Seven findings, all taken.
- **The descriptor went stale after the upgrading write.** Round 1 made it
read the file instead of the policy, but it was still computed once and
cached beside the selection — so the first `set` under a newly-set
passphrase encrypted the file while `/api/config` kept serving "still
unencrypted" for the rest of the session, describing bytes this very
process had just changed. The *selection* stays cached (the banner, the
payload, and the store doing the writing must agree on which store it
is); the file descriptor is re-derived per call, which costs one read of
a small file per config fetch.
- **The mount check asked the wrong question.** Comparing a directory's
`st_dev` against its parent's detects a mount *at* that path, but a
volume mounted at `/home/node` leaves `/home/node/.mcp-inspector` an
ordinary subdirectory sharing its parent's device — so a durable
container setup was judged unmounted and demoted to session-only
`memory`. It now reads `/proc/self/mountinfo` and asks whether the
directory is *under* any mount other than `/`, which also catches the
same-device bind mount no `st_dev` test can see. Where mountinfo is
unreadable (macOS, Windows, a `/proc`-less container) it falls back to
the device comparison, now against `/` rather than the parent.
- **A decrypted payload was cast, not checked.** GCM proves the bytes are
authentic, not that they parse to the right shape. An array passes
`typeof === "object"`, takes the named assignment, and then
`JSON.stringify` drops every named property of an array — so `set` would
resolve having written a file without the secret it was handed. Silent
loss on the one operation whose entire contract is that it does not lose
things. Both branches now validate a non-array object of string values,
and a shape refusal is deliberately not rethrown as a key mismatch,
which would send the user to fix a working passphrase.
- **The read-modify-write cycle was only serialized in-process.** A
durable file is shared state and a second Inspector on the same box (a
CLI run beside a web session) could read the same map and overwrite the
first one's save, both reporting success. Mutations now take a
`mkdir`-based lock. A lock left by a killed process is stolen after 10s
— one `docker kill` must not brick secret writes permanently, which
would be a worse failure than the race. If the lock cannot be created at
all, the write proceeds unlocked rather than denying a real user a real
secret to prevent a race with a process that may not exist. Reads do not
lock: `writeStoreFile` is atomic, so a reader sees the old file or the
new one, never a torn one.
- **The permission repair was fire-and-forget while the docs promised
0600.** A file owned by another user, or on a read-only mount, stayed
exposed while the footer described it as protected. It now verifies the
resulting mode and warns, naming the actual mode, when it could not be
tightened.
- **`Group`'s theme carried a domain-named `secretStorageFooter`
variant**, which AGENTS.md reserves for app-wide primitive styling.
Renamed to the structural `stickyModalFooter`; the secret-storage
meaning stays in the element that owns it.
- The PR description still claimed the salt made a short passphrase safe,
contradicting the corrected comment and README. Updated.
Tests: both mount layouts that motivated the change (mount-at and
mount-above) plus the sibling-prefix, space-escaped, first-run, and
no-mountinfo cases; the array and non-string refusals on both the
plaintext and the authentic-ciphertext paths (the latter through a
hand-built fixture, since the store's own writer cannot produce that
state); lock exclusion, stale-lock stealing, the un-lockable fallback, and
two independent store instances racing; the permission report in all three
states; and the descriptor no longer going stale within one process. Full
`npm run ci` green — 5,688 tests under the coverage gate.
Signed-off-by: cliffhall <cliff@futurescale.com>
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