Comment-only. The colon-padding note said the anchored regex 'rejects the
directory in FIRST position — which is exactly where the fix puts it'. True in
this fixture, which runs env -i with no MOSAIC_RUNTIME_BIN so the bootstrap
directory leads, but stated as a property of the fix. In general the directory
sits second, after MOSAIC_RUNTIME_BIN, and it reads as a contradiction of the
source comment corrected in c7ee3cb.
Found in review by rhodey, who also noted the same sentence is live in the PR
description. No executable line changed.
The comment said the bootstrapped-node candidate 'is first'; it is inserted
second, after MOSAIC_RUNTIME_BIN. The ordering itself is correct — an explicit
override should outrank a bootstrap — so this is a wording defect in a
load-bearing comment, not a behaviour change. No executable line is touched.
Found in review by mos-claude (review 166).
On a host with no system Node, tools/install.sh bootstraps one into
~/.mosaic/node/current/bin and records it in ~/.profile. The fleet unit runs
`env -i ... bash --noprofile --norc`, so ~/.profile is never read — that is
deliberate — and _build_runtime_bin_prefix did not name the directory itself.
Runtime binaries are `#!/usr/bin/env node`, so the pane resolved `mosaic` and
then died on `env: 'node': No such file or directory` after an install that
reported success. Measured on a greenfield VM.
The existing `npm config get prefix` branch cannot cover it: that reports a
package prefix (~/.npm-global), never a Node runtime directory.
The test case asserts the property rather than the string — it runs the pane for
real with a Node-shebang `mosaic` and requires the pane to have executed. A PATH
substring check would pass on a fix that put the directory in the wrong position.
Red without the launcher change, green with it, rest of the suite unaffected.
Review finding from scooby. This case does not use run_start, so
install_pane_binaries' symlinks land under a home its launcher never consults
(HOME is the trusted parent here). It resolves mosaic and pi through
MOSAIC_RUNTIME_BIN=$FAKE_BIN instead. Valid path, valid green — and a trap for
anyone who later drops that env var believing the symlinks cover it, which
would break the #1241 binary check rather than exercise it.
Comment only; no behavior change. Harness rc=0.
Refs #1241.
Review finding from scooby: this PR added a failure branch the harness
structurally could not reach. The fake tmux answered `has-session` only for
`=_holder:0.0`, so every non-holder agent landed in the session-is-gone branch
no matter what — the `elif` (tmux still reports the session, no pane PID after
the retries) had zero coverage and no way to get any.
That is the same shape as the bug this PR exists to fix, one layer down: a code
path shipped green where the gate that should measure it cannot. Less severe,
because the branch fails closed at exit 69 rather than reporting success — but
"the harness can't reach it" is the sentence that precedes the next silent
regression, so it gets closed here rather than filed.
`MOSAIC_TEST_HELD_SESSIONS` lets a case name targets the shim should also
answer for. It answers them only AFTER `new-session`, and that detail is the
whole trick: the launcher asks `has-session` about the same name twice — once
at line 255 where a yes means "already running, exit 0", and once at 417 where
a yes means "the session survived". A shim answering yes to both short-circuits
at the first and never reaches the branch under test. It would have looked like
coverage while measuring the idempotency path.
Both failure modes were measured, not reasoned about:
- toggle absent (the old shim): `code=pane-did-not-survive` — the case lands on
the wrong branch, which is exactly the unreachability being reported.
- toggle answering unconditionally: launcher exits 0 via the idempotency
short-circuit — "launcher reported success over a session with no resolvable
pane PID".
- toggle gated on new-session: `code=pane-pid-unresolved`, exit 69.
The case also asserts the diagnostic is not `pane-did-not-survive` and does not
mention the heartbeat, so the two pane faults cannot collapse into one message.
Gates: bash -n · launcher harness rc=0 · test-fleet-units.sh (real tmux) rc=0 ·
fleet specs 342 passed.
Refs #1241.
`mosaic fleet start` returned 0 over three dead panes. The launcher knew,
and said the wrong thing at the wrong severity to the wrong layer.
The pane runs `mosaic yolo <runtime>` under PANE_PATH with a cleared
environment. When that binary is absent the pane dies in under a second,
tmux destroys the session, and the diagnostic goes with it. The launcher
then found no PANE_PID, printed a WARNING about the *heartbeat sidecar*,
and exited 0 — so systemd logged "Finished ... successfully" and
`fleet start` reported success. `fleet ps` was the only component telling
the truth.
Two changes, both in start-agent-session.sh:
1. Before any effect, resolve `mosaic` and the roster's runtime against
PANE_PATH — the pane's own view of the path, not the launcher's.
`mosaic yolo <runtime>` calls checkRuntime(runtime) and looks for a
binary named exactly like the runtime, so this asks the same question
the pane will ask a moment later, while an operator can still see the
answer. Absent binary -> exit 69, code=missing-binary, no session
created.
2. Replace the dead-pane WARNING+exit-0. An absent session one second
after new-session is a runtime that died on startup, not a heartbeat
problem -> exit 69, code=pane-did-not-survive, with the command to run
by hand to see why. A present session with no pane PID after five
attempts -> code=pane-pid-unresolved. Neither branch kills the
session; destroying a possibly-live pane on a guess is worse than
leaving it for inspection.
Exit 69 (EX_UNAVAILABLE) is deliberate: the 64s already in this file mean
the projection was bad, and here the data is fine and the host is not
ready. Callers separate the cases by `code=`, the same way fail_env's
codes share 64.
This propagates for free. `fleet start` calls runChecked() for the holder
and each agent, and runChecked throws on non-zero, so layers 4 and 5 stop
lying without a TypeScript change. Two adjacent defects are left for a
follow-up issue rather than widened into this diff: the per-agent loop
aborts on the first failure instead of attempting all and reporting an
aggregate, and runChecked's bare throw surfaces the launcher's message
under a Node unhandled-rejection stack trace because program.parse() is
synchronous.
Tests:
- test-start-agent-session.sh gains three cases: `mosaic` absent from the
pane path, the runtime absent from the pane path, and a pane that does
not survive. Each was verified individually red against the unmodified
origin/next launcher.
- The two cases asserting a valid launch now supply a pane PID. Until now
the suite's one success path was itself a dead pane the launcher
reported as fine.
- The harness fakes `npm` so PANE_PATH stops depending on whatever the
host has installed, and fails loudly if the host provides `mosaic` or
`pi` in the system path, where the missing-binary cases would not be
measurable at all.
- test-fleet-units.sh gains a `pi` shim in its runtime bin. The real-tmux
harness named `pi` in its roster and never installed it; the new
preflight caught it.
Refs #1241
fred
jason.woltje