`AcPrincipal.did: Option<String>` → `Option<guildhouse_did::Did>`.
The AuthorizationContext now carries a W3C-canonical typed DID;
malformed DIDs fail at deserialize time rather than propagating
into the corpus_check / session state.
SessionState.principal stays a String — it can also hold a Unix
username in ungoverned mode, so a typed Did would force
Option<Did> there and complicate the chain. The render at
SessionState::from_ac now goes Did → as_str() instead of cloning
the legacy String. Behaviour at the audit-leaf level is
unchanged when the AC carries a valid `did:web:...` payload.
Phase 0 of DESIGN-DID-INTEGRATION-2026-04-29 §5.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Tyler J King <tking@guildhouse.dev>
corpus_check() previously returned Allowed as soon as it found a file by
name in the corpus directory keyed by CID. The CID acted as a directory
label, not a content commitment. An attacker with write access to the
corpus directory could plant a malicious binary under a legitimate CID
and it would execute with that CID's authorization.
This change hashes the binary at the resolved path and compares to the
CID its directory is named for. Mismatches return a new ContentMismatch
variant; unreadable binaries return ReadFailed. Both are execution-denied
states — main.rs handles each explicitly with exit code 3 (previously
used only for Denied).
Both error classes emit Chronicle-shaped structured tracing events
(target: "chronicle") with stable event_type constants from
libgsh::chronicle_events. The field shape matches what substrate-chronicle's
post-io_uring emission API is expected to require; migration to direct
Chronicle emission becomes a mechanical translation once that API
stabilizes.
The tamper signal is that the binary and its directory name disagree.
This closes the execution-path half of the CID-content verification
audit fix — admission (corpus-operator) rejects CID forgery before the
enforcement ConfigMap is written; execution (libgsh) rejects any tamper
that landed after admission. Defense in depth across both layers.
Kernel-layer CID verification (the third layer, where eBPF LSM hooks
authorize by binary name via FNV-1a hash of comm) is explicit backlog,
deferred to Bifrost where in-kernel hashing or a ring-buffer userspace
verifier can be evaluated properly.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Tyler J King <tking@guildhouse.dev>
