Skip unchanged Unity proto generation in CI

.github/workflows/unity_build.yml

@@ -16,6 +16,8 @@ on:
       - "scripts/build_windows_plugin.sh"
       - "ci/github_actions/build_unity.sh"
       - "ci/github_actions/test_unity_editmode.sh"
+      - "ci/github_actions/detect_unity_proto_changes.sh"
+      - "ci/github_actions/ensure_unity_protos.sh"
       - "ci/github_actions/ensure_bazel_installed.sh"
       - ".github/actions/setup-bazel/**"
       - "ci/github_actions/detect_addressables_changes.sh"
@@ -41,6 +43,8 @@ on:
       - "scripts/build_windows_plugin.sh"
       - "ci/github_actions/build_unity.sh"
       - "ci/github_actions/test_unity_editmode.sh"
+      - "ci/github_actions/detect_unity_proto_changes.sh"
+      - "ci/github_actions/ensure_unity_protos.sh"
       - "ci/github_actions/ensure_bazel_installed.sh"
       - ".github/actions/setup-bazel/**"
       - "ci/github_actions/detect_addressables_changes.sh"
@@ -103,15 +107,34 @@ jobs:
           clean: false  # Library/ persists between runs on self-hosted runners
           fetch-depth: 2
 
+      - name: Detect Unity proto changes
+        id: unity-protos
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            BASE_SHA="${{ github.event.pull_request.base.sha }}"
+          else
+            BASE_SHA="${{ github.event.before }}"
+          fi
+
+          ./ci/github_actions/detect_unity_proto_changes.sh "$BASE_SHA" "${{ github.sha }}"
+
       - name: Clean stale files
         run: |
           git clean -ffd
           UNITY_ROOT="src/main/csharp/net/eagle0/clients/unity/eagle0"
           # These ignored proto outputs are mutually exclusive across proto-generation
-          # layouts. Clean both before regenerating to avoid stale DLL/source duplicates
-          # when a self-hosted runner switches between main and PR branches.
+          # layouts. Always clean generated source protos; clean the DLL only when
+          # proto inputs changed so unchanged runs can reuse the previous DLL
+          # without paying Bazel analysis/startup cost.
           rm -rf "$UNITY_ROOT/Assets/GeneratedProtos"
-          rm -rf "$UNITY_ROOT/Assets/Plugins/Eagle0Protos"
+          if [ "${{ steps.unity-protos.outputs.changed }}" = "true" ]; then
+            rm -rf "$UNITY_ROOT/Assets/Plugins/Eagle0Protos"
+          else
+            echo "Keeping existing Eagle0Protos DLL because Unity proto inputs are unchanged."
+          fi
           LIBRARY_DIR="src/main/csharp/net/eagle0/clients/unity/eagle0/Library"
           VERSION_CACHE="$LIBRARY_DIR/.last_unity_version"
           PROJECT_VERSION_FILE="src/main/csharp/net/eagle0/clients/unity/eagle0/ProjectSettings/ProjectVersion.txt"
@@ -158,6 +181,8 @@ jobs:
         uses: ./.github/actions/setup-bazel
 
       - name: Run Unity EditMode tests
+        env:
+          UNITY_PROTOS_CHANGED: ${{ steps.unity-protos.outputs.changed }}
         run: ./ci/github_actions/test_unity_editmode.sh
 
       - name: Archive EditMode test artifacts
@@ -218,15 +243,34 @@ jobs:
           clean: false  # Library/ persists between runs on self-hosted runners
           fetch-depth: 2  # Keep the previous main commit available for Addressables change detection
 
+      - name: Detect Unity proto changes
+        id: unity-protos
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            BASE_SHA="${{ github.event.pull_request.base.sha }}"
+          else
+            BASE_SHA="${{ github.event.before }}"
+          fi
+
+          ./ci/github_actions/detect_unity_proto_changes.sh "$BASE_SHA" "${{ github.sha }}"
+
       - name: Clean stale files
         run: |
           git clean -ffd
           UNITY_ROOT="src/main/csharp/net/eagle0/clients/unity/eagle0"
           # These ignored proto outputs are mutually exclusive across proto-generation
-          # layouts. Clean both before regenerating to avoid stale DLL/source duplicates
-          # when a self-hosted runner switches between main and PR branches.
+          # layouts. Always clean generated source protos; clean the DLL only when
+          # proto inputs changed so unchanged runs can reuse the previous DLL
+          # without paying Bazel analysis/startup cost.
           rm -rf "$UNITY_ROOT/Assets/GeneratedProtos"
-          rm -rf "$UNITY_ROOT/Assets/Plugins/Eagle0Protos"
+          if [ "${{ steps.unity-protos.outputs.changed }}" = "true" ]; then
+            rm -rf "$UNITY_ROOT/Assets/Plugins/Eagle0Protos"
+          else
+            echo "Keeping existing Eagle0Protos DLL because Unity proto inputs are unchanged."
+          fi
           LIBRARY_DIR="src/main/csharp/net/eagle0/clients/unity/eagle0/Library"
           VERSION_CACHE="$LIBRARY_DIR/.last_unity_version"
           PROJECT_VERSION_FILE="src/main/csharp/net/eagle0/clients/unity/eagle0/ProjectSettings/ProjectVersion.txt"
@@ -287,6 +331,8 @@ jobs:
 
