[teamleaderleo]

Adopted and rebased (2026-10-25). The lane that opened this died on cmux16; hb-acpmux adopted it. The branch is now one squashed commit on feat-cmux-next plus a rustfmt-only commit. #24303 had already landed the web side (the AcpmuxContextBreakdown type, contextBreakdownOf, and the session-start test it reads), so that part is dropped here. What stays is the daemon side that produces contextBreakdown and _acpmux/mcp/reconnect. The daemon's output matches the type #24303 reads: categories[{id?, name, tokens, kind}], memoryFiles, mcpTools, optional skills, totalTokens and maxTokens. Base had changed some of the same code, so four conflicts were resolved by hand:

• hub/permissions.rs keeps base's goal_write/mark_cleared and saves on goal_write || breakdown_changed.
• hub/views.rs keeps goal beside contextBreakdown.
• server/requests.rs: initialize lists base's extensions plus MUX_MCP_RECONNECT.
• docs/acpmux-schema.json: base's SessionDetail plus the contextBreakdown text.

The earlier "SDK schema drift checker" red was the stale merge. At this head, test_check_sdk_schema.py and check-sdk-schema.py both pass, and bun run acpmux-protocol:check is clean.

Tests at this head (fleet, cmux-ci test)

• cargo fmt --check is clean and cargo clippy -p acpmux --all-targets -D warnings passes. The first run caught three rustfmt lines; commit 7ed6a0d fixes them.
• cargo test -p cmux-agent-pane-policy passes (Swift and TypeScript parity included).
• cargo test -p acpmux: all of the PR's tests pass (claude_stdio::context_usage_tests, hub_integration context_window and claude_failover, local_app_trust_gate). Three tests fail, and each fails the same way on base 337d37c:
  • daemon_chat_open fails its open-read budget (5.3 MB against a 4 MB budget).
  • session_pool::pooled_sessions_end_with_the_daemon_and_after_a_crash fails 3 of 3 runs on base and on head.
  • harness_login::codex_bridge_status is flaky: it passed 3 of 3 on rerun at both base and head.
• Webviews: agent-pane-session-start.test.ts passes 4 of 4, and bun run typecheck finds no errors.

Review

A fresh Codex (gpt-6-astra, xhigh) reviewed this head and said SHIP. It checked:

• that the four earlier review rounds' fixes survived the rebase (the trust gate, cleanup when a reconnect times out, breakdown persistence, the failover clear, the generation guard against a retired agent);
• the conflict resolutions;
• that the breakdown shape matches what agent pane: the Context card and the context ring show Claude Code's /context breakdown #24303 reads.

Stop conditions: no new timer or observer. The reconnect request has a 30 s bound (RECONNECT_TIMEOUT), and its pending entry is removed when that bound runs out.

The agent pane's Inspector needs Claude Code's /context breakdown for its Context card and a way to reconnect a failed MCP server. acpmux now supplies both for Claude Code chats.

Context breakdown. When a turn ends (its result), acpmux sends Claude Code get_context_usage with detail: "summary". That mode uses the last response's usage, so it makes no token-count API calls. The request goes out after the turn's answer, so the turn never waits on it. acpmux trims the reply and keeps it on the session. _acpmux/info and attach return it as contextBreakdown. It also goes out as a session_info_update with _meta.acpmux.contextBreakdown, so an attached pane gets it live. The shape:

{"categories": [{"id": "system_prompt", "name": "System prompt", "tokens": 3000, "kind": "used"}],
 "memoryFiles": [{"path": "/repo/CLAUDE.md", "type": "Project", "tokens": 120}],
 "mcpTools": [{"name": "mcp__cmux__a", "serverName": "cmux", "tokens": 40}],
 "skills": [{"name": "pdf", "tokens": 30}],
 "totalTokens": 3900, "maxTokens": 200000}

• id appears only when Claude Code gives one.
• kind is used, free, buffer or deferred.
• skills appears only when skills take context.
• Each list holds at most the 50 largest rows.
• Grid rows and colors are dropped. The raw reply is not logged; only the trimmed update is.

