[teamleaderleo]

A capped cached transcript could first show raw activity, then replace it with the folded completed turn when attach supplied its missing prompt. Preserve that prompt when capping a visited chat and prepare it during read-ahead so equal-data attach keeps the first rows and their layout.

Code cards keep visible text until the worker draws, with matching fallback font, header label and final-newline geometry. Authentication preflight keeps sending disabled and its tooltip, but no longer inserts then removes a 20px “Checking…” row above the composer. Actual sign-in failures retain their notice. The temporary row originated in #26643.

Static transcript previews now mount their complete supplied snapshot, with the host theme and font applied before React renders. Previously the gallery painted an empty shell and delivered its already-known rows in a later task. Delayed-host, New Tab and mock-daemon scenes retain their asynchronous startup. This corrects the gallery mount path; it does not establish native cold-open performance.

Current head 877032d08e0d4cee4c3a10681dcfdafa4ffb0fc6 merges base cd679bd6f02bd8984a855c1aefe5a8ecbc7a2d00. The sole conflict carries base's configureMessageLineLook call into applyPaneTheme, preserving message-row styling at initial mount and subsequent bridge updates. All other PR changes are retained. Independent Claude Opus 5.5 medium review passed at this exact head. The resolved theme configuration matches base's calls in order; the rest of the reviewed patch is unchanged. Host-safe lint and exact-range static checks passed. Focused fleet verification and the official webview verdict are pending.

Prior integration head 1400922180b7adaca6a5ca09b481bf4148da3599 passed independent Opus 5.5 medium review and focused fleet verification: 28 tests, 324 assertions, no skips, typecheck across 4,241 files, and scoped lint. Its three-round transcript metrics were Chromium 0.4 ms / WebKit 1 ms settle after paint, with CLS 0 in both. Those results are historical after this base merge.

The three apparent gallery shift regressions at 071a377 reproduce identically on its exact base when both use the same browser. Scoped attribution records completed renders, both matching named guard failures, and the experiment's final metadata failure; it is not a full-run pass. Browser setup is fixed separately by #33836.

Prior head 7049de3f0b623fd40fbc4c023792481bc46e05b8 had independent Claude Opus 5.5 medium SHIP. Paired first-mount verification at 7049de3f passed: 14 tests, 251 assertions, and typecheck across 4,212 files. Both baseline first-frame tests fail on the empty shell. The eight completed-turn/switch rows below were measured at 1339cad9; the preview rows were measured at 7049de3f before this base merge.

Leo's request:

"man me clicking into some of these workspaces and tabs / sometimes i see like / the text shows up right on click but the actual thing loads a second later / ... / you should be able to simply see the text rendered instantly wherever it is"
"even for remote things it should be fast"

Performance

metric	before	after	delta	harness or run link
Cold-prefetched completed turn: swap frames	65	0	−65	same-harness red/green, chat-switch-prefetch.test.ts
Warm capped completed turn: swap frames	71	0	−71	same run, full first visit then capped revisit
Post-first-text shift score, cold/warm	0.021789 / 0.021789	0 / 0	−0.021789 / −0.021789	same run, includes recent-input shifts and composer geometry
Code handoff: blank frames	8	0	−8	same run, code-block-highlight-height.test.ts, held worker
Standard switch: unread first paint	272.9 ms	247.9 ms	−25.0 ms	benchmark, LATENCY=150 bun bench/chat-switch.bench.ts 3 300
Standard switch: read-ahead first paint	94.9 ms	85.5 ms	−9.4 ms	same benchmark
Standard switch: unread/read-ahead shift	0 / 0	0 / 0	0	same benchmark
Standard switch: idle wakeups	0	0	0	same benchmark
Static preview: Chromium settle after paint	139.7 ms	0.5 ms	−139.2 ms	paired ui-stability at 7049de3f, 3 rounds
Static preview: WebKit settle after paint	305 ms	1 ms	−304 ms	same run, unchanged harness
Static preview: Chromium/WebKit CLS	0 / 0	0 / 0	0 / 0	same run
Static preview: Chromium navigation→settled	793.4 ms	766.2 ms	−27.2 ms	same run
Static preview: WebKit navigation→settled	1269 ms	1290 ms	+21 ms	same run
Static preview: idle wakeups/5 s, each engine	1	1	0	existing relative-time clock

Same-worker production-path pair at 1339cad9 (historical, same seed/harness on cmux10s; HQ receipt):

metric	base	head	delta	harness or artifact
Sidebar first content	673.2 ms	640.3 ms	−32.9 ms (−4.9%)	same-worker chat-open, n=3; base/head artifacts
Reopen first content	638.7 ms	640.2 ms	+1.5 ms	same harness
Restore first content	2846 ms	2759 ms	−87 ms	same harness; CEF startup dominated
Flashes	0	0	0	same harness; distinct from native swap/CLS

These are historical production-path latency measurements, not native frame-strip swap or CLS evidence. The warm frame strip did not capture the CEF transcript, so native 0/0 remains unclaimed.

The standard benchmark has short turns and does not reproduce the capped-turn defect; the dedicated regression above does. Numbers compare the same source and harness with only this production patch reversed/restored. These are completed-turn browser results, not a claim that every fresh native or offline remote chat is one-render. Syntax-color changes remain #33523; unfinished cached turns remain #33529. #33580 owns persisted remote opener metadata and its peerCopy.ts adapter; this PR preserves #33155's peer-copy provenance and does not change storage.

Earlier production-path validation at 1339cad9: 48 targeted tests passed (202 assertions), with six expected baseline regressions. Typecheck hit seven existing errors in the unchanged streaming-no-flicker test from #33526; the correction is already on base (#33545), and verification with only that unchanged base test corrected found no type errors in 4,161 files. Independent Claude Opus 5.5 medium review: SHIP at 1339cad928dbefe2a0563fd6a68fe6de7dff562e. Host-safe web lint passed. The frame sampler records row text/rectangles, composer rectangle, width, scrollTop and scrollHeight through attach; its observer, frame callback and deadline are cleaned up. Production adds no timer or animation loop.

Scenes: agent-pane.transcript#conversation (static first mount); capped completed Codex turn in test/chat-switch-prefetch.test.ts; agent-pane.transcript#copy-last-code-block; test/browser/code-handoff-height.html. 2x light/dark scene captures were opened by the independent reviewer: readable cards without blank/clipped text; syntax colors are a later paint tracked separately. Reference: private codex/live/transcript-worked-for-collapsed-summary. Specs: leo-workspace/design/chat-transcript.md and design/composer.md (routine state belongs in controls, not added narration rows).

Risk: cached turn preparation and asynchronous code rendering. InitialChat is preview-only; production still calls mountAcpmux() without a seed. A future production initial-state caller must initialize the full receive/trust/harness/persistence path. The new first-frame tests use bounded frame samplers with cleanup and assert actual fixture text, row/line geometry, width and scroll across equal snapshot delivery. Send/auth behavior has explicit pending and settled regression coverage, including click, Enter, and the resend handle. One extra bounded opener read may run in background for a page that begins mid-turn; nothing new waits on the click.

Agent session: agent session

Webview health run 41667274334 finished its render steps. Two health shards reported only base-red attribution failures in Judge the red states against the base; logs name agent-pane.claude-desktop-tool-summary#failed-open and agent-pane.subagent-split-pair#default as red the same way on base cd679bd6f02b. No setup or render failure is attributed to this PR. The official webview verdict is complete; its only failures are the base-red states named above.

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[github-actions]

cmux status _{(one comment, edited in place; each line is updated by the job that owns it)}

Review 877032d: HQ feed card · gallery before/after runs · checks

App of this head (app.zip, kept 1 day)

gh workflow run reload-build.yml -R manaflow-ai/cmux --ref feat-cmux-next -f tag=pr33460 -f ref=lane/perf-one-render -f platform=macos -f backend_mode=local

Gallery before/after for 877032d: 16 states rendered, 4 images differ, 3311 more touched states not rendered. Images are in the run's artifact, not on this public PR; the independent review of this head reads them on its own, so the PR needs no hand-made screenshots of these states.

gh run download 41667274114 -R manaflow-ai/cmux -n gallery-advisory-33460-877032d08e0d4cee4c3a10681dcfdafa4ffb0fc6 (then read gallery-review.json)

States

State	Theme	Status	Diff	Picked by
agent-pane.access-offer/turn-no-credits	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.access-offer/turn-no-credits	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.access-offer/turn-low-credits	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.access-offer/turn-low-credits	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.access-offer/turn-no-offer	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.access-offer/turn-no-offer	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.activity-line-looks/none	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.activity-line-looks/none	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.activity-line-looks/spinner	Apple System Colors Light	changed	0.0622%	own conversation.css
agent-pane.activity-line-looks/spinner	Apple System Colors	changed	0.0503%	own conversation.css
agent-pane.activity-line-looks/kind	Apple System Colors Light	changed	0.0258%	own conversation.css
agent-pane.activity-line-looks/kind	Apple System Colors	changed	0.0245%	own conversation.css
agent-pane.activity-line-looks/aligned	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.activity-line-looks/aligned	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.approval-edits/single	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.approval-edits/single	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.approval-edits/grouped	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.approval-edits/grouped	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.approval-edits/single-multiedit	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.approval-edits/single-multiedit	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.approval-edits/grouped-multiedit	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.approval-edits/grouped-multiedit	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.approval-edits/single-long	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.approval-edits/single-long	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.approval-edits/grouped-long	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.approval-edits/grouped-long	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.attachment-source/before	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.attachment-source/before	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.attachment-source/corner	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.attachment-source/corner	Apple System Colors	unchanged	0%	own conversation.css
agent-pane.attachment-source/small	Apple System Colors Light	unchanged	0%	own conversation.css
agent-pane.attachment-source/small	Apple System Colors	unchanged	0%	own conversation.css

