fix: add hash-based deduplication to OpenAPI spec update workflow

.github/workflows/update-openapi-spec.yml

@@ -70,6 +70,43 @@ jobs:
             echo "new-version=$NEW_VERSION" >> $GITHUB_OUTPUT
             echo "new-paths=$NEW_PATHS" >> $GITHUB_OUTPUT
             echo "New spec version: $NEW_VERSION, paths: $NEW_PATHS"
+
+            # Compute content hash for deduplication
+            SPEC_HASH=$(sha256sum resources/openapi-spec.json | cut -d' ' -f1)
+            echo "spec-sha256=$SPEC_HASH" >> $GITHUB_OUTPUT
+            echo "Spec content hash: $SPEC_HASH"
+          fi
+
+      - name: Determine branch name
+        id: branch-info
+        if: steps.update-spec.outputs.has-changes == 'true'
+        run: |
+          SPEC_HASH="${{ steps.update-spec.outputs.spec-sha256 }}"
+          if [ -z "$SPEC_HASH" ] || [ "$SPEC_HASH" = "unknown" ]; then
+            SPEC_HASH=$(sha256sum resources/openapi-spec.json | cut -d' ' -f1)
+          fi
+          BRANCH="update-openapi-spec-${SPEC_HASH:0:12}"
+          echo "branch=$BRANCH" >> $GITHUB_OUTPUT
+          echo "Using branch $BRANCH for this update"
+
+      - name: Check for existing PR
+        id: existing-pr
+        if: steps.update-spec.outputs.has-changes == 'true'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          BRANCH="${{ steps.branch-info.outputs.branch }}"
+          if [ -z "$BRANCH" ]; then
+            echo "exists=false" >> $GITHUB_OUTPUT
+            exit 0
+          fi
+
+          PR_COUNT=$(gh pr list --state open --head "$BRANCH" --repo "$GITHUB_REPOSITORY" --json number --jq 'length')
+          if [ "$PR_COUNT" -gt 0 ]; then
+            echo "An open PR already exists for $BRANCH (count: $PR_COUNT)"
+            echo "exists=true" >> $GITHUB_OUTPUT
+          else
+            echo "exists=false" >> $GITHUB_OUTPUT
           fi
 
       - name: Update search database
@@ -96,7 +133,7 @@ jobs:
           fi
 
       - name: Create Pull Request
-        if: steps.update-spec.outputs.has-changes == 'true'
+        if: steps.update-spec.outputs.has-changes == 'true' && steps.existing-pr.outputs.exists != 'true'
         uses: peter-evans/create-pull-request@v6
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
@@ -107,9 +144,10 @@ jobs:
             - Version: ${{ steps.current-spec.outputs.current-version }} → ${{ steps.update-spec.outputs.new-version }}
             - Paths: ${{ steps.current-spec.outputs.current-paths }} → ${{ steps.update-spec.outputs.new-paths }}
             - Regenerated DuckDB search database for API search functionality
+            - Content hash: ${{ steps.update-spec.outputs.spec-sha256 }}
 
             Auto-generated by update-openapi-spec workflow
-          branch: update-openapi-spec-${{ github.run_number }}
+          branch: ${{ steps.branch-info.outputs.branch }}
           delete-branch: true
           title: "chore: update OpenAPI specification to v${{ steps.update-spec.outputs.new-version }}"
           body: |
@@ -154,12 +192,18 @@ jobs:
       - name: Summary
         run: |
           if [ "${{ steps.update-spec.outputs.has-changes }}" = "true" ]; then
-            echo "✅ OpenAPI spec and search database updated successfully"
-            echo "📊 Version: ${{ steps.current-spec.outputs.current-version }} → \
-              ${{ steps.update-spec.outputs.new-version }}"
-            echo "🔧 Paths: ${{ steps.current-spec.outputs.current-paths }} → ${{ steps.update-spec.outputs.new-paths }}"
-            echo "🗃️ Search database regenerated for Python API search MCP server"
-            echo "📋 PR created with both OpenAPI spec and DuckDB database updates"
+            if [ "${{ steps.existing-pr.outputs.exists }}" = "true" ]; then
+              echo "ℹ️ OpenAPI spec update matches an existing open PR."
+              echo "🔁 Reusing branch ${{ steps.branch-info.outputs.branch }}"
+            else
+              echo "✅ OpenAPI spec and search database updated successfully"
+              echo "📊 Version: ${{ steps.current-spec.outputs.current-version }} → \
+                ${{ steps.update-spec.outputs.new-version }}"
+              echo "🔧 Paths: ${{ steps.current-spec.outputs.current-paths }} → \
+                ${{ steps.update-spec.outputs.new-paths }}"
+              echo "🗃️ Search database regenerated for Python API search MCP server"
+              echo "📋 PR created with both OpenAPI spec and DuckDB database updates"
+            fi
           else
             echo "ℹ️ OpenAPI spec is already up to date - no database update needed"
           fi