**108 IS LINUX'S NUMBER, NOT THE FLOOR.** Darwin's `sun_path` is 104
(xnu `bsd/sys/un.h`) and pmacs supports macOS --- CI runs a
`macos-latest` leg --- so a Linux-derived limit passes on the machine
that writes it and bind-fails on the other. **The usable PATH length is
one less than the array**, because the stored value is NUL-terminated:
103 on Darwin, 107 on Linux. The script takes **103**, and the
diagnostic says which platform's floor it is quoting.
**THE NESTED CASE IS NOW RULED, NOT ACCOMMODATED BY LOOSENING THE
GUARD.** The reserve exists for fixtures that bind sockets under
TMPDIR; this script's own behaviour suite runs nested gates whose plans
are synthetic and bind nothing, so charging them the fixture reserve
rejects a configuration that cannot suffer the failure it guards
against. Exempting nested runs was rejected --- it makes the guard
untestable in the very configuration the tests exercise, and "this run
is nested" is not reliably knowable. **The suite roots its gates at a
short base instead**, so a nested TMPDIR is ~24 bytes rather than ~71
and clears the real reserve. Recorded in revision 6 with the rejected
alternative, and with the obligation that a future row which DOES bind
a socket must move off that base and take the reserve with it.
**MIRRORING THE MARKER NAMES WAS NOT ENOUGH; THE TYPES ARE PART OF THE
CONTRACT.** `match_marker` requires `.git` to be a DIRECTORY and the
seven language markers to be FILES, so `[ -e ]` rejected ancestors
project detection walks straight past. The case is not exotic: **a git
WORKTREE has a `.git` FILE**, so every worktree in this repository
would have tripped the guard. It tests `[ -d ]` for `.git` and `[ -f ]`
for the rest, with a witness covering all three shapes --- `.git` file
accepted, `.git` directory refused, `Cargo.toml` directory accepted.
That witness keys on WHICH marker the gate named rather than on whether
a refusal happened, because the ancestors of any base a test can create
are outside its control; "no refusal" is not a claim it can make
anywhere, while "the refusal did not name MY file" is. `M-G-4` reverts
the guard to existence-only and the row fails.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
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