Add initial plumbing for a local explorer worker by emily-shen · Pull Request #12034 · cloudflare/workers-sdk

emily-shen · 2026-01-21T17:31:40Z

Currently with a no-op local explorer worker.

By commit:

create a new fixture with many bindings for testing
Add resource api worker to miniflare. This includes an 'unsafeLocalExplorer' flag that we do not set on the proxy miniflare instance in ProxyController. This means the resource api stuff only runs in the user worker's miniflare instance. We also reuse miniflare's magic proxy proxyBindings to give the local explorer worker access to the user's resource bindings, as this already contains the user worker's resource bindings.
Add X_LOCAL_EXPLORER to gate this experimental feature

Tests
- Tests included/updated
- Automated tests not possible - manual testing has been completed as follows:
- Additional testing not necessary because:
Public documentation
- Cloudflare docs PR(s):
- Documentation not necessary because: experimental feature

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

changeset-bot · 2026-01-21T17:31:45Z

🦋 Changeset detected

Latest commit: a6b0cff

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pkg-pr-new · 2026-01-21T17:39:33Z

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@12034

@cloudflare/kv-asset-handler

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miniflare

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@cloudflare/pages-shared

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@cloudflare/unenv-preset

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@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@12034

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@12034

@cloudflare/workers-editor-shared

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@cloudflare/workers-utils

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wrangler

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commit: a6b0cff

devin-ai-integration

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 3 additional flags.

fixtures/local-mode-tests/vitest.config.mts

.changeset/polite-years-exist.md

packages/miniflare/src/plugins/core/index.ts

petebacondarwin · 2026-01-22T11:18:35Z

packages/miniflare/src/workers/core/entry.worker.ts

 		request = new Request(request, { cf });

-		// The proxy client will always specify an operation
+		// The magic proxy client (used by getPlatformProxy) will always specify an operation


For another day... perhaps we should go through the code and change all "magic proxy" (and other references to this) to just be "platform proxy"?

packages/workers-utils/src/environment-variables/factory.ts

fixtures/worker-with-resources/src/index.ts

vicb · 2026-01-22T11:29:00Z

fixtures/worker-with-resources/tests/index.test.ts

+		});
+
+		afterAll(async () => {
+			await stop?.();


nit: I find it nice to return a fn from BeforeAll for something init'd there

fixtures/worker-with-resources/src/index.ts

fixtures/worker-with-resources/package.json

packages/miniflare/src/plugins/core/index.ts

packages/miniflare/src/workers/core/entry.worker.ts

devin-ai-integration

Devin Review found 1 new potential issue.

View issue and 5 additional flags in Devin Review.

packages/miniflare/test/plugins/resource-viewer/index.spec.ts

devin-ai-integration

Devin Review found 1 new potential issue.

View issue and 6 additional flags in Devin Review.

packages/miniflare/src/plugins/core/index.ts

petebacondarwin · 2026-01-22T16:23:58Z

packages/miniflare/src/workers/local-explorer/api.worker.ts

+
+export default class LocalExplorerAPI extends WorkerEntrypoint {
+	async fetch(): Promise<Response> {
+		return new Response("Hello from local explorer API");


NIT:

Suggested change

return new Response("Hello from local explorer API");

return Response.json({message: "Hello from local explorer API"});

or

Suggested change

return new Response("Hello from local explorer API");

return Response.json({});

or perhaps some HTTP unimplemented error?

petebacondarwin · 2026-01-22T17:16:12Z

packages/workers-utils/src/environment-variables/misc-variables.ts

+ * `X_LOCAL_EXPLORER` enables the local explorer UI at /cdn-cgi/explorer.
+ * This is an experimental feature flag. Defaults to false when not set.
+ */
+export const getLocalExplorerFromEnv = getBooleanEnvironmentVariableFactory({


Can we make this sound more like a boolean flag?

Suggested change

export const getLocalExplorerFromEnv = getBooleanEnvironmentVariableFactory({

export const getLocalExplorerEnabledFromEnv = getBooleanEnvironmentVariableFactory({

sgtm! i'll change that in my next PR though if that's okay!

workers-devprod added this to workers-sdk Jan 21, 2026

github-project-automation bot moved this to Untriaged in workers-sdk Jan 21, 2026

emily-shen force-pushed the emily/ui-api branch from 32b8d90 to 9d828fd Compare January 21, 2026 17:33

emily-shen added 4 commits January 22, 2026 10:57

create fixture with many bindings

353e159

Add resource api worker to miniflare

e808900

gate behind experimental flag

e3cc79c

add tests

8e70548

emily-shen force-pushed the emily/ui-api branch from 084049e to 8e70548 Compare January 22, 2026 10:57

emily-shen marked this pull request as ready for review January 22, 2026 10:58

emily-shen requested a review from a team as a code owner January 22, 2026 10:58

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fixups

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emily-shen changed the title ~~Add initial plumbing for a resource inspector worker~~ Add initial plumbing for a local explorer worker Jan 22, 2026

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emily-shen force-pushed the emily/ui-api branch 2 times, most recently from 8e8b07b to 85ee118 Compare January 22, 2026 14:38

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emily-shen force-pushed the emily/ui-api branch from 85ee118 to e584ddc Compare January 22, 2026 14:43

rename to local explorer and more fixups

a6b0cff

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petebacondarwin approved these changes Jan 22, 2026

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emily-shen merged commit 05714f8 into main Jan 22, 2026
45 of 48 checks passed

emily-shen deleted the emily/ui-api branch January 22, 2026 17:34

github-project-automation bot moved this from Approved to Done in workers-sdk Jan 22, 2026

NuroDev mentioned this pull request Jan 22, 2026

Fix broken lockfile #12054

Merged

5 tasks

workers-devprod mentioned this pull request Jan 22, 2026

Version Packages #12045

Merged

	return new Response("Hello from local explorer API");
	return Response.json({message: "Hello from local explorer API"});

	return new Response("Hello from local explorer API");
	return Response.json({});

	export const getLocalExplorerFromEnv = getBooleanEnvironmentVariableFactory({
	export const getLocalExplorerEnabledFromEnv = getBooleanEnvironmentVariableFactory({

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