fix: narrow clack cancellations past a unique symbol - #48
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Eight type errors on main, in a file nobody had edited. CI runs `npm install` against a gitignored lockfile, so it resolves `@clack/prompts@^1.1.0` fresh on every run and had moved from 1.1.0 to 1.8.1, where the cancel value is typed as a `unique symbol` rather than a plain `symbol`. `assertNotCancelled<T>(value: T | symbol)` relied on `symbol` binding that slot exactly. A `unique symbol` does not, so `T` absorbed the whole union and the assertion narrowed nothing: every prompt result stayed `string | unique symbol` and failed at each use. Taking `T` whole and asserting `Exclude<T, symbol>` narrows the same way under both versions. Type check goes 8 errors to 0, lint clean, 98 tests pass. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]> Claude-Session: https://claude.ai/code/session_011Ft4s2sjp46Rik8zjbaawf
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mainis red with eight type errors insrc/cli/commands.ts, a file nobody edited.CI runs
npm installandpackage-lock.jsonis gitignored, so dependency ranges resolve fresh on every run.@clack/prompts@^1.1.0has moved from 1.1.0 to 1.8.1, where the cancel value is typed as aunique symbolinstead of a plainsymbol.assertNotCancelled<T>(value: T | symbol): asserts value is Tdepended onsymbolbinding that slot exactly. Aunique symboldoes not bind it, soTinferred as the whole union and the assertion narrowed nothing. Every prompt result stayedstring | unique symboland failed at each use site.Taking
Twhole and assertingExclude<T, symbol>narrows identically under both versions.Verified locally against the version CI actually installs (1.8.1):
The underlying exposure is separate and left alone: with the lockfile ignored, any dependency's next minor can turn
mainred without a commit. Pinning or committing the lockfile is a call for this repository to make.🤖 Generated with Claude Code
https://claude.ai/code/session_011Ft4s2sjp46Rik8zjbaawf