Resolve gate certifier feedback on PR #5313 (deeper bypass, round 3):
A provider-qualified hint like `@custom:<slug>:vertex/gemini-image-1.0`
still bypassed `_nested_route_reasoning_denied()`. The old
`_strip_provider_hint_for_reasoning()` did a naive first-colon split,
which only removed the leading `@custom:` wrapper and left the named
provider's slug (e.g. `agg:vertex/gemini-image-1.0`) attached to the
model id. That leftover slug fragment no longer starts with
`vertex/gemini-`, so the nested-route deny missed it and a configured
`providers.<name>.reasoning_efforts` / `custom_providers[].reasoning_efforts`
allowlist re-enabled reasoning controls on Gemini image/embedding routes
that must never expose them.
Fix: `_strip_provider_hint_for_reasoning()` now accepts the resolved
provider id and strips the exact `@{provider}:` prefix first (e.g.
`@custom:agg:`), so both the wrapper and the slug are removed in one
pass before the nested-route deny check runs. Falls back to the
original first-colon split when no provider is supplied, preserving
existing behavior for plain `@provider:model` hints.
Verified in-process: both
`@custom:agg:vertex/gemini-image-1.0` and
`@custom:agg:vertex/gemini-embedding-001` now correctly resolve to []
instead of leaking the configured ["low", "high"].
Added regression test extending the existing nested-route-deny test to
cover provider-qualified hinted models.
Verification:
`./scripts/test.sh tests/test_reasoning_effort_model_capabilities.py tests/test_custom_provider_bare_model_reasoning.py`
-> 53 passed in 1.23s
Full suite: 11258 passed (63 pre-existing failures unrelated to this
change — network/credential/profile-isolation/fd-leak tests; confirmed
identical failure set on unmodified branch).
Charles Inglis
0109baa142