More MCP work

.gitignore

@@ -51,3 +51,4 @@ GPF-output/**
 
 __pycache__/
 .clangd-query.pid
+.clangd-query/

Plugins/BlueprintMCP/Source/BlueprintMCP/Public/MCPHandler.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "CoreMinimal.h"
+#include "UObject/Interface.h"
 #include "UObject/Object.h"
 #include "Dom/JsonObject.h"
 #include "MCPHandler.generated.h"

Plugins/BlueprintMCP/Source/BlueprintMCP/Public/MCPServer.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "CoreMinimal.h"
+#include "Async/Future.h"
 #include "Dom/JsonObject.h"
 #include "MCPUtils.h"
 class FSocket;

build.py

@@ -323,6 +323,7 @@ def build_compile_commands_from_integration():
     if len(clangs) != 1: sys.exit("Couldn't identify correct clang++ compiler in UnrealEngine thirdparty directory")
     clang = str(clangs[0])
     # Build the table of source files and RSP files.
+    # First, scan unity Module.*.o.rsp files and expand their #included .cpp files.
     mods1 = Path(f"{INTEGRATION}/Intermediate/Build/{OS}").rglob(f"UnrealEditor/{DEBUG}/**/Module.*.o.rsp")
     mods1p = Path(f"{INTEGRATION}/Plugins").rglob(f"Intermediate/Build/{OS}/x64/UnrealEditor/{DEBUG}/**/Module.*.o.rsp")
     mods2 = Path(f"{UNREALENGINE}/Engine/Intermediate/Build/{OS}").rglob("UnrealEditor/Development/**/Module.*.o.rsp")
@@ -334,6 +335,15 @@ def build_compile_commands_from_integration():
         for subfile in cpp_files_included_by(cpp):
             abs = os.path.abspath(os.path.join(f"{UNREALENGINE}/Engine/Source", subfile))
             cpp_to_rsp[abs] = rsp
+    # Also pick up non-unity .cpp files that have their own .o.rsp (e.g. files
+    # excluded from unity builds). Only include if the .cpp file actually exists.
+    standalone1 = Path(f"{INTEGRATION}/Intermediate/Build/{OS}").rglob(f"UnrealEditor/{DEBUG}/**/*.cpp.o.rsp")
+    standalone1p = Path(f"{INTEGRATION}/Plugins").rglob(f"Intermediate/Build/{OS}/x64/UnrealEditor/{DEBUG}/**/*.cpp.o.rsp")
+    for rsp_path in itertools.chain(standalone1, standalone1p):
+        rsp = str(rsp_path)
+        cpp = os.path.abspath(rsp.removesuffix(".o.rsp"))
+        if cpp not in cpp_to_rsp and os.path.exists(cpp):
+            cpp_to_rsp[cpp] = rsp
     # Generate compile commands.
     entries = []
     ccdir = f"{UNREALENGINE}/Engine/Source"

tools/clangd-query.py

@@ -149,6 +149,22 @@ class ClangdDaemon:
 
     def __init__(self):
         clangd_path, clangd_args = read_workspace_config()
+
+        # Give the daemon its own compile-commands dir so it gets a separate
+        # clangd index cache (clangd stores .cache/ next to compile_commands.json).
+        daemon_cc_dir = os.path.join(PROJECT_DIR, ".clangd-query")
+        os.makedirs(daemon_cc_dir, exist_ok=True)
+        cc_link = os.path.join(daemon_cc_dir, "compile_commands.json")
+        cc_src = os.path.join(PROJECT_DIR, ".vscode", "compile_commands.json")
+        if os.path.islink(cc_link) or os.path.exists(cc_link):
+            os.unlink(cc_link)
+        os.symlink(cc_src, cc_link)
+
+        # Replace --compile-commands-dir in args to point to our dir
+        clangd_args = [
+            f"--compile-commands-dir={daemon_cc_dir}" if a.startswith("--compile-commands-dir") else a
+            for a in clangd_args
+        ]
         cmd = [clangd_path] + clangd_args + ["-j=4"]
 
         self.proc = subprocess.Popen(
@@ -164,6 +180,8 @@ class ClangdDaemon:
         self.events = {}
         self.index_loaded = threading.Event()
         self.opened_files = set()
+        self.diagnostics = {}  # uri -> list of diagnostics
+        self.diag_events = {}  # uri -> threading.Event
 
         threading.Thread(target=self._stdout_reader, daemon=True).start()
         threading.Thread(target=self._stderr_reader, daemon=True).start()
@@ -173,6 +191,14 @@ class ClangdDaemon:
             msg = read_lsp_message(self.proc.stdout)
             if msg is None:
                 break
+            # Handle server-initiated diagnostics notifications
+            if msg.get("method") == "textDocument/publishDiagnostics":
+                uri = msg["params"]["uri"]
+                with self.lock:
+                    self.diagnostics[uri] = msg["params"]["diagnostics"]
+                    if uri in self.diag_events:
+                        self.diag_events[uri].set()
+                continue
             msg_id = msg.get("id")
             if msg_id is not None and msg_id in self.pending:
                 with self.lock:
@@ -241,6 +267,20 @@ class ClangdDaemon:
             resp = self.send_request("workspace/symbol", {"query": args[0]})
             return resp
 
+        if cmd == "diagnostics":
+            filepath = args[0]
+            abs_path = os.path.abspath(filepath)
+            uri = f"file://{abs_path}"
+            # Set up event before opening so we don't miss the notification
+            with self.lock:
+                self.diag_events[uri] = threading.Event()
+            self.open_file(abs_path)
+            self.diag_events[uri].wait(timeout=30)
+            with self.lock:
+                diags = self.diagnostics.get(uri, [])
+                self.diag_events.pop(uri, None)
+            return {"result": diags}
+
         if cmd == "definition":
             filepath, line, col = args[0], int(args[1]), int(args[2])
             abs_path = os.path.abspath(filepath)
@@ -408,15 +448,27 @@ def start_daemon():
         sys.exit(1)
 
 
-def send_query(query):
+def send_query(query, retries=3):
     """Send a query to the daemon and return the response."""
-    sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    for attempt in range(retries):
-    sock.settimeout(60)
+        try:
-    sock.connect(SOCKET_PATH)
+            sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-    sock_send(sock, query)
+            sock.settimeout(60)
-    result = sock_recv(sock)
+            sock.connect(SOCKET_PATH)
-    sock.close()
+            sock_send(sock, query)
-    return result
+            result = sock_recv(sock)
+            sock.close()
+            return result
+        except (ConnectionResetError, ConnectionRefusedError, BrokenPipeError, OSError):
+            sock.close()
+            if attempt < retries - 1:
+                import time
+                time.sleep(2)
+                # Daemon may have died — restart it
+                if not daemon_is_alive():
+                    start_daemon()
+            else:
+                raise
 
 
 def ensure_daemon():
@@ -444,6 +496,22 @@ def format_symbol_results(resp):
         print(f"{path}:{line} [{kind}] {qualified}")
 
 
+def format_diagnostics(resp):
+    if not resp or "result" not in resp:
+        print("No diagnostics (or clangd error).", file=sys.stderr)
+        return
+    diags = resp["result"]
+    if not diags:
+        print("No problems found.")
+        return
+    for d in diags:
+        line = d.get("range", {}).get("start", {}).get("line", 0) + 1
+        col = d.get("range", {}).get("start", {}).get("character", 0) + 1
+        severity = {1: "error", 2: "warning", 3: "info", 4: "hint"}.get(d.get("severity", 0), "unknown")
+        msg = d.get("message", "")
+        print(f"  {line}:{col} [{severity}] {msg}")
+
+
 def format_location_results(resp, label="results"):
     if not resp or "result" not in resp:
         print(f"No {label} (or clangd error).", file=sys.stderr)
@@ -485,6 +553,10 @@ def main():
         if len(args) < 1:
             print("Usage: clangd-query.py symbol <name>", file=sys.stderr)
             sys.exit(1)
+    elif command == "diagnostics":
+        if len(args) < 1:
+            print("Usage: clangd-query.py diagnostics <file>", file=sys.stderr)
+            sys.exit(1)
     elif command in ("definition", "references"):
         if len(args) < 3:
             print(f"Usage: clangd-query.py {command} <file> <line> <col>",
@@ -500,6 +572,8 @@ def main():
 
     if command == "symbol":
         format_symbol_results(resp)
+    elif command == "diagnostics":
+        format_diagnostics(resp)
     elif command == "definition":
         format_location_results(resp, "definition")
     elif command == "references":