fix: move tmate debug session inside pytest step to avoid hanging

The issue was that tmate was placed before pytest step, but the hang
occurs during pytest execution. Now tmate starts inside the test step
and provides connection info before running tests.

.github/workflows/build-reusable.yml

@@ -228,14 +228,6 @@ jobs:
           python -c "from leann_backend_diskann import _diskannpy; print('_diskannpy imported successfully')" || echo "Failed to import _diskannpy"
           ls -la $(python -c "import leann_backend_diskann; import os; print(os.path.dirname(leann_backend_diskann.__file__))" 2>/dev/null) 2>/dev/null || echo "Failed to list module directory"
 
-      # Enable tmate debugging session if requested
-      - name: Setup tmate session for debugging
-        if: ${{ inputs.debug_enabled }}
-        uses: mxschmitt/action-tmate@v3
-        with:
-          detached: true
-          timeout-minutes: 30
-          limit-access-to-actor: true
       - name: Run tests with pytest
         env:
           CI: true  # Mark as CI environment to skip memory-intensive tests
@@ -249,6 +241,31 @@ jobs:
           # Activate virtual environment
           source .venv/bin/activate || source .venv/Scripts/activate
 
+          # Start tmate session INSIDE the test step if debug enabled
+          if [[ "${{ inputs.debug_enabled }}" == "true" ]]; then
+            echo "🔧 DEBUG MODE: Starting tmate session before tests..."
+            # Install tmate if not available
+            if ! command -v tmate &> /dev/null; then
+              if [[ "$RUNNER_OS" == "Linux" ]]; then
+                sudo apt-get update && sudo apt-get install -y tmate
+              elif [[ "$RUNNER_OS" == "macOS" ]]; then
+                brew install tmate
+              fi
+            fi
+            
+            # Start tmate session in background
+            tmate -S debug-session new-session -d 
+            echo "🔗 Tmate session created. Connection info:"
+            tmate -S debug-session display -p '#{tmate_ssh}'
+            echo "🔗 Web session: $(tmate -S debug-session display -p '#{tmate_web}')"
+            echo "⏱️  Session will timeout after 30 minutes"
+            echo "💡 You can now SSH in and run: pytest tests/ -vv --capture=no"
+            echo "💡 Or run diagnostics: bash scripts/diagnose_hang.sh"
+            echo ""
+            echo "Waiting 60 seconds for you to connect..."
+            sleep 60
+          fi
+
           # Define comprehensive diagnostic function
           diag() {
             echo "===== COMPREHENSIVE DIAGNOSTICS BEGIN ====="