[No QA] Paralellize typecheck

[jmusial]

Explanation of Change

Run the four typecheck projects concurrently instead of sequentially in scripts/typecheck.ts, cutting full typecheck wall time by ~30% (16.4s → 11.4s cold, 1.45s → 1.05s warm) with per-project output grouping preserved.

Details in proposal linked below.

[No QA] because it only affects dev tooling

Fixed Issues

$ #99889
PROPOSAL:
https://expensify.slack.com/archives/C08CZDJFJ77/p1788162565862549

Tests

1. Run npm run typecheck in the console
2. Command completes and user can see it's output

Offline tests

N/A

QA Steps

N/A

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
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Screenshots/Videos

N/A

[jmusial]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

Reviewed commit: e08bd3e696

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[melvin-bot]

@abzokhattab Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

[abzokhattab]

Looks like it broke tests .. weird .. is it already broken on main?

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 2b6948d6ee

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[jmusial]

Looks like it broke tests .. weird .. is it already broken on main?

Yeah broken on main. Someone put current date in the test and it worked yesterday, but not today xd

[abzokhattab]

@MelvinBot review

[abzokhattab]

Reviewer Checklist

• I have verified the author checklist is complete (all boxes are checked off).
• I verified the correct issue is linked in the ### Fixed Issues section above
• I verified testing steps are clear and they cover the changes made in this PR
  • I verified the steps for local testing are in the Tests section
  • I verified the steps for Staging and/or Production testing are in the QA steps section
  • I verified the steps cover any possible failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
• I checked that screenshots or videos are included for tests on all platforms
• I included screenshots or videos for tests on all platforms
• I verified that the composer does not automatically focus or open the keyboard on mobile unless explicitly intended. This includes checking that returning the app from the background does not unexpectedly open the keyboard.
• I verified tests pass on all platforms & I tested again on:
  • Android: HybridApp
  • Android: mWeb Chrome
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  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• If there are any errors in the console that are unrelated to this PR, I either fixed them (preferred) or linked to where I reported them in Slack
• I verified proper code patterns were followed (see Reviewing the code)
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I verified that this PR follows the guidelines as stated in the Review Guidelines
• I verified other components that can be impacted by these changes have been tested, and I retested again (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar have been tested & I retested again)
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• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
• If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• For any bug fix or new feature in this PR, I verified that sufficient unit tests are included to prevent regressions in this flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.
• I have checked off every checkbox in the PR reviewer checklist, including those that don't apply to this PR.

Screenshots/Videos

Android: HybridApp

Android: mWeb Chrome

iOS: HybridApp

iOS: mWeb Safari

MacOS: Chrome / Safari

[MelvinBot]

Review: no blocking issues

The change is correct. One suggestion worth applying, plus a calibration note on the perf claim.

Suggestion: don't withhold all output until the last project finishes

scripts/typecheck.ts:38-49 awaits Promise.all before printing anything, so the console stays silent for the whole run and then dumps everything at once. On a cold run that's ~16s of nothing, and the Type checking <x>... header now prints after the work rather than before it.

Awaiting the already-started promises in order gives identical concurrency but starts printing as soon as project 1 lands, still grouped and still in a stable order:

const running = projects.map(async (project) => {
    // ...unchanged...
    return {tsconfig, result};
});

const failed: string[] = [];
for (const promise of running) {
    const {tsconfig, result} = await promise;
    console.log(`\nType checking ${tsconfig}...`);
    // ...unchanged...
}

The CI gain is closer to ~10%, not 30%

CI runs on blacksmith-4vcpu-ubuntu-2404, and tsgo already parallelizes internally, so four concurrent compilers contend for the same 4 vCPUs. Measured Type check with TypeScript step durations:

	Duration
This PR (runs 33606904648, 33606284878)	27s, 30s
Recent main-based PRs (33611143973, 33606988258, 33610619246)	32s, 31s, 33s

Still a real win, just smaller than the local numbers in the description — worth a tweak to the PR body so nobody is surprised later.

The failing check is pre-existing

test (job 3) fails on tests/unit/NextStepUtilsTest.ts › scheduled submit enabled › monthly on the 2nd — a date-dependent assertion, nothing to do with scripts/typecheck.ts. jmusial's answer to abzokhattab is correct.

Also: the P1 inline comment from Codex on .github/actions/javascript/isDeployChecklistLocked/index.js is stale — that file is no longer in the diff (only scripts/typecheck.ts is). Safe to resolve.

What I checked and found clean

• Output ordering — Promise.all resolves in input order, so the reporting loop still reports projects in DEFAULT_PROJECTS order regardless of completion order.
• .tsbuildinfo collisions — each project derives its own path from its tsconfig path, and the four resolve to distinct files (tsconfig.ts7.tsbuildinfo, tsconfig.bun.ts7.tsbuildinfo, tsconfig.node.ts7.tsbuildinfo, server/victory-chart-renderer/tsconfig.ts7.tsbuildinfo). No concurrent writers to the same file.
• Project references — none of the four tsconfigs use references/composite, and the run is -p --noEmit, so there's no shared build output for the concurrent runs to race on.
• Fail-behavior — .nothrow() keeps a type error from rejecting the Promise.all, so "check every project even after one fails" still holds, and the failed[]/process.exit(1) aggregation is unchanged.
• Diagnostic formatting — adding .quiet() does not cost you colors or --pretty code frames. Bun's $ already buffers through a pipe by default ("the shell will write to the current process's stdout and stderr, as well as buffering that output"), so tsc saw a non-TTY before this PR too.

Nit, very low severity: if $ ever throws for a reason .nothrow() doesn't cover (e.g. the tsc bin is missing after a bad install), Promise.all rejects immediately while the other compilers keep running, and the script dies with an unhandled rejection plus orphaned children. Promise.allSettled would tidy that up, but it only fires on a broken node_modules.

---

view run

[abzokhattab]

LGTM .. no issues found

[OSBotify]

✋ This PR was not deployed to staging yet because QA is ongoing. It will be automatically deployed to staging after the next production release.

[OSBotify]

🚀 Deployed to staging by https://github.com/mountiny in version: 9.4.70-0 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅

[OSBotify]

🚀 Deployed to staging by https://github.com/mountiny in version: 9.4.72-0 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