default cwd to /workspace for all exec, pty, and job calls

All subprocess and PTY spawns now start in WORKSPACE_DIR (default /workspace)
instead of inheriting /app from the Python process.

server/main.py

@@ -18,6 +18,8 @@ from typing import Any
 logging.basicConfig(level=logging.INFO, format="%(asctime)s [%(levelname)s] %(message)s")
 log = logging.getLogger("mcp")
 
+WORKSPACE = os.environ.get("WORKSPACE_DIR", "/workspace")
+
 import pyte
 import ptyprocess
 import uvicorn
@@ -49,6 +51,7 @@ class PtySession:
             ["/bin/bash", "--login"],
             dimensions=(rows, cols),
             env={**os.environ, "TERM": "xterm-256color", "COLUMNS": str(cols), "LINES": str(rows)},
+            cwd=WORKSPACE,
         )
         self._reader = threading.Thread(target=self._read_loop, daemon=True)
         self._reader.start()
@@ -100,6 +103,7 @@ class BackgroundJob:
             stderr=subprocