**THE PROPAGATION WITNESS DID NOT OBSERVE INHERITANCE.** The runner's
`eval` expanded `$TMPDIR` in the PARENT before `sh -c` ever started, so
the child received an already-substituted literal --- and an unexported
`TMPDIR=` would have passed the row unchanged. Single-quoted inside
`sh -c` now, so the CHILD expands it. **M-G-1b keeps the assignment and
removes only `export`: the row fails.** That is the mutation the
previous version could not catch, and the reason to prefer it over
M-G-1's blunter deletion.
**THE RESERVE WAS NOT THE MAXIMUM.**
`/.tmpXXXXXX/directory-target.sock` is 33 bytes
(`tests/gpu_invocation_acceptance.rs`), so paths of 76-78 passed the
30-byte guard and still blew the 108-byte limit during the CRDT sweep.
Reserve is 48 now --- the measured maximum plus ~45% headroom. And the
length is counted in BYTES: `${#var}` counts CHARACTERS under a UTF-8
locale while `sun_path` is byte-limited, so a multibyte path measured
short and passed a check it should fail.
**A MANAGED ROOT IS NOT INHERENTLY MARKER-FREE**, and assuming it was
rebuilt the original defect one directory up: a `.git` in `$HOME`, a
marker above `$HOME/build`, or a contaminated
`PMACS_GATE_TARGET_ROOT`. Placement under a directory the gate owns is
NECESSARY, NOT SUFFICIENT, and the old test proved only placement. The
gate now walks the ancestors and refuses, naming the marker it found.
`PMACS_GATE_ALLOW_ANCESTOR_MARKER` is the documented test-only escape,
beside `PMACS_GATE_TARGET_ROOT` in kind and risk: the behaviour tests
run under a tempdir whose ancestors they do not control, on a machine
whose `/tmp` carries this very marker, and their plans are synthetic so
no markerless fixture exists to re-root. **The check is witnessed by a
row that deliberately does not set it**, and M-G-3 (check removed)
fails that row.
**The guard leaked what it exists to manage.** It created both
temporary areas and exited before the trap was armed, so every
rejection left an AMBIENT and a TMPDIR behind. The trap is installed
first now; verified by rejecting a run and finding neither.
**`tmp/$$` with `mkdir -p` was not fresh.** PIDs are reused, so after a
SIGKILL it silently ADOPTS a leftover directory and the run inherits
another run's fixtures. `mktemp -d` fails rather than reuses.
**Prose corrected to match.** The handoff described
`<target>/gate-tmp/<stamp>-<pid>`; the implementation uses
`<gate-root>/tmp/<mktemp>`. Comments called the shared parent
per-worktree and pruned --- it is neither: `--prune` only considers
directories carrying an ownership marker, so the parent is skipped and
each run removes its own leaf.
**AND THE LANE CLAIMED A FRAMING EXCEPTION THAT DOES NOT EXIST.**
`AGENTS.md` says framing -> approval -> branch -> implement,
unconditionally; "the fix was already recorded as standing" is not an
exemption it grants. `docs/gate-script-framing.md` is amended as
**revision 6, AWAITING APPROVAL** --- a widening of §2's existing
isolation responsibility rather than a new feature, which is why it
amends that document instead of opening another. **This PR must not
merge before that revision is approved.**
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
1bd52b7f0d