diff --git a/.github/workflows/build-ghosttykit.yml b/.github/workflows/build-ghosttykit.yml
index 1f2fb84f..ec787452 100644
--- a/.github/workflows/build-ghosttykit.yml
+++ b/.github/workflows/build-ghosttykit.yml
@@ -69,7 +69,7 @@ jobs:
               exit 1
             fi
           fi
-          cd ghostty && zig build -Demit-xcframework=true -Demit-macos-app=false -Doptimize=ReleaseFast
+          cd ghostty && zig build -Demit-xcframework=true -Demit-macos-app=false -Dxcframework-target=universal -Doptimize=ReleaseFast
 
       - name: Package xcframework
         if: steps.check-release.outputs.exists == 'false'
diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index 18caadc3..f645b45c 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -12,7 +12,7 @@ on:
         type: boolean
 
 concurrency:
-  group: nightly-build
+  group: nightly-build-${{ github.ref_name }}
   cancel-in-progress: true
 
 permissions:
@@ -28,6 +28,7 @@ jobs:
       should_build: ${{ steps.decide.outputs.should_build }}
       head_sha: ${{ steps.decide.outputs.head_sha }}
       short_sha: ${{ steps.decide.outputs.short_sha }}
+      should_publish: ${{ steps.decide.outputs.should_publish }}
     steps:
       - name: Decide whether a nightly build is needed
         id: decide
@@ -38,46 +39,58 @@ jobs:
           script: |
             const forceBuild = process.env.FORCE_BUILD === 'true';
             const { owner, repo } = context.repo;
+            const requestedRef = context.ref.startsWith('refs/heads/')
+              ? context.ref.replace('refs/heads/', '')
+              : 'main';
+            const isMainRef = requestedRef === 'main';
 
-            const branch = await github.rest.repos.getBranch({
-              owner,
-              repo,
-              branch: 'main',
-            });
-            const headSha = branch.data.commit.sha;
-
-            let nightlySha = null;
-            try {
-              const ref = await github.rest.git.getRef({
+            let headSha = context.sha;
+            if (isMainRef) {
+              const branch = await github.rest.repos.getBranch({
                 owner,
                 repo,
-                ref: 'tags/nightly',
+                branch: 'main',
               });
-              if (ref.data.object.type === 'commit') {
-                nightlySha = ref.data.object.sha;
-              } else if (ref.data.object.type === 'tag') {
-                const tagObject = await github.rest.git.getTag({
-                  owner,
-                  repo,
-                  tag_sha: ref.data.object.sha,
-                });
-                nightlySha = tagObject.data.object.sha;
-              }
-            } catch (error) {
-              if (error.status !== 404) throw error;
+              headSha = branch.data.commit.sha;
             }
 
-            const shouldBuild = forceBuild || nightlySha !== headSha;
+            let nightlySha = null;
+            if (isMainRef) {
+              try {
+                const ref = await github.rest.git.getRef({
+                  owner,
+                  repo,
+                  ref: 'tags/nightly',
+                });
+                if (ref.data.object.type === 'commit') {
+                  nightlySha = ref.data.object.sha;
+                } else if (ref.data.object.type === 'tag') {
+                  const tagObject = await github.rest.git.getTag({
+                    owner,
+                    repo,
+                    tag_sha: ref.data.object.sha,
+                  });
+                  nightlySha = tagObject.data.object.sha;
+                }
+              } catch (error) {
+                if (error.status !== 404) throw error;
+              }
+            }
+
+            const shouldBuild = !isMainRef || forceBuild || nightlySha !== headSha;
             core.setOutput('should_build', shouldBuild ? 'true' : 'false');
             core.setOutput('head_sha', headSha);
             core.setOutput('short_sha', headSha.slice(0, 7));
+            core.setOutput('should_publish', isMainRef ? 'true' : 'false');
             core.summary
               .addHeading('Nightly build decision')
               .addTable([
-                [{data: 'main HEAD', header: true}, headSha],
+                [{data: 'requested ref', header: true}, requestedRef],
+                [{data: 'build HEAD', header: true}, headSha],
                 [{data: 'nightly tag', header: true}, nightlySha ?? '(missing)'],
                 [{data: 'force build', header: true}, String(forceBuild)],
                 [{data: 'should build', header: true}, String(shouldBuild)],
+                [{data: 'should publish', header: true}, String(isMainRef)],
               ])
               .write();
 
@@ -86,7 +99,7 @@ jobs:
     if: needs.decide.outputs.should_build == 'true'
     runs-on: macos-15
     steps:
-      - name: Checkout main
+      - name: Checkout build ref
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           ref: ${{ needs.decide.outputs.head_sha }}
@@ -138,40 +151,53 @@ jobs:
           echo "Derived Sparkle public key: $DERIVED_PUBLIC_KEY"
           echo "SPARKLE_PUBLIC_KEY=$DERIVED_PUBLIC_KEY" >> "$GITHUB_ENV"
 
-      - name: Build app (Release)
+      - name: Build Apple Silicon app (Release)
         run: |
-          xcodebuild -scheme cmux -configuration Release -derivedDataPath build \
+          xcodebuild -scheme cmux -configuration Release -derivedDataPath build-arm \
+            -destination 'platform=macOS,arch=arm64' \
             -clonedSourcePackagesDirPath .spm-cache \
+            ARCHS="arm64" \
+            ONLY_ACTIVE_ARCH=YES \
             CODE_SIGNING_ALLOWED=NO ASSETCATALOG_COMPILER_APPICON_NAME=AppIcon-Nightly build
 
