fix: SSH compatibility with fish shell on remote host

- Remove bash -c from remote_exec (pass command as single SSH arg)
- Fix remote_write_file to pass bash -c script as single quoted string
- Add LogLevel=ERROR to suppress SSH warning messages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

haproxy_mcp/ssh_ops.py

@@ -22,6 +22,7 @@ def _ssh_base_cmd() -> list[str]:
         "ssh",
         "-o", "StrictHostKeyChecking=no",
         "-o", "UserKnownHostsFile=/dev/null",
+        "-o", "LogLevel=ERROR",
         "-o", "BatchMode=yes",
         "-o", "ConnectTimeout=10",
         "-p", str(SSH_PORT),
@@ -35,6 +36,9 @@ def _ssh_base_cmd() -> list[str]:
 def remote_exec(command: str, timeout: int = SUBPROCESS_TIMEOUT) -> subprocess.CompletedProcess:
     """Execute a command on the remote host via SSH.
 
+    The command is passed as a single SSH argument so the remote shell
+    interprets it as-is (compatible with fish, bash, zsh).
+
     Args:
         command: Shell command to execute remotely
         timeout: Command timeout in seconds
@@ -46,7 +50,7 @@ def remote_exec(command: str, timeout: int = SUBPROCESS_TIMEOUT) -> subprocess.C
         subprocess.TimeoutExpired: If command times out
         OSError: If SSH command fails to execute
     """
-    ssh_cmd = _ssh_base_cmd() + ["bash", "-c", command]
+    ssh_cmd = _ssh_base_cmd() + [command]
     logger.debug("SSH exec: %s", command)
     return subprocess.run(
         ssh_cmd,
@@ -81,7 +85,8 @@ def remote_read_file(path: str) -> str:
 def remote_write_file(path: str, content: str) -> None:
     """Write content to a file on the remote host atomically.
 
-    Uses temp file + mv for atomic write, matching local behavior.
+    Uses bash explicitly for bash-specific syntax ($(mktemp), $tmpf).
+    The entire script is passed as a single argument to 'bash -c'.
 
     Args:
         path: Absolute file path on remote host
@@ -91,9 +96,9 @@ def remote_write_file(path: str, content: str) -> None:
         IOError: If write fails
     """
     ssh_cmd = _ssh_base_cmd()
-    # Atomic write: write to temp file, then rename (force bash for compatibility)
-    remote_script = f"tmpf=$(mktemp {path}.tmp.XXXXXX) && cat > \"$tmpf\" && mv \"$tmpf\" {path}"
-    ssh_cmd.extend(["bash", "-c", remote_script])
+    # Atomic write via bash (single-quoted to survive remote shell interpretation)
+    remote_script = f"tmpf=$(mktemp {path}.tmp.XXXXXX) && cat >\"$tmpf\" && mv \"$tmpf\" {path}"
+    ssh_cmd.append(f"bash -c '{remote_script}'")
 
     logger.debug("SSH write: %s (%d bytes)", path, len(content))
     result = subprocess.run(