Closes#2248.
Completes SEP-2640 support across all three clients, and closes the one
obligation #2234 deliberately left open.
- `checkSkillFrontmatterMatch` compares a served SKILL.md's own YAML
frontmatter against the entry the listing advertised, field by field. No
digest can cover this: a digest is taken over the bytes the server served,
so it proves the file was not altered in transit and says nothing about
whether the listing described it honestly. Needs a real YAML parser; `yaml`
was already a root dependency, so this adds no package — but it does newly
put it on core/'s import graph, hence the three bundler `external` lists.
- `resources/directory/read`: result schemas defined against the normative
text, `InspectorClient.readResourceDirectory`, a Directory section on the
Skills screen, and `--method resources/directory/read` in the CLI. The
client refuses the call locally when the server did not declare
`directoryRead`, which is the SEP's MUST NOT. A child the directory lists
but the entry does not is marked `not listed` rather than merged into the
manifest — the SEP calls a directory result a live observation and forbids
treating it as extending the manifest.
- CLI: `skills/list`, `skills/get` and `resources/directory/read`, plus
`--verify` — one NDJSON report per skill, a summary on stderr, exit 7 on a
violation. Reads are sequential; a conforming manifest may declare 512
entries.
- TUI: a Skills pane, shown only when the server declares the extension. Each
row carries its conformance verdict as a glyph as well as a colour, since
the pane is read over ssh and through script(1). Enter verifies.
- `verifySkills` re-throws `AuthRecoveryRequiredError` rather than recording
it per file: it says the session's authorization expired, so absorbing it
would report N identical read failures and swallow the error the TUI and
the web commands key off to reauthorize.
Two open questions settled, both in code comments where they will be found:
`skills/get` carries no caching attributes because SEP-2640 leaves the
question open in as many words, so requiring them would fail a conforming
server; and there is no `PagedSkillsState` because every consumer of this
list is a whole-catalog verdict — computed over page one of three, "this
server's skills conform" is not merely partial but wrong.
The fixture grows two skills, both for checks that were otherwise
undemonstrable: `lying-listing` (listing and file disagree, digest still
verifies) and `stale-manifest` (serves a file its manifest does not declare).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ND46Ci64DC3tzBy9aG81Nc
Signed-off-by: cliffhall <cliff@futurescale.com>
The review finally quoted the normative text, which is what I asked for
across five rounds before declining: SEP-2640's `skills/list` section says
"In protocol versions 2026-07-28 and later, the result also carries …
`ttlMs` and `cacheScope`." So the era-aware validation is in.
- skillsSchemas: `ModernListSkillsResultSchema` = the page plus the base
list envelope, with field shapes mirroring `ModernResultEnvelopeSchema`
in `listSalvage.ts` so this repo's two statements of a modern envelope
cannot drift. `InspectorClient.listSkills` picks it from the negotiated
era; the legacy shape stays permissive, because those are 2026-era
attributes a legacy server has no business sending.
Nothing else catches this: `skills/*` is consumer-owned, so it is absent
from the SDK's cacheable-method registry and a modern server answering
`{ skills: [] }` was reaching the conformance UI as a clean list.
- skills.ts: count `frontmatter.description` (and `name`) length in Unicode
CODE POINTS. `String.length` counts UTF-16 code units, so 600 non-BMP
characters measured as 1200 and a perfectly valid description was
reported `malformed-description` — a conforming server failed by an
off-by-encoding, which is the direction this module works hardest to
avoid. The Agent Skills reference validator uses Python `len()`.
- #2248 narrowed: the `skills/list` half is settled here; what remains is
whether `skills/get` carries the same attributes.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018kfrH3uRNUM4JAk1reKtyY
Signed-off-by: cliffhall <cliff@futurescale.com>
- SkillsScreen: actually call `skills/get`. The client method and its
tests existed but no production caller invoked it, so #2234's acceptance
criterion ("skills/get retrieves a single entry") was unmet and a server
author's required handler could not be exercised. The detail pane now
fetches the selected URI on demand and reports whether the fetched entry
AGREES with the one skills/list advertised — both describe the same
skill, so a disagreement is a server bug only a side-by-side fetch shows.
