Review follow-ups on the model_overrides feature:
- ONE canonical override schema everywhere. get_model_info previously
merged the override dict raw into the models.dev catalog shape
({**raw, **override}), so the documented context_window/supports_*
keys silently did nothing on that path (cost guard, inventory) while
working in capabilities/context paths — same config key, two
incompatible schemas. Overrides are now translated into the catalog
shape at the get_model_info boundary (_override_to_catalog_shape),
and sub-dicts (limit, modalities) are MERGED, not clobbered — an
override setting only context_window no longer wipes the catalog's
limit.output.
- _default is now a FILL-GAP default, not an override: it applies only
to models the catalog does not know (the #8731/#84482 self-unblock
path) and never displaces catalog data. A
_default: {context_window: 128000} can no longer clamp every model
of a provider. Explicit per-provider+model entries keep their
win-over-catalog semantics.
- Early-chain _override_context_window (model_metadata step 0b) is
explicit-only, so a _default can never preempt custom_providers
per-model settings or live probes; fill-gap defaults apply at the
lookup_models_dev_context catalog-miss boundary (step 5f) instead.
This fixes the precedence inversion where a provider/global _default
silently overrode an explicit per-endpoint per-model context_length.
- Provider keys accept BOTH id spaces (Hermes id and models.dev id:
copilot/github-copilot both work) and model ids match
case-insensitively, mirroring catalog lookup.
- Malformed override values (context_window: '512k') log a one-shot
warning instead of being silently swallowed.
- DEFAULT_CONFIG comment: removed the false family/dated-snapshot
inheritance claim, documented the recognized field list, fill-gap
semantics, and the id-space rule.
- Tests: rewritten for the new contracts (fill-gap invariants,
dual-id-space keys, sub-dict merge preservation, one-shot warning);
added a real-config-yaml e2e plumbing test (mutation-checked: fails
when the config key wiring is broken).