The headline is a correction to my own claim rather than a new defect.
**The optimistic verify is weaker than the comment said it was.** It
described the residual as a crash between the write and the verifying read.
The reviewer pointed out that no crash is needed: order two writers as
write-A, verify-A, write-B, verify-B and both report success while A's entry
is gone — A's verify simply ran before there was anything to see, and B did
nothing wrong. A crash is one instance of that shape, not the whole of it.
The trace in the old comment quietly assumed A verifies *after* B writes,
which nothing guarantees.
Corrected in the doc comment, the README and the spec, and the honest
summary is now stated rather than implied: this converges in every
interleaving where the clobber lands before the verify, it is not mutual
exclusion, and a deployment that needs the guarantee wants an OS-backed lock
from a dedicated library — not another hand-rolled election. It remains
better than what it replaced, which lost updates across a wider set of
interleavings and could not be closed at all with what Node exposes.
The other findings:
- **An envelope naming the cipher still is not an openable one.** Round 9
added a `kdf`/`data` presence check; three dot-separated strings satisfied
it while an empty tag, a 4-byte IV or `N: 3` still made every decrypt
throw — so the quiet "Encrypted file" footer went to a file whose next
save was guaranteed to fail. Now validates part sizes, a non-empty
ciphertext, and the scrypt cost parameters (node rejects a non-power-of-two
`N` synchronously, out of the derivation rather than the decrypt). A
positive control asserts a file we actually wrote still reads as encrypted.
- **`encryptionUnknown` + `looseMode` claimed an exposure it had not
established.** With both set, `plaintext` is absent, so a `!== false` test
landed on "anyone who can read it can read the secrets in it" — about a
file that may well hold ciphertext we simply could not classify. Three-way
now, in `secretStorageCaveat` and mirrored in the footer's tooltip, with a
test on each.
- **The README described a lock that no longer exists**, which is the worst
kind of stale doc: it stated a durability guarantee the code had stopped
providing. Rewritten to describe the actual design, including the residual.
- **The private-method access in the concurrency test** now carries the
justification the repo's TypeScript rules require: the asserted shape is
`writeMap`'s real signature, so a rename breaks the line instead of
silently detaching the stub, and a production injection seam would let the
real write path drift from the tested one.
Also updates `specification/v2_servers_file.md`, which still described #1356's
world: one keychain-only store, and unavailability as a hard error. It now
covers store selection and the probe, the file format and lazy encryption
upgrade, the concurrency design and its residual, the `getStrict`/`getMany`
seams and the two traps `getStrict` hit, the durability gate on migration,
the keychain hand-off and its conditional delete, and how the active store is
surfaced.
Full `npm run ci` green. (One unrelated `AppRenderer` theme-flip test failed
once under full-suite parallelism and passes in isolation with and without
these changes — a flake, not a regression.)
Signed-off-by: cliffhall <cliff@futurescale.com>
Four findings, all suppressed, all real. Three are the same mistake in
different places: a state that was never established being reported as a
confident answer.
- **`readOnDiskEncryption` conflated "no file" with "unreadable file".**
Both answered `null`, and the descriptor falls back to the configured
write policy on `null` — so a passphrase-configured install reported
"File (encrypted)" about a file whose envelope had never parsed, and
which `set` was in fact about to refuse rather than overwrite. It now
returns a four-state result, and only `absent` falls back to the policy
(honestly: the first write really will create it that way). `unreadable`
produces `encryptionUnknown` on the descriptor, `plaintext` is omitted
entirely so nothing can read a default out of it, and the label, caveat,
tone and footer all carry "unreadable" rather than guessing a mode.
- **The loose-mode warning overstated exposure for an encrypted file.**
"Anyone who can read it can read the secrets in it" is false when the
file is ciphertext — a reader gets the bytes and still needs the
passphrase. Both the caveat and the footer tooltip now branch on
encryption: the passphrase becomes the only protection, which is the
real consequence. Overstating it is not harmless, because a warning that
cries wolf is discounted on the occasion it is literally true.
- **The keychain hand-off could invert its own keychain-wins rule.**
`SecretStore.get` answers `null` both for a missing entry and for a
keychain it could not read, and the migration *writes* on `null` — so a
transient read failure would overwrite a newer keychain value with the
older file copy. Added an optional `getStrict` (throws instead of
swallowing) implemented by `KeyringSecretStore`, with
`secretStoreGetStrict` falling back to `get` for stores whose reads
cannot fail. A throw now aborts the hand-off with the file left in
place, so the next run retries.
