[workers-utils] Fix compat date resolution in workspaces

[ksawaneh]

getLocalWorkerdCompatibilityDate() could fail in workspaces because it used require.resolve("miniflare"), and miniflare’s main points at dist/ (which may not exist until built). That caused the function to fall back even though workerd is installed.

This change:

• Resolves miniflare/package.json instead, so resolution works even before miniflare is built
• Updates the unit test to use Wrangler’s workspace context for resolution
• Adds a changeset for @cloudflare/workers-utils

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:

Commands run:

• pnpm check

• pnpm test:ci --filter @cloudflare/workers-utils

• Public documentation

  • Cloudflare docs PR(s):
  • Documentation not necessary because: no user-facing behavior/docs change (internal resolution fix + tests)

A picture of a cute animal (not mandatory, but encouraged)

/_/\
( o.o )

^ <

---

[changeset-bot]

🦋 Changeset detected

Latest commit: 3981ff3

The changes in this PR will be included in the next version bump.

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[petebacondarwin]

Nice little trick!

[petebacondarwin]

I'm a bit worried that this is brittle due to relying upon the relative location of the wrangler package compared to this file. But I guess it is only in a test and if it changes the test will break and we'll know to change it.

[pkg-pr-new]

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@11910

@cloudflare/kv-asset-handler

npm i https://pkg.pr.new/@cloudflare/kv-asset-handler@11910

miniflare

npm i https://pkg.pr.new/miniflare@11910

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@11910

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@11910

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@11910

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@11910

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@11910

@cloudflare/workers-utils

npm i https://pkg.pr.new/@cloudflare/workers-utils@11910

wrangler

npm i https://pkg.pr.new/wrangler@11910

commit: 3981ff3

[petebacondarwin]

@claude can you rebase and fix the conflicts on this PR

[claude]

Claude encountered an error —— View job

Failed with exit code 128

---

I'll analyze this and get back to you.

[devin-ai-integration]

Devin Review found 1 potential issue.

View issue and 2 additional flags in Devin Review.

[petebacondarwin]

Really sorry! I messed up this branch when rebasing and lost your commits.
I have recreated as best I can...

[devin-ai-integration]

Devin Review found 1 new potential issue.

View issue and 2 additional flags in Devin Review.

[devin-ai-integration]

🟡 Test passes file path instead of directory path to getLocalWorkerdCompatibilityDate

The test passes a file path (wranglerPackageJson) as projectPath, but getLocalWorkerdCompatibilityDate expects a directory path and appends package.json to it.

Click to expand

How the bug is triggered

The test at lines 17-22 does:

const wranglerPackageJson = fileURLToPath(
    new URL("../../wrangler/package.json", import.meta.url)
);
const { date, source } = getLocalWorkerdCompatibilityDate({
    projectPath: wranglerPackageJson,
});

But getLocalWorkerdCompatibilityDate at packages/workers-utils/src/compatibility-date.ts:40-42 does:

const projectRequire = module.createRequire(
    path.join(projectPath, "package.json")
);

So if projectPath is /path/to/wrangler/package.json, then path.join(projectPath, "package.json") becomes /path/to/wrangler/package.json/package.json, which is an invalid path.

Actual vs Expected

• Actual: The test passes a file path, resulting in an invalid path like /path/to/wrangler/package.json/package.json
• Expected: The test should pass a directory path like /path/to/wrangler

Impact

The test will fail because module resolution will fail with the invalid path, causing the function to fall back to the fallback date instead of successfully resolving workerd's compatibility date.

Recommendation: Change the test to pass a directory path instead of a file path:

const wranglerDir = fileURLToPath(
    new URL("../../wrangler", import.meta.url)
);
const { date, source } = getLocalWorkerdCompatibilityDate({
    projectPath: wranglerDir,
});

---

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[dario-piotrowicz]

if we go with the solution in #12387 I think the changes here will become irrelevant.

I do think that we need to proceed with #12387 since that solution addresses the following issue: in pnpm projects that have a wrangler dependency but not a direct miniflare dependency, require.resolve("miniflare") (and also require.resolve("miniflare/package.json")) results in a module-not-found error (since pnpm strictly isolated dependencies by default).

[petebacondarwin]

Hey @ksawaneh - thanks for this contribution. I think we are going to land #12387 instead, which should also solve this problem. So I'm going to close this PR.