fix(anthropic): preserve routed response model metadata - #1121

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✅ Deterministic PR hygiene checks passed.

Thank you — your diagnosis here was correct and independent, and I want that on the record.

The fix for #1117 is landing as #1138. For the implementation I built on #1122, which covers native passthrough response metadata and alias-collision cases that this PR does not — but you identified the same root cause (the final-route rewrite of parsed.modelId leaking into client-facing response.model) on your own, and the campaign PR credits you for it alongside @giulioleone097.

Duplicate work is a cost you paid, not one you caused; two people finding the same real defect independently is a signal the defect was worth fixing.

Leaving this PR open for you to close or continue.

Closing — the defect you diagnosed is fixed on dev.

#1117 is resolved by #1138 (merge commit 2a13ed83e). For the implementation I built on #1122, which also covers native passthrough response metadata and alias-collision cases this PR does not — but you identified the same root cause independently (the final-route rewrite of parsed.modelId leaking into client-facing response.model), and the stack PR credits you for that diagnosis alongside @giulioleone097.

Closing as superseded rather than rejected. Duplicate work is a cost you paid, not one you caused; two people independently finding the same real defect is a signal it was worth fixing.

Verified: 9,593 pass / 0 fail on the merged tree; CI green on the exact dev SHA.