-      - name: Inject nightly identity and metadata
+      - name: Build universal app (Release)
+        run: |
+          xcodebuild -scheme cmux -configuration Release -derivedDataPath build-universal \
+            -destination 'generic/platform=macOS' \
+            -clonedSourcePackagesDirPath .spm-cache \
+            ARCHS="arm64 x86_64" \
+            ONLY_ACTIVE_ARCH=NO \
+            CODE_SIGNING_ALLOWED=NO ASSETCATALOG_COMPILER_APPICON_NAME=AppIcon-Nightly build
+
+      - name: Verify nightly binary architectures
+        run: |
+          set -euo pipefail
+          ARM_APP_BINARY="build-arm/Build/Products/Release/cmux.app/Contents/MacOS/cmux"
+          ARM_CLI_BINARY="build-arm/Build/Products/Release/cmux.app/Contents/Resources/bin/cmux"
+          APP_BINARY="build-universal/Build/Products/Release/cmux.app/Contents/MacOS/cmux"
+          CLI_BINARY="build-universal/Build/Products/Release/cmux.app/Contents/Resources/bin/cmux"
+          ARM_APP_ARCHS="$(lipo -archs "$ARM_APP_BINARY")"
+          ARM_CLI_ARCHS="$(lipo -archs "$ARM_CLI_BINARY")"
+          APP_ARCHS="$(lipo -archs "$APP_BINARY")"
+          CLI_ARCHS="$(lipo -archs "$CLI_BINARY")"
+          echo "Arm app binary architectures: $ARM_APP_ARCHS"
+          echo "Arm CLI binary architectures: $ARM_CLI_ARCHS"
+          echo "App binary architectures: $APP_ARCHS"
+          echo "CLI binary architectures: $CLI_ARCHS"
+          [[ "$ARM_APP_ARCHS" == "arm64" ]]
+          [[ "$ARM_CLI_ARCHS" == "arm64" ]]
+          [[ "$APP_ARCHS" == *arm64* && "$APP_ARCHS" == *x86_64* ]]
+          [[ "$CLI_ARCHS" == *arm64* && "$CLI_ARCHS" == *x86_64* ]]
+
+      - name: Inject nightly identities and metadata
         run: |
           set -euo pipefail
-          APP_DIR="build/Build/Products/Release"
-          APP_PLIST="${APP_DIR}/cmux.app/Contents/Info.plist"
           SHORT_SHA="${{ needs.decide.outputs.short_sha }}"
+          ARM_APP_DIR="build-arm/Build/Products/Release"
+          UNIVERSAL_APP_DIR="build-universal/Build/Products/Release"
 
-          # --- Separate app identity: "cmux NIGHTLY" with its own bundle ID ---
-          /usr/libexec/PlistBuddy -c "Set :CFBundleName cmux NIGHTLY" "$APP_PLIST"
-          /usr/libexec/PlistBuddy -c "Set :CFBundleDisplayName cmux NIGHTLY" "$APP_PLIST"
-          /usr/libexec/PlistBuddy -c "Set :CFBundleIdentifier com.cmuxterm.app.nightly" "$APP_PLIST"
-
-          # Rename the .app bundle to match the display name
-          mv "${APP_DIR}/cmux.app" "${APP_DIR}/cmux NIGHTLY.app"
-
-          # Update plist path after rename
-          APP_PLIST="${APP_DIR}/cmux NIGHTLY.app/Contents/Info.plist"
-
-          # --- Sparkle: point at the nightly appcast ---
-          /usr/libexec/PlistBuddy -c "Delete :SUPublicEDKey" "$APP_PLIST" >/dev/null 2>&1 || true
-          /usr/libexec/PlistBuddy -c "Delete :SUFeedURL" "$APP_PLIST" >/dev/null 2>&1 || true
-          /usr/libexec/PlistBuddy -c "Add :SUPublicEDKey string ${SPARKLE_PUBLIC_KEY}" "$APP_PLIST"
-          /usr/libexec/PlistBuddy -c "Add :SUFeedURL string https://github.com/manaflow-ai/cmux/releases/download/nightly/appcast.xml" "$APP_PLIST"
-
-          # Marketing version: append -nightly.YYYYMMDD so users can identify the channel and date
-          BASE_MARKETING=$(/usr/libexec/PlistBuddy -c "Print :CFBundleShortVersionString" "$APP_PLIST")
+          BASE_MARKETING=$(/usr/libexec/PlistBuddy -c "Print :CFBundleShortVersionString" "${ARM_APP_DIR}/cmux.app/Contents/Info.plist")
           NIGHTLY_DATE=$(date -u +%Y%m%d)
-          /usr/libexec/PlistBuddy -c "Set :CFBundleShortVersionString ${BASE_MARKETING}-nightly.${NIGHTLY_DATE}" "$APP_PLIST"
 
