fix: harden server start/stop guards

1 files changed, 18 insertions, 1 deletions

diff --git a/app/backends/servers.py b/app/backends/servers.py
index 965d7df..986d82a 100644
--- a/app/backends/servers.py
+++ b/app/backends/servers.py
@@ -27,6 +27,7 @@ import signal
 import subprocess
 import sys
 import time
+from datetime import datetime
 from pathlib import Path
 from typing import Callable, List, Optional
 
@@ -253,6 +254,15 @@ def start(spec, progress: ProgressCallback = None,
         return True
 
     LOG_DIR.mkdir(parents=True, exist_ok=True)
+    # Refuse to double-start: a live pid file means a previous start is
+    # still booting (or its process is wedged). Spawning a second server
+    # on the same port would orphan the first with no pid record left.
+    if alive(spec.name):
+        report({"kind": "error",
+                "message": f"a {spec.name} server (pid "
+                           f"{pid_for(spec.name)}) is already starting or "
+                           "running; stop it first"})
+        return False
     pid_file = _pid_path(spec.name)
     if pid_file.exists():
         try:
@@ -261,7 +271,10 @@ def start(spec, progress: ProgressCallback = None,
             pass
 
     cwd = getattr(spec, "cwd", None)
-    log_handle = _log_path(spec.name).open("w", encoding="utf-8")
+    # Append so an earlier boot's output survives (crash-loop debugging);
+    # the child inherits the handle and the parent's copy is closed right
+    # after the spawn, so nothing leaks here.
+    log_handle = _log_path(spec.name).open("a", encoding="utf-8")
     popen_kwargs = {"stdout": log_handle, "stderr": subprocess.STDOUT}
     if cwd is not None:
         popen_kwargs["cwd"] = str(cwd)
@@ -277,6 +290,10 @@ def start(spec, progress: ProgressCallback = None,
                 "message": f"could not start server: {exc}"})
         log_handle.close()
         return False
+    log_handle.write(f"\n=== boot {datetime.now():%Y-%m-%d %H:%M:%S} "
+                     f"(pid {proc.pid}) ===\n")
+    log_handle.flush()
+    log_handle.close()
 
     pid_file.write_text(str(proc.pid), encoding="utf-8")
     report({"kind": "starting", "name": spec.name,