[teamleaderleo]

Completed HTML writes from every harness use the existing artifact preview. A full recorded ACP diff or a whole-file write input opens the document; a replacement-only edit snippet does not masquerade as an entire HTML file.

Leo asked: "the /side thing i heard somebody really liked in codex... and i think html/html artifacts and that kinda good viewing and good support for it would be cool" and "like the claude.ai artifacts but imagien you didnt need to only have it on claude.ai...".

This builds on #25190. It preserves that PR's HTML/SVG/JSX aliases, preview surface, and exports, and replaces its detector with one pure helper shared by all harnesses. The helper accepts completed edit/fileChange records, keeps canonical file identity, recovers complete Write inputs even when the old contents are unknown, and excludes failed/running calls, shell commands, and partial or legacy unmarked Edit/replace snippets. It never reads a file or reconstructs a patch.

Each immutable completed tool update is parsed once through a weak cache. This adds no timer, scroll handling, storage, or per-token transcript walk. Recovered from the earlier nx-artifact-detect-1025 work at ddd3631.

A fresh Astra review found that Codex adoption labels multi-file changes “Edit N files,” including complete added HTML files. The final repair verifies per-file whole-add provenance through normalized tool records, preserving legacy snippet rejection. Final head, focused red→green and independent re-review receipts are pending; no SHIP is claimed yet.

Observed / Not run

• Recovered detector run40486752560: red9pass/13fail, then30/30head and full web check including typecheck pass.
• Recovered final capture run40487775047:10/10cases pass for Claude/Codex/pi/Gemini/legacy partial Edit, in light and dark. The final provenance regression will run at the stacked head; the older fixtures missed Codex adopted multi-file additions.
• No disk reads, tool execution, storage, polling or per-token transcript walk are introduced.

Agent session: agent session

[teamleaderleo]

Owned by an agent session · session

[blacksmith-sh]

Found 78 test failures on Blacksmith runners:

Failures

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...and 68 more test failures. View all on Blacksmith

^{Need help on this PR? Tag @codesmith-bot with what you need.}

[cmux-bot]

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

Unclear: web / react-apps-check failed: no known signature; failed step: Check webview test shards.

CI failed on dbb878f831 (run 40522816915 attempt 1): 1 code, 1 unknown.

Job	Verdict	Why
web / react-apps-check (1)	code	a web test failed
web / react-apps-check	unknown	no known signature; failed step: Check webview test shards

Failures:

• seen on other PRs agent-pane-background-tasks.test.ts the summary card lists the chat's background tasks: running ones first, the finished folded: failed (job)
• seen on other PRs agent-pane-hairline-focus.test.ts composer at 1x: focus is the resting hairline a step brighter, no ring: failed (job)
• seen on other PRs agent-pane-hairline-focus.test.ts newtab at 1x: focus is the resting hairline a step brighter, no ring: failed (job)
• seen on other PRs agent-pane-hairline-focus.test.ts composer at 2x: focus is the resting hairline a step brighter, no ring: failed (job)
• seen on other PRs agent-pane-hairline-focus.test.ts newtab at 2x: focus is the resting hairline a step brighter, no ring: failed (job)
• seen on other PRs agent-pane-hairline-focus.test.ts under Increase Contrast a focused edge keeps the resting edge, never a dimmer one: failed (job)
• seen on other PRs agent-pane-hairline-focus.test.ts keyboard focus changes what a solid Send, Stop, the prompt editor's Send and a plain button paint; s...: failed (job)
• seen on other PRs agent-pane-jump-latest-motion.test.ts chromium: a reply streaming in during Jump to latest's glide is followed to its latest row: failed (job)

Matched log lines

web / react-apps-check (1): (fail) the summary card lists the chat's background tasks: running ones first, the finished folded [1634.56ms]

Not re-run automatically: web / react-apps-check (1), web / react-apps-check are not machine failures.

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.

CI fast guards failed on dbb878f831 (https://github.com/manaflow-ai/cmux/actions/runs/40522816915). It does not block the merge; a red guard merged into main breaks it for every open PR.
The log named no failed step; see the run.

Agents: python3 scripts/ci/guard_attribution.py fix applies the mechanical fixes locally.

[teamleaderleo]

Orphaned: no activity for 65 h, and no lane holds a lease on it. The orphan sweep could not merge feat-cmux-next in: conflicts in Packages/macOS/CmuxNext/Sources/CmuxNextAgentPane/AgentPaneRenderFrame.swift, Packages/macOS/CmuxNext/Tests/CmuxNextAgentPaneTests/AgentPaneArtifactNavigationTests.swift, release-notes/next/highlights/interactive-chat-artifacts.md, webviews/src/agent-session/acpmux/conversation/ArtifactPanel.tsx, webviews/src/agent-session/acpmux/conversation/artifactSandbox.ts, webviews/src/agent-session/acpmux/conversation/writtenArtifacts.tsx, webviews/test/artifact-html.test.tsx, webviews/test/artifact-panel-sandbox.test.tsx. Listed for a lane to resolve.

[lawrencecchen]

Conflict wave: feat-cmux-next already contains this PR's change. 50e69a6 "feat(agent-chat): detect complete HTML writes from every harness (carry #26219) (#28732)" landed it. Of this PR's added lines, 881 of 969 are present in feat f06d9bd; the rest are later changes on feat to the same code. I pushed no merge. I did not close the PR; a person can close it.

[teamleaderleo]

Superseded by #28732 (merged), the carry of this complete-HTML-write detection. Closing this copy.