           # Build number: unique/monotonic per workflow run attempt so same-day
           # nightlies and reruns still compare as newer in Sparkle.
@@ -181,23 +207,49 @@ jobs:
           else
             NIGHTLY_BUILD="${NIGHTLY_DATE}000000"
           fi
-          /usr/libexec/PlistBuddy -c "Set :CFBundleVersion ${NIGHTLY_BUILD}" "$APP_PLIST"
-
-          # Use an immutable DMG filename in appcast URLs so old appcasts keep
-          # pointing at matching archives while nightly assets roll forward.
-          NIGHTLY_DMG_IMMUTABLE="cmux-nightly-macos-${NIGHTLY_BUILD}.dmg"
           echo "NIGHTLY_BUILD=${NIGHTLY_BUILD}" >> "$GITHUB_ENV"
-          echo "NIGHTLY_DMG_IMMUTABLE=${NIGHTLY_DMG_IMMUTABLE}" >> "$GITHUB_ENV"
 
-          # Embed commit SHA for bug reports
-          /usr/libexec/PlistBuddy -c "Delete :CMUXCommit" "$APP_PLIST" >/dev/null 2>&1 || true
-          /usr/libexec/PlistBuddy -c "Add :CMUXCommit string ${SHORT_SHA}" "$APP_PLIST"
+          ARM_DMG_IMMUTABLE="cmux-nightly-macos-${NIGHTLY_BUILD}.dmg"
+          UNIVERSAL_DMG_IMMUTABLE="cmux-nightly-universal-macos-${NIGHTLY_BUILD}.dmg"
+          echo "NIGHTLY_DMG_IMMUTABLE=${ARM_DMG_IMMUTABLE}" >> "$GITHUB_ENV"
+          echo "NIGHTLY_UNIVERSAL_DMG_IMMUTABLE=${UNIVERSAL_DMG_IMMUTABLE}" >> "$GITHUB_ENV"
+
+          prepare_variant() {
+            local app_dir="$1"
+            local bundle_id="$2"
+            local feed_url="$3"
+            local app_plist="$app_dir/cmux.app/Contents/Info.plist"
+
+            /usr/libexec/PlistBuddy -c "Set :CFBundleName cmux NIGHTLY" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Set :CFBundleDisplayName cmux NIGHTLY" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Set :CFBundleIdentifier ${bundle_id}" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Delete :SUPublicEDKey" "$app_plist" >/dev/null 2>&1 || true
+            /usr/libexec/PlistBuddy -c "Delete :SUFeedURL" "$app_plist" >/dev/null 2>&1 || true
+            /usr/libexec/PlistBuddy -c "Add :SUPublicEDKey string ${SPARKLE_PUBLIC_KEY}" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Add :SUFeedURL string ${feed_url}" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Set :CFBundleShortVersionString ${BASE_MARKETING}-nightly.${NIGHTLY_DATE}" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Set :CFBundleVersion ${NIGHTLY_BUILD}" "$app_plist"
+            /usr/libexec/PlistBuddy -c "Delete :CMUXCommit" "$app_plist" >/dev/null 2>&1 || true
+            /usr/libexec/PlistBuddy -c "Add :CMUXCommit string ${SHORT_SHA}" "$app_plist"
+            mv "$app_dir/cmux.app" "$app_dir/cmux NIGHTLY.app"
+          }
+
+          prepare_variant \
+            "$ARM_APP_DIR" \
+            "com.cmuxterm.app.nightly" \
+            "https://github.com/manaflow-ai/cmux/releases/download/nightly/appcast.xml"
+          prepare_variant \
+            "$UNIVERSAL_APP_DIR" \
+            "com.cmuxterm.app.nightly.universal" \
+            "https://github.com/manaflow-ai/cmux/releases/download/nightly/appcast-universal.xml"
 
           echo "Nightly app name: cmux NIGHTLY"
-          echo "Nightly bundle ID: com.cmuxterm.app.nightly"
+          echo "Nightly arm64 bundle ID: com.cmuxterm.app.nightly"
+          echo "Nightly universal bundle ID: com.cmuxterm.app.nightly.universal"
           echo "Nightly marketing version: ${BASE_MARKETING}-nightly.${NIGHTLY_DATE}"
           echo "Nightly build number: ${NIGHTLY_BUILD}"
-          echo "Nightly immutable DMG: ${NIGHTLY_DMG_IMMUTABLE}"
+          echo "Nightly arm64 immutable DMG: ${ARM_DMG_IMMUTABLE}"
+          echo "Nightly universal immutable DMG: ${UNIVERSAL_DMG_IMMUTABLE}"
           echo "Commit SHA: ${SHORT_SHA}"
 
       - name: Import signing cert
@@ -223,7 +275,7 @@ jobs:
           security set-key-partition-list -S apple-tool:,apple: -s -k "$KEYCHAIN_PASSWORD" build.keychain
           security list-keychains -d user -s build.keychain
 
-      - name: Codesign app
+      - name: Codesign apps
         env:
           APPLE_SIGNING_IDENTITY: ${{ secrets.APPLE_SIGNING_IDENTITY }}
         run: |
@@ -231,16 +283,20 @@ jobs:
             echo "Missing APPLE_SIGNING_IDENTITY secret" >&2
             exit 1
           fi
-          APP_PATH="build/Build/Products/Release/cmux NIGHTLY.app"
           ENTITLEMENTS="cmux.entitlements"
-          CLI_PATH="$APP_PATH/Contents/Resources/bin/cmux"
-          if [ -f "$CLI_PATH" ]; then
-            /usr/bin/codesign --force --options runtime --timestamp --sign "$APPLE_SIGNING_IDENTITY" --entitlements "$ENTITLEMENTS" "$CLI_PATH"
-          fi
-          /usr/bin/codesign --force --options runtime --timestamp --sign "$APPLE_SIGNING_IDENTITY" --entitlements "$ENTITLEMENTS" --deep "$APP_PATH"
-          /usr/bin/codesign --verify --deep --strict --verbose=2 "$APP_PATH"
+          for APP_PATH in \
+            "build-arm/Build/Products/Release/cmux NIGHTLY.app" \
+            "build-universal/Build/Products/Release/cmux NIGHTLY.app"
+          do
+            CLI_PATH="$APP_PATH/Contents/Resources/bin/cmux"
+            if [ -f "$CLI_PATH" ]; then
+              /usr/bin/codesign --force --options runtime --timestamp --sign "$APPLE_SIGNING_IDENTITY" --entitlements "$ENTITLEMENTS" "$CLI_PATH"
+            fi
+            /usr/bin/codesign --force --options runtime --timestamp --sign "$APPLE_SIGNING_IDENTITY" --entitlements "$ENTITLEMENTS" --deep "$APP_PATH"
+            /usr/bin/codesign --verify --deep --strict --verbose=2 "$APP_PATH"
+          done
 
-      - name: Notarize app and dmg
+      - name: Notarize apps and dmgs
         env:
           APPLE_ID: ${{ secrets.APPLE_ID }}
           APPLE_APP_SPECIFIC_PASSWORD: ${{ secrets.APPLE_APP_SPECIFIC_PASSWORD }}
@@ -251,41 +307,62 @@ jobs:
             echo "Missing notarization secrets (APPLE_ID, APPLE_APP_SPECIFIC_PASSWORD, APPLE_TEAM_ID)" >&2
             exit 1
           fi
-          APP_PATH="build/Build/Products/Release/cmux NIGHTLY.app"
-          ZIP_SUBMIT="cmux-nightly-notary.zip"
-          DMG_RELEASE="cmux-nightly-macos.dmg"
-          ditto -c -k --sequesterRsrc --keepParent "$APP_PATH" "$ZIP_SUBMIT"
-          APP_SUBMIT_JSON="$(xcrun notarytool submit "$ZIP_SUBMIT" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" --wait --output-format json)"
-          APP_SUBMIT_ID="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])' <<<"$APP_SUBMIT_JSON")"
-          APP_STATUS="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["status"])' <<<"$APP_SUBMIT_JSON")"
-          if [ "$APP_STATUS" != "Accepted" ]; then
-            echo "App notarization failed with status: $APP_STATUS" >&2
-            xcrun notarytool log "$APP_SUBMIT_ID" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" || true
-            exit 1
-          fi
-          xcrun stapler staple "$APP_PATH"
-          xcrun stapler validate "$APP_PATH"
-          spctl -a -vv --type execute "$APP_PATH"
-          rm -f "$ZIP_SUBMIT"
-          create-dmg \
-            --identity="$APPLE_SIGNING_IDENTITY" \
-            "$APP_PATH" \
-            ./
-          mv ./"cmux NIGHTLY"*.dmg "$DMG_RELEASE" 2>/dev/null || mv ./cmux*.dmg "$DMG_RELEASE"
-          DMG_SUBMIT_JSON="$(xcrun notarytool submit "$DMG_RELEASE" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" --wait --output-format json)"
-          DMG_SUBMIT_ID="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])' <<<"$DMG_SUBMIT_JSON")"
-          DMG_STATUS="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["status"])' <<<"$DMG_SUBMIT_JSON")"
-          if [ "$DMG_STATUS" != "Accepted" ]; then
-            echo "DMG notarization failed with status: $DMG_STATUS" >&2
-            xcrun notarytool log "$DMG_SUBMIT_ID" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" || true
-            exit 1
-          fi
-          xcrun stapler staple "$DMG_RELEASE"
-          xcrun stapler validate "$DMG_RELEASE"
+          notarize_and_package() {
+            local app_path="$1"
+            local dmg_release="$2"
+            local dmg_immutable="$3"
+            local zip_submit="${dmg_release%.dmg}-notary.zip"
+            local dmg_tmp_dir
+            local created_dmg
 
-          # Keep a stable filename for humans and an immutable filename used
-          # by appcast URLs to prevent signature/asset mismatch races.
-          cp "$DMG_RELEASE" "$NIGHTLY_DMG_IMMUTABLE"
+            ditto -c -k --sequesterRsrc --keepParent "$app_path" "$zip_submit"
+            APP_SUBMIT_JSON="$(xcrun notarytool submit "$zip_submit" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" --wait --output-format json)"
+            APP_SUBMIT_ID="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])' <<<"$APP_SUBMIT_JSON")"
+            APP_STATUS="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["status"])' <<<"$APP_SUBMIT_JSON")"
+            if [ "$APP_STATUS" != "Accepted" ]; then
+              echo "App notarization failed for $app_path with status: $APP_STATUS" >&2
+              xcrun notarytool log "$APP_SUBMIT_ID" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" || true
+              exit 1
+            fi
+            xcrun stapler staple "$app_path"
+            xcrun stapler validate "$app_path"
+            spctl -a -vv --type execute "$app_path"
+            rm -f "$zip_submit"
+
+            dmg_tmp_dir="$(mktemp -d)"
+            create-dmg \
+              --identity="$APPLE_SIGNING_IDENTITY" \
+              "$app_path" \
+              "$dmg_tmp_dir"
+            created_dmg="$(find "$dmg_tmp_dir" -maxdepth 1 -name '*.dmg' | head -n 1)"
+            if [ -z "$created_dmg" ]; then
+              echo "Failed to locate created DMG for $app_path" >&2
+              exit 1
+            fi
+            mv "$created_dmg" "$dmg_release"
+            rm -rf "$dmg_tmp_dir"
+
+            DMG_SUBMIT_JSON="$(xcrun notarytool submit "$dmg_release" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" --wait --output-format json)"
+            DMG_SUBMIT_ID="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])' <<<"$DMG_SUBMIT_JSON")"
+            DMG_STATUS="$(python3 -c 'import json,sys; print(json.load(sys.stdin)["status"])' <<<"$DMG_SUBMIT_JSON")"
+            if [ "$DMG_STATUS" != "Accepted" ]; then
+              echo "DMG notarization failed for $dmg_release with status: $DMG_STATUS" >&2
+              xcrun notarytool log "$DMG_SUBMIT_ID" --apple-id "$APPLE_ID" --team-id "$APPLE_TEAM_ID" --password "$APPLE_APP_SPECIFIC_PASSWORD" || true
+              exit 1
+            fi
+            xcrun stapler staple "$dmg_release"
+            xcrun stapler validate "$dmg_release"
+            cp "$dmg_release" "$dmg_immutable"
+          }
+
+          notarize_and_package \
+            "build-arm/Build/Products/Release/cmux NIGHTLY.app" \
+            "cmux-nightly-macos.dmg" \
+            "$NIGHTLY_DMG_IMMUTABLE"
+          notarize_and_package \
+            "build-universal/Build/Products/Release/cmux NIGHTLY.app" \
+            "cmux-nightly-universal-macos.dmg" \
+            "$NIGHTLY_UNIVERSAL_DMG_IMMUTABLE"
 
       - name: Upload dSYMs to Sentry
         env:
@@ -298,9 +375,11 @@ jobs:
             exit 0
           fi
           brew install getsentry/tools/sentry-cli || true
-          sentry-cli debug-files upload --include-sources build/Build/Products/Release/
+          sentry-cli debug-files upload --include-sources \
+            build-arm/Build/Products/Release/ \
+            build-universal/Build/Products/Release/
 
-      - name: Generate Sparkle appcast (nightly)
+      - name: Generate Sparkle appcasts (nightly)
         env:
           SPARKLE_PRIVATE_KEY: ${{ secrets.SPARKLE_PRIVATE_KEY }}
         run: |
@@ -309,8 +388,22 @@ jobs:
             exit 1
           fi
           ./scripts/sparkle_generate_appcast.sh "$NIGHTLY_DMG_IMMUTABLE" nightly appcast.xml
+          ./scripts/sparkle_generate_appcast.sh "$NIGHTLY_UNIVERSAL_DMG_IMMUTABLE" nightly appcast-universal.xml
+
+      - name: Upload branch nightly artifacts
+        if: needs.decide.outputs.should_publish != 'true'
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+        with:
+          name: cmux-nightly-${{ needs.decide.outputs.short_sha }}
+          path: |
+            cmux-nightly-macos*.dmg
+            cmux-nightly-universal-macos*.dmg
+            appcast.xml
+            appcast-universal.xml
+          if-no-files-found: error
 
       - name: Move nightly tag to built commit
+        if: needs.decide.outputs.should_publish == 'true'
         run: |
           set -euo pipefail
           git config user.name "github-actions[bot]"
@@ -319,6 +412,7 @@ jobs:
           git push origin refs/tags/nightly --force
 
       - name: Publish nightly release assets
+        if: needs.decide.outputs.should_publish == 'true'
         uses: softprops/action-gh-release@a06a81a03ee405af7f2048a818ed3f03bbf83c7b # v2
         with:
           tag_name: nightly
@@ -328,13 +422,19 @@ jobs:
           body: |
             Automated nightly build for `${{ needs.decide.outputs.short_sha }}`.
 
-            **cmux NIGHTLY** is a separate app (bundle ID `com.cmuxterm.app.nightly`) that can be installed alongside the stable release. It receives nightly updates automatically via its own Sparkle feed.
+            **cmux NIGHTLY** has two update tracks:
+            - Apple Silicon: bundle ID `com.cmuxterm.app.nightly`, feed `appcast.xml`
+            - Universal: bundle ID `com.cmuxterm.app.nightly.universal`, feed `appcast-universal.xml`
 
