docs: add observable deprecation note to subscriptions reference projects by supermadu7 · Pull Request #7429 · trpc/trpc · GitHub

🎯 Changes

This PR replaces the deprecated @trpc/server/observable API with the modern async function* generator pattern in the standalone-server reference project.

Additionally, it adds a deprecation notice to the Subscriptions documentation (www/docs/server/subscriptions.md) to clearly warn users that the observable API will be removed in tRPC v12 and provides instructions to migrate to async generators.

✅ Checklist

I have followed the steps listed in the Contributing guide.
If necessary, I have added documentation related to the changes made.
I have added or updated the tests related to the changes made.

Summary by CodeRabbit

Refactor
- Updated the standalone server’s subscription implementation to use async function* generators instead of the deprecated observable-based approach.
- Random number streaming behavior remains the same, including clean termination when the client unsubscribes or disconnects.
Documentation
- Added a warning that the older subscription API is deprecated (planned removal) and guidance to migrate to async generator-based subscriptions.
- Linked to a reference project to help with migration.

…ects

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
next-prisma-starter	Ready	Preview	Jul 4, 2026 7:37pm
og-image	Ready	Preview, Comment	Jul 4, 2026 7:37pm

Pull request overview

Updates the subscriptions documentation and the standalone-server reference project to steer users away from the deprecated @trpc/server/observable API and toward the recommended async function* generator pattern ahead of tRPC v12.

Changes:

Added a deprecation warning in the Subscriptions docs under “Reference projects”.
Replaced the observable-based randomNumber subscription in the standalone-server example with an async generator implementation.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
www/docs/server/subscriptions.md	Adds a caution block warning about @trpc/server/observable deprecation and pointing to the updated example.
examples/standalone-server/src/server.ts	Migrates the randomNumber subscription implementation from observable to an async function* generator.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info ⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: a3fb2b70-97d1-4cf3-ae03-02e3c5a40f88

📥 Commits

Reviewing files that changed from the base of the PR and between 277f3ee and d770f3e.

📒 Files selected for processing (2)

examples/standalone-server/src/server.ts
www/docs/server/subscriptions.md

✅ Files skipped from review due to trivial changes (1)

www/docs/server/subscriptions.md

🚧 Files skipped from review as they are similar to previous changes (1)

examples/standalone-server/src/server.ts

📝 Walkthrough

Walkthrough

The standalone-server example's randomNumber subscription is rewritten from an observable-based implementation to an async generator that yields values until the abort signal fires. The subscriptions documentation adds a deprecation caution for the observable API.

Changes

Deprecate observable in favor of async generators

Layer / File(s)	Summary
Async generator subscription example examples/standalone-server/src/server.ts	Removes the observable import and replaces the subscription implementation with an async generator that yields { randomNumber } every 200ms and stops when the signal is aborted.
Deprecation notice in subscriptions docs www/docs/server/subscriptions.md	Adds a caution callout stating @trpc/server/observable is deprecated and will be removed in tRPC v12, with guidance to migrate to async function* generators.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant Server
  participant Signal

  Client->>Server: subscribe to randomNumber
  loop every 200ms
    Server->>Server: yield {randomNumber}
    Server->>Client: emit value
  end
  Client->>Signal: unsubscribe/disconnect
  Signal->>Server: abort signal
  Server->>Server: exit loop

Possibly related PRs

trpc/trpc#6932: Also removes @trpc/server/observable usage from example server code.

Suggested labels: ♻️ autoupdate

Suggested reviewers: KATT

🚥 Pre-merge checks | ✅ 5 ✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change: adding an observable deprecation note for subscriptions reference projects.
Description check	✅ Passed	The description follows the required template and includes the issue link, change summary, and completed checklist items.
Linked Issues check	✅ Passed	The PR updates the subscriptions reference example to async generators and adds deprecation guidance for the deprecated observable API.
Out of Scope Changes check	✅ Passed	The changes stay within the stated scope of updating subscription reference docs and the standalone-server example.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches 🧪 Generate unit tests (beta)

Create PR with unit tests

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

Comment @coderabbitai help to get the list of available commands.

