DO NOT MERGE: cloudflare w/o do support

[NathanFlurry]

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[NathanFlurry]

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• DO NOT MERGE: cloudflare w/o do support #3890 👈 (View in Graphite)
• chore(engine): provide detailed error for invalid serverless sse event #3881 : 1 other dependent PR (#3891 )
• main

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[claude]

PR Review: Cloudflare Workers Support (DO NOT MERGE)

Overview

This PR adds support for running RivetKit on Cloudflare Workers without Durable Objects. The changes configure the chat-room example to connect to an external engine instance and handle request routing appropriately.

---

Code Quality & Best Practices

✅ Positive

• Good commenting: The added configuration options in actors.ts have clear inline comments explaining each setting
• Proper async handling: The server handler correctly uses async for the handler function

⚠️ Issues & Recommendations

1. Path manipulation could be more robust (examples/chat-room/src/server.ts:8)

const strippedPath = url.pathname.replace(/^\/api\/rivet/, "");

• This regex doesn't anchor the end, so /api/rivet/api/rivet/foo would incorrectly become /api/rivet/foo
• Consider: url.pathname.replace(/^\/api\/rivet(?=\/|$)/, "")
• Better yet, if basePath is always "/", why not handle this at the framework level or make the route more specific?

2. Cloudflare Workers detection is fragile (rivetkit-typescript/packages/rivetkit/src/registry/index.ts:53-55)

const isCloudflareWorkers =
    typeof navigator \!== "undefined" &&
    navigator.userAgent === "Cloudflare-Workers";

• User agent detection is brittle and can break if Cloudflare changes their worker runtime
• Consider checking for Cloudflare-specific globals instead: typeof DurableObjectNamespace \!== "undefined" or similar
• The check should be documented with why setTimeout isn't allowed in Cloudflare Workers global scope

3. wrangler.json formatting (examples/chat-room/wrangler.json)

• File has inconsistent indentation (starts with spaces, mixed formatting)
• Missing trailing newline
• The placeholder "worker-name" should be updated to something meaningful like "rivet-chat-room" or documented as needing replacement

4. Hardcoded development URLs (examples/chat-room/src/actors.ts:30,40)

• http://localhost:6420 and http://localhost:8787/api/rivet are hardcoded
• For a proper implementation (even experimental), these should be environment variables or configuration
• At minimum, add comments explaining these are development-only values

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Potential Bugs

1. Request cloning potential issue (examples/chat-room/src/server.ts:10)

const modifiedRequest = new Request(url.toString(), c.req.raw);

• Creating a new Request from the old one copies most properties, but the body stream can only be read once
• If c.req.raw has already been read (unlikely in this flow, but possible), this will fail
• Consider testing with POST/PUT requests with bodies to ensure this works correctly

2. Race condition in registry initialization (rivetkit-typescript/packages/rivetkit/src/registry/index.ts:56-61)

• In Cloudflare Workers, the runtime won't auto-initialize via setTimeout
• First request must trigger initialization, but there's no guarantee #ensureRuntime() is called before handler() is invoked
• The handler() method does call #ensureRuntime(), so this should work, but the code comment implies auto-preparation is important for some reason

---

Performance Considerations

1. URL parsing on every request (examples/chat-room/src/server.ts:7-10)

• Creating a new URL object and Request object for every request adds overhead
• For high-traffic scenarios, consider if there's a way to configure basePath handling once rather than per-request

2. Runtime initialization

• The #ensureRuntime() pattern with promise caching is good for avoiding multiple initializations
• However, in Cloudflare Workers without the setTimeout, cold starts will include runtime initialization time on the first request

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Security Concerns

1. Open CORS/origin handling

• No validation of incoming requests or origin checking visible in this PR
• If this is meant for production use (even experimental), consider adding request validation

2. Wildcard route handler (examples/chat-room/src/server.ts:5)

• app.all("/api/rivet/*", ...) accepts all HTTP methods
• Ensure the registry.handler properly validates allowed methods

---

Test Coverage

⚠️ No tests included

• This PR adds new functionality but includes no test cases
• At minimum, should test:
  • Path stripping logic with various inputs
  • Cloudflare Workers detection logic
  • Request handling with different HTTP methods and body content
  • Configuration validation

---

Configuration & Documentation

1. wrangler.json validation

• Missing required fields for a complete wrangler configuration:
  • Should have node_compatibility or appropriate compat flags documented
  • Missing other typical fields like account_id (though those may be intentionally omitted for an example)

2. Setup instructions needed

• How do developers run this? What engine needs to be running on port 6420?
• How do they start the Cloudflare Worker locally?
• This should be documented in the example README

---

Summary

This is clearly marked as "DO NOT MERGE" and appears to be experimental work. The core approach is sound, but there are several issues that should be addressed before this could be merged:

Must Fix:

1. Cloudflare Workers detection mechanism (fragile user-agent check)
2. wrangler.json formatting and placeholder values
3. Add tests for new functionality
4. Document the setup/usage process

Should Fix:

1. Path manipulation regex (security/correctness)
2. Hardcoded localhost URLs (make configurable)
3. Consider URL/Request creation overhead

Nice to Have:

1. Request validation/security hardening
2. More robust error handling
3. Performance optimizations for cold starts

---

Recommendation

Given the "DO NOT MERGE" status, this appears to be a proof-of-concept. Before this could be production-ready:

1. Address the runtime detection fragility
2. Add comprehensive tests
3. Extract hardcoded values to configuration
4. Document the setup process
5. Consider whether the path-stripping approach is the right architectural choice

The code demonstrates a working approach but needs hardening for production use.

[pkg-pr-new]

More templates

• actor-actions
• example-ai-agent
• example-ai-and-user-generated-actors-freestyle
• chat-room
• example-cloudflare-workers
• example-cloudflare-workers-hono
• example-cloudflare-workers-inline-client
• cross-actor-actions
• example-cursors
• example-cursors-raw-websocket
• custom-serverless
• example-sqlite
• example-elysia
• example-experimental-durable-streams-ai-agent
• hello-world
• example-hono
• hono-react
• example-kitchen-sink
• multi-region
• native-websockets
• next-js
• example-raw-fetch-handler
• example-raw-websocket-handler
• example-raw-websocket-handler-proxy
• example-react
• scheduling
• state
• example-stream
• example-trpc

@rivetkit/cloudflare-workers

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/cloudflare-workers@3890

@rivetkit/db

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/db@3890

@rivetkit/framework-base

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/framework-base@3890

@rivetkit/next-js

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/next-js@3890

@rivetkit/react

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/react@3890

rivetkit

pnpm add https://pkg.pr.new/rivet-dev/rivet/rivetkit@3890

@rivetkit/sql-loader

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/sql-loader@3890

@rivetkit/virtual-websocket

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/virtual-websocket@3890

@rivetkit/engine-runner

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/engine-runner@3890

@rivetkit/engine-runner-protocol

pnpm add https://pkg.pr.new/rivet-dev/rivet/@rivetkit/engine-runner-protocol@3890

commit: 1c18fb1