Writing the tests turned up one more, in code the review had passed:
`parseOwner` recorded a garbled pid as `-1`, and `process.kill(-1, 0)` is
a *wildcard* asking about every process this user can signal — it answers
"alive" almost always, which would have made a lock with a corrupt stamp
permanently unstealable. Only a positive pid is usable now; anything else
is treated as no pid at all and the mtime decides.
Tests: the four envelope states kept distinct; the descriptor refusing to
guess, with the genuine no-file case as the control; strict-read abort
without a write and with the file preserved, plus a store whose `get` and
`getStrict` disagree so the test proves which one the migration consults;
encryption-aware wording asserted in both directions in the caveat and the
band; three unusable owner stamps and a wildcard pid; and the descriptor
shapes that must now be rejected — neither half of the encryption question
answered, or both. Full `npm run ci` green — 5,750 tests under the
coverage gate.
Signed-off-by: cliffhall <cliff@futurescale.com>
Repairs origin as well as answering the review. 2d2c787e committed the
`absorbFileSecretsIntoKeyring` tests without the implementation they
import, so the branch has been failing `tsc` since; this commit brings the
source across.
Round 5's four findings (two inline, two suppressed):
- **The stale-lock takeover was still racy.** Round 4 made *stealing*
liveness-aware but left the takeover as remove-then-recreate, which is
not an election: two waiters can both judge the same lock stale, the
first removes it and takes a fresh one, and the second then removes
*that* — both inside the section, which is the lost update the takeover
exists to prevent. Claiming is now an atomic `rename` to a
token-unique name, so exactly one waiter can take a given stale lock and
the losers get ENOENT. A failed claim also falls through to the deadline
instead of `continue`ing, so a takeover that can never succeed times out
rather than spinning forever on a swallowed error.
- **Every `stat` failure was read as "no file yet".** An existing file we
cannot inspect (EACCES on the directory, a mode-less filesystem) then
produced no warning at all, and the footer went on stating owner-only
permissions having verified nothing. There is now a third state,
`unknown`, carried end to end: `permissionsUnknown` on the descriptor, a
caveat that says the permissions could not be checked, a `warn` tone, and
its own branch in the footer sentence — which otherwise would have
claimed "Owner-only permissions." by omission, the same bug one layer up.
- **mountinfo decoded only `\040`.** The kernel escapes tab, newline and
backslash too (`\011`, `\012`, `\134`), so a mounted path containing any
of them was compared in its escaped form, matched nothing, and read as
the container's writable layer — `memory` selected and persistence
silently lost on a box that had arranged for it. Decoded as octal in
general now, since the rule is octal-in-general and a future addition
would otherwise reintroduce exactly this.
- **File-backed secrets vanished once a keychain appeared.** Save secrets
without libsecret, install libsecret, and the next run selects the
keychain and stops seeing them: still on disk, read by nothing, and
nothing looks broken. `absorbFileSecretsIntoKeyring` hands them over on
the run that finds a keychain, under the rules the two existing plaintext
migrations already use — keychain wins on conflict, the file is removed
only on complete success, and a file that cannot be read is never
deleted, because that is precisely the case where the values would be
lost.
Tests: a two-waiter race over one stale lock asserting a single holder
throughout; `unknown` from `readSecretFilePermissions` through the
descriptor to the footer sentence and tone; the hand-off's happy path,
keychain-wins, write-failure, undecryptable-file, empty-file,
malformed-key, and explicitly-configured-keyring cases; and six more
rejected descriptor shapes, including each file-only field on a non-file
kind. Full `npm run ci` green — 5,732 tests under the coverage gate.
Signed-off-by: cliffhall <cliff@futurescale.com>
Reads "Memory (this session only): Secrets are not written anywhere and
are lost on exit." — shorter tail than "lost when the Inspector exits",
and a colon separating the store from what follows it.
The colon is added at the footer's composition, not inside
`secretStorageLabel`. The label is also consumed alone by
`secretStorageSummary`, which appends " at <path>" for a file-backed
store, so a colon baked into the label would print
"File (encrypted): at /path" in the startup banner. It renders only when
a detail actually follows.
The caveat string is shared with the banner's warning line, so the
terminal picks up the shorter wording too.
Signed-off-by: cliffhall <cliff@futurescale.com>
Nine findings (six inline, three suppressed), all taken. Two were serious.
