docs(runs,cleanup): record the measured ceiling on the live-session removal guard (#732) - #753
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`BaseTmuxBackend.list_window_ids` folded every non-zero `list-windows` exit
to `[]`, so a server erroring while its windows were alive read as an empty
session — a crash to the liveness probe, and a verified kill to the ctl-window
prune.
Answer `[]` only when stderr proves the session gone; raise `MultiplexerError`
otherwise. The proof wordings live in `BaseTmuxBackend._SESSION_GONE_STDERR`
("no server running", "can't find session"), matched case-insensitively, and a
leaf whose multiplexer words absence differently overrides the tuple.
Measured on the real binaries rather than the docs — tmux 3.4 and psmux 3.3.8
(66cf613), probed under an isolated registry so no live session was touched:
tmux list-windows -t =ghost rc 1 can't find session gone
tmux no server rc 1 no server running gone
psmux list-windows -t =ghost rc 1 no server running gone
psmux tampered key, windows ALIVE rc 1 Invalid session key unknowable
psmux wrong port, windows ALIVE rc 1 connection timed out unknowable
The last two are the defect made reproducible: identical exit code, session
demonstrably still serving its windows. They also rule out the simpler fixes —
a `has_session` round trip folds those same faults to False by its own
contract, and raising on every non-zero makes an ordinary vanished session
unverifiable, inventing a phantom survivor the prune re-reports forever.
Both psmux gone-wordings contain "no server running", so the leaf needs no
override; that is a measurement, not an omission.
All seven `_window_alive` call sites plus `prune_ctl_windows` already handle
`MultiplexerError` as "unknown, not dead" — the seam and its callers were
written for this, only the backend never raised. No engine change was needed.
`list_windows` and `session_options` get the same lens with the opposite
conclusion: they read metadata, not liveness, and their sentinel degrades
toward doing nothing, so `[]`/`{}` stays — but they now warn when the failure
proved nothing.
Known gaps:
- The full Windows suite last ran before the final fix: 7196 passed, 16 failed,
249 skipped, every failure in the known environmental categories (symlink
privilege x10, skill-sync drift x6). Post-fix verification covered the five
touched test files on both platforms: Windows 693 passed, Linux 718 passed,
no failures either side. The remainder of the Windows suite is unverified
against the final commit by choice; CI is the backstop.
- `uv run pyright` reports 7 pre-existing errors, all POSIX-only `os`
attributes in untouched `platform_util.py`. None in changed files.
- The metadata siblings keep their sentinel, so bmad-code-org#562 and bmad-code-org#538 stay open.
Closes bmad-code-org#525
…ment CodeRabbit, both accepted: - The CHANGELOG entry was a six-line narrative where AGENTS.md asks for terse, scannable and imperative. Condensed to one line; the reasoning lives in the commit and the PR, which is where it belongs. - `test_list_windows_does_not_probe_options_for_an_empty_listing` still said the base answers `[]` for a missing binary "silently, without spawning". That described the discarded pre-gate revision; the test's own assertion two dozen lines below proves one `list-windows` spawn happens and only the warning is suppressed. Left as written it invites restoring the early PATH return, which is exactly the regression the Linux gate caught on this branch.
