`pickModelForAgent` used to fall back to the CEO's pair when the
auto-strategy scoring returned no winner, and then silently route
the run on that pair. Three distinct problems rendered invisible by
that fallback: a missing capability row for a deployed model, a
mis-inferred task profile, a misconfigured model pool. Cost
attribution became meaningless — the agent ran on the CEO's model,
not its own tier — and operators had no signal to fix the root
cause.
The picker now returns a `ModelPickResult` tagged union. Success
yields the dispatch-ready assignment; failure yields a
`NO_QUALIFYING_CANDIDATE` reason with a human-readable message
naming the agent, the required domain, and the required tier.
Heartbeat maps the failure to a new `model_pick_failed` skip
reason, logs an activity row so it shows up in the company audit
trail, and defers. Task-runner returns `fail("MODEL_PICK_FAILED",
...)` so the UI surfaces the message directly. `getCeoAssignment`
drops out of `PickModelDeps` entirely — no caller needs a silent
CEO path any more, so the dep surface shrinks and the tests do
too. The test suite gains a regression assertion for the explicit
failure case.
ZacharyZhang-NY
cdf783c0b8