@mytec: feat: Phase 3.0 Architecture Refactor ✅

Major refactoring of RFCP backend:
- Modular propagation models (8 models)
- SharedMemoryManager for terrain data
- ProcessPoolExecutor parallel processing
- WebSocket progress streaming
- Building filtering pipeline (351k → 15k)
- 82 unit tests

Performance: Standard preset 38s → 5s (7.6x speedup)

Known issue: Detailed preset timeout (fix in 3.1.0)

desktop/main.js

@@ -446,12 +446,17 @@ function killAllRfcpProcesses() {
 }
 
 /**
- * Graceful shutdown: API call first, then multi-strategy force kill.
+ * Graceful shutdown: API call first, then PID-tree kill, then name-based kill.
+ *
+ * The backend's /shutdown endpoint kills workers by name and schedules
+ * os._exit(3s) as a safety net.  We then do PID-tree kill (most reliable
+ * on Windows — catches all child processes) while the main PID is still
+ * alive, followed by name-based kill as final sweep.
  */
 async function gracefulShutdown() {
   log('[SHUTDOWN] Starting graceful shutdown...');
 
-  // Step 1: Ask backend to clean up workers and exit
+  // Step 1: Ask backend to clean up workers (pool shutdown + name kill)
   try {
     const controller = new AbortController();
     const timeout = setTimeout(() => controller.abort(), 2000);
@@ -461,16 +466,20 @@ async function gracefulShutdown() {
     });
     clearTimeout(timeout);
     log('[SHUTDOWN] Backend acknowledged shutdown');
-    // Wait for backend to cleanup
-    await new Promise(r => setTimeout(r, 1000));
+    // Brief wait for pool.shutdown() to take effect
+    await new Promise(r => setTimeout(r, 500));
   } catch (_e) {
     log('[SHUTDOWN] Backend did not respond — force killing');
   }
 
-  // Step 2: Force kill everything
+  // Step 2: PID-tree kill — most reliable, catches all child processes
+  // Must run while main backend PID is still alive (before os._exit safety net)
+  killBackend();
+
+  // Step 3: Name-based kill — catches any orphans not in the process tree
   killAllRfcpProcesses();
 
-  // Step 3: Wait and verify
+  // Step 4: Wait and verify
   await new Promise(r => setTimeout(r, 500));
   log('[SHUTDOWN] Shutdown complete');
 }