[juliusmarminge]

Stacked on https://git.cafe/pingdotgg/t3code/pulls/26290. On a phone, a copied thread link (https://app.t3.codes/threads/<env>/<thread>) opened the browser, which then offered the app. With T3 Code installed, the link now opens the thread in the app directly. Both PRs already change native code, so they can ship in one release.

How it works

• app.t3.codes claims its thread links. apps/web/public/.well-known/ gets apple-app-site-association.json and assetlinks.json, both scoped to /threads/* and listing the production, preview, and dev apps. Apple fetches the file without an extension, so vercel.ts rewrites /.well-known/apple-app-site-association to the .json file, which Vercel serves as application/json. A rewrite is not a redirect, which Apple refuses. On app.t3.codes, requests go through to the latest channel's deployment, which serves both files.
• The apps claim app.t3.codes. iOS adds applinks:app.t3.codes next to the existing Clerk domains. Android adds a verified (autoVerify) intent filter for https://app.t3.codes/threads/.
• The app routes the link. https://app.t3.codes is a linking prefix, so /threads/<env>/<thread> reaches the existing threads/:environmentId/:threadId route that t3code://threads/… already uses, including ?prompt= handling. Other app.t3.codes paths are not claimed and stay in the browser.
• Identifiers. The Apple team ID (ARK85ZXQ4Z) and bundle IDs come from app.config.ts. The Android SHA-256 signing fingerprints are copied from https://clerk.t3.codes/.well-known/assetlinks.json, which already verifies these apps for passkeys. app.config.test.ts checks that every variant's identifiers appear in both files and that its native config claims the hosted app's host.
• Desktop. No change. There is no cross-browser way for a desktop app installed outside a store to claim https links, so the chooser and Remember my choice stay the way there.

Shipping order

• The files must be live on app.t3.codes before the new mobile builds reach users. Android verifies autoVerify filters at install time, and iOS fetches through Apple's CDN, which caches. After the web deploy, check https://app-site-association.cdn-apple.com/a/v1/app.t3.codes and Google's Digital Asset Links API for each package.
• The native config changes, so this needs a store build, as https://git.cafe/pingdotgg/t3code/pulls/26290 already does.

Behaviour to know

• With the app installed, a phone skips the chooser. Someone not connected to the thread's machine lands in the app's existing "Thread on another machine" handling instead of the chooser. They can still open the link in the browser (long-press on iOS) to get the chooser.

Testing

• apps/mobile/app.config.test.ts: each variant's bundle ID and package appear in the two files, and its config claims applinks:app.t3.codes and the /threads/ intent filter. Dropping the dev app from the Apple file fails the development row.
• vp run check:changed: format, lint, knip, typecheck (34 packages), tests (22 files), and the React compiler check pass.
• Not run: a native build, a device install, or a deploy. Universal links and app links can only be verified against the deployed files with a signed build.

Claude Opus 5.5 in Claude Code, run from T3 Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — Copied thread links now open the installed mobile app directly instead of showing the browser chooser. Human review is needed to confirm this default destination change, including the experience when the app is not connected to the thread's machine.

No code changes detected at b3b6216. Prior analysis still applies.

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Important

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• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: t3code/shared/thread-app-links
• File: .coderabbit.config.ts
• Commit: b3b6216
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Team
• Run ID: 69b510e1-1337-4571-b272-2c1a6d2e2bc4

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Walkthrough

The mobile app and hosted site now associate HTTPS links on app.t3.codes under /threads/ with the app. React Navigation recognizes the hosted URL, link filtering checks route text without query or fragment content, and thread-sharing instructions describe how links open in different contexts.

Changes: Thread link handling

Layer / File(s)	Summary
Platform association and link configuration apps/web/public/.well-known/*, apps/web/vercel.ts, apps/mobile/app.config.ts, apps/mobile/app.config.test.ts	The site publishes iOS and Android associations for the production, preview, and development app identifiers. Mobile configuration adds iOS and verified Android handling for HTTPS /threads/ links on app.t3.codes. Tests check the configured links and app identifiers against the association files.
App navigation and route filtering apps/mobile/src/App.tsx, apps/mobile/src/lib/appLinking.ts, apps/mobile/src/lib/appLinking.test.ts, docs/user/prompt-links.md	React Navigation adds the hosted app URL as a link prefix. shouldHandleAppLink checks route text before query and fragment markers; its test includes an HTTPS URL with matching marker strings in the query. The instructions describe app and non-app link behavior.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  actor User
  participant OS as Mobile operating system
  participant Site as Hosted site
  participant App as T3 Code app
  participant Navigation as React Navigation
  User->>OS: Open HTTPS thread link
  OS->>Site: Request platform association
  Site-->>OS: Return app association
  OS->>App: Open matching thread link
  App->>Navigation: Match hosted URL prefix

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Possibly related issues

• Copy thread references cannot be opened outside T3 Code #28151 — The issue requests public URLs that identify an environment and thread and open through mobile navigation. This change associates HTTPS thread links with the mobile app.

Merge Risk: Moderate · previous review 301aa

Verify the deployed Apple association endpoint before relying on iOS users opening thread links directly in the app.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the primary change: copied thread links now open the mobile app.
Description check		The description provides the problem, implementation details, scope, shipping considerations, behavior, and focused verification results. It does not use the template headings exactly and does not exp…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Explanation

The description provides the problem, implementation details, scope, shipping considerations, behavior, and focused verification results. It does not use the template headings exactly and does not explicitly document maintainer approval, but it is otherwise sufficiently complete.

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Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: t3code/shared/thread-app-links
• File: .coderabbit.config.ts
• Commit: 301aaab
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Team
• Run ID: 9173e77f-9f34-4dd0-96da-624c5b7efc08

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Files selected for processing: 2

• apps/mobile/src/lib/appLinking.test.ts
• apps/mobile/src/lib/appLinking.ts

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