2026-08-17-omnigent-omnigent-s-max-cost-usd-is-still-a-downgrade-gate-not-a-hard-stop

Omnigent's max_cost_usd is still a downgrade gate, not a hard stop, unless you write expensive_models: [].

Nothing, and that is the finding. Across v0.8.0, v0.8.1, v0.8.2 and v0.9.0 the semantics of max_cost_usd are unchanged. _resolve_expensive_models at v0.9.0 lines 380-414 returns block_all_models=True when expensive_models is None or [] -- that path is a true hard stop, and it was established by #1631 on 2026-06-30, before this window. Supply a non-empty expensive_models list and you get the downgrade gate: over budget, tool calls are DENYed while the session sits on a listed model and ALLOWed again once it moves to a cheaper one. The cap is evaluated at the request phase as well as the tool-call phase, and it fails closed when the active model is undeterminable.

Channel: tagged-release. Ancestry: Read the policy source at https://raw.githubusercontent.com/omnigent-ai/omnigent/v0.9.0/omnigent/policies/builtins/cost.py and diffed it against the same file at v0.7.0: the only differences across the whole window are type-annotation and isinstance hardening from the pyrefly lint sweep (commit 1262652a039c, 2026-08-03, #3972). No semantic change. gh api "repos/omnigent-ai/omnigent/commits?path=omnigent/policies/builtins/cost.py&since=2026-08-01" returns exactly one commit, that lint sweep. The docstring at v0.9.0 lines 21-28 still reads: "once spend reaches this, the policy forces a model downgrade. Rather than stopping the session, it DENYs while the session is still on an expensive model ... the budget becomes a 'downgrade gate,' not a hard stop."

Operator consequence: Read your own config rather than the feature name. If you wrote cost_budget with an explicit expensive_models list expecting the number to stop the session, it does not -- it forces a model switch and the session keeps spending on the cheaper arm. Omitting expensive_models entirely, or setting it to [], is the hard stop. Nothing in this window changed that, so anyone who checked in July does not need to re-check.

Receipt

• https://github.com/omnigent-ai/omnigent/blob/v0.9.0/omnigent/policies/builtins/cost.py