From 00e0f90b69d26920f282eeacc2e778fe9ceade77 Mon Sep 17 00:00:00 2001
From: HAL9000 <HAL9000@cleverthis.com>
Date: Wed, 13 May 2026 21:19:47 +0000
Subject: [PATCH] fix(lsp): cleanup subprocess on failed initialization in
 StdioTransport.start()\n\nWrap post-Popen code in try/except to ensure
 subprocess resources are\nproperly cleaned up if the spawned process dies
 immediately or if any\nunexpected exception occurs. Detect already-dead
 processes via poll() and\nraise LspError with exit code details. Use suppress
 to prevent stop() errors\from masking the original exception.

---
 src/cleveragents/lsp/transport.py | 36 ++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/src/cleveragents/lsp/transport.py b/src/cleveragents/lsp/transport.py
index c85262cff..ad700f27a 100644
--- a/src/cleveragents/lsp/transport.py
+++ b/src/cleveragents/lsp/transport.py
@@ -18,6 +18,7 @@ and issue #826.
 
 from __future__ import annotations
 
+import contextlib
 import json
 import os
 import select
@@ -126,11 +127,36 @@ class StdioTransport:
                 details={"command": self._command, "error": str(exc)},
             ) from exc
 
-        logger.info(
-            "lsp.transport.started",
-            pid=self._process.pid,
-            command=self._command,
-        )
+        # If anything goes wrong after Popen succeeds (process already dies
+        # immediately, unexpected exception), make sure the subprocess is
+        # cleaned up before propagating.  A dead process with open pipe fds
+        # would otherwise leak file descriptors until garbage collection.
+        try:
+            logger.info(
+                "lsp.transport.started",
+                pid=self._process.pid,
+                command=self._command,
+            )
+
+            # If the child already exited during or right after spawn
+            # (e.g. missing shared library, runtime crash), clean it up
+            # immediately rather than leaving a dead process with open fds.
+            if self._process.poll() is not None:
+                code = self._process.returncode
+                self.stop()  # closes pipes and reaps child
+                raise LspError(
+                    f"LSP server exited immediately (exit code {code})",
+                    details={"command": self._command, "args": self._args},
+                )
+
+        except BaseException:
+            # Ensure the subprocess is terminated before propagating.
+            # Use suppress to prevent stop() errors from masking the active
+            # exception — either way we always re-raise whatever was caught.
+            if self._process is not None:
+                with contextlib.suppress(BaseException):
+                    self.stop()
+            raise
 
     def stop(self, timeout: float = _GRACEFUL_SHUTDOWN_TIMEOUT) -> int | None:
         """Terminate the subprocess gracefully, then force-kill if needed.
-- 
2.52.0