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Cap-goCap-go/capgo-skills/skills/capacitor-deep-linking/SKILL.md

capacitor-deep-linking

Skill75 starsChanged 32 days agoMITView on GitHub

Implements and debugs deep links in Capacitor apps - custom URL schemes, iOS Universal Links (apple-app-site-association, Associated Domains entitlement), Android App Links (assetlinks.json, autoVerify), and routing via @capacitor/app `appUrlOpen` + `App.getLaunchUrl()`. Covers the Capacitor 8.5+ UIScene change where AppDelegate `application(_:open:options:)` and `continue userActivity` stop being called and custom handling must move to SceneDelegate, plus cold vs warm launch testing. Use when links open Safari/Chrome instead of the app, `appUrlOpen` never fires, the launch URL is lost on cold start, or OAuth redirects do not return to the app. Do not use for the full UIScene migration (capacitor-uiscene-migration), push notification taps (capacitor-push-notifications), or social login plugin setup (capacitor-plugins).

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1 other project uses a version of this.

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We split this skill into the rules it gives an agent

5 rules. About 0 are common, 3 are distinctive, and 2 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈3

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 2

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Prefer verified https links for anything security-sensitive (OAuth, magic links).

    line 34
  2. Very specific:

    Inspect first: Read capacitor.config.*, ios/App/App/Info.plist, ios/App/App/*.entitlements, ios/App/App/AppDelegate.swift, …

    line 38
  3. Very specific:

    No scene manifest -> AppDelegate path still works on 8.5 core, but Xcode 27 / Capacitor 9 require the scene lifecycle.

    line 41
  4. Distinctive:

    Only load a reference when its topic is in play.

    line 50
  5. Distinctive:

    Run every row on a physical device (Universal Links do not work reliably from the Simulator address bar.

    line 114

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Deep Linking in Capacitor

Route custom-scheme links, iOS Universal Links, and Android App Links into the web app.

When to Use

TRIGGER when:

  • Adding myapp:// schemes, Universal Links, or App Links to a Capacitor app
  • Links open the browser instead of the app, or open the app but land on the home page
  • appUrlOpen fires on warm open but the URL is missing on cold launch (or the reverse)
  • Deep links broke after updating to Capacitor 8.5+ / adopting SceneDelegate.swift
  • OAuth / magic-link / payment redirects must come back into the app
  • adb shell pm get-app-links shows none or 1024 instead of verified

Do not use:

  • Full AppDelegate -> SceneDelegate migration of an app: capacitor-uiscene-migration
  • Notification tap routing: capacitor-push-notifications
  • Native log capture while debugging: ios-android-logs
  • Sign in with Apple / Google plugin config: capacitor-plugins

Link Types

TypePlatformFormatNeeds hosted fileVerified ownership
Custom schemebothmyapp://product/123nono (any app can claim it)
Universal LinksiOShttps://example.com/product/123/.well-known/apple-app-site-associationyes
App LinksAndroid 6+https://example.com/product/123/.well-known/assetlinks.jsonyes

Prefer verified https links for anything security-sensitive (OAuth, magic links). Custom schemes can be hijacked by another app.

Workflow

  1. Inspect first. Read capacitor.config.*, ios/App/App/Info.plist, ios/App/App/*.entitlements, ios/App/App/AppDelegate.swift, ios/App/App/SceneDelegate.swift (if present), android/app/src/main/AndroidManifest.xml, and the @capacitor/app version in package.json.
  2. Decide the iOS lifecycle path.
    • UIApplicationSceneManifest present in Info.plist (Capacitor 8.5+ template or migrated app) -> URL events arrive in SceneDelegate. Any custom code in AppDelegate application(_:open:options:) or application(_:continue:restorationHandler:) is dead code. See references/ios-scene-delegate.md.
    • No scene manifest -> AppDelegate path still works on 8.5 core, but Xcode 27 / Capacitor 9 require the scene lifecycle. Hand the migration to capacitor-uiscene-migration.
  3. Install @capacitor/app (npm install @capacitor/app && npx cap sync).
  4. Register the JS handler once, at app bootstrap (before the router renders), using both appUrlOpen and getLaunchUrl(). See below.
  5. Configure platforms: custom scheme (Info.plist CFBundleURLTypes, Android <intent-filter>), then verified links per platform:
    • iOS Universal Links: references/ios-universal-links.md
    • Android App Links: references/android-app-links.md
  6. Route in the framework router: references/routing-patterns.md (React, Vue, Angular, OAuth callbacks, deferred links).
  7. Verify with the cold/warm matrix below on a real device.

Only load a reference when its topic is in play.

