diff --git a/.github/workflows/build-ghosttykit.yml b/.github/workflows/build-ghosttykit.yml
index ec787452..80850f50 100644
--- a/.github/workflows/build-ghosttykit.yml
+++ b/.github/workflows/build-ghosttykit.yml
@@ -8,9 +8,10 @@ on:
 
 jobs:
   build-ghosttykit:
-    # Never run Depot jobs for fork pull requests (avoid billing on external PRs).
+    # Never run WarpBuild jobs for fork pull requests (avoid billing on external PRs).
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
-    runs-on: depot-macos-latest
+    runs-on: warp-macos-15-arm64-6x
+    timeout-minutes: 20
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -61,13 +62,18 @@ jobs:
         if: steps.check-release.outputs.exists == 'false'
         run: |
           set -euo pipefail
-          if ! command -v zig >/dev/null 2>&1; then
-            if command -v brew >/dev/null 2>&1; then
-              brew install zig
-            else
-              echo "zig is required to build GhosttyKit.xcframework. Install zig and retry." >&2
-              exit 1
-            fi
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
           cd ghostty && zig build -Demit-xcframework=true -Demit-macos-app=false -Dxcframework-target=universal -Doptimize=ReleaseFast
 
diff --git a/.github/workflows/ci-macos-compat.yml b/.github/workflows/ci-macos-compat.yml
index 2b7e06c9..4682df7b 100644
--- a/.github/workflows/ci-macos-compat.yml
+++ b/.github/workflows/ci-macos-compat.yml
@@ -13,8 +13,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-14, macos-15]
+        include:
+          - os: warp-macos-15-arm64-6x
+            timeout: 20
+            smoke: true
     runs-on: ${{ matrix.os }}
+    timeout-minutes: ${{ matrix.timeout }}
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -39,45 +43,48 @@ jobs:
           echo "Selected: $XCODE_APP"
           echo "DEVELOPER_DIR=$XCODE_DIR" >> "$GITHUB_ENV"
           export DEVELOPER_DIR="$XCODE_DIR"
-          xcodebuild -version
+          XCODE_VER="$(xcodebuild -version | head -1)"
+          echo "XCODE_VER=$XCODE_VER" >> "$GITHUB_ENV"
+          echo "$XCODE_VER"
           xcrun --sdk macosx --show-sdk-path
           sw_vers
 
+      - name: Cache GhosttyKit.xcframework
+        id: cache-ghosttykit
+        uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
+        with:
+          path: GhosttyKit.xcframework
+          key: ghosttykit-${{ hashFiles('.gitmodules', 'ghostty') }}
+
       - name: Download pre-built GhosttyKit.xcframework
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        if: steps.cache-ghosttykit.outputs.cache-hit != 'true'
         run: |
-          set -euo pipefail
-          GHOSTTY_SHA=$(git -C ghostty rev-parse HEAD)
-          TAG="xcframework-$GHOSTTY_SHA"
-          URL="https://github.com/manaflow-ai/ghostty/releases/download/$TAG/GhosttyKit.xcframework.tar.gz"
-          echo "Downloading xcframework for ghostty $GHOSTTY_SHA"
-          MAX_RETRIES=30
-          RETRY_DELAY=20
-          for i in $(seq 1 $MAX_RETRIES); do
-            if curl -fSL -o GhosttyKit.xcframework.tar.gz "$URL"; then
-              echo "Download succeeded on attempt $i"
-              break
-            fi
-            if [ "$i" -eq "$MAX_RETRIES" ]; then
-              echo "Failed to download xcframework after $MAX_RETRIES attempts" >&2
-              exit 1
-            fi
-            echo "Attempt $i/$MAX_RETRIES failed, retrying in ${RETRY_DELAY}s..."
-            sleep $RETRY_DELAY
-          done
-          tar xzf GhosttyKit.xcframework.tar.gz
-          rm GhosttyKit.xcframework.tar.gz
-          test -d GhosttyKit.xcframework
+          ./scripts/download-prebuilt-ghosttykit.sh
 
       - name: Install zig
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
 
-      - name: Clean DerivedData
-        run: rm -rf ~/Library/Developer/Xcode/DerivedData/GhosttyTabs-*
+      - name: Cache DerivedData
+        uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
+        with:
+          path: ~/Library/Developer/Xcode/DerivedData/GhosttyTabs-*
+          key: deriveddata-${{ matrix.os }}-${{ env.XCODE_VER }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.pbxproj') }}
+          restore-keys: |
+            deriveddata-${{ matrix.os }}-${{ env.XCODE_VER }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}-
+            deriveddata-${{ matrix.os }}-${{ env.XCODE_VER }}-
 
       - name: Cache Swift packages
         uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
@@ -147,6 +154,7 @@ jobs:
           fi
 
       - name: Create virtual display
+        if: matrix.smoke
         run: |
           set -euo pipefail
           echo "=== Display before ==="
@@ -162,6 +170,7 @@ jobs:
           system_profiler SPDisplaysDataType 2>/dev/null || echo "(no display info)"
 
       - name: Build app for smoke test
+        if: matrix.smoke
         run: |
           set -euo pipefail
           SOURCE_PACKAGES_DIR="$PWD/.ci-source-packages"
@@ -171,6 +180,7 @@ jobs:
             -destination "platform=macOS" build
 
       - name: Smoke test
+        if: matrix.smoke
         run: |
           set -euo pipefail
           chmod +x scripts/smoke-test-ci.sh
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 34a52dbc..6ba43368 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,7 +13,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
-      - name: Validate Depot runner guards
+      - name: Validate WarpBuild runner guards
         run: ./tests/test_ci_self_hosted_guard.sh
 
       - name: Validate create-dmg version pinning
@@ -50,7 +50,10 @@ jobs:
         run: bun tsc --noEmit
 
   tests:
-    runs-on: macos-15
+    # Never run WarpBuild jobs for fork pull requests (avoid billing on external PRs).
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: warp-macos-15-arm64-6x
+    timeout-minutes: 20
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -60,35 +63,57 @@ jobs:
       - name: Select Xcode
         run: |
           set -euo pipefail
-          XCODE_APP="$(ls -d /Applications/Xcode_*.app 2>/dev/null | sort | tail -n 1 || true)"
-          if [ -z "$XCODE_APP" ]; then
-            XCODE_APP="/Applications/Xcode.app"
+          if [ -d "/Applications/Xcode.app/Contents/Developer" ]; then
+            XCODE_DIR="/Applications/Xcode.app/Contents/Developer"
+          else
+            XCODE_APP="$(ls -d /Applications/Xcode*.app 2>/dev/null | sort | tail -n 1 || true)"
+            if [ -n "$XCODE_APP" ]; then
+              XCODE_DIR="$XCODE_APP/Contents/Developer"
+            else
+              echo "No Xcode.app found under /Applications" >&2
+              exit 1
+            fi
           fi
-          XCODE_DIR="$XCODE_APP/Contents/Developer"
-          if [ ! -d "$XCODE_DIR" ]; then
-            echo "No Xcode found under /Applications" >&2
-            exit 1
-          fi
-          echo "Selected: $XCODE_APP"
           echo "DEVELOPER_DIR=$XCODE_DIR" >> "$GITHUB_ENV"
           export DEVELOPER_DIR="$XCODE_DIR"
           xcodebuild -version
-          xcrun --sdk macosx --show-sdk-path
+
+      - name: Cache GhosttyKit.xcframework
+        id: cache-ghosttykit
+        uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
+        with:
+          path: GhosttyKit.xcframework
+          key: ghosttykit-${{ hashFiles('.gitmodules', 'ghostty') }}
 
       - name: Download pre-built GhosttyKit.xcframework
+        if: steps.cache-ghosttykit.outputs.cache-hit != 'true'
         run: |
           ./scripts/download-prebuilt-ghosttykit.sh
 
       - name: Install zig
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
 
-      - name: Clean DerivedData
-        run: |
-          # Remove stale build cache to avoid incremental build errors
-          rm -rf ~/Library/Developer/Xcode/DerivedData/GhosttyTabs-*
+      - name: Cache DerivedData
+        uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
+        with:
+          path: ~/Library/Developer/Xcode/DerivedData/GhosttyTabs-*
+          key: deriveddata-tests-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.pbxproj') }}
+          restore-keys: |
+            deriveddata-tests-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}-
+            deriveddata-tests-
 
       - name: Cache Swift packages
         uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
@@ -183,10 +208,14 @@ jobs:
 
           CMUX_CLI_BIN="$CLI_BIN" python3 tests/test_cli_version_memory_guard.py
 
-  tests-depot:
-    # Never run Depot jobs for fork pull requests (avoid billing on external PRs).
+  tests-build-and-lag:
+    # Build the full cmux scheme and run the lag regression on WarpBuild.
+    # XCUITests cannot run on WarpBuild (Virtualization.framework limitation:
+    # XCUIApplication stuck "Running Background", 62s activation timeout per
+    # test). Interactive UI tests run via test-e2e.yml on GitHub-hosted runners.
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
-    runs-on: depot-macos-latest
+    runs-on: warp-macos-15-arm64-6x
+    timeout-minutes: 20
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -211,25 +240,49 @@ jobs:
           export DEVELOPER_DIR="$XCODE_DIR"
           xcodebuild -version
 
+      - name: Cache GhosttyKit.xcframework
+        id: cache-ghosttykit-lag
+        uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
+        with:
+          path: GhosttyKit.xcframework
+          key: ghosttykit-${{ hashFiles('.gitmodules', 'ghostty') }}
+
       - name: Download pre-built GhosttyKit.xcframework
+        if: steps.cache-ghosttykit-lag.outputs.cache-hit != 'true'
         run: |
           ./scripts/download-prebuilt-ghosttykit.sh
 
       - name: Install zig
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
 
-      - name: Clean DerivedData
-        run: rm -rf ~/Library/Developer/Xcode/DerivedData/GhosttyTabs-*
+      - name: Cache DerivedData
+        uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
+        with:
+          path: ~/Library/Developer/Xcode/DerivedData/GhosttyTabs-*
+          key: deriveddata-build-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.pbxproj') }}
+          restore-keys: |
+            deriveddata-build-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}-
+            deriveddata-build-
 
       - name: Cache Swift packages
         uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
         with:
           path: .ci-source-packages
-          key: spm-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}
-          restore-keys: spm-
+          key: spm-build-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}
+          restore-keys: spm-build-
 
       - name: Resolve Swift packages
         run: |
@@ -251,6 +304,15 @@ jobs:
             sleep $((attempt * 5))
           done
 
+      - name: Build app
+        run: |
+          set -euo pipefail
+          SOURCE_PACKAGES_DIR="$PWD/.ci-source-packages"
+          xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug \
+            -clonedSourcePackagesDirPath "$SOURCE_PACKAGES_DIR" \
+            -disableAutomaticPackageResolution \
+            -destination "platform=macOS" build
+
       - name: Create virtual display
         run: |
           set -euo pipefail
@@ -261,41 +323,6 @@ jobs:
           echo "VDISPLAY_PID=$VDISPLAY_PID" >> "$GITHUB_ENV"
           sleep 3
 
