`docs/TOOL-CALL-ARCHITECTURE.md` §3 calls deploying the MCP door "config,
not code". It is not, and the reason is authentication.
`/mcp/skills` authenticates with `AuthService::authenticate`, which
returns a full `AuthedUser` carrying the user's role. There is no
narrower credential in the system. So pointing a mission container at the
door means writing a bearer token into a file inside that container — and
mission agents run arbitrary `Bash` with egress and no read gate, which
is this platform's own documented security posture. An owner-scoped token
there turns "the agent runs commands in a sandbox" into "the agent drives
the whole ClawMates API as the owner".
Checked before building this rather than assumed: no such credential is
in a mission container today. The runtime's config.toml has no
`[mcp.servers]` block and no bearer, so the door would have been a NEW
exposure, not an existing one.
So: `auth_sessions.scope`, defaulting to `full`. `authenticate` now
delegates to `authenticate_scoped(token, SCOPE_FULL)`, which means **every
existing caller rejects a narrow token** and a route must opt in by naming
the scope it accepts. `/mcp/skills` is the only opt-in.
Fail closed on purpose. The likely mistake here is adding a scope and
forgetting to wire its check; this way that mistake grants nothing rather
than granting everything.
`mint_scoped` refuses to mint a `full` token — a caller reaching for it
wants a narrow credential, and handing back a full one because an
argument was wrong is exactly the failure the column exists to prevent,
and it would be invisible because the token would work.
The test that matters is not that the door accepts the token, it is that
nothing else does. Negative-controlled: removing the scope comparison
fails `a_scoped_token_is_refused_by_every_unscoped_caller`.
`.sqlx` regenerated — `authenticate` is a compile-checked query and CI
builds with SQLX_OFFLINE=true.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_018i9Ten1LU4jUr5d7TAWda9
