diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 00000000..706332bd
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  ui-tests:
+    runs-on: self-hosted
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Select Xcode
+        run: |
+          set -euo pipefail
+          if [ -d "/Applications/Xcode.app/Contents/Developer" ]; then
+            XCODE_DIR="/Applications/Xcode.app/Contents/Developer"
+          else
+            XCODE_APP="$(ls -d /Applications/Xcode*.app 2>/dev/null | head -n 1 || true)"
+            if [ -n "$XCODE_APP" ]; then
+              XCODE_DIR="$XCODE_APP/Contents/Developer"
+            else
+              echo "No Xcode.app found under /Applications" >&2
+              exit 1
+            fi
+          fi
+          echo "DEVELOPER_DIR=$XCODE_DIR" >> "$GITHUB_ENV"
+          export DEVELOPER_DIR="$XCODE_DIR"
+          xcodebuild -version
+          xcrun --sdk macosx --show-sdk-path
+
+      - name: Run UI tests
+        run: |
+          xcodebuild \
+            -project GhosttyTabs.xcodeproj \
+            -scheme cmux \
+            -configuration Debug \
+            -destination 'platform=macOS' \
+            -only-testing:GhosttyTabsUITests/UpdatePillUITests \
+            test
diff --git a/CLAUDE.md b/CLAUDE.md
index 77e2e0a6..54946b24 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -26,6 +26,14 @@ xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug -des
 ./scripts/reload2.sh
 ```
 
+## E2E mac UI tests
+
+Run UI tests on the UTM macOS VM (never on the host machine):
+
+```bash
+ssh cmux-vm 'cd /Users/cmux/GhosttyTabs && xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug -destination "platform=macOS" -only-testing:GhosttyTabsUITests/UpdatePillUITests test'
+```
+
 ## Release
 
 Tagging a version triggers the GitHub Actions release workflow and uploads the notarized zip.
diff --git a/GhosttyTabsUITests/UpdatePillUITests.swift b/GhosttyTabsUITests/UpdatePillUITests.swift
index d82b3a55..8c0f211b 100644
--- a/GhosttyTabsUITests/UpdatePillUITests.swift
+++ b/GhosttyTabsUITests/UpdatePillUITests.swift
@@ -58,6 +58,45 @@ final class UpdatePillUITests: XCTestCase {
         XCTAssertGreaterThanOrEqual(hiddenAt - shownAt, 4.8)
     }
 
+    func testCheckForUpdatesUsesMockFeedWithUpdate() {
+        let systemSettings = XCUIApplication(bundleIdentifier: "com.apple.systempreferences")
+        systemSettings.terminate()
+        let app = launchAppWithMockFeed(mode: "available", version: "9.9.9")
+
+        let pill = app.descendants(matching: .any)["UpdatePill"]
+        XCTAssertTrue(pill.waitForExistence(timeout: 5.0))
+        XCTAssertTrue(waitForLabel(pill, label: "Update Available: 9.9.9", timeout: 5.0))
+        assertVisibleSize(pill)
+        attachScreenshot(name: "mock-update-available")
+    }
+
+    func testCheckForUpdatesUsesMockFeedWithNoUpdate() {
+        let systemSettings = XCUIApplication(bundleIdentifier: "com.apple.systempreferences")
+        systemSettings.terminate()
+        let timingPath = FileManager.default.temporaryDirectory
+            .appendingPathComponent("cmux-ui-test-timing-\(UUID().uuidString).json")
+        let app = launchAppWithMockFeed(mode: "none", version: "9.9.9", timingPath: timingPath)
+
+        let pill = app.descendants(matching: .any)["UpdatePill"]
+        XCTAssertTrue(pill.waitForExistence(timeout: 5.0))
+        XCTAssertTrue(waitForLabel(pill, label: "No Updates Available", timeout: 5.0))
+        assertVisibleSize(pill)
+        attachScreenshot(name: "mock-no-updates")
+
+        let gone = XCTNSPredicateExpectation(
+            predicate: NSPredicate(format: "exists == false"),
+            object: pill
+        )
+        XCTAssertEqual(XCTWaiter().wait(for: [gone], timeout: 7.0), .completed)
+
+        let payload = loadTimingPayload(from: timingPath)
+        let shownAt = payload["noUpdateShownAt"] ?? 0
+        let hiddenAt = payload["noUpdateHiddenAt"] ?? 0
+        XCTAssertGreaterThan(shownAt, 0)
+        XCTAssertGreaterThan(hiddenAt, shownAt)
+        XCTAssertGreaterThanOrEqual(hiddenAt - shownAt, 4.8)
+    }
+
     private func waitForLabel(_ element: XCUIElement, label: String, timeout: TimeInterval) -> Bool {
         let predicate = NSPredicate(format: "label == %@", label)
         let expectation = XCTNSPredicateExpectation(predicate: predicate, object: element)
@@ -77,6 +116,21 @@ final class UpdatePillUITests: XCTestCase {
         add(attachment)
     }
 
+    private func launchAppWithMockFeed(mode: String, version: String, timingPath: URL? = nil) -> XCUIApplication {
+        let app = XCUIApplication()
+        app.launchEnvironment["CMUX_UI_TEST_MODE"] = "1"
+        app.launchEnvironment["CMUX_UI_TEST_FEED_URL"] = "https://cmuxterm.test/appcast.xml"
+        app.launchEnvironment["CMUX_UI_TEST_FEED_MODE"] = mode
+        app.launchEnvironment["CMUX_UI_TEST_UPDATE_VERSION"] = version
+        app.launchEnvironment["CMUX_UI_TEST_TRIGGER_UPDATE_CHECK"] = "1"
+        if let timingPath {
+            app.launchEnvironment["CMUX_UI_TEST_TIMING_PATH"] = timingPath.path
+        }
+        app.launch()
+        app.activate()
+        return app
+    }
+
     private func loadTimingPayload(from url: URL) -> [String: Double] {
         guard let data = try? Data(contentsOf: url),
               let object = try? JSONSerialization.jsonObject(with: data) as? [String: Double] else {
diff --git a/Sources/AppDelegate.swift b/Sources/AppDelegate.swift
index 345d4271..21abd4bd 100644
--- a/Sources/AppDelegate.swift
+++ b/Sources/AppDelegate.swift
@@ -32,6 +32,11 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         titlebarAccessoryController.start()
 #if DEBUG
         UpdateTestSupport.applyIfNeeded(to: updateController.viewModel)
+        if ProcessInfo.processInfo.environment["CMUX_UI_TEST_TRIGGER_UPDATE_CHECK"] == "1" {
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.25) { [weak self] in
+                self?.updateController.checkForUpdates()
+            }
+        }
 #endif
     }
 
diff --git a/Sources/Update/UpdateDelegate.swift b/Sources/Update/UpdateDelegate.swift
index 8c5ae35b..7e1f5ba0 100644
--- a/Sources/Update/UpdateDelegate.swift
+++ b/Sources/Update/UpdateDelegate.swift
@@ -3,6 +3,14 @@ import Cocoa
 
 extension UpdateDriver: SPUUpdaterDelegate {
     func feedURLString(for updater: SPUUpdater) -> String? {
+#if DEBUG
+        let env = ProcessInfo.processInfo.environment
+        if let override = env["CMUX_UI_TEST_FEED_URL"], !override.isEmpty {
+            UpdateTestURLProtocol.registerIfNeeded()
+            recordFeedURLString(override, usedFallback: false)
+            return override
+        }
+#endif
         let infoURL = Bundle.main.object(forInfoDictionaryKey: "SUFeedURL") as? String
         let fallback = "https://github.com/manaflow-ai/cmuxterm/releases/latest/download/appcast.xml"
         let feedURLString = (infoURL?.isEmpty == false) ? infoURL! : fallback