-      - name: Run UI tests
-        run: |
-          set -euo pipefail
-          SOURCE_PACKAGES_DIR="$PWD/.ci-source-packages"
-          # SidebarResizeUITests hangs on headless runners (mouse drag simulation
-          # doesn't work without a physical display, even with virtual display).
-          # Skip it in CI; it runs fine on local machines.
-          run_ui_tests() {
-            xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug \
-              -clonedSourcePackagesDirPath "$SOURCE_PACKAGES_DIR" \
-              -disableAutomaticPackageResolution \
-              -destination "platform=macOS" \
-              -maximum-test-execution-time-allowance 120 \
-              -only-testing:cmuxUITests \
-              -skip-testing:cmuxUITests/SidebarResizeUITests test 2>&1
-          }
-
-          # xcodebuild exits 65 even for expected failures (XCTExpectFailure).
-          # Capture output and fail only if there are unexpected failures.
-          set +e
-          OUTPUT=$(run_ui_tests)
-          EXIT_CODE=$?
-          set -e
-
-          echo "$OUTPUT"
-          if [ "$EXIT_CODE" -ne 0 ]; then
-            SUMMARY=$(echo "$OUTPUT" | grep "Executed.*tests.*with.*failures" | tail -1)
-            if echo "$SUMMARY" | grep -q "(0 unexpected)"; then
-              echo "All failures are expected, treating as pass"
-            else
-              echo "Unexpected test failures detected"
-              exit 1
-            fi
-          fi
-
       - name: Run workspace churn typing-lag regression
         run: |
           set -euo pipefail
diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index 8f7e48de..9ffc7fbb 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -99,7 +99,8 @@ jobs:
   build-sign-notarize-nightly:
     needs: decide
     if: needs.decide.outputs.should_build == 'true'
-    runs-on: depot-macos-latest
+    runs-on: warp-macos-15-arm64-6x
+    timeout-minutes: 20
     steps:
       - name: Checkout build ref
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -151,8 +152,18 @@ jobs:
       - name: Install build deps
         if: needs.decide.outputs.should_publish != 'true' || steps.current_head_prebuild.outputs.still_current == 'true'
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
           npm install --global "create-dmg@${CREATE_DMG_VERSION}"
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index ff6b33b1..73346b50 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -14,7 +14,8 @@ env:
 
 jobs:
   build-sign-notarize:
-    runs-on: depot-macos-latest
+    runs-on: warp-macos-15-arm64-6x
+    timeout-minutes: 20
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -99,8 +100,18 @@ jobs:
       - name: Install build deps
         if: steps.guard_release_assets.outputs.skip_all != 'true'
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
           npm install --global "create-dmg@${CREATE_DMG_VERSION}"
 
diff --git a/.github/workflows/test-depot.yml b/.github/workflows/test-depot.yml
index 536c5a14..c6edb871 100644
--- a/.github/workflows/test-depot.yml
+++ b/.github/workflows/test-depot.yml
@@ -28,7 +28,8 @@ on:
 
 jobs:
   tests:
-    runs-on: depot-macos-latest
+    runs-on: warp-macos-15-arm64-6x
+    timeout-minutes: 20
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
@@ -84,8 +85,18 @@ jobs:
 
       - name: Install zig
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
 
       - name: Create virtual display
diff --git a/.github/workflows/test-e2e.yml b/.github/workflows/test-e2e.yml
index a61e5eee..54d145bd 100644
--- a/.github/workflows/test-e2e.yml
+++ b/.github/workflows/test-e2e.yml
@@ -20,17 +20,18 @@ on:
         default: true
         type: boolean
       runner:
-        description: "Runner OS (macos-15 or macos-26)"
+        description: "Runner OS (Depot runners for GUI activation support)"
         required: false
-        default: "macos-15"
+        default: "depot-macos-latest"
         type: choice
         options:
-          - macos-15
-          - macos-26
+          - depot-macos-latest
+          - depot-macos-14
 
 jobs:
   e2e:
-    runs-on: ${{ inputs.runner || 'macos-15' }}
+    runs-on: ${{ inputs.runner || 'depot-macos-latest' }}
+    timeout-minutes: 20
     env:
       TEST_REF: ${{ inputs.ref || github.ref }}
     steps:
@@ -92,8 +93,18 @@ jobs:
 
       - name: Install zig
         run: |
-          if ! command -v zig >/dev/null 2>&1; then
-            brew install zig
+          ZIG_REQUIRED="0.15.2"
+          if command -v zig >/dev/null 2>&1 && zig version 2>/dev/null | grep -q "^${ZIG_REQUIRED}"; then
+            echo "zig ${ZIG_REQUIRED} already installed"
+          else
+            echo "Installing zig ${ZIG_REQUIRED} from tarball"
+            curl -fSL "https://ziglang.org/download/${ZIG_REQUIRED}/zig-aarch64-macos-${ZIG_REQUIRED}.tar.xz" -o /tmp/zig.tar.xz
+            tar xf /tmp/zig.tar.xz -C /tmp
+            sudo mkdir -p /usr/local/bin /usr/local/lib
+            sudo cp -f /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/zig /usr/local/bin/zig
+            sudo cp -rf /tmp/zig-aarch64-macos-${ZIG_REQUIRED}/lib /usr/local/lib/zig
+            export PATH="/usr/local/bin:$PATH"
+            zig version
           fi
 
