feat: #61 Plugin system — backend API, sandboxed Web Worker, hooks wired to real app flow, user guide, 47+21 tests

backend/main.py

@@ -614,6 +614,22 @@ async def lifespan(app: FastAPI):
         loop = asyncio.get_running_loop()
         await loop.run_in_executor(_search_executor, init_inverted_index)
 
+        # Scan for plugins in all vaults
+        logger.info("Scanning for plugins...")
+        from backend.indexer import vault_config
+        from backend.plugins import get_plugin_registry
+        registry = get_plugin_registry()
+        for vault_name, cfg in vault_config.items():
+            vault_path = cfg.get("path")
+            if vault_path:
+                try:
+                    plugins = registry.scan_vault(vault_name, vault_path)
+                    logger.info(f"Vault '{vault_name}': found {len(plugins)} plugin(s)")
+                    from backend.plugins import emit_vault_mounted
+                    emit_vault_mounted(vault_name, vault_path)
+                except Exception as e:
+                    logger.warning(f"Plugin scan failed for vault '{vault_name}': {e}")
+
         # Start file watcher
         config = _load_config()
         watcher_enabled = config.get("watcher_enabled", True)
@@ -738,6 +754,14 @@ try:
 except ImportError as e:
     logger.warning(f"Could not load push notifications router: {e}")
 
+# Plugins system endpoints
+try:
+    from backend.plugins import router as plugins_router
+    app.include_router(plugins_router)
+    logger.info("Plugins router mounted at /api/plugins/*")
+except ImportError as e:
+    logger.warning(f"Could not load plugins router: {e}")
+
 # Resolve frontend path relative to this file
 FRONTEND_DIR = Path(__file__).resolve().parent.parent / "frontend"
 
@@ -1778,6 +1802,9 @@ async def api_file_delete(vault_name: str, path: str = Query(..., description="R
             "vault": vault_name,
             "path": path,
         })
+
+        from backend.plugins import emit_file_deleted
+        emit_file_deleted(vault_name, path)
         
         # Remove from recent files
         remove_recent(current_user["username"], vault_name, path)
@@ -2072,6 +2099,8 @@ async def api_file_create(
             "path": body.path,
         })
         await dispatch_webhooks("file_created", {"vault": vault_name, "path": body.path})
+        from backend.plugins import emit_file_created
+        emit_file_created(vault_name, body.path)
         
         return {"success": True, "path": body.path}
     except PermissionError: