Greptile Summary

This PR fixes a bug (#57066) where openrouter:free and openrouter:auto were mis-resolved to anthropic/openrouter:free because parseModelRef only splits on / and resolveConfiguredModelRef had no special handling for the colon-separated shorthand. The fix introduces a OPENROUTER_COMPAT_ALIASES constant map and checks it before any slash-split or provider-fallback logic in both parseModelRef and resolveConfiguredModelRef.

Key changes:

• New OPENROUTER_COMPAT_ALIASES constant maps openrouter:free → meta-llama/llama-3.3-70b-instruct:free and openrouter:auto → auto, both on the openrouter provider.
• Both resolution entry points (parseModelRef and resolveConfiguredModelRef) now short-circuit on a compat-alias match before any splitting or provider inference, using { ...compatAlias } shallow copies.
• Comprehensive new tests cover case-insensitivity (OPENROUTER:FREE), leading/trailing whitespace, and correct provider attribution in resolveConfiguredModelRef.
• Most other diff lines are mechanical formatting reformats (80-col wrapping) with no logic change.

One minor inconsistency to be aware of: resolveConfiguredModelRef checks compat aliases before user-defined aliases, while resolveModelRefFromString checks user-defined aliases before delegating to parseModelRef (where compat aliases are resolved). In practice this only matters if a user explicitly defines a custom alias named openrouter:free, which is an unlikely and unsupported configuration.

Confidence Score: 4/5

Safe to merge; the core bug fix is correct and well-tested, with one minor alias-priority inconsistency worth addressing.

The fix correctly resolves the reported mis-attribution bug with proper shallow copies and case-insensitive lookup. Tests are thorough. Score is 4 rather than 5 only because of the alias-priority inconsistency between resolveConfiguredModelRef and resolveModelRefFromString — a user who defines a custom alias named openrouter:free will see different behavior depending on which resolution path is taken.

src/agents/model-selection.ts — the compat-alias priority relative to user-defined aliases in resolveConfiguredModelRef vs. resolveModelRefFromString should be aligned.

This is a comment left during a code review.
Path: src/agents/model-selection.ts
Line: 330-336

Comment:
**Alias priority inconsistency with `resolveModelRefFromString`**

In `resolveConfiguredModelRef`, compat aliases are checked *before* user-defined aliases (line 333), so `OPENROUTER_COMPAT_ALIASES` always wins. However, in `resolveModelRefFromString` (lines 294–315), user-defined aliases are checked *before* `parseModelRef` is called — meaning a user-configured alias named `openrouter:free` would win there.

These two code paths disagree on priority. If a user defines a custom alias `openrouter:free` pointing to a different model, `resolveConfiguredModelRef` will silently ignore it, while any other caller that goes through `resolveModelRefFromString` will respect it. Consider making the priority uniform (either compat-first everywhere or user-first everywhere) or documenting the intentional asymmetry in a comment.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "fix(models): return shallow copy from Op..." | Re-trigger Greptile}