       - name: Create virtual display
@@ -161,8 +172,8 @@ jobs:
         uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
         with:
           path: .ci-source-packages
-          key: spm-${{ inputs.runner || 'macos-15' }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}
-          restore-keys: spm-${{ inputs.runner || 'macos-15' }}-
+          key: spm-${{ inputs.runner || 'depot-macos-latest' }}-${{ hashFiles('GhosttyTabs.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved') }}
+          restore-keys: spm-${{ inputs.runner || 'depot-macos-latest' }}-
 
       - name: Resolve Swift packages
         run: |
diff --git a/tests/test_ci_self_hosted_guard.sh b/tests/test_ci_self_hosted_guard.sh
index 3b4f7f65..c3a5281c 100755
--- a/tests/test_ci_self_hosted_guard.sh
+++ b/tests/test_ci_self_hosted_guard.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 # Regression test for https://github.com/manaflow-ai/cmux/issues/385.
-# Ensures Depot-hosted UI tests are never run for fork pull requests.
+# Ensures paid/gated CI jobs are never run for fork pull requests.
 set -euo pipefail
 
 ROOT_DIR="$(cd "$(dirname "$0")/.." && pwd)"
@@ -9,21 +9,35 @@ WORKFLOW_FILE="$ROOT_DIR/.github/workflows/ci.yml"
 EXPECTED_IF="if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository"
 
 if ! grep -Fq "$EXPECTED_IF" "$WORKFLOW_FILE"; then
-  echo "FAIL: Missing fork pull_request guard for tests in $WORKFLOW_FILE"
+  echo "FAIL: Missing fork pull_request guard in $WORKFLOW_FILE"
   echo "Expected line:"
   echo "  $EXPECTED_IF"
   exit 1
 fi
 
+# tests: must use WarpBuild runner with fork guard (paid runner)
 if ! awk '
-  /^  tests-depot:/ { in_tests=1; next }
+  /^  tests:/ { in_tests=1; next }
   in_tests && /^  [^[:space:]]/ { in_tests=0 }
-  in_tests && /runs-on: depot-macos-latest/ { saw_depot=1 }
+  in_tests && /runs-on: warp-macos-15-arm64-6x/ { saw_warp=1 }
   in_tests && /github.event.pull_request.head.repo.full_name == github.repository/ { saw_guard=1 }
-  END { exit !(saw_depot && saw_guard) }
+  END { exit !(saw_warp && saw_guard) }
 ' "$WORKFLOW_FILE"; then
-  echo "FAIL: tests-depot block must keep both depot-macos-latest runner and fork guard"
+  echo "FAIL: tests block must keep both warp-macos-15-arm64-6x runner and fork guard"
   exit 1
 fi
 
-echo "PASS: tests-depot Depot runner fork guard is present"
+# tests-build-and-lag: must use WarpBuild runner with fork guard (paid runner)
+if ! awk '
+  /^  tests-build-and-lag:/ { in_tests=1; next }
+  in_tests && /^  [^[:space:]]/ { in_tests=0 }
+  in_tests && /runs-on: warp-macos-15-arm64-6x/ { saw_warp=1 }
+  in_tests && /github.event.pull_request.head.repo.full_name == github.repository/ { saw_guard=1 }
+  END { exit !(saw_warp && saw_guard) }
+' "$WORKFLOW_FILE"; then
+  echo "FAIL: tests-build-and-lag block must keep both warp-macos-15-arm64-6x runner and fork guard"
+  exit 1
+fi
+
+echo "PASS: tests WarpBuild runner fork guard is present"
+echo "PASS: tests-build-and-lag WarpBuild runner fork guard is present"