**The memory fallback made the migrations destructive.** Both migrations —
mcp.json in the remote server, client.json in `node-persistence` — lift a
plaintext secret off disk, write it to the secret store, and then delete it
from the file. That trade is safe only while the store is at least as
durable as the disk, which held by construction while `InMemorySecretStore`
was a test double. Making it a production fallback broke it: on an
unmounted container a plain `GET /api/servers` would have moved a user's
existing secrets into RAM and lost them at exit — destroying data on a
read.
`SecretStore` gains an optional `isDurable()`, absent meaning durable, and
both migrations withhold the disk delete when it answers false (the value
is still loaded, so the session behaves normally). The production fallback
is now a named `SessionSecretStore` rather than the bare
`InMemorySecretStore`, so the suite's many doubles keep standing in for a
*working keychain* — which is what they are there to be — and only code
that deliberately chooses RAM in production says so.
**Round 2's per-call descriptor never reached anyone.** Both web servers
resolved it once at startup and baked it into `initialConfig`, which
`/api/config` serves unchanged — so the freshness fix was inert for its
only consumer. The route now takes a `secretStorageResolver` and calls it
per request.
The lock needed three more fixes, and they compound:
- **Release removed whatever directory was at the path.** A holder whose
work outran the stale threshold would delete the *next* owner's lock,
letting a third writer into a section two processes believed they held.
Ownership is now stamped with a random token and release only removes a
lock still carrying it.
- **The timeout fell through to an unlocked write** — under contention,
the one moment another writer is provably active. It now throws
`SecretFileLockTimeoutError`, which `set` is allowed to do.
- **The first write of every process bypassed the lock**, because the
secrets directory does not exist yet and `mkdir` failed ENOENT. The
parent is created first. First writes are exactly when two processes are
most likely to start together.
Fixing the timeout exposed a fourth: with stale (10s) below timeout, a
waiter stole from a holder that was merely *slow* rather than dead —
reinstating the lost update. A holder now heartbeats its lock, so
"stale" means the holder is gone, and the timeout is what a live-but-slow
holder produces. Lock timings are injectable so the tests can exercise
contention, staleness, and timeout without spending the real intervals.
Also: the loose-permission state is carried into `SecretStorageInfo` as
`looseMode` and rendered as the caveat (it outranks the encryption caveat —
a file others can read is a live exposure, while "unencrypted" is a
property of a file only its owner can open), rather than living in a
startup log the browser cannot see; and `usableSecretStorage` validates
`pendingEncryption` and `looseMode` as the optional booleans/numbers they
are (`pendingEncryption: "false"` is truthy and would have printed advice
that is the opposite of the truth) and rejects file-only fields on a
keychain or memory descriptor.
Tests: both migrations against a session store with a durable control
alongside, so the guard is visibly the difference; `/api/config` serving a
changing resolver and falling back without one; lock ownership after a
steal, the timeout under a live holder, no-steal from a slow holder, and a
locked first write; `looseMode` through the descriptor, the caveat
ordering, and the tone; and five more rejected payload shapes. Full
`npm run ci` green — 5,704 tests under the coverage gate.
Signed-off-by: cliffhall <cliff@futurescale.com>
Six findings, all taken.
- The descriptor reported the *write policy*, not the file. Adding
`MCP_INSPECTOR_SECRET_KEY` to an install that already has a plaintext
file flipped `store.encrypted` immediately, so the banner and footer
claimed "File (encrypted)" while the existing secrets sat readable
until the next `set`. `FileSecretStore.readOnDiskEncryption()` now
reads the envelope (never the payload, so it needs no passphrase) and
the descriptor is built from that. The transitional state gets its own
`pendingEncryption` flag, which changes the advice without softening
the verdict — "set a passphrase" is the wrong thing to tell someone who
already has, so the caveat names the pending write instead.
- The secrets file ignored the configured storage directory. A container
mounting only that directory was judged unmounted, fell back to
`memory`, and lost secrets the user had arranged to keep.
`defaultSecretFilePath()` now follows `MCP_STORAGE_DIR` — the variable
that already relocates OAuth tokens and `client.json` — between the
explicit `MCP_INSPECTOR_SECRET_FILE` and the `~/.mcp-inspector`
default. (The issue comment called it `MCP_INSPECTOR_STORAGE_DIR`; no
such variable exists.)