`live_session_may_be_ours` reads a listing that omits a live session as "no session", so `delete`, `archive` and `clean` can remove a run directory the session still depends on. The degrade was already documented as a decision; what was missing was its cost. Behavior is unchanged — this records the ceiling and gives it a retirement path. Two ways to meet it, both measured on psmux 3.3.8 (66cf613) under an isolated registry: - A `has-session` whose 500 ms connect does not land reaps a live session's registry entry. `ls` then exits 0 without that session, nothing on stderr, until the server's registry maintenance re-writes it — a nominal 5 s check in the server's own loop, so the window has no hard bound (1.7 s was one measured sample; the server pid was alive throughout). - A process whose PATH lacks the binary reads every session as absent, for as long as that PATH lasts. The binary is per-process; the server is not. The two do not even look alike — a reap takes one entry, so the listing may still name every other session, while a missing binary yields nothing at all — but both reach the guard as the same verdict, this run's name is not in the listing, which is exactly what a genuinely dead session produces. Why no stronger guard. The listing does not fail, it answers wrongly: exit 0, empty, clean stderr. The discrimination added for the window-listing seam reads exit codes and stderr, and neither is on this path, so there is nothing to condition on. Retry-with-delay pays more than the window on every removal that finds no session, which is the common case, and `clean` pays it per run. A tag-first read draws on the same listing and is blind in the same window. Warning whenever the multiplexer is unusable fires on every box that simply has none. A proof discipline was built and withdrawn earlier over four review rounds, each refuting its newest proof source; the transports offer no proof of absence. The psmux half is a defect, not a design: four sibling reap sites in that binary gate on `ConnectionRefused` because "a timeout means busy-but-alive and must not be deleted" (their own comment), the `has-session` site does not, and tmux 3.4 blocks rather than reaps under the same treatment. Reported as psmux/psmux#622. When a release carries the fix and the supported floor moves to it, only the PATH case remains. No version gate is possible meanwhile — there is no detectable condition to gate on. All three cited mechanisms were relocated by symbol on psmux master 80362fa and are unchanged since v3.3.8; 42 commits touch those paths, none of them these. Verified on both platforms: Windows 7197 passed, Linux 7397 passed, failures only in the known local environmental categories. Two claims from an earlier draft were refuted in review and corrected. Closes bmad-code-org#732
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Included review availability: Your plan provides up to 2 included reviews per hour; 0 remain after this review. WalkthroughThe multiplexer seam now distinguishes proven session loss from failed listings. Liveness raises for unproven failures, while metadata reads retain sentinels and emit warnings. Tests and documentation cover tmux, psmux, pruning, and removal behavior. ChangesMultiplexer listing verdicts
Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: 🔵 Low · up to The change documents an existing removal-guard limitation without altering runtime behavior, but the documentation still gives conflicting --force behavior for destructive commands, which could mislead users. Merge is reasonable with explicit owner follow-up to reconcile that text. Sequence Diagram(s)sequenceDiagram
participant CleanupCommand
participant BaseTmuxBackend
participant Multiplexer
CleanupCommand->>BaseTmuxBackend: check session liveness
BaseTmuxBackend->>Multiplexer: list window IDs
Multiplexer-->>BaseTmuxBackend: empty listing or failed query
BaseTmuxBackend-->>CleanupCommand: absent, removed, or unverifiable result
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✅ Passed checks (3 passed)
Full details: Linked Issues checkExplanation The pull request addresses Full details: Out of Scope Changes checkExplanation The pull request includes executable behavior changes in src/bmad_loop/adapters/tmux_base.py, including new error handling and session-gone classification, although the stated objective says behavior remains unchanged and focuses on documentation. Resolution Remove the executable tmux behavior changes and related tests if this is intended to remain a documentation-only change. Otherwise, update the pull request objectives and linked issue scope to explicitly include the new listing-error behavior. Full details: Docstring CoverageExplanation Docstring coverage is 61.54% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 52 functions across 9 files. (1 skipped: 1 unsupported.)
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Actionable comments posted: 3
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Inline comments:
In `@CHANGELOG.md`:
- Around line 48-56: Shorten the changelog entry to a terse, scannable
imperative statement under the Unreleased section, preserving the user-visible
behavior, the affected delete, archive, and clean commands, and the upstream
retirement path tied to psmux/psmux#622 and the supported-version floor; move
measured timing and registry details to docs/FEATURES.md or issue `#732`.
In `@docs/FEATURES.md`:
- Line 291: Update the removal-behavior documentation to distinguish delete and
archive from clean: delete and archive stop the engine only when engine_liveness
is alive, warn and proceed when it is unknown, and with --force skip
_refuse_live_session without killing the agent session. State that clean has no
force bypass and relies on live_session_may_be_ours, so incomplete session
listings may still allow removal.
In `@src/bmad_loop/runs.py`:
- Around line 2367-2370: Update the documentation passage describing
BaseTmuxBackend.list_sessions and mux_sessions() so it states that _run
SubprocessError and OSError failures return an empty list rather than raise;
reserve raised cases for backend selection or out-of-tree backends raising
MultiplexerError.
