model-fallback-policy.md

Model Fallback Policy

ask, rescue, review, adversarial-review, health, status, and result should expose a top-level model when the provider CLI makes one knowable.

The preferred source is always the provider's own current run output:

1. Parse model metadata from the provider's stdout/stderr event stream.
2. If the current run omits model metadata, use the host companion's cached provider model as defaultModel.
3. Populate that cache only from explicit user model selection, status-only auth inspection, health, or explicit setup --probe-auth output. The default setup path deliberately skips model-based auth probes and may not yield a model.

This is intentionally a final fallback, not a shared model-extraction framework. Provider modules keep their own parser logic because upstream event shapes differ. The registry only threads defaultModel through once every provider-specific parser has had the first chance to report a model.

Guardrail

plugins/polycli/scripts/tests/integration.test.mjs includes an integration test that runs setup against a fake provider which reports a model, then runs ask against a stream that deliberately omits every model field. The expected result is that ask --json still returns the cached setup model.

That test is the sustainability signal for Q2. If it fails, fix the cache/fallback contract or update this policy before changing provider-specific fallbacks.