             [Download cmux-nightly-macos.dmg](https://github.com/manaflow-ai/cmux/releases/download/nightly/cmux-nightly-macos.dmg)
+            [Download cmux-nightly-universal-macos.dmg](https://github.com/manaflow-ai/cmux/releases/download/nightly/cmux-nightly-universal-macos.dmg)
           files: |
             cmux-nightly-macos-${{ github.run_id }}*.dmg
             cmux-nightly-macos.dmg
+            cmux-nightly-universal-macos-${{ github.run_id }}*.dmg
+            cmux-nightly-universal-macos.dmg
             appcast.xml
+            appcast-universal.xml
           overwrite_files: true
 
       - name: Cleanup keychain
diff --git a/CLAUDE.md b/CLAUDE.md
index e1c1c942..d2cba8c8 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -49,7 +49,7 @@ xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug -des
 When rebuilding GhosttyKit.xcframework, always use Release optimizations:
 
 ```bash
-cd ghostty && zig build -Demit-xcframework=true -Doptimize=ReleaseFast
+cd ghostty && zig build -Demit-xcframework=true -Dxcframework-target=universal -Doptimize=ReleaseFast
 ```
 
 When rebuilding cmuxd for release/bundling, always use ReleaseFast:
diff --git a/GhosttyTabs.xcodeproj/project.pbxproj b/GhosttyTabs.xcodeproj/project.pbxproj
index fade9fc0..444419f2 100644
--- a/GhosttyTabs.xcodeproj/project.pbxproj
+++ b/GhosttyTabs.xcodeproj/project.pbxproj
@@ -784,6 +784,7 @@
 				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
+				ONLY_ACTIVE_ARCH = NO;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
@@ -859,7 +860,7 @@
 					"-framework",
 					Carbon,
 				);
-				ONLY_ACTIVE_ARCH = YES;
+				ONLY_ACTIVE_ARCH = NO;
 				PRODUCT_BUNDLE_IDENTIFIER = com.cmuxterm.app;
 				PRODUCT_NAME = cmux;
 				SPARKLE_PUBLIC_KEY = "avjcgKibf1FTvhIjLBxhd+0HSpsXU4D0IGlVk8cgqRc=";
@@ -901,6 +902,7 @@
 				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				PRODUCT_NAME = cmux;
 				PRODUCT_MODULE_NAME = cmux_cli;
+				ONLY_ACTIVE_ARCH = NO;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
 				SWIFT_VERSION = 5.0;
@@ -932,7 +934,7 @@
 				GENERATE_INFOPLIST_FILE = YES;
 				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				MARKETING_VERSION = 0.61.0;
-				ONLY_ACTIVE_ARCH = YES;
+				ONLY_ACTIVE_ARCH = NO;
 				PRODUCT_BUNDLE_IDENTIFIER = com.cmuxterm.appuitests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_VERSION = 5.0;
@@ -968,7 +970,7 @@
 				GENERATE_INFOPLIST_FILE = YES;
 				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				MARKETING_VERSION = 0.61.0;
-				ONLY_ACTIVE_ARCH = YES;
+				ONLY_ACTIVE_ARCH = NO;
 				PRODUCT_BUNDLE_IDENTIFIER = com.cmuxterm.apptests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_VERSION = 5.0;
diff --git a/scripts/build-sign-upload.sh b/scripts/build-sign-upload.sh
index ac870d30..08d1f84c 100755
--- a/scripts/build-sign-upload.sh
+++ b/scripts/build-sign-upload.sh
@@ -61,7 +61,7 @@ echo "Pre-flight checks passed"
 # --- Build GhosttyKit (if needed) ---
 if [ ! -d "GhosttyKit.xcframework" ]; then
   echo "Building GhosttyKit..."
-  cd ghostty && zig build -Demit-xcframework=true -Demit-macos-app=false -Dxcframework-target=native -Doptimize=ReleaseFast && cd ..
+  cd ghostty && zig build -Demit-xcframework=true -Demit-macos-app=false -Dxcframework-target=universal -Doptimize=ReleaseFast && cd ..
   rm -rf GhosttyKit.xcframework
   cp -R ghostty/macos/GhosttyKit.xcframework GhosttyKit.xcframework
 else
diff --git a/scripts/setup.sh b/scripts/setup.sh
index bcfeb818..7384ef62 100755
--- a/scripts/setup.sh
+++ b/scripts/setup.sh
@@ -58,7 +58,7 @@ else
         echo "==> Building GhosttyKit.xcframework (this may take a few minutes)..."
         (
             cd ghostty
-            zig build -Demit-xcframework=true -Doptimize=ReleaseFast
+            zig build -Demit-xcframework=true -Dxcframework-target=universal -Doptimize=ReleaseFast
         )
         # Stamp the build output with the SHA it was built from
         echo "$GHOSTTY_SHA" > "$LOCAL_SHA_STAMP"
diff --git a/scripts/sparkle_generate_appcast.sh b/scripts/sparkle_generate_appcast.sh
index bfcfb64a..644562bd 100755
--- a/scripts/sparkle_generate_appcast.sh
+++ b/scripts/sparkle_generate_appcast.sh
@@ -70,14 +70,23 @@ while (( ${#padded_key} % 4 != 0 )); do
 done
 printf "%s" "$padded_key" > "$key_file"
 
+generated_appcast_path="$archives_dir/$(basename "$OUT_PATH")"
+
 "$generate_appcast" \
   --ed-key-file "$key_file" \
   --download-url-prefix "$DOWNLOAD_URL_PREFIX" \
   --full-release-notes-url "$RELEASE_NOTES_URL" \
   "$archives_dir"
 
-if [[ ! -f "$archives_dir/appcast.xml" ]]; then
-  echo "appcast.xml not generated." >&2
+if [[ ! -f "$generated_appcast_path" ]]; then
+  fallback_generated_appcast="$(find "$archives_dir" -maxdepth 1 -name '*.xml' | head -n 1)"
+  if [[ -n "$fallback_generated_appcast" ]]; then
+    generated_appcast_path="$fallback_generated_appcast"
+  fi
+fi
+
+if [[ ! -f "$generated_appcast_path" ]]; then
+  echo "Expected appcast was not generated." >&2
   exit 1
 fi
 
@@ -85,7 +94,7 @@ fi
 # to sign the DMG and inject the signature. generate_appcast silently skips
 # signing when the public key derived from the private key doesn't match the
 # SUPublicEDKey in the app's Info.plist.
-if ! grep -q 'sparkle:edSignature' "$archives_dir/appcast.xml"; then
+if ! grep -q 'sparkle:edSignature' "$generated_appcast_path"; then
   echo "Warning: generate_appcast did not add edSignature. Using sign_update fallback..."
   SIGNATURE=$("$sign_update" -p --ed-key-file "$key_file" "$DMG_PATH")
   DMG_LENGTH=$(stat -f%z "$DMG_PATH")
@@ -95,7 +104,7 @@ if ! grep -q 'sparkle:edSignature' "$archives_dir/appcast.xml"; then
   # Inject sparkle:edSignature and correct length into the enclosure element
   python3 -c "
 import sys
-xml = open('$archives_dir/appcast.xml').read()
+xml = open('$generated_appcast_path').read()
 sig = '$SIGNATURE'
 length = '$DMG_LENGTH'
 # Add edSignature to enclosure
@@ -103,12 +112,12 @@ xml = xml.replace(
     'type=\"application/octet-stream\"',
     'sparkle:edSignature=\"' + sig + '\" length=\"' + length + '\" type=\"application/octet-stream\"'
 )
-open('$archives_dir/appcast.xml', 'w').write(xml)
+open('$generated_appcast_path', 'w').write(xml)
 print('  Injected edSignature into appcast.xml')
 "
 fi
 
-cp "$archives_dir/appcast.xml" "$OUT_PATH"
+cp "$generated_appcast_path" "$OUT_PATH"
 echo "Generated appcast at $OUT_PATH"
 
 # Verify the appcast has a signature
diff --git a/tests/test_ci_universal_release_settings.sh b/tests/test_ci_universal_release_settings.sh
new file mode 100644
index 00000000..634a015d
--- /dev/null
+++ b/tests/test_ci_universal_release_settings.sh
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Regression test for universal GhosttyKit and Release build settings.
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "$0")/.." && pwd)"
+
+for file in \
+  "$ROOT_DIR/.github/workflows/build-ghosttykit.yml" \
+  "$ROOT_DIR/scripts/setup.sh" \
+  "$ROOT_DIR/scripts/build-sign-upload.sh"
+do
+  if ! grep -Fq -- '-Dxcframework-target=universal' "$file"; then
+    echo "FAIL: $file must build GhosttyKit with -Dxcframework-target=universal"
+    exit 1
+  fi
+done
+
+if ! awk '
+  /\/\* Release \*\// { in_release=1; next }
+  in_release && /ONLY_ACTIVE_ARCH = YES;/ { saw_yes=1 }
+  in_release && /ONLY_ACTIVE_ARCH = NO;/ { saw_no=1 }
+  in_release && /name = Release;/ { in_release=0 }
+  END { exit !(saw_no && !saw_yes) }
+' "$ROOT_DIR/GhosttyTabs.xcodeproj/project.pbxproj"; then
+  echo "FAIL: Release configurations in project.pbxproj must use ONLY_ACTIVE_ARCH = NO"
+  exit 1
+fi
+
+echo "PASS: GhosttyKit builds universal and Release configs disable ONLY_ACTIVE_ARCH"
diff --git a/tests/test_nightly_universal_build.sh b/tests/test_nightly_universal_build.sh
new file mode 100644
index 00000000..e86dbf36
--- /dev/null
+++ b/tests/test_nightly_universal_build.sh
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# Regression test for dual nightly macOS tracks.
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "$0")/.." && pwd)"
+WORKFLOW_FILE="$ROOT_DIR/.github/workflows/nightly.yml"
+
+if ! awk '
+  /^      - name: Build Apple Silicon app \(Release\)/ { in_arm=1; next }
+  /^      - name: Build universal app \(Release\)/ { in_universal=1; next }
+  in_arm && /^      - name:/ { in_arm=0 }
+  in_universal && /^      - name:/ { in_universal=0 }
+  in_arm && /-destination '\''platform=macOS,arch=arm64'\''/ { saw_arm_destination=1 }
+  in_arm && /ARCHS="arm64"/ { saw_arm_archs=1 }
+  in_arm && /ONLY_ACTIVE_ARCH=YES/ { saw_arm_only_active_arch=1 }
+  in_universal && /-destination '\''generic\/platform=macOS'\''/ { saw_universal_destination=1 }
+  in_universal && /ARCHS="arm64 x86_64"/ { saw_universal_archs=1 }
+  in_universal && /ONLY_ACTIVE_ARCH=NO/ { saw_universal_only_active_arch=1 }
+  END {
+    exit !(saw_arm_destination && saw_arm_archs && saw_arm_only_active_arch && saw_universal_destination && saw_universal_archs && saw_universal_only_active_arch)
+  }
+' "$WORKFLOW_FILE"; then
+  echo "FAIL: nightly workflow must force Apple Silicon nightly to arm64-only and universal nightly to both slices"
+  exit 1
+fi
+
+if ! awk '
+  /^      - name: Verify nightly binary architectures/ { in_verify=1; next }
+  in_verify && /^      - name:/ { in_verify=0 }
+  in_verify && /lipo -archs "\$ARM_APP_BINARY"/ { saw_arm_app=1 }
+  in_verify && /lipo -archs "\$ARM_CLI_BINARY"/ { saw_arm_cli=1 }
+  in_verify && /lipo -archs "\$APP_BINARY"/ { saw_app=1 }
+  in_verify && /lipo -archs "\$CLI_BINARY"/ { saw_cli=1 }
+  in_verify && /\[\[ "\$ARM_APP_ARCHS" == "arm64" \]\]/ { saw_arm_app_assert=1 }
+  in_verify && /\[\[ "\$ARM_CLI_ARCHS" == "arm64" \]\]/ { saw_arm_cli_assert=1 }
+  END { exit !(saw_arm_app && saw_arm_cli && saw_app && saw_cli && saw_arm_app_assert && saw_arm_cli_assert) }
+' "$WORKFLOW_FILE"; then
+  echo "FAIL: nightly workflow must verify arm-only and universal slices with lipo"
+  exit 1
+fi
+
+if ! grep -Fq 'com.cmuxterm.app.nightly.universal' "$WORKFLOW_FILE"; then
+  echo "FAIL: nightly workflow must set a distinct .universal bundle ID"
+  exit 1
+fi
+
+if ! grep -Fq 'https://github.com/manaflow-ai/cmux/releases/download/nightly/appcast-universal.xml' "$WORKFLOW_FILE"; then
+  echo "FAIL: nightly workflow must publish a separate universal appcast feed"
+  exit 1
+fi
+
+if ! grep -Fq './scripts/sparkle_generate_appcast.sh "$NIGHTLY_UNIVERSAL_DMG_IMMUTABLE" nightly appcast-universal.xml' "$WORKFLOW_FILE"; then
+  echo "FAIL: nightly workflow must generate a separate universal appcast"
+  exit 1
+fi
+
+if ! grep -Fq "core.setOutput('should_publish', isMainRef ? 'true' : 'false');" "$WORKFLOW_FILE"; then
+  echo "FAIL: nightly decide step must expose should_publish based on whether the ref is main"
+  exit 1
+fi
+
+if ! awk '
+  /^      - name: Upload branch nightly artifacts/ { in_upload=1; next }
+  in_upload && /^      - name:/ { in_upload=0 }
+  in_upload && /if: needs\.decide\.outputs\.should_publish != '\''true'\''/ { saw_if=1 }
+  in_upload && /uses: actions\/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4/ { saw_upload=1 }
+  in_upload && /cmux-nightly-macos\*\.dmg/ { saw_arm_artifacts=1 }
+  in_upload && /cmux-nightly-universal-macos\*\.dmg/ { saw_universal_artifacts=1 }
+  in_upload && /appcast-universal\.xml/ { saw_universal_appcast=1 }
+  END { exit !(saw_if && saw_upload && saw_arm_artifacts && saw_universal_artifacts && saw_universal_appcast) }
+' "$WORKFLOW_FILE"; then
+  echo "FAIL: non-main nightly runs must upload both nightly variants and both appcasts"
+  exit 1
+fi
+
+if ! awk '
+  /^      - name: Move nightly tag to built commit/ { in_move=1; next }
+  in_move && /^      - name:/ { in_move=0 }
+  in_move && /if: needs\.decide\.outputs\.should_publish == '\''true'\''/ { saw_move_if=1 }
+  END { exit !saw_move_if }
+' "$WORKFLOW_FILE"; then
+  echo "FAIL: moving the nightly tag must be gated to main nightly publishes"
+  exit 1
+fi
+
+if ! awk '
+  /^      - name: Publish nightly release assets/ { in_publish=1; next }
+  in_publish && /^      - name:/ { in_publish=0 }
+  in_publish && /if: needs\.decide\.outputs\.should_publish == '\''true'\''/ { saw_publish_if=1 }
+  in_publish && /cmux-nightly-universal-macos-\$\{\{ github\.run_id \}\}\*\.dmg/ { saw_universal_immutable=1 }
+  in_publish && /cmux-nightly-universal-macos\.dmg/ { saw_universal_stable=1 }
+  in_publish && /appcast-universal\.xml/ { saw_universal_appcast=1 }
+  END { exit !(saw_publish_if && saw_universal_immutable && saw_universal_stable && saw_universal_appcast) }
+' "$WORKFLOW_FILE"; then
+  echo "FAIL: main nightly publish must include the universal assets and appcast"
+  exit 1
+fi
+
+echo "PASS: nightly workflow keeps separate Apple Silicon and universal nightly tracks"