Summary

• Fix DTS build errors in core-schemas introduced by PR fix(core-schemas): upgrade to Zod v4 for CLI compatibility #5107
• Replace incorrect z.function({ input, output }) with z.custom<T>() + validator

Problem

PR #5107 upgraded core-schemas to Zod v4 and attempted to use:

z.function({ input: z.tuple([]), output: z.promise(...) })

This syntax is incorrect for Zod v4 because:

• In Zod v4, z.function() is a function factory, not a schema
• It cannot be used inside z.object()
• Causes DTS build errors: "Object literal may only specify known properties, but 'input' does not exist"

References:

• Zod v4 changelog: https://zod.dev/v4/changelog#zfunction
• Official workaround: v4: what is the replacement for using z.function as a schema? colinhacks/zod#4143
• Zod custom API: https://zod.dev/api#custom

Solution

Use z.custom<T>() with runtime validator:

pollFn: z.custom<() => Promise<unknown>>((val) => typeof val === "function")
onProgress: z.custom<(current: number, total: number) => void>((val) => typeof val === "function")

This approach:

• ✅ Fixes DTS build errors
• ✅ Preserves TypeScript type inference
• ✅ Adds runtime function validation (Zod best practice)

Why CI Didn't Catch This

CI runs pnpm check-types which executes tsc --noEmit and does detect the error.

However, Turbo's remote cache caused the check to be skipped:

1. PR fix(core-schemas): upgrade to Zod v4 for CLI compatibility #5107 only changed package.json (dependency version)
2. Turbo cached the type check results from before the breaking change
3. Subsequent PRs didn't modify core-schemas files
4. Cache kept being reused, CI never actually ran type check

Verification

Before (main branch):

$ pnpm build
# DTS Build error
src/auth/kilocode.ts(36,23): error TS2561: Object literal may only specify known properties, 
but 'input' does not exist

After (this PR):

$ pnpm build
# DTS ⚡️ Build success

Test Plan

• Type check passes: pnpm check-types
• Build succeeds: pnpm build (ESM, CJS, DTS all pass)
• Type inference verified: PollingOptions type still correct
• Runtime validation added: typeof val === "function"

cc #5107