- `version` was never checked before the plaintext branch, so a
`{ version: 2, encryption: "none" }` file was read and silently
rewritten as version 1, discarding whatever the newer format added —
the same destroy-to-satisfy-an-additive-request case the encrypted
branch already refuses. Checked first now, so the answer no longer
depends on which encryption mode the newer writer chose.
- The doc comment claimed a per-file salt made "a short, memorable value
safe to use". It does not: the salt defeats precomputation, not
guessing, and the scrypt cost is deliberately a few milliseconds
because it runs on every read and write. Both the comment and the
README now say to use a high-entropy value, generated rather than
chosen.
- `usableSecretStorage` validated only `kind`, so a partial
`{ kind: "file" }` was cast through and — because a missing `plaintext`
is falsy — rendered as the quiet, neutral *encrypted* file. That is the
confident half-answer the guard exists to reject, produced by the
absence of information rather than by any claim the backend made.
`reason`, `durable`, and each kind's own required fields are checked.
- The footer's inline `Tooltip` carried four static props; extracted to a
`CaveatTooltip` constant per the `.withProps()` rule.
Tests cover each: the policy/file disagreement in both directions and the
no-file-yet fallback, `MCP_STORAGE_DIR` and its precedence against
`MCP_INSPECTOR_SECRET_FILE`, the version refusal (asserting the bytes
survive it) split from the unrecognized-cipher refusal it used to be
conflated with, `readOnDiskEncryption` including the keyless and
unparseable cases, five new rejected descriptor shapes, and the changed
caveat. Full `npm run ci` green.
Signed-off-by: cliffhall <cliff@futurescale.com>
Closes#1950
Before this, a box with no reachable OS keychain — the published
container (no D-Bus session, #1848), Android/Termux (no platform binary,
#1905), a minimal Linux install without libsecret — could not persist an
OAuth client secret or a stdio `env:` value at all. `KeyringSecretStore`
degraded into a store that silently holds nothing: `get` returned null,
`delete` no-opped, and `set` hard-failed with a 503. That is the correct
failure behavior, but it left the documented, supported way to run the
Inspector with no secret persistence whatsoever.
Adds the two missing implementations and, more importantly, the policy
that picks one and the surfaces that say which was picked.
- `FileSecretStore` — one `0600` JSON document at
`~/.mcp-inspector/secrets.json`, encrypted with AES-256-GCM whenever
`MCP_INSPECTOR_SECRET_KEY` is set (scrypt, per-file random salt). The
whole map is encrypted as a unit rather than value-by-value so the
account names — `${serverId}:${field}` — are hidden too; a per-value
scheme would leave a readable index of which servers you hold a client
secret for. A file that can no longer be decrypted reads as empty
(matching the interface's read tolerance) but *refuses to be written*,
because replacing a file of still-valid secrets to satisfy an additive
request destroys data.
- `secret-store-selection.ts` — the policy.
`MCP_INSPECTOR_SECRET_STORE=keyring|file|memory` wins outright;
otherwise probe the keychain and, if unreachable, fall back loudly. The
fallback is `memory` in a container whose secrets directory is not on a
mount, and `file` otherwise — so mounting the volume the README already
recommends for the catalog flips the same run to durable storage with
no configuration, and an unmounted container gets the honest answer
rather than a file `--rm` will discard. Cached per process so the
banner, `/api/config`, and the store doing the writing cannot disagree.
- Automatic, but never silent. The downgrade prints at startup, rides
`GET /api/config`, and is named in a permanent 32px footer at the
bottom of both dialogs that accept a secret. A startup banner is seen
once by whoever started the process; a toast is seen once; a
dismissible banner is the thing a user dismisses before doing the work
it describes. The plaintext and memory cases render their caveat inline
in a warning tone — a warning you must hover to discover is not one.
- `SecretStoreUnavailableError` is now the base every store's `set`
throws, so the routes translate one condition into a 503 instead of
matching `KeychainUnavailableError` by name.
Docs: the container section of the root README gains a table of which
store you get and how to make secrets survive, plus the
`MCP_INSPECTOR_SECRET_KEY` upgrade/mismatch rules.
Tests: the existing interface contract block is extracted to
`secretStoreContract.ts` and run against all three implementations, so
none can drift on the availability contract. `FileSecretStore` is tested
against a real temp filesystem — mode, cross-instance round-trip, that
the ciphertext does not contain the plaintext, the read-modify-write
race, and every refusal path. Full `npm run ci` passes, per-file gate
included.
Signed-off-by: cliffhall <cliff@futurescale.com>
cliffhall