_{Pick other states with a Gallery: entry.id, entry.id/variant line in the PR body.}

Passes: CI passes on 877032d08e.

CI passes on 877032d08e (run 41667274759 attempt 1).

Written by scripts/ci/classify_failures.py (ci-failure-attribution.yml); signatures are its SIGNATURES table. A machine verdict is the runner's fault, not this PR's; yours means the failing file is one this PR changes, also red on main that main's latest full suite fails the same way, seen on other PRs that it failed on another pull request's run lately.

web and size checks: green

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.4168460606701 (2e9aa60ffa)
• cmux NEXT nightly 1.0.0-nightly.4168717571501 (4ca639b0ca)
• cmux NEXT nightly 1.0.0-nightly.4168960686802 (6076a8e983)
• cmux NEXT nightly 1.0.0-nightly.4169064870802 (3bfe74f2e0)

The feat-cmux-next push run https://github.com/manaflow-ai/cmux/actions/runs/41683707440 at 2e9aa60 failed: cmux-next checks (god files, concurrency, crash safety, l10n).
Those jobs last passed at 7ab967b. This pull request is one of 1 merged since: #33460.
If the failure is in your change, fix forward on feat-cmux-next. Pull requests run only the tiers their paths reach (docs/ci/cmux-next-tiers.md); label a batch PR full-ci to run them all before merging.

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[teamleaderleo]

Review (claude opus-5.5 medium, independent subagent): SHIP at 740f010

Visual verdict: code only; fleet captures pending. Independent reviewer checked retained turn opener and stale-read guards, visible code fallback, font/label/newline parity, and final test-only corrections. The test now advertises the one turn its journal contains and permits the rail's independent prompt-index request; zero-swap/shift assertions remain unchanged. No blocking code findings.

Follow-ups: syntax-color handoff tracked in #33523; offline peer-snapshot opener metadata remains a known gap. Fleet red/green result and visual inspection are pending; this is not a test pass.

[teamleaderleo]

Focused gallery reconciliation at the exact failing merge tree (31953cdcdb5f40946bf7dfe4e6e39bea8142e10d) and its base (41f05ffcd61f8076538aaaa732a95a7cacb769e0): run 41629199610 passed all eight targeted light/dark cases in merge → base → restored merge order, using the original Chrome 156.0.8078.80. Source trees and final restoration were verified.

GitActions keyboard/include-new shift was 0.029849550145617604 in every stage, below the original failed 0.05704566790037136. Font picker had no violations; the new RTL alignment violation was absent (11 known violations remain). Normalized actual-font/network/style receipts matched across stages. This does not establish a font-fallback cause or clear the original full-shard failures by itself.

The named webview red is undergoing a complete exact merge/base comparison in a separate focused run. No new product commit; head remains 1339cad928dbefe2a0563fd6a68fe6de7dff562e. Native capture evidence is still incomplete.

[teamleaderleo]

Completed per-test base attribution: run 41631324917, logs/artifact, verifies the exact CI merge tree 31953cdcdb5f40946bf7dfe4e6e39bea8142e10d and exact base 41f05ffcd61f8076538aaaa732a95a7cacb769e0.

• agent-pane-subagent-of-untitled.test.ts > a name acpmux generated after the agent never shows in the pill: both fail at line 112 clicking .cv-subagent-done filtered by Reviewer, with the identical 30000 ms locator timeout. Each run completes 0 pass / 1 fail / 3 filtered out / Ran 1 test across 1 file; neither is a runner timeout or crash. Agent chat: a subagent paged out of view keeps its name in "Subagent finished" and "Sent to" #33252 changed the row to prefer its task, Review the uploader branch; the test and renderer are unchanged between these trees. The selector repair has been routed to its original owner.
• ThisTree.test_every_compile_job_names_its_warm_sources: both fail the identical assertion that stable-next.yml:swift-suites wires deriveddata-reuse while declared exempt. Each completes one test with one assertion failure.

