test(ai): select the copilot codex model dynamically in the tool-call-id handoff tests

[code-yeongyu]

Why

Release-time typecheck keeps breaking on a retired github-copilot ModelId pin. publish-npm.yml -> scripts/release.mjs regenerates the model catalog live from models.dev, then runs tsc. A test that passes a literal id into getModel's ModelId parameter fails the moment upstream drops that id, even when the live test is skipIf-gated.

This class of failure hit senpi on 2026-08-28 (fireworks-models.test.ts:45) and again today: release run 33842146239 failed because gpt-5.2-codex left the live github-copilot catalog. #1353 unblocked 2026.9.4-2 by swapping the pin to gpt-5.3-codex. That is still a literal pin, so the next retirement repeats the outage.

What changed

• packages/ai/test/tool-call-id-normalization.test.ts: the two getModel("github-copilot", ...) pins (and the openrouter openai/gpt-5.2-codex pins) now select a family match from getModels(...). No literal string flows into getModel's ModelId parameter.
• If the catalog has no match, the helper throws github-copilot catalog has no codex-family model; update the test (and a sibling message for openrouter) instead of silently skipping.
• Token-gated live handoff coverage is unchanged. A small non-gated unit test asserts the helper returns a /codex/ id on the committed catalog and throws that explicit message for an empty stub catalog.

Verification

• bunx tsc --noEmit exit 0 on the committed catalog
• npm --prefix packages/ai run generate-models (live) then bunx tsc --noEmit exit 0; regen discarded
• bunx vitest run packages/ai/test/tool-call-id-normalization.test.ts green (2 passed, 4 skipIf'd without tokens)
• bunx biome check --error-on-warnings packages/ai/test exit 0
• node scripts/check-pr-changelog.mjs --base origin/main exit 0 (test-only; no runtime source)

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Summary by cubic

Fixes release-time typecheck failures by selecting the Copilot Codex model dynamically in the tool-call-id handoff tests. The tests previously used hardcoded model IDs that would break when models.dev retired them; now they pick a codex-family model from the live catalog and throw a clear error if none exists.

^{Written for commit a0a43c5. Summary will update on new commits.}