JS Handler (the part every app needs)

import { App, type URLOpenListenerEvent } from '@capacitor/app';

let lastHandled: string | undefined;

function route(rawUrl: string) {
  if (rawUrl === lastHandled) return; // cold start can deliver the same URL to both paths
  lastHandled = rawUrl;
  const url = new URL(rawUrl);
  // myapp://product/123 -> host "product", pathname "/123"
  // https://example.com/product/123 -> pathname "/product/123"
  const path = url.protocol.startsWith('http')
    ? url.pathname
    : `/${url.host}${url.pathname}`;
  router.navigate(path + url.search); // your router
}

export async function initDeepLinks() {
  await App.addListener('appUrlOpen', (event: URLOpenListenerEvent) => route(event.url));
  const launch = await App.getLaunchUrl(); // resolves undefined or { url }
  if (launch?.url) route(launch.url);
}

Traps:

  • Custom scheme URLs parse with the first segment as host, not pathname. Normalize both forms as above.
  • Register the listener at bootstrap, not inside a lazily loaded page. A listener added after the event fired never sees it; getLaunchUrl() is the fallback for cold start.
  • Wrap state updates from the listener in your framework's zone/run loop (Angular NgZone.run) or navigation silently does nothing.
  • Dedupe: on cold start the URL can be reachable via both getLaunchUrl() and appUrlOpen.
  • Validate and allow-list paths before navigating; a deep link is untrusted input.

Custom Scheme Config

iOS ios/App/App/Info.plist:

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleURLName</key>
    <string>com.example.app</string>
    <key>CFBundleURLSchemes</key>
    <array><string>myapp</string></array>
  </dict>
</array>

Android AndroidManifest.xml, inside the existing MainActivity (keep the template's android:launchMode="singleTask" so warm opens reuse the activity):

<intent-filter>
  <action android:name="android.intent.action.VIEW" />
  <category android:name="android.intent.category.DEFAULT" />
  <category android:name="android.intent.category.BROWSABLE" />
  <data android:scheme="myapp" />
</intent-filter>

Verification

Run every row on a physical device (Universal Links do not work reliably from the Simulator address bar; tap from Notes/Messages instead).

ScenarioiOSAndroid
Custom scheme, warmxcrun simctl openurl booted "myapp://product/123"adb shell am start -W -a android.intent.action.VIEW -d "myapp://product/123" com.example.app
Custom scheme, coldkill app, then same commandadb shell am force-stop com.example.app, then same command
Verified link, warmtap https://example.com/product/123 in Notesadb shell am start -W -a android.intent.action.VIEW -c android.intent.category.BROWSABLE -d "https://example.com/product/123"
Verified link, coldswipe app away, tap linkforce-stop, then same command
Ownership checkcurl -sI https://example.com/.well-known/apple-app-site-association (200, no redirect)adb shell pm get-app-links com.example.app shows verified

Pass criteria: each case lands on the right route, appUrlOpen logs once, and on cold start getLaunchUrl() returns the URL. After a Capacitor 8.5 scene migration, re-run the full matrix: cold launch takes a different native path (scene(_:willConnectTo:options:)) than warm open (scene(_:openURLContexts:) / scene(_:continue:)).

Grep for dead handlers after migration:

grep -n "open url: URL\|continue userActivity" ios/App/App/AppDelegate.swift
grep -n "SceneDelegateProxy" ios/App/App/SceneDelegate.swift

Error Handling

Symptom / messageCauseFix
Link opens in Safari, app installedAASA not fetched, wrong appID, entitlement missing, or user long-pressed and chose "Open in Safari"Check AASA via Apple CDN, TEAMID.bundleId, applinks: entitlement; long-press link and choose "Open in App" to reset
Custom AppDelegate URL code stopped running after 8.5 updateScene manifest exists; iOS calls SceneDelegate insteadMove logic to SceneDelegate (reference: ios-scene-delegate)
Warm opens work, cold launch lands on homeListener registered late, or custom SceneDelegate code ignores connectionOptionsCall getLaunchUrl() at bootstrap; keep SceneDelegateProxy.shared.scene(_:willConnectTo:options:)
Safari cannot open the page because the address is invalidCustom scheme not registered in installed buildAdd CFBundleURLTypes, rebuild (not just cap sync)
Error: Activity not started, unable to resolve IntentNo intent-filter matches scheme/hostFix <data> entries; reinstall app
pm get-app-links shows 1024 or noneassetlinks.json unreachable, wrong package, or wrong SHA-256 (often the Play App Signing key)Fix file, then adb shell pm verify-app-links --re-verify com.example.app
Android shows app chooser for https linkDomain not verified (autoVerify missing or failed)Add android:autoVerify="true", re-verify
OAuth redirect returns to browser tab, not appRedirect URI does not match registered scheme / verified domainRegister exact redirect URI; prefer verified https link

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