Greptile Summary

This PR fixes a bug where pressing Ctrl+C or Escape during a @clack/prompts interactive prompt in models auth commands caused the library's cancel symbol to be coerced to the string "Symbol(clack:cancel)" and written to auth-profiles.json, resulting in 401 errors on subsequent use. The fix introduces a guardCancel<T> helper that checks isCancel(value), prints a "Cancelled." message, and calls process.exit(0) before the bogus value can propagate. All three local prompt wrappers (confirm, text, select) are updated to async functions that pass their results through guardCancel.

Key changes:

• New guardCancel<T>(value: T | symbol): T function using isCancel from @clack/prompts for clean cancellation handling.
• confirm, text, and select wrappers made async and wrapped with guardCancel.
• Removed now-unnecessary explicit as TokenProvider | "custom" cast for provider in modelsAuthAddCommand — TypeScript correctly infers "anthropic" | "custom" from the options literals.
• The modelsAuthLoginCommand code path uses a separate createClackPrompter() abstraction (prompter.select) and is outside the scope of this fix; whether it handles cancellation is a separate concern.

Confidence Score: 5/5

• This PR is safe to merge — it is a targeted bug fix with no regressions and correct TypeScript typing.
• The change is minimal and well-scoped: a single guardCancel helper is added and applied consistently to all three local prompt wrappers. The process.exit(0) path after cancel() is the idiomatic clack pattern. TypeScript typing is preserved (inference for provider is equivalent to the removed explicit cast). No new external dependencies or side-effects are introduced beyond those already present. The fix directly addresses the root cause described in the issue.
• No files require special attention.

_{Last reviewed commit: 8bc215e}

Landed. Thank you @MumuTW.

What I did:

• rebased onto latest main via a temp landing branch
• kept the cancel-guard fix and hardened it to treat symbol values as cancel
• added regression test coverage in src/commands/models/auth.test.ts to prevent cancelled token persistence
• added changelog entry under 2026.3.7 fixes mentioning fix: guard clack cancel symbol in models auth CLI prompts #38951 and @MumuTW
• ran full gate before commit: pnpm lint && pnpm build && pnpm test
• landed to main with co-author trailer

SHA hashes:

• original PR commit: 8bc215e6d5dc
• landed commit on main: 2ada1b71b

Thanks again for the fix.