When Claude Code refuses the request (older CLIs answer "not supported"), the field stays null.

MCP reconnect. The new _acpmux/mcp/reconnect {sessionId, server} sends Claude Code's mcp_reconnect (serverName) to the chat's running process.

• It answers {} on success, or with Claude Code's own error.
• On success, the server's row reads connected in mcpServers. Watchers get session_changed kind tools.
• It never starts a process. A chat without a running Claude Code is refused, because its servers connect when it starts.
• Other harnesses are refused with data.reason: mcp.unsupported.
• Remote browsers are refused with tools.remote, the same rule as set_tools, because reconnecting restarts the server's configured command.
• New capability: mcp-reconnect-v1.
• Also updated: the docs schema, the protocol IR and the generated web method list.

Web pane. The contextBreakdown type and its reading in direct.ts already landed with the Context card in #24303, so this PR no longer carries them. It adds direct.ts reconnectMcp(server) and clears the breakdown on a failover record. cmux-agent-pane-policy and AcpmuxPaneMethods.swift list _acpmux/mcp/reconnect as a session-scoped request, so the app's pane relay forwards it.

Observed / Not run

• Observed: scripts/web-lint.sh passed and scripts/cmux-next/prepush-gate.py reported no new violations. Claude Code 2.1.307's own control schema shows the get_context_usage reply shape and the mcp_reconnect request it parses.
• Not run locally: cargo, per the no-local-build rule. The acpmux Rust tests (new: claude_stdio/context_usage_tests.rs and three tests in tests/hub_integration/context_window.rs) run on the fleet against this head and in PR CI.
• Not run: a live Claude Code session through the pane.

No capture: acpmux protocol change, no UI

Changelog

none

Agent session: big-red
🤖 Generated with Claude Code

[github-actions]

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

Review 7ed6a0d: 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=pr24223 -f ref=session-panel-acpmux-context -f platform=macos -f backend_mode=local

Probably yours: accent-glass-invariants.test.ts, agent-pane-bottom-stack.test.ts, agent-pane-short-pane-composer.test.ts and 2 more fails here but not on main's latest full suite. Seen on other PRs too (likely flaky): claimPaint.test.tsx, claimPaint.test.tsx, agent-pane-agents-pill.test.ts and 8 more. This PR merged before its CI finished: fix forward on main.

CI failed on 7ed6a0d161 (run 40244236342 attempt 1): 2 code, 1 unknown.
macOS jobs did not run: compile and app tests were skipped: Fast static checks skipped.

Job	Verdict	Why
web / react-apps-base-check (4)	code	a web test failed
web / react-apps-base-check (2)	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)
• new in this PR accent-glass-invariants.test.ts no orange or system accent and no opaque glass on 2095 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)
• new in this PR agent-pane-bottom-stack.test.ts in a short pane the transcript keeps room and the queue scrolls inside its height: 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)
• ... 6 more in the job logs

Matched log lines

web / react-apps-base-check (4): (fail) a pooled Settings page claimed by the host reports its paint once its first screen is in [258.53ms]
web / react-apps-base-check (2): (fail) in a short pane the transcript keeps room and the queue scrolls inside its height [979.78ms]

Not re-run automatically: web / react-apps-base-check (4), web / react-apps-base-check (2), 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 1894a48 to compare; do not merge until green; see lane-rules
red: web / Web status; base red: the same failure on the base 1894a48; does not block
red: web / react-apps-base-check (2); no finished base run on 1894a48 to compare; do not merge until green; see lane-rules
red: web / react-apps-base-check (4); no finished base run on 1894a48 to compare; do not merge until green; see lane-rules
red: web / react-apps-check; base red: the same failure on the base 1894a48; does not block

Gallery before/after for 7ed6a0d: 16 states rendered, 9 images differ, 1877 more touched states not rendered. Images are in the run's artifact, not on this public PR.

gh run download 40244236256 -R manaflow-ai/cmux -n gallery-advisory-24223-7ed6a0d1610fcbf6c3a0b8506b4bb9b012749ae0 (then read gallery-review.json)

