diff --git a/.github/workflows/_ci-clients.yml b/.github/workflows/_ci-clients.yml
index 465c4b93ef..e56b31dbd1 100644
--- a/.github/workflows/_ci-clients.yml
+++ b/.github/workflows/_ci-clients.yml
@@ -142,6 +142,8 @@ jobs:
         run: swift test --package-path mobile/ios/BuzzPushKit
       - name: Test native pagination geometry
         run: /bin/bash scripts/test-mobile-pagination.sh
+      - name: Trust pinned Swift source-copy plugin
+        run: python3 scripts/trust-ios-package-plugin.py --trust-file "$HOME/Library/org.swift.swiftpm/security/plugins.json"
       - name: Build complete iOS simulator app
         run: cd mobile && flutter build ios --simulator --debug --no-pub
       - name: Test native pagination accessibility
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f134626afb..1126c7e863 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -617,3 +617,8 @@ their sign-off. When in doubt, check with your legal team.
 
 *Thank you for contributing to Buzz. Every bug report, documentation fix,
 and code contribution makes the project better for everyone. 🐝*
+
+The iOS Swift dependency uses `SharedSourcesPlugin` to copy its shared Swift sources.
+Xcode users must approve this plugin when prompted. CI trusts only its reviewed
+commit fingerprint using `scripts/trust-ios-package-plugin.py`; package upgrades
+require reviewing the plugin before updating that fingerprint.
diff --git a/scripts/trust-ios-package-plugin.py b/scripts/trust-ios-package-plugin.py
new file mode 100644
index 0000000000..843af8c971
--- /dev/null
+++ b/scripts/trust-ios-package-plugin.py
@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+"""Trust only Buzz's reviewed, pinned Swift build plugin on a build worker."""
+import argparse
+import json
+from pathlib import Path
+
+
+def trust_plugin(destination, root):
+    """Preserve other trust entries and reject an unreviewed package revision."""
+    entry = {
+        "fingerprint": "e70a10e036a55fffea31568f0af92d69b6d449cd",
+        "packageIdentity": "swift-secp256k1",
+        "targetName": "SharedSourcesPlugin",
+    }
+    lock = json.loads((root / "mobile/ios/Runner.xcworkspace/xcshareddata/swiftpm/Package.resolved").read_text())
+    pin = next(pin for pin in lock["pins"] if pin["identity"] == entry["packageIdentity"])
+    if pin["state"]["revision"] != entry["fingerprint"]:
+        raise ValueError("Review the changed Swift plugin before updating its trusted fingerprint")
+    entries = json.loads(destination.read_text()) if destination.exists() else []
+    if not isinstance(entries, list):
+        raise ValueError("Expected a Swift plugin trust list")
+    if entry not in entries:
+        entries.append(entry)
+        destination.parent.mkdir(parents=True, exist_ok=True)
+        destination.write_text(json.dumps(entries, indent=2) + "\n")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--trust-file", type=Path, required=True)
+    args = parser.parse_args()
+    trust_plugin(args.trust_file, Path(__file__).resolve().parent.parent)