ci: point xcode to the mounted cache path by Namespace (#10978)

.github/workflows/release-tag.yml

@@ -184,7 +184,9 @@ jobs:
       - name: Build Ghostty.app
         run: |
           cd macos
-          xcodebuild -target Ghostty -configuration Release
+          xcodebuild -target Ghostty -configuration Release \
+            COMPILATION_CACHE_CAS_PATH=/Users/runner/Library/Developer/Xcode/DerivedData/CompilationCache.noindex \
+            COMPILATION_CACHE_KEEP_CAS_DIRECTORY=YES
 
       # Add all our metadata to Info.plist so we can reference it later.
       - name: Update Info.plist

.github/workflows/release-tip.yml

@@ -278,7 +278,9 @@ jobs:
       - name: Build Ghostty.app
         run: |
           cd macos
-          xcodebuild -target Ghostty -configuration Release
+          xcodebuild -target Ghostty -configuration Release \
+            COMPILATION_CACHE_CAS_PATH=/Users/runner/Library/Developer/Xcode/DerivedData/CompilationCache.noindex \
+            COMPILATION_CACHE_KEEP_CAS_DIRECTORY=YES
 
       # We inject the "build number" as simply the number of commits since HEAD.
       # This will be a monotonically always increasing build number that we use.
@@ -531,7 +533,9 @@ jobs:
       - name: Build Ghostty.app
         run: |
           cd macos
-          xcodebuild -target Ghostty -configuration Release
+          xcodebuild -target Ghostty -configuration Release \
+            COMPILATION_CACHE_CAS_PATH=/Users/runner/Library/Developer/Xcode/DerivedData/CompilationCache.noindex \
+            COMPILATION_CACHE_KEEP_CAS_DIRECTORY=YES
 
       # We inject the "build number" as simply the number of commits since HEAD.
       # This will be a monotonically always increasing build number that we use.
@@ -725,7 +729,9 @@ jobs:
       - name: Build Ghostty.app
         run: |
           cd macos
-          xcodebuild -target Ghostty -configuration Release
+          xcodebuild -target Ghostty -configuration Release \
+            COMPILATION_CACHE_CAS_PATH=/Users/runner/Library/Developer/Xcode/DerivedData/CompilationCache.noindex \
+            COMPILATION_CACHE_KEEP_CAS_DIRECTORY=YES
 
       # We inject the "build number" as simply the number of commits since HEAD.
       # This will be a monotonically always increasing build number that we use.

.github/workflows/test.yml

@@ -644,13 +644,19 @@ jobs:
       # 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
+        run: |
+          cd macos
+          xcodebuild -target Ghostty \
+            COMPILATION_CACHE_CAS_PATH=/Users/runner/Library/Developer/Xcode/DerivedData/CompilationCache.noindex \
+            COMPILATION_CACHE_KEEP_CAS_DIRECTORY=YES
 
       # 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"
+          xcodebuild -target Ghostty-iOS "CODE_SIGNING_ALLOWED=NO" \
+            COMPILATION_CACHE_CAS_PATH=/Users/runner/Library/Developer/Xcode/DerivedData/CompilationCache.noindex \
+            COMPILATION_CACHE_KEEP_CAS_DIRECTORY=YES
 
   build-macos-freetype:
     runs-on: namespace-profile-ghostty-macos-tahoe