States

State	Theme	Status	Diff	Picked by
agent-pane.addressed-message/relayed	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.addressed-message/relayed	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent	Apple System Colors Light	changed	0.0099%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent	Apple System Colors	changed	0.0094%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-subagents	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-subagents	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-hover	Apple System Colors Light	changed	0.0105%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-hover	Apple System Colors	changed	0.0092%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-opened	Apple System Colors Light	changed	0.0112%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-opened	Apple System Colors	changed	0.0099%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-opened-long	Apple System Colors	changed	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/sent-opened-long	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/outcomes	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/outcomes	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/both-directions	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/both-directions	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/both-directions-opened	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-message-row/both-directions-opened	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/paused	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/paused	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/held-list	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/held-list	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/repeating	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/repeating	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/cap	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/cap	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/release-failed	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/release-failed	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/resumed	Apple System Colors Light	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-pair-note/resumed	Apple System Colors	unchanged	0%	imports model.ts (1 hops)
agent-pane.agent-runs/before	Apple System Colors	changed	0.0496%	imports model.ts (1 hops)
agent-pane.agent-runs/before	Apple System Colors Light	changed	0.0062%	imports model.ts (1 hops)

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

[teamleaderleo]

Owned by hb-acpmux on big-red · took over from session 01a16a59 · session

[blacksmith-sh]

Found 48 test failures on Blacksmith runners:

Failures

Test	View Logs
/tmp/tmp9v3fnf9w/summary-fail.json (live):/summary-fail.json (live):	View Logs
/tmp/tmpjuf3kgx9/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
bench OTHER_SWIFT_FLAGS is 'OTHER_SWIFT_FLAGS=$(inherited) -DCMUX_BENCH_HOOKS -DCMUX_BL OCKING_CHECKS'/ bench OTHER_SWIFT_FLAGS is 'OTHER_SWIFT_FLAGS=$(inherited) -DCMUX_BENCH_HOOKS -DCMUX_BL OCKING_CHECKS'	View Logs
bench OTHER_SWIFT_FLAGS is 'OTHER_SWIFT_FLAGS=$(inherited) -DCMUX_BENCH_HOOKS -DCMUX_BL OCKING_CHECKS'/ bench OTHER_SWIFT_FLAGS is 'OTHER_SWIFT_FLAGS=$(inherited) -DCMUX_BENCH_HOOKS -DCMUX_BL OCKING_CHECKS'	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

...and 38 more test failures. View all on Blacksmith: run 40244236342, run 40244236327

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

[teamleaderleo]

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

[teamleaderleo]

cmux-next guards / nightly-guards / workflow-guard-tests / release-notary is red on 15 of 15 fresh feat-cmux-next PR heads in the last 2:00:00, so it is most likely a base red, not this PR's. The base-reds lane has it; a base merge picks up the fix once it lands.

[teamleaderleo]

cmux-next / cmux-next checks (god files, concurrency, crash safety, l10n) › Checks job structure is red on 12 of 13 fresh feat-cmux-next PR heads in the last 2:00:00, so it is most likely a base red, not this PR's. The base-reds lane has it; a base merge picks up the fix once it lands.

[teamleaderleo]

cmux-next / cmux-next checks (god files, concurrency, crash safety, l10n) › No new SwiftUI (macOS UI is AppKit) is red on 12 of 13 fresh feat-cmux-next PR heads in the last 2:00:00, so it is most likely a base red, not this PR's. The base-reds lane has it; a base merge picks up the fix once it lands.

[teamleaderleo]

Review (codex gpt-6-astra xhigh, hb-orphan-context-review): SHIP at 7ed6a0d. Fleet app compile-check passed at this head (job a37490bb8aca4e7ef735ffe2); remaining reds match base.

[teamleaderleo]

base-red-watch: cmux-next / cmux-next Release compile (fleet fast check) went red on feat-cmux-next in https://github.com/manaflow-ai/cmux/actions/runs/40249733805 (first red at f08f46b, last green at 6af1ee1). Suspect: #24223 (commit f08f46b). If it is yours, fix forward on feat-cmux-next.