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CHANGELOG.mddocs/FEATURES.mdsrc/bmad_loop/adapters/multiplexer.pysrc/bmad_loop/adapters/psmux_backend.pysrc/bmad_loop/adapters/tmux_base.pysrc/bmad_loop/runs.pysrc/bmad_loop/tui/launch.pytests/test_multiplexer.pytests/test_psmux_backend.pytests/test_runs.pytests/test_tui_launch.py
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| - `bmad-loop delete <run-id>` — delete a run directory and its out-of-tree control-plane dir (`--force` stops it first if live). | ||
| - `bmad-loop archive <run-id>` — compress a run into `.bmad-loop/archive` and remove it, control-plane dir included (`--force` stops it first if live). The tarball holds the run dir, so it carries no `events/`. It is staged through an exclusively created temp under a fresh unpredictable name per attempt, so a planted name is never followed or reused, the failure cleanup is provably its own, and a temp stranded by a kill cannot deny later attempts; the tarball is `fsync`ed before the publish — the run dir is removed immediately after, so it is the only remaining copy. A published archive lands at mode `0600` rather than a umask-derived one (#591). | ||
| - Removal refuses while a matching agent session is live that the project cannot prove is another one's, even when the engine is dead: for an untagged session the run dir is the last ownership proof `cleanup` can read, so removing it would leak the session ([#419](https://github.com/bmad-code-org/bmad-loop/issues/419)). A session tagged to another project carries its own proof and never blocks. Run `cleanup` first, having confirmed the session is this project's (`attach`): for an _untagged_ session `cleanup` proves ownership by that same run dir, so two projects sharing a run id can prune each other's. Or pass `--force`, which removes anyway and kills nothing. `clean` leaves such a run untouched and reports it as protected. | ||
| - Removal refuses while a matching agent session is live that the project cannot prove is another one's, even when the engine is dead: for an untagged session the run dir is the last ownership proof `cleanup` can read, so removing it would leak the session ([#419](https://github.com/bmad-code-org/bmad-loop/issues/419)). A session tagged to another project carries its own proof and never blocks. Run `cleanup` first, having confirmed the session is this project's (`attach`): for an _untagged_ session `cleanup` proves ownership by that same run dir, so two projects sharing a run id can prune each other's. Or pass `--force`, which removes anyway and kills nothing. `clean` leaves such a run untouched and reports it as protected. The check is an observation with a measured ceiling ([#732](https://github.com/bmad-code-org/bmad-loop/issues/732)): a listing that omits a live session reads as "no session", so removal proceeds. Two ways to meet it, both measured on psmux 3.3.8 — a `has-session` whose 500 ms connect does not land reaps a live session's registry entry, and until the server's registry maintenance re-writes it `ls` omits that session while exiting 0 with nothing on stderr (that maintenance runs on a nominal 5 s check in the server's own loop, so the window has no hard bound; 1.7 s was one measured sample); and a process whose PATH lacks the multiplexer binary reads every session as absent for as long as that PATH lasts, however long the server keeps running. The first is a successful query with an incomplete answer and the second is a missing binary, and they do not even look alike — a reap takes one entry, so its listing may still name every other session, while a missing binary yields nothing at all — but both reach the guard as the same verdict, this run's name is not in the listing, which is what a genuinely dead session produces too. So it accepts both rather than wedging every removal path behind `--force`. If a removal does strand a session, clear it with `kill-session` on `bmad-loop-<run-id>` — but neither failure leaves it reachable straight away: restore the multiplexer to PATH first, and after a reap wait for the server's next registry tick to republish the entry, or the target will not resolve. On psmux the sessions live in the per-project registry, so run it with the export `bmad-loop mux` prints. Confirm the session is this project's before killing, since the name carries no project — and note that `attach` is no longer the way to do it: it resolves the run directory first, which the removal just deleted. Attach in the multiplexer directly instead, and for an _untagged_ session accept that the run dir it lost was its only ownership proof, so what is left is the session's own contents and what you know of the run. |
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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win
🔎 Supported by static analysis
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rg -n -C 12 \
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sed -n '280,296p' docs/FEATURES.md
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Clarify --force and session-observation behavior.
delete and archive stop the engine only when engine_liveness is alive; unknown only warns and proceeds. With --force, delete_run and archive_run skip _refuse_live_session but do not kill the agent session. clean has no force bypass; it protects sessions that live_session_may_be_ours detects, but an incomplete listing can allow removal. State these behaviors separately.
🤖 Prompt for AI Agents
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In `@docs/FEATURES.md` at line 291, Update the removal-behavior documentation to
distinguish delete and archive from clean: delete and archive stop the engine
only when engine_liveness is alive, warn and proceed when it is unknown, and
with --force skip _refuse_live_session without killing the agent session. State
that clean has no force bypass and relies on live_session_may_be_ours, so
incomplete session listings may still allow removal.