           ./ci/github_actions/detect_addressables_changes.sh "$BASE_SHA" "${{ github.sha }}"
       - name: Build Windows unity
+        env:
+          UNITY_PROTOS_CHANGED: ${{ steps.unity-protos.outputs.changed }}
         run: ./ci/github_actions/build_unity.sh "${{ env.EAGLE0_BUILD_DIR }}/eagle0WIN" "${{ steps.addressables.outputs.changed }}" "${{ steps.addressables.outputs.changed }}"
 
       - name: Save build SHA for Bee/ cache invalidation

ci/github_actions/build_unity.sh

@@ -8,7 +8,7 @@ BUILD_BASE="${EAGLE0_BUILD_DIR:-/tmp/eagle0}"
 COMMIT=$(/usr/bin/git rev-parse --short HEAD)
 
 /bin/echo "build protos"
-./scripts/build_protos.sh
+./ci/github_actions/ensure_unity_protos.sh
 
 git log -3
 

ci/github_actions/detect_unity_proto_changes.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+BASE_SHA=${1:-}
+HEAD_SHA=${2:-HEAD}
+OUTPUT_FILE=${GITHUB_OUTPUT:-}
+
+if [ -z "$BASE_SHA" ] || [[ "$BASE_SHA" =~ ^0+$ ]]; then
+    echo "No usable base SHA for this run; building Unity protos as a safe default."
+    changed=true
+elif ! git cat-file -e "$BASE_SHA^{commit}"; then
+    echo "Base SHA $BASE_SHA is not available locally; building Unity protos as a safe default."
+    changed=true
+else
+    UNITY_PROTO_INPUT_PREFIXES=(
+        "src/main/protobuf/"
+        "src/main/csharp/net/eagle0/clients/unity/eagle0/BUILD.bazel"
+        "scripts/build_protos.sh"
+        "ci/github_actions/detect_unity_proto_changes.sh"
+        "ci/github_actions/ensure_unity_protos.sh"
+        "MODULE.bazel"
+        "MODULE.bazel.lock"
+        ".bazelrc"
+        "WORKSPACE"
+    )
+
+    is_unity_proto_input() {
+        local file="$1"
+        for prefix in "${UNITY_PROTO_INPUT_PREFIXES[@]}"; do
+            if [[ "$file" == "$prefix"* ]]; then
+                return 0
+            fi
+        done
+
+        return 1
+    }
+
+    changed=false
+    while IFS= read -r file; do
+        if is_unity_proto_input "$file"; then
+            echo "Unity-proto-impacting change: $file"
+            changed=true
+            break
+        fi
+    done < <(git diff --name-only "$BASE_SHA" "$HEAD_SHA")
+fi
+
+if [ "$changed" = "true" ]; then
+    echo "Building Unity protos because their inputs changed."
+else
+    echo "Skipping Unity proto build; no Unity proto inputs changed."
+fi
+
+if [ -n "$OUTPUT_FILE" ]; then
+    echo "changed=$changed" >> "$OUTPUT_FILE"
+else
+    echo "changed=$changed"
+fi

ci/github_actions/ensure_unity_protos.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+UNITY_ROOT="src/main/csharp/net/eagle0/clients/unity/eagle0"
+PLUGIN_DIR="$UNITY_ROOT/Assets/Plugins/Eagle0Protos"
+GENERATED_SOURCES_DIR="$UNITY_ROOT/Assets/GeneratedProtos"
+PROTO_DLL="$PLUGIN_DIR/Eagle0Protos.dll"
+PROTO_XML="$PLUGIN_DIR/Eagle0Protos.xml"
+UNITY_PROTOS_CHANGED=${UNITY_PROTOS_CHANGED:-true}
+
+if [ "$UNITY_PROTOS_CHANGED" = "false" ] && [ -s "$PROTO_DLL" ] && [ -s "$PROTO_XML" ]; then
+    echo "Skipping Unity proto build; existing Eagle0Protos DLL/XML are present and proto inputs are unchanged."
+    rm -rf "$GENERATED_SOURCES_DIR"
+    exit 0
+fi
+
+if [ "$UNITY_PROTOS_CHANGED" = "false" ]; then
+    echo "Unity proto inputs are unchanged, but generated DLL/XML are missing; rebuilding."
+fi
+
+./scripts/build_protos.sh

ci/github_actions/test_unity_editmode.sh

@@ -16,7 +16,7 @@ RESULTS_PATH="${BUILD_BASE}/editmode-test-results.xml"
 mkdir -p "$BUILD_BASE"
 
 echo "Building protos"
-./scripts/build_protos.sh
+./ci/github_actions/ensure_unity_protos.sh
 
 echo "Running Unity EditMode tests"