- core/mcp/sha256.ts: a dependency-free SHA-256, used when `crypto.subtle`
is absent. `SubtleCrypto` needs a secure context, and this app is
documented as servable over plain HTTP on a LAN IP — where every skill
verification threw and the UI reported a read failure for files it had
fetched fine. Checked against the FIPS 180-4 vectors and differentially
against WebCrypto.
- skills.ts: require the `skill:` scheme in `normalizeSkillUri`. Checking
only that a URI was hierarchical let `https://demo/SKILL.md` pass the
name and root checks — a manifest pointing anywhere on the web, reported
as conforming.
- skills.ts: `missing-digest` and `missing-size` are errors. Both are
required fields, and an omitted `size` is what lets a server slip past
the 16 MiB pre-fetch limit while the UI reports zero errors. `warning`
is now reserved for what is legal yet unverifiable — `"dynamic"`.
- SkillsScreen: key the "Verify all" batch guard to the manifest. A global
flag left a newly selected skill's button disabled until the previous
skill's reads settled — forever, if one hung.
Not changed, deliberately: whether a modern-era `skills/list` result MUST
carry the SEP-2549 caching attributes. #2234's analysis records it as open
and the review asserts the opposite; neither reading was checked against
the normative text. Leaving the schema permissive accepts a server that
omits them, while tightening on a wrong reading would reject conforming
responses — the more expensive direction. `skillsSchemas.ts` states this
and #2248 settles it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018kfrH3uRNUM4JAk1reKtyY
Signed-off-by: cliffhall <cliff@futurescale.com>
- SkillsScreen: key verdicts and React elements by manifest ROW INDEX,
not URI. The checker deliberately tolerates a duplicated URI so it can
report `duplicate-resource`; a URI key collided those rows into one
verdict, so verifying either updated both and "Verify all" raced two
different digest/size declarations into the same slot.
- SkillsScreen: hold the invalidation generation in React state keyed by
the manifest, not a ref bumped during render. `useValueChange` runs its
callback during render and requires setState-only purity — an abandoned
render left the ref incremented and silently discarded a live
verification.
- SkillsScreen: title a size disagreement "Size mismatch" and render its
reason. `verifySkillResource` catches it before hashing, so the alert
was showing "actual undefined" under "Digest mismatch".
- SkillsScreen: pass `contents` to ContentViewer so a base64 SKILL.md
renders. The text-block form substituted "" and painted a blank preview
for a file verification had just read correctly.
- skills.ts: add `malformed-size` for a size that is not a non-negative
safe integer, and exclude such values from the 16 MiB total. A negative
one could pull the sum back under the limit and hide a violation.
- managedSkillsState: make the overlap guard per-session instead of a
boolean. A disconnect during an in-flight walk left it set, so the
reconnect's own load no-oped and was never retried — permanently, if
the stale request never settled. A stale `finally` can no longer clear
the live session's guard either.
- skillsSchemas: require the `{ skill }` envelope for `skills/get`. The
accepted SEP settles it, and normalizing an inline entry would let a
non-conforming response past the one place that could report it.
- #2248 and the PR description: corrected — they said
`ReadResourceDirectoryResultSchema` was already declared, which round 1
removed. #2248 now owns defining it, and records the frontmatter
cross-check gap too.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018kfrH3uRNUM4JAk1reKtyY
Signed-off-by: cliffhall <cliff@futurescale.com>
- skills.ts: report a manifest that omits the skill's own SKILL.md
(an empty list included), duplicate URIs, entries outside the skill
root, and a missing size. `Conforms` was reachable for manifests that
break invariants SEP-2640 states.