🧹 Nitpick comments (1)

examples/standalone-server/src/server.ts (1)
47-47: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Avoid destructuring in the function parameter.

async function* ({ signal }) destructures directly in the parameter declaration. As per coding guidelines: "Never destructure in function parameter declarations." Destructure signal from opts inside the function body instead.
♻️ Proposed fix
-  randomNumber: publicProcedure.subscription(async function* ({ signal }) {
+  randomNumber: publicProcedure.subscription(async function* (opts) {
     // Loop until the client disconnects and triggers the abort signal
-    while (!signal?.aborted) {
+    while (!opts.signal?.aborted) {
       // Yield the random number instead of using emit.next()
       yield { randomNumber: Math.random() };
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@examples/standalone-server/src/server.ts` at line 47, The subscription
handler in publicProcedure should not destructure its argument in the async
function* parameter list. Update the randomNumber subscription to accept the
options object as a single parameter and destructure signal inside the function
body instead, so the handler follows the no-destructuring-in-parameters
guideline.
Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@examples/standalone-server/src/server.ts`:
- Line 47: The subscription handler in publicProcedure should not destructure
its argument in the async function* parameter list. Update the randomNumber
subscription to accept the options object as a single parameter and destructure
signal inside the function body instead, so the handler follows the
no-destructuring-in-parameters guideline.

ℹ️ Review info ⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: d3da6c94-78f7-44d0-b8aa-26f750e54a6b

📥 Commits

Reviewing files that changed from the base of the PR and between 340811b and 277f3ee.

📒 Files selected for processing (2)

examples/standalone-server/src/server.ts
www/docs/server/subscriptions.md

Open in StackBlitz

@trpc/client

npm i https://pkg.pr.new/@trpc/client@7429

@trpc/next

npm i https://pkg.pr.new/@trpc/next@7429

@trpc/openapi

npm i https://pkg.pr.new/@trpc/openapi@7429

@trpc/react-query

npm i https://pkg.pr.new/@trpc/react-query@7429

@trpc/server

npm i https://pkg.pr.new/@trpc/server@7429

@trpc/tanstack-react-query

npm i https://pkg.pr.new/@trpc/tanstack-react-query@7429

@trpc/upgrade

npm i https://pkg.pr.new/@trpc/upgrade@7429

commit: 80e015d

Hi team! I've implemented the fix for #7368 (migrating the standalone-server to async generators and updating the docs). The PR is ready, but it looks like the @trpc/upgrade test/transforms.test.ts > hooks > hooks optimistic-update.tsx test is flaking in the CI pipeline (it passes cleanly on my local machine). Could a maintainer take a look or re-run the failed job when you have a moment?

docs: add observable deprecation note to subscriptions reference proj…

277f3ee

…ects

Copilot AI review requested due to automatic review settings July 4, 2026 19:19

supermadu7 requested review from a team as code owners July 4, 2026 19:19

Copilot started reviewing on behalf of supermadu7 July 4, 2026 19:19 View session

vercel Bot deployed to Preview – trpc-next-app-dir July 4, 2026 19:19 View deployment

vercel Bot deployed to Preview – next-prisma-starter July 4, 2026 19:19 View deployment

vercel Bot deployed to Preview – og-image July 4, 2026 19:20 View deployment

vercel Bot deployed to Preview – examples-todomvc July 4, 2026 19:20 View deployment

Copilot AI reviewed Jul 4, 2026

View reviewed changes

vercel Bot deployed to Preview – www July 4, 2026 19:22 View deployment

chore: apply lint and formatting fixes

d770f3e

vercel Bot deployed to Preview – trpc-next-app-dir July 4, 2026 19:23 View deployment

vercel Bot deployed to Preview – next-prisma-starter July 4, 2026 19:23 View deployment

vercel Bot deployed to Preview – og-image July 4, 2026 19:23 View deployment

vercel Bot deployed to Preview – examples-todomvc July 4, 2026 19:24 View deployment

coderabbitai Bot reviewed Jul 4, 2026

View reviewed changes

vercel Bot deployed to Preview – www July 4, 2026 19:25 View deployment

supermadu7 added 2 commits July 4, 2026 19:32

chore: trigger CI re-run for flaky test

a57db85

chore: merge bot formatting changes

80e015d

vercel Bot deployed to Preview – trpc-next-app-dir July 4, 2026 19:37 View deployment

vercel Bot deployed to Preview – next-prisma-starter July 4, 2026 19:37 View deployment

vercel Bot deployed to Preview – og-image July 4, 2026 19:37 View deployment

vercel Bot deployed to Preview – examples-todomvc July 4, 2026 19:37 View deployment

vercel Bot deployed to Preview – www July 4, 2026 19:38 View deployment

docs: add observable deprecation note to subscriptions reference projects by supermadu7 · Pull Request #7429 · trpc/trpc · GitHub

Uh oh!

Uh oh!

docs: add observable deprecation note to subscriptions reference projects - #7429

docs: add observable deprecation note to subscriptions reference projects#7429
supermadu7 wants to merge 4 commits into
trpc:mainfrom
supermadu7:fix/subscriptions-observable-deprecation

supermadu7 commented Jul 4, 2026 •
edited by coderabbitai Bot
Loading

Uh oh!

Uh oh!

vercel Bot commented Jul 4, 2026 •
edited
Loading

Uh oh!

Uh oh!

Copilot AI left a comment

Uh oh!

coderabbitai Bot commented Jul 4, 2026 •
edited
Loading

Uh oh!

Uh oh!

coderabbitai Bot left a comment

Uh oh!

pkg-pr-new Bot commented Jul 4, 2026 •
edited
Loading

Uh oh!

Uh oh!

supermadu7 commented Jul 4, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

+              :::caution Deprecation Notice
+              The `@trpc/server/observable` API is deprecated and will be removed in tRPC v12.
+              Please migrate your subscriptions to use `async function*` generators instead.

+                randomNumber: publicProcedure.subscription(async function* ({ signal }) {
+                  // Loop until the client disconnects and triggers the abort signal
+                  while (!signal?.aborted) {
+                    // Yield the random number instead of using emit.next()
+                    yield { randomNumber: Math.random() };
+                    // Wait for 200ms before the next loop instead of using setInterval
+                    await new Promise((resolve) => setTimeout(resolve, 200));
+                  }
                 }),

docs: add observable deprecation note to subscriptions reference projects by supermadu7 · Pull Request #7429 · trpc/trpc · GitHub

Uh oh!

Uh oh!

docs: add observable deprecation note to subscriptions reference projects - #7429

docs: add observable deprecation note to subscriptions reference projects#7429supermadu7 wants to merge 4 commits intotrpc:maintrpc/trpc:mainfrom supermadu7:fix/subscriptions-observable-deprecationsupermadu7/trpc:fix/subscriptions-observable-deprecationCopy head branch name to clipboard

Conversation

supermadu7 commented Jul 4, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🎯 Changes

✅ Checklist

Summary by CodeRabbit

Uh oh!

vercel Bot commented Jul 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

coderabbitai Bot commented Jul 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Changes

Sequence Diagram(s)

Uh oh!

coderabbitai Bot left a comment

Choose a reason for hiding this comment

Uh oh!

pkg-pr-new Bot commented Jul 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

supermadu7 commented Jul 4, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

docs: add observable deprecation note to subscriptions reference projects#7429
supermadu7 wants to merge 4 commits into
trpc:mainfrom
supermadu7:fix/subscriptions-observable-deprecation

supermadu7 commented Jul 4, 2026 •
edited by coderabbitai Bot
Loading

vercel Bot commented Jul 4, 2026 •
edited
Loading

coderabbitai Bot commented Jul 4, 2026 •
edited
Loading

pkg-pr-new Bot commented Jul 4, 2026 •
edited
Loading