[codex] Fix TypeScript build cache flake

[blove]

Summary

• moves TypeScript incremental build-info files for emitting packages into their dist output directories
• adds a CI guard that requires emitting package tsconfigs to keep tsBuildInfoFile under dist and confirms Turbo caches dist/**
• runs the guard in both the CI validate job and the release ci:validate script before pnpm build

Root cause

tsc -b was writing tsconfig.tsbuildinfo next to each package tsconfig, while Turbo only cached/restored dist/**. If dist disappeared but the root-level .tsbuildinfo survived, TypeScript considered @dawn-ai/sdk up to date and emitted no declarations. @dawn-ai/core then ran after the SDK task, but packages/sdk/dist/index.d.ts was still missing, causing the intermittent TS2307 cascade.

Putting build-info files in dist makes declarations and TypeScript incremental state share the same lifecycle: clean, cache restore, and cache eviction now move them together.

Validation

• pnpm check:build-cache
• pnpm lint
• rm -rf packages/*/dist packages/*/*.tsbuildinfo apps/web/.next examples/chat/web/.next && pnpm build
• pnpm build (warm cache, 17/17 cached)
• 3x stale-state repro: stale packages/sdk/tsconfig.tsbuildinfo, deleted SDK/core dist, turbo run build --filter=@dawn-ai/core --force --concurrency=10
• 3x cache replay: deleted SDK/core dist, turbo run build --filter=@dawn-ai/core --concurrency=10
• pnpm typecheck
• node scripts/check-changesets.mjs (skipped: no user-facing changes)

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Project	Deployment	Actions	Updated (UTC)
dawnai	Ready	Preview, Comment	Jun 25, 2026 4:31am

[github-actions]

Automated approval: this PR received an intelligent (AI) code review. See the review comments on this PR.

[github-actions]

Claude finished @blove's task in 2m 20s —— View job

---

PR Review: Fix TypeScript build cache flake

Tasks:

• Gather context and understand the PR
• Read CLAUDE.md for repo guidelines
• Review the diff and changed files
• Analyze the new validation script
• Review CI configuration changes
• Post findings

---

Summary

This PR correctly identifies and fixes a real source of CI flakiness. The root cause analysis is sound: tsc -b writes .tsbuildinfo next to each tsconfig, but Turbo only restores dist/**. When dist/ was evicted but the stale root-level .tsbuildinfo survived, TypeScript skipped re-emitting, causing downstream declaration-not-found errors. Moving the build-info files into dist/ makes TypeScript's incremental state share the same lifecycle as its output — a clean, correct fix.

The validation script and CI guard are a good defense-in-depth addition.

---

Findings

Correctness

All 13 emitting packages updated correctly. Every package with outDir: "dist" and noEmit !== true now has tsBuildInfoFile: "dist/tsconfig.tsbuildinfo". The CLI's split (tsconfig.json with noEmit: true, tsconfig.build.json with noEmit: false) is handled cleanly.

packages/sdk/tsconfig.contracts.json sets noEmit: true but still sets tsBuildInfoFile: "dist/tsconfig.contracts.tsbuildinfo". TypeScript writes the build-info file even when noEmit is true (for --incremental), and putting it in dist/ means Turbo will cache/restore it along with everything else. This is the right call.

.gitignore is fine. It already ignores dist/ (and *.tsbuildinfo), so the new locations won't be accidentally committed.

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Observations on scripts/check-build-cache-config.mjs

1. The guard doesn't resolve extends.
The script reads only each file's own compilerOptions, not the inherited ones from the extends chain. A new tsconfig that inherits outDir from a base config without setting it directly would silently bypass the check. This isn't a problem today (all emitting tsconfigs set their own outDir), but it's a latent gap.

// scripts/check-build-cache-config.mjs:31
const compilerOptions = config.compilerOptions ?? {}
const outDir = compilerOptions.outDir   // won't see inherited outDir

If this becomes a concern, resolving the extends chain (or at minimum flagging tsconfigs where outDir is missing locally but the file isn't noEmit) would close the gap. Fix this →

2. Only packages/ is checked.
apps/ and examples/ are out of scope. This is likely intentional (Next.js and example apps use their own build systems), but worth documenting with a comment in the script so future contributors understand the boundary.

3. Hardcoded tsconfig.tsbuildinfo name.
The first check enforces {outDir}/tsconfig.tsbuildinfo exactly. If a package ever needed two emitting tsconfigs writing to the same outDir, they'd both be required to use the same path, causing a conflict. The tsconfig.contracts.json case avoids this today only because it has noEmit: true. Not an issue now, but worth knowing if the pattern grows.

---

CI integration

Placing check:build-cache before pnpm build in both the CI validate job and the ci:validate script is the right order — it fails fast on misconfiguration rather than letting a broken build cache silently succeed.

---

Verdict

This looks good to merge. The fix is correct, minimal, and comprehensive. The validation script is a nice long-term regression guard. The observations above are minor and none block correctness.

[github-actions]

Automated approval: this PR received an intelligent (AI) code review. See the review comments on this PR.

[github-actions]

Claude finished @blove's task in 1m 47s —— View job

---

PR Review: Fix TypeScript build cache flake

Tasks:

• Gather context and understand the PR
• Read CLAUDE.md for repo guidelines
• Read the diff and changed files
• Analyze the validation script
• Review CI configuration changes
• Post findings

---

Summary

The root cause analysis is correct and the fix is sound. tsc -b writes .tsbuildinfo next to each tsconfig by default, but Turbo only caches/restores dist/**. When Turbo evicted dist/ but the root-level .tsbuildinfo survived, TypeScript skipped re-emitting declarations. Moving tsBuildInfoFile into dist/ aligns TypeScript's incremental state with Turbo's cache lifecycle — a clean fix.

---

Correctness

All 13 emitting tsconfigs updated correctly. Every package with outDir: "dist" and noEmit !== true now has tsBuildInfoFile: "dist/tsconfig.tsbuildinfo".

CLI split handled correctly. packages/cli/tsconfig.json has noEmit: true (no outDir, no tsBuildInfoFile required). Only tsconfig.build.json — which sets noEmit: false — needed the tsBuildInfoFile addition.

tsconfig.contracts.json handled correctly. It sets noEmit: true with tsBuildInfoFile: "dist/tsconfig.contracts.tsbuildinfo". TypeScript still writes build-info when incremental: true, and putting it in dist/ means Turbo evicts it together with SDK's declarations. The distinct filename (tsconfig.contracts.tsbuildinfo vs tsconfig.tsbuildinfo) avoids collision with the regular SDK build-info.

.gitignore is already correct — both dist/ and *.tsbuildinfo are present, so no new paths will be accidentally committed.

---

Script analysis (scripts/check-build-cache-config.mjs)

One correctness observation: the second check's outDir fallback (line 47).

!toPosix(tsBuildInfoFile).startsWith(`${toPosix(outDir ?? "dist")}/`)

When outDir is undefined (e.g., a noEmit: true config that inherits outDir via extends), this falls back to "dist". Today that's fine — all noEmit tsconfigs either have no tsBuildInfoFile (so the check is skipped) or explicitly put it under dist/. But if a future tsconfig has noEmit: true, inherits a non-"dist" outDir, and sets tsBuildInfoFile accordingly, this check would misfire. Low risk since the fallback matches the convention, but worth noting.

No extends resolution — already noted in the prior review. The script reads only each file's own compilerOptions, not inherited ones. A new tsconfig that inherits outDir from a base config without setting it locally would bypass the first check (line 33). Not an issue today since all emitting tsconfigs set their own outDir, but a latent gap.

No error handling on JSON parsing. readJson will throw a bare Node.js stack trace on malformed JSON. Minor — this would only affect contributors who accidentally break a tsconfig file.

Turbo output check is correct. dist/** is present in turbo.json's build.outputs, so this check passes today and will catch any future removal.

---

CI changes

Placing check:build-cache before pnpm build in both the CI validate job and ci:validate script is the right order — it fails fast on misconfiguration rather than letting a broken cache state silently pass.

---

Verdict

Looks good to merge. The fix is correct, minimal, and comprehensive across all 13 emitting packages. The validation script is a solid regression guard. The script observations above are minor and none affect correctness today.

[github-actions]

Claude finished @blove's task in 1m 37s —— View job

---

PR Review: Fix TypeScript build cache flake

Tasks:

• Gather context and understand the PR
• Read CLAUDE.md for repo guidelines
• Review the diff and changed files
• Analyze the validation script
• Post findings

---

Summary

The fix is correct and well-scoped. The root cause (Turbo evicting dist/ but leaving a stale root-level .tsbuildinfo that fooled tsc into skipping re-emission) is accurately diagnosed, and moving tsBuildInfoFile into dist/ is the right remedy. Declarations and incremental state now share the same Turbo cache lifecycle.

Verified:

• turbo.json already has dist/** in build outputs — no change needed there
• All 14 emitting tsconfigs set outDir: "dist" locally (not via inheritance), so the validation script's extends-resolution gap (see below) has no current impact
• .gitignore covers both *.tsbuildinfo and dist/ — no risk of accidental commits
• CI guard is placed before pnpm build in both the validate job and ci:validate script — fails fast on misconfiguration

---

Findings

scripts/check-build-cache-config.mjs — one latent gap

The script reads compilerOptions.outDir directly from each file without resolving the extends chain (scripts/check-build-cache-config.mjs:31). A future tsconfig that inherits outDir without declaring it locally would pass the check silently even if it lacks a tsBuildInfoFile.

// Line 31 — outDir from the extends chain is invisible here
const outDir = compilerOptions.outDir

This isn't a current issue — every package sets outDir locally — but the fallback outDir ?? "dist" in the second check (line 49) papers over the gap for tsconfig.contracts.json (which inherits outDir: "dist" from tsconfig.json). Worth a comment in the script to make the assumption explicit, or a light extends-resolution step to close it properly. Fix this →

Other observations (non-blocking)

• Scope: Only packages/ is validated. apps/ and examples/ are intentionally excluded (Next.js / example apps use their own build systems). A one-line comment in the script explaining this boundary would help future contributors.
• tsconfig.contracts.json: noEmit: true with tsBuildInfoFile: "dist/tsconfig.contracts.tsbuildinfo" is correct — TypeScript still writes incremental state for --incremental even when not emitting, and placing it in dist/ means it travels with the cache.

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Verdict

Good to merge. The fix is minimal, correct, and comprehensive. The validation script is a solid regression guard. The extends-resolution gap is latent, not current, and doesn't block this change.