01-11 stopped new installs from ever taking a shipped credential, but did
nothing for the nodes that already did — those gateways still answer to a
password published in this repository.
rotate_compromised_gateway_credential() detects an EXACT match against the
denylist and replaces the pair; absent, unique, or merely unrecognised values
are left alone and return false. That distinction is the point: an operator
who deliberately set their own credential also has an "unrecognised" one, and
rotating it would be the same class of harm as leaving the default in place.
It hangs off resolve_dynamic_env beside ensure_generated_secrets, gated on the
gateway's app id, so an affected node heals on its next reconcile tick. There
is deliberately no teardown here: the new hash changes the resolved secret env,
which changes secret_env_hash, which the drift check reads as a container-label
mismatch — so the platform's own recreate path rebuilds the gateway around its
unchanged data directory, ports, volumes and name.
Rotation is self-terminating (the value written is not on the denylist, so the
next tick is a no-op) and errors propagate rather than being swallowed, because
the atomic write leaves the previous credential intact on failure.
Bcrypt generation was factored out of ensure_one into write_bcrypt_pair, which
both generation and rotation call — 01-11's SUMMARY claimed such a helper
existed but the arm was still inline, and rotation cannot reuse
ensure_gateway_credential because its idempotent fast path returns early
exactly when the file is present, which is the case rotation acts on.
Also fixes cargo fmt drift left by 42652547 in install.rs.
Verified: 6 new tests, secrets suite 16/16; full suite 1008 passed with one
known wall-clock flake (green 4/4 in isolation). NOT verified on a node —
Task 2's blocking checkpoint has not been run, so FED-07 stays open.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