The comparison harness succeeds because all four named executions completed and source/index restoration was verified; it does not mean those tests passed. These two reds reproduce on base. The official webview verdict is still red; this receipt does not rewrite it. Original gallery-shard failures remain separately documented in the preceding comment.

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[teamleaderleo]

Final-head validation at 7049de3f0b623fd40fbc4c023792481bc46e05b8: paired first-mount run passed 14 tests / 251 assertions and typecheck (4,212 files). The unchanged stability harness measured Chromium 139.7→0.5 ms and WebKit 305→1 ms after first paint; CLS stayed 0 in both. The body records the full comparison and its preview-only scope.

The release-notary guard's ThisTree.test_every_compile_job_names_its_warm_sources failure is reproduced by name and exact error on this head and base 2a48ef76ce442a85d2c83af440b49d13726a87d3: stable-next.yml:perf-budgets is exempt but its steps wire ['deriveddata-reuse']; list them under 'warm' instead. Completed paired attribution; relevant source trees are identical. Both runs completed normally with one failure, no crash. This is an unrelated base warning. The routed webview verdict is still running; the PR remains held for it.

[teamleaderleo]

Native capture evidence (Debug builds, base = this PR's merge-base 2a48ef76, head 7049de3f, synthetic 500-thought chat):

scenario	base	head
Cold chat open (trace timing + 250 ms video)	not comparable (the chat tab opened in front on base, so the run switched away from it)	first content 732 ms, longest empty 543 ms; reply visible from the first video sample after open and stays
Warm tab switch (sampled frames)	172 samples, 2 distinct	211 samples, 2 distinct; reply verified after the switch
chat-open, same machine, median first content	sidebar 595 / reopen 683 / restore 3156 ms	pending

The warm sampled frames do not show the transcript page itself, so they neither prove nor disprove a swap; this is not a one-render 0/0 claim. Same-machine head numbers for chat-open are still running. Native evidence is advisory and does not block landing.

[teamleaderleo]

Exact-source attribution for head 071a377: run 41657645538, artifact 13240104144, compared merge 90ebf2d with base 1ac26c7. All 32 renders completed. Using the same browser, both trees give identical Git Actions and repository-search shift scores: full Chrome produces the same three reds on both; headless-shell passes both. The workflow's mixed browser comparison explains these apparent regressions; #33836 fixes that setup.

Both named guard failures also complete identically on the two trees: DigestTests.test_the_repository_highlights_validate (team invitation highlight missing its link) and ThisTree.test_every_compile_job_names_its_warm_sources (perf-budgets exemption). No crash or incomplete run is excused.

The experiment remains marked failed: its final optional CDP command-line metadata assertion failed after the renders and reports completed. Launch options and browser.version are recorded (Chrome 156.0.8078.79; shell 156.0.8078.80, identical across trees within each mode), and exact source-tree/restoration checks passed. This is scoped attribution evidence, not a claim that the full run passed.

[teamleaderleo]

Review (claude opus-5.5 medium, independent subagent): SHIP at 1400922

Visual verdict: code only; this base merge changes none of the PR's rendered UI. The independent reviewer verified that the PR's added/removed lines are unchanged against its new base, and the only conflict keeps mock transport preparation before the mount. Primary integration inspection agrees; working tree is clean.

Follow-ups: existing gallery run 41659686211 exercises agent-pane.new-chat-no-shift#send-to-streaming in both themes. Focused final-head verification is dispatched. This receipt is a code review, not a test pass. Earlier tracked follow-ups, including #33523, remain.

[teamleaderleo]

Review (claude opus-5.5 medium, independent subagent): SHIP at 877032d

Visual verdict: code only. The conflict resolution preserves base's new message-row styling on both mount paths. The reviewer verified that applyPaneTheme matches base's inline configuration calls exactly, in the same order; the remaining PR patch is unchanged. Primary inspection agrees. Scoped lint and static checks passed.

Follow-ups: exact-head fleet verification 41667496265 and official webview results are pending; this is not a test-pass receipt. Carried follow-ups, including #33523, remain.

[teamleaderleo]

Webview health attribution for run 41667274334: health (1) and health (5) failed only in Judge the red states against the base. Their logs identify the red states as base reds on cd679bd6f02b: agent-pane.claude-desktop-tool-summary#failed-open and agent-pane.subagent-split-pair#default; all listed comparison warnings also say red the same way on base. No render/setup failure is attributed to this PR. The official webview check is still finishing; no merge action taken while it is pending.