[teamleaderleo]

Leo, 2026-10-24, word for word, looking at a codex exec review that renders as a plain "Command" row:

"this is mildly interesting i think being able to do it like a cmux-next natively rendered thing of subsession/non-same-model-family subagent would be a cool depiction"

"plus supporting the situation better in acpmux"

This is the first of two PRs. It adds the part that reads which agent a shell call starts. The next PR uses it to render such a call as a Subagent: the same card and Session Info row that sub-sessions and subagents get. It's split to stay under the ~800-line limit.

What changes

webviews/src/agent-session/acpmux/subagents/agentRuns.ts (new, not wired in yet):

• agentRun(command) returns the agent a shell command starts: its harness, model, effort, prompt, acpmux session name and host. It returns undefined when the command starts no agent.
• It reads the command with a real shell tokenizer, not a search of the text. The tokenizer handles quotes, $'…', escapes, ;/&&/||/|, { … } and ( … ), comments, $(…)/backquotes (kept as one word), fd redirections like 2>&1, and <, <</<<- heredocs and <<< here-strings as standard input.
• It looks through wrappers that just run the next words: VAR=x, env, nohup, exec, time, nice, caffeinate, timeout/gtimeout, sr, and perl -e 'alarm N; exec @ARGV'. It also re-parses the command strings that reach HOST '…', ssh HOST '…' and sh|bash|zsh -c '…' run. reach and ssh give the host, and the outer stdin is passed into the inner command.
• Each agent CLI's grammar is one declarative table entry: what starts a non-interactive run (codex exec, claude -p, acpmux run|new|exec), which options take a value, and where the model, effort, session name and prompt are. That covers Codex's -m and -c model_reasoning_effort=…/-c model=…, Claude's --model/--effort, and acpmux's -m HARNESS[/MODEL], -e, -n, --host and --prompt-file. --help/--version start nothing, and neither does another subcommand (acpmux send). A bare acpmux new -n x with no prompt starts nothing either.
• Helpers for the card: promptTitle (the first line of the prompt that says something), runModel ("gpt-6-astra xhigh"), harnessFamily/harnessLabel, runReply (Codex's final message after its tokens used log, with Claude Code's "Shell cwd was reset" trailer removed), and backgroundOutputPath.

Risk

None at runtime: nothing imports the module yet. The next PR wires it into the subagent fold.

Tests

agentRuns.test.ts uses commands Claude Code recorded on 2026-10-24, with the paths scrubbed: a Codex review through reach with its prompt on stdin, the perl alarm wrapper, a heredoc prompt, a nohup sh -c inside reach behind a pipe, and acpmux new/run, sr codex and claude -p. Negatives from the same recordings: grep "codex exec", codex exec --help, pgrep -fl 'codex exec|…', a heredoc whose text mentions codex exec, acpmux send, a bare acpmux new, claude mcp list. The webview CI jobs run the suite: huge-blue is out of memory right now, so it wasn't run locally. An independent Codex review comes before landing.

Agent session: cosmic-gray

🤖 Generated with Claude Code

---

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[github-actions]

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

Review aaa81e2: 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=pr25040 -f ref=claude/xfamily-agent-runs -f platform=macos -f backend_mode=local

Unclear: web / react-apps-check failed: no known signature; failed step: Check webview test shards. This PR merged before its CI finished: fix forward on main.

CI failed on aaa81e2b16 (run 40162552319 attempt 1): 4 code, 1 unknown.

Job	Verdict	Why
web / react-apps-base-check (1)	code	a web test failed
web / react-apps-base-check (2)	code	a web test failed
web / react-apps-base-check (3)	code	a web test failed
web / react-apps-base-check (4)	code	a web test failed
web / react-apps-check	unknown	no known signature; failed step: Check webview test shards

Failures:

• seen on other PRs claimPaint.test.tsx a pooled Settings page claimed by the host reports its paint once its first screen is in: failed (job)
• seen on other PRs claimPaint.test.tsx a Settings page loaded fresh reports its first paint once its first screen is in: failed (job)
• seen on other PRs accent-glass-invariants.test.ts no orange or system accent and no opaque glass on 2047 gallery stages: failed (job)
• seen on other PRs agent-pane-agents-pill.test.ts by default the running agents sit in the tray above the composer, not in the transcript: failed (job)
• 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-queue-collapse.test.ts a long queue > an opened long queue keeps Show less and the focused row in sight, never a half row (...: failed (job)
• seen on other PRs agent-pane-queue-collapse.test.ts a long queue > an opened queue with a two-line row shows whole rows only, no row under another (capt...: failed (job)
• ... 22 more in the job logs

Matched log lines

web / react-apps-base-check (1): (fail) a pooled Settings page claimed by the host reports its paint once its first screen is in [173.10ms]
web / react-apps-base-check (2): (fail) a long queue > an opened long queue keeps Show less and the focused row in sight, never a half row (capture, 2026-10-15) [1262.56ms]
web / react-apps-base-check (3): (fail) every step is one 26px row on one rhythm, across transcript rows [1242.47ms]
web / react-apps-base-check (4): (fail) chromium > a prompt the fold hides, run elsewhere, leaves no room as the stack shrinks, opens and closes [5213.45ms]

Not re-run automatically: web / react-apps-base-check (1), web / react-apps-base-check (2), web / react-apps-base-check (3), web / react-apps-base-check (4), 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.

red: cmux-next checks (god files, concurrency, crash safety, l10n); no finished base run on 7921f4f to compare; do not merge until green; see lane-rules
red: web / Web status; NEW: green on the base 7921f4f; do not merge until green; see lane-rules
red: web / react-apps-base-check (1); no finished base run on 7921f4f to compare; do not merge until green; see lane-rules
red: web / react-apps-base-check (2); no finished base run on 7921f4f to compare; do not merge until green; see lane-rules
red: web / react-apps-base-check (3); no finished base run on 7921f4f to compare; do not merge until green; see lane-rules
red: web / react-apps-base-check (4); no finished base run on 7921f4f to compare; do not merge until green; see lane-rules
red: web / react-apps-check; no finished base run on 7921f4f to compare; do not merge until green; see lane-rules

Tour of aaa81e2b16 (run): no media. The tour did not run: only webview code changed (2 path(s)), which the gallery advisory run checks in Linux Chromium on the pull request (its artifact holds any captures); add the media-tour-mac label, then re-add media-tour, to tour it on a Mac.

Gallery before/after for aaa81e2: the capture produced no images (run).

[blacksmith-sh]

Found 98 test failures on Blacksmith runners:

Failures

Test	View Logs
/tmp/tmp3i7mpnaw/summary-fail.json (live):/summary-fail.json (live):	View Logs
/tmp/tmp4nw8ip_z/summary-missing.json (live):/summary-missing.json (live):	View Logs
[new_workspaces] debug.new_workspace timed 0 of 50 new workspace rows/ [new_workspaces] debug.new_workspace timed 0 of 50 new workspace rows	View Logs
[new_workspaces] the window draws no frames/[new_workspaces] the window draws no frames	View Logs
[tabs] debug.tab_switch timed 0 of 40 switches/ [tabs] debug.tab_switch timed 0 of 40 switches	View Logs
[tabs] the window draws no frames/[tabs] the window draws no frames	View Logs
convention violations found (ERROR lines above)./ convention violations found (ERROR lines above).	View Logs
nightly.yml prepare-nightly-variant: 'Package prepared app for signing' is not in list/ nightly.yml prepare-nightly-variant: 'Package prepared app for signing' is not in list	View Logs
test/agent-pane-queue-collapse.test.ts/agent-pane-queue-collapse.test	View Logs
test/agent-pane-queue-collapse.test.ts/agent-pane-queue-collapse.test	View Logs

...and 88 more test failures. View all on Blacksmith: run 40162552319, run 40162552294, run 40162552276

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[teamleaderleo]

Bead cx-5g2bx created for this PR by the cmux coordinator.

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[github-actions]

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.4016599569701 (99f66bfa0c)
• cmux NEXT nightly 1.0.0-nightly.4016664586501 (c6ebb072b1)
• cmux NEXT nightly 1.0.0-nightly.4016783882601 (6c8013633b)
• cmux NEXT nightly 1.0.0-nightly.4016807535201 (bc010d814e)