picker frame with `pending: true` placeholder rows immediately, then enrichment hydrates each row with its full prompt / branch / customTitle. Why this matters: - The legacy single-call path took ~30 ms median for a page of 20 on a warm cache (reading head/tail per file). Within tail-buffer pooling and lazy message counts, that's already fine on modern NVMe — but on slow disks, NFS, or a project with thousands of sessions it scales linearly with page size and dominates the time-to-first- visible-row. - Lite-only first frame measures ~1 ms in the same conditions. Enrichment runs in parallel with the user's eyes registering the picker frame, so even if the IO budget is identical, perceived latency stops being a function of N. `SessionListItem` is now `pending`-aware: every field except `sessionId / mtime / filePath` (and the new `fileSize`) is optional, because lite items omit them. Callers that already coped with the optional `messageCount` keep working; one ACP integration callsite needed a `?? cwd` fallback. The legacy `listSessions(opts)` is a thin wrapper around `listSessionsLite + enrichSessions` — same public shape, same project- filter semantics — so SDK / WebUI / VSCode-companion callers don't break. Tests: - listSessionsLite returns stat-only items (regression pin: no jsonl.readLines call during the lite phase). - enrichSessions applies the project-hash filter and drops siblings living in a shared chats dir. - Picker renders the first frame from lite items before enrichment resolves: a held-open enrich Promise lets the test inspect the intermediate placeholder frame, then verify the swap-in. Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>
…ession-list-progressive
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Summary
Splits
SessionService.listSessionsinto a stat-onlylistSessionsLiteand anenrichSessionsstep, then wires the picker to render the first frame from lite items immediately while enrichment hydrates each row in the background. The legacylistSessions(opts)is preserved as a thin wrapper around both, so SDK / WebUI / VSCode-companion callers don't break.Why
After #3897, the per-page cost of
listSessionsfor 20 rows is ~30 ms median on local NVMe — fine on modern hardware, but it scales linearly with page size and dominates time-to-first-visible-row on slow disks, NFS, and large-N projects.This PR decouples first-paint latency from N entirely:
listSessionsLitesize=20enrichSessions20 rowslistSessionssize=20First frame goes from ~30 ms → ~1 ms. Enrichment cost is unchanged but happens in parallel with the user's eyes registering the picker frame.
Visual proof (tmux capture, with 800 ms enrich delay injected for demo)
T+86ms — lite phase, picker frame already painted, every row a placeholder:
T+906ms — enrichment lands, rows swap to real metadata:
The injected delay was reverted before commit; on local NVMe the swap is imperceptible.
Type changes
SessionListItem's shape is now lite-aware:sessionId,mtime,filePath, plus the newfileSize?(cheap stat field)pending?: boolean—truewhile still in lite formcwd,startTime,prompt,gitBranch,customTitle,titleSource) are now optionalmessageCountwas already optional from #3897. Existing consumers that handle the optional case (e.g.vscode-ide-companion's?? messages.length, the picker'stypeof === 'number'check) keep working unchanged. One ACP integration callsite needed acwd ?? cwdfallback.Picker changes
useSessionPicker: initial-load + load-more both call lite first, then enrich in the background. AbortController on unmount cancels in-flight enrichment.SessionPicker.tsx: pending rows render…<sessionId-prefix>in the dim color slot; metadata row hides the time/branch suffix when fields are absent.Compatibility
listSessions(opts)returns the same shape it always did — same project-filter semantics, same pagination cursor (with the wrapper looping when sibling-project files drop out during enrichment, matching pre-split behaviour).cwdif a head record decode failed mid-page.Test plan
tsc --noEmitclean for bothpackages/coreandpackages/clivitest runforsessionService.test.ts(47 cases, +2 new),sessionStorageUtils.test.ts(44 cases),sessionService.rename.test.ts(17 cases) — 108/108 passvitest runforStandaloneSessionPicker.test.tsx(38 cases, +1 new),sessionPickerUtils.test.ts,useResumeCommand.test.ts— 60/60 passlistSessionsLitedoes not calljsonl.readLines— guards against silently re-introducing head IO into the fast pathenrichSessionsapplies the project-hash filter — sibling-project files in a shared chats dir get dropped during enrichment, matching pre-split semantics/resumeagainst 313-session / 127 MB chats dir confirms the lite frame appears at T+~86 ms and rows swap as enrichment completes🤖 Generated with Claude Code