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Verified the claims and they hold — delete and archive stop the engine only on engine_liveness alive, unknown warns and proceeds, --force skips _refuse_live_session without killing the session, and clean has no force bypass. Declining it here anyway, on scope: none of that behaviour is changed by this PR, which only records a measured ceiling on the listing the guard reads. The bullet already carries the load-bearing parts for that ceiling — --force removes anyway and kills nothing, and clean leaves such a run untouched and reports it as protected. Widening it into a full account of the removal paths belongs in its own change, where it can be reviewed against the code it describes rather than as a rider on a docs commit. Happy to file that as an issue if you want it tracked.
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@dracic, understood. The scope boundary is reasonable for this PR.
Would you like me to open a follow-up issue for the broader delete, archive, and clean behavior documentation?
🐇
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…ure claim CodeRabbit, two of three accepted: - The CHANGELOG entry ran nine lines where AGENTS.md asks for terse and scannable. Condensed to one, keeping the user-visible outcome, the affected commands and the retirement path; the measurement stays in docs/FEATURES.md and in the issue, which is where a reader who wants it will look. - `live_session_may_be_ours` claimed the query-failure branch of `list_sessions` "is the raise". It is not: the bundled backend folds `SubprocessError` and `OSError` into the same `[]` as a missing binary and a dead server, and only an out-of-tree backend raises here. The passage now says so, which strengthens rather than weakens the argument around it — three indistinguishable sentinels and no raise is a worse read than two. Declined: expanding the docs/FEATURES.md bullet with `--force` and `engine_liveness` semantics. Verified those claims hold, but they describe behavior this change does not touch, and the bullet already carries the load-bearing parts — `--force` removes anyway and kills nothing, `clean` has no force bypass and reports such runs as protected. Worth its own issue rather than widening this one.
1 participant
live_session_may_be_oursreads a listing that omits a live session as "no session", sodelete,archiveandcleancan remove a run directory the session still depends on — for an untagged session, its only ownership proof. The degrade was already documented as a deliberate decision. What was missing was its cost. This records the ceiling and gives it a retirement path. Behavior is unchanged.The two ways to meet the ceiling
Both measured on psmux 3.3.8 (
66cf613) under an isolatedPSMUX_DATA_DIR:has-sessionwhose 500 ms connect does not land deletes a live session's registry entry.lsthen exits 0 without that session and with nothing on stderr, until the server's registry maintenance re-writes it — a nominal 5 s check inside the server's own loop, so the window has no hard bound (1.7 s was one measured sample; the server pid was alive throughout).The two do not even look alike — a reap takes one entry, so its listing may still name every other session, while a missing binary yields nothing at all — but both reach the guard as the same verdict: this run's name is not in the listing. Which is exactly what a genuinely dead session produces.
Why not a stronger guard
The listing does not fail, it answers wrongly. Exit 0, empty, clean stderr. The stderr discrimination added for the window-listing seam in #751 reads exit codes and stderr, and is not on this call path anyway — so there is nothing here for a stronger guard to condition on.
The named alternatives were weighed and refused:
cleanpays it per run, to close a window that needs a removal and a reap within the same few secondsWhat is left is the accepted ceiling, written down in the guard and in
docs/FEATURES.md— including how to recover if a removal does strand a session — so an operator meets it as a documented limit rather than a surprise.The psmux half is a defect, and has a retirement path
Four sibling reap sites in that binary gate on
ConnectionRefused, with the rule in their own comment: "a timeout means busy-but-alive and must not be deleted." Thehas-sessionsite does not, and it also skips the PID anchor its siblings consult. tmux 3.4 blocks rather than reaping under the same treatment, and never mutates registry state from a read-only predicate (measured).Reported upstream as psmux/psmux#622. When a release carries the fix and the supported floor moves to it, only the PATH case remains and the ceiling shrinks to it. No version gate is possible in the meantime — there is no detectable condition to gate on.
All three cited psmux mechanisms were relocated by symbol on master
80362faand are unchanged sincev3.3.8: 42 commits touch those paths, none of them these.Verification
test_runs.pyre-run after the final wording rounds: Linux 343/343; the Windows failures in that file areWinError 1314, proven environmental by the green Linux run of the same file.git diff --checkclean; pyright unchanged._session_proved_goneis not on this call path, and "both costs arrive as the same empty listing" was contradicted by the branch's own test.Closes #732
Summary by CodeRabbit
Bug Fixes
Documentation