Switch macOS builds to Tahoe (Beta 7 currently) (#8328)

This switches our macOS builds to build on Tahoe, rather than on
Sequoia.

The primary motivation is to get builds out using a new Xcode version
(our builds at the time of writing this are _still produced_ with beta
1! ONE!). Every subsequent beta has had bugs that have prevented us from
upgrading, amusingly enough. But the later betas _also_ have a bunch of
fixes I want to get in. I hope this one works...

The reason we have to use Tahoe instead of Sequoia is because on
Sequoia, builds in CI _crash xcodebuild_. This is definitely an Apple
bug but I can't reproduce it locally to create a bug report, so I'm not
sure what to do.

.github/workflows/release-pr.yml

@@ -47,7 +47,7 @@ jobs:
           sentry-cli dif upload --project ghostty --wait dsym.zip
 
   build-macos:
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -57,9 +57,9 @@ jobs:
           fetch-depth: 0
 
       # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -95,6 +95,7 @@ jobs:
         run: |
           cd macos
           sudo xcode-select -s /Applications/Xcode_26.0.app
+          xcodebuild -version
           xcodebuild -target Ghostty -configuration Release
 
       # We inject the "build number" as simply the number of commits since HEAD.
@@ -201,7 +202,7 @@ jobs:
           destination-dir: ./
 
   build-macos-debug:
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -211,9 +212,9 @@ jobs:
           fetch-depth: 0
 
       # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -249,6 +250,7 @@ jobs:
         run: |
           cd macos
           sudo xcode-select -s /Applications/Xcode_26.0.app
+          xcodebuild -version
           xcodebuild -target Ghostty -configuration Release
 
       # We inject the "build number" as simply the number of commits since HEAD.

.github/workflows/release-tag.yml

@@ -120,7 +120,7 @@ jobs:
 
   build-macos:
     needs: [setup]
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     env:
       GHOSTTY_VERSION: ${{ needs.setup.outputs.version }}
@@ -130,9 +130,9 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -141,6 +141,9 @@ jobs:
       - name: XCode Select
         run: sudo xcode-select -s /Applications/Xcode_16.4.app
 
+      - name: Xcode Version
+        run: xcodebuild -version
+
       - name: Setup Sparkle
         env:
           SPARKLE_VERSION: 2.6.4
@@ -291,7 +294,7 @@ jobs:
 
   appcast:
     needs: [setup, build-macos]
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     env:
       GHOSTTY_VERSION: ${{ needs.setup.outputs.version }}
       GHOSTTY_BUILD: ${{ needs.setup.outputs.build }}

.github/workflows/release-tip.yml

@@ -154,7 +154,7 @@ jobs:
         )
       }}
 
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -163,10 +163,10 @@ jobs:
           # Important so that build number generation works
           fetch-depth: 0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -374,7 +374,7 @@ jobs:
         )
       }}
 
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -383,10 +383,10 @@ jobs:
           # Important so that build number generation works
           fetch-depth: 0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -554,7 +554,7 @@ jobs:
         )
       }}
 
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -563,10 +563,10 @@ jobs:
           # Important so that build number generation works
           fetch-depth: 0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty

.github/workflows/test.yml

@@ -18,7 +18,6 @@ jobs:
       - build-nix
       - build-snap
       - build-macos
-      - build-macos-tahoe
       - build-macos-matrix
       - build-windows
       - flatpak-check-zig-cache
@@ -273,16 +272,16 @@ jobs:
             ghostty-source.tar.gz
 
   build-macos:
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     needs: test
     steps:
       - name: Checkout code
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -315,7 +314,7 @@ jobs:
           cd macos
           xcodebuild -target Ghostty-iOS "CODE_SIGNING_ALLOWED=NO"
 
-  build-macos-tahoe:
+  build-macos-matrix:
     runs-on: namespace-profile-ghostty-macos-tahoe
     needs: test
     steps:
@@ -334,45 +333,8 @@ jobs:
       - name: Xcode Select
         run: sudo xcode-select -s /Applications/Xcode_26.0.app
 
-      - name: get the Zig deps
+      - name: Xcode Version
-        id: deps
+        run: xcodebuild -version
-        run: nix build -L .#deps && echo "deps=$(readlink ./result)" >> $GITHUB_OUTPUT
-
-      # GhosttyKit is the framework that is built from Zig for our native
-      # Mac app to access.
-      - name: Build GhosttyKit
-        run: nix develop -c zig build --system ${{ steps.deps.outputs.deps }} -Demit-macos-app=false
-
-      # The native app is built with native Xcode tooling. This also does
-      # codesigning. IMPORTANT: this must NOT run in a Nix environment.
-      # Nix breaks xcodebuild so this has to be run outside.
-      - name: Build Ghostty.app
-        run: cd macos && xcodebuild -target Ghostty
-
-      # Build the iOS target without code signing just to verify it works.
-      - name: Build Ghostty iOS
-        run: |
-          cd macos
-          xcodebuild -target Ghostty-iOS "CODE_SIGNING_ALLOWED=NO"
-
-  build-macos-matrix:
-    runs-on: namespace-profile-ghostty-macos-sequoia
-    needs: test
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-
-      # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
-        with:
-          nix_path: nixpkgs=channel:nixos-unstable
-      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
-        with:
-          name: ghostty
-          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
-
-      - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.0.app
 
       - name: get the Zig deps
         id: deps
@@ -672,16 +634,16 @@ jobs:
           nix develop -c zig build -Dsentry=${{ matrix.sentry }}
 
   test-macos:
-    runs-on: namespace-profile-ghostty-macos-sequoia
+    runs-on: namespace-profile-ghostty-macos-tahoe
     needs: test
     steps:
       - name: Checkout code
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -690,6 +652,9 @@ jobs:
       - name: Xcode Select
         run: sudo xcode-select -s /Applications/Xcode_26.0.app
 
+      - name: Xcode Version
+        run: xcodebuild -version
+
       - name: get the Zig deps
         id: deps
         run: nix build -L .#deps && echo "deps=$(readlink ./result)" >> $GITHUB_OUTPUT