- skills.ts: cross-check the declared byte length before hashing. A size
that disagrees fails verification on its own — the digest is taken over
the bytes the server served, so agreeing with it says nothing about
whether the manifest describes them.
- skills.ts: copy the view instead of slicing its backing store in
`sha256Digest`. `SharedArrayBuffer.prototype.slice()` returns another
SharedArrayBuffer, which `crypto.subtle.digest` rejects — the cast
claimed to handle the exact input that would have thrown. No cast now.
- skills.ts: state the one obligation NOT checked here — that an entry's
frontmatter matches the fetched SKILL.md's. The digest cannot cover it,
and closing it needs a YAML parser, so it is tracked on #2248.
- managedSkillsState: cap the walk at LIST_MAX_PAGES. The repeated-cursor
guard only catches a server stuck on one cursor; endlessly unique ones
walked forever. Raises rather than truncating, like the salvage walk.
- managedSkillsState: gate every write on a session generation, so a walk
that resolves after a disconnect or destroy cannot repopulate a cleared
store or deliver the previous session's skills into the next.
- inspectorClient: send a cursor when it is `!== undefined`, not when it
is truthy. An opaque cursor may be `""`, and dropping it re-requested
page one — which the store then reported as a repeated-cursor failure.
- SkillsScreen: key verdict invalidation on the manifest (URI + digests +
sizes), not the URI alone. A Refresh that changed the manifest left a
green badge attached to a digest nothing had checked.
- SkillsScreen: epoch-guard every read continuation, so a fetch that
resolves after the selection moved on cannot write into the new one.
- SkillsScreen: bound "Verify all" to 4 concurrent reads. A conforming
manifest may hold 512 files.
- skillsSchemas: drop the guessed `resources/directory/read` result
schema. Nothing calls it, so an unverified shape could sit wrong
indefinitely; phase 3 adds it against the normative text.
- skills-http.json: declare the extension bare. It advertised
`directoryRead: true` with no handler, so Connection Info reported
"Supported" for a method that answers -32601.
- types.ts: restore the Tasks doc comment the Skills interface displaced.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018kfrH3uRNUM4JAk1reKtyY
Signed-off-by: cliffhall <cliff@futurescale.com>
Adds detection, enumeration, and conformance checking for the Skills
extension (`io.modelcontextprotocol/skills`) — phases 1 and 2 of #2234,
which is everything its Acceptance list names.
Skills is a *server*-declared extension, read off the connecting server's
`capabilities.extensions`, so it is deliberately absent from
`ADVERTISABLE_EXTENSIONS` — that registry is what the Inspector advertises
and the user toggles, and an entry there would be a meaningless toggle.
`skills/list` and `skills/get` are consumer-owned extension methods that
neither era codec defines, so the SDK's era gate skips them and they go out
as ordinary `client.request` calls with explicit result schemas. The
raw-wire channel modern `tasks/*` needs is not used, and the Skills tab is
not era-gated: a legacy-era server that declares the extension is serving it.
The checks are the point, not the list view. `core/mcp/skills.ts` reports
each obligation SEP-2640 states — the name/path invariant, the digest
format, the 512-entry and 16 MiB limits, and `resources: "dynamic"`, which
means integrity cannot be verified at all. Digest verification hashes the
fetched bytes with WebCrypto and returns a mismatch with both digests
attached rather than throwing, because showing a mismatch loudly is the
whole value proposition.
Files are fetched on demand: SEP-2640 is explicit that a `resources/read`
of a `SKILL.md` is not a load and confers no standing, so none of the SEP's
host machinery is implemented.
The `skills-http` fixture serves four skills over two pages, three of them
deliberately non-conforming — without those the verification code is
untestable.
Phase 3 (CLI, TUI, `resources/directory/read`, paged mode) is #2248.
Closes#2234
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018kfrH3uRNUM4JAk1reKtyY
Signed-off-by: cliffhall <cliff@futurescale.com>
cliffhall