core: updated validate yaml for valid pr check

.github/workflows/datastructures-algorithms-validate.yaml

@@ -1,27 +1,44 @@
 name: datastructures-algorithms-validate
 
-# Triggers when a PR is opened or updated, targeting the 'release' branch
+# Triggers when a PR is opened or updated, targeting 'release' OR 'main'
 on:
   pull_request:
     types: [opened, synchronize]
-    branches: 
-      - 'release'
-      - 'main'
+    branches:
+      - release
+      - main
 
 jobs:
-  # --- Job 1: Lint, Build, and Test ---
+  # --- Job 1: The "Gate" Job ---
+  # This job runs first to validate the PR path.
+  enforce-branch-strategy:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Block invalid PR path
+        # This step ONLY runs if the path is INVALID
+        # Wrap the entire logical operation in ${{...}}
+        if: ${{ !((startsWith(github.event.pull_request.head.ref, 'feature-') && github.event.pull_request.base.ref == 'release') || (github.event.pull_request.head.ref == 'release' && github.event.pull_request.base.ref == 'main')) }}
+        run: |
+          echo "::error:: This PR path (${{ github.event.pull_request.head.ref }} -> ${{ github.event.pull_request.base.ref }}) is not allowed."
+          echo "::error:: Allowed paths are: 'feature-*' -> 'release' OR 'release' -> 'main'."
+          exit 1
+
+      - name: Approve valid PR path
+        # This step ONLY runs if the path is VALID (for logging)
+        if: (startsWith(github.event.pull_request.head.ref, 'feature-') && github.event.pull_request.base.ref == 'release') || (github.event.pull_request.head.ref == 'release' && github.event.pull_request.base.ref == 'main')
+        run: |
+          echo "Valid PR path. Proceeding to build and test..."
+
+  # --- Job 2: Lint, Build, and Test ---
   lint-build-test:
-
-    # This job will ONLY run if:
-    # 1. (Source is 'feature-*' AND Target is 'release')
-    # OR
-    # 2. (Source is 'release' AND Target is 'main')
-    if: (startsWith(github.event.pull_request.head.ref, 'feature-') && github.event.pull_request.base.ref == 'release') || (github.event.pull_request.head.ref == 'release' && github.event.pull_request.base.ref == 'main')
+    # This job WAITS for 'enforce-branch-strategy' to succeed
+    needs: enforce-branch-strategy
+
     runs-on: windows-latest
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4 # Use v4
+      uses: actions/checkout@v4
 
     - name: Setup MSVC
       uses: ilammy/msvc-dev-cmd@v1