fix: prevent TUI gateway stdin EOF crash across all TUI-context subprocess calls

When Hermes runs in TUI mode, the gateway child process communicates with
the Node.js parent over a JSON-RPC protocol on stdin. Subprocess calls that
inherit this stdin fd can trigger a race condition where the child's stdin
read returns EOF, causing the gateway to exit cleanly (exit code 0) mid-tool-
execution.

This is the same root cause as issue #14036 (byterover plugin) and PR #39257
(SSH environment backend). This commit applies the fix — stdin=subprocess.DEVNULL
— to all 85 subprocess.run() and subprocess.Popen() calls that execute inside
the TUI gateway child process.

Scope: TUI-context code only (agent/, tools/, plugins/, tui_gateway/server.py).
CLI code (cli.py, hermes_cli/), tests, scripts, and gateway process management
are excluded — they don't run inside the TUI child and inherit the terminal's
stdin, not the JSON-RPC pipe.

85 call sites across 28 files. All files pass syntax check.

agent/anthropic_adapter.py

@@ -821,6 +821,7 @@ def _read_claude_code_credentials_from_keychain() -> Optional[Dict[str, Any]]:
             capture_output=True,
             text=True,
             timeout=5,
+            stdin=subprocess.DEVNULL,
         )
     except (OSError, subprocess.TimeoutExpired):
         logger.debug("Keychain: security command not available or timed out")
@@ -1165,7 +1166,7 @@ def run_oauth_setup_token() -> Optional[str]:
 
     # Run interactively — stdin/stdout/stderr inherited so user can interact
     try:
-        subprocess.run([claude_path, "setup-token"])
+        subprocess.run([claude_path, "setup-token"], stdin=subprocess.DEVNULL)
     except (KeyboardInterrupt, EOFError):
         return None
 

agent/context_references.py

@@ -290,6 +290,7 @@ def _expand_git_reference(
             capture_output=True,
             text=True,
             timeout=30,
+            stdin=subprocess.DEVNULL,
         )
     except subprocess.TimeoutExpired:
         return f"{ref.raw}: git command timed out (30s)", None
@@ -482,6 +483,7 @@ def _rg_files(path: Path, cwd: Path, limit: int) -> list[Path] | None:
             capture_output=True,
             text=True,
             timeout=10,
+            stdin=subprocess.DEVNULL,
         )
     except (FileNotFoundError, OSError, subprocess.TimeoutExpired):
         return None

agent/lsp/install.py

@@ -262,6 +262,7 @@ def _install_npm(
             capture_output=True,
             text=True,
             timeout=300,
+            stdin=subprocess.DEVNULL,
         )
         if proc.returncode != 0:
             logger.warning(
@@ -310,6 +311,7 @@ def _install_go(pkg: str, bin_name: str) -> Optional[str]:
             text=True,
             timeout=600,
             env=env,
+            stdin=subprocess.DEVNULL,
         )
         if proc.returncode != 0:
             logger.warning(
@@ -347,6 +349,7 @@ def _install_pip(pkg: str, bin_name: str) -> Optional[str]:
             capture_output=True,
             text=True,
             timeout=300,
+            stdin=subprocess.DEVNULL,
         )
         if proc.returncode != 0:
             logger.warning(

agent/secret_sources/bitwarden.py

@@ -274,6 +274,7 @@ def _platform_asset_name() -> str:
                 capture_output=True,
                 text=True,
                 timeout=2,
+                stdin=subprocess.DEVNULL,
             )
             if "musl" in (res.stdout + res.stderr).lower():
                 libc = "musl"
@@ -525,6 +526,7 @@ def _run_bws_list(
             capture_output=True,
             text=True,
             timeout=_BWS_RUN_TIMEOUT,
+            stdin=subprocess.DEVNULL,
         )
     except subprocess.TimeoutExpired as exc:
         raise RuntimeError(

agent/skill_preprocessing.py

@@ -74,6 +74,7 @@ def run_inline_shell(command: str, cwd: Path | None, timeout: int) -> str:
             text=True,
             timeout=max(1, int(timeout)),
             check=False,
+            stdin=subprocess.DEVNULL,
         )
     except subprocess.TimeoutExpired:
         return f"[inline-shell timeout after {timeout}s: {command}]"

agent/transports/codex_app_server.py

@@ -378,6 +378,7 @@ def check_codex_binary(
             capture_output=True,
             text=True,
             timeout=10,
+            stdin=subprocess.DEVNULL,
         )
     except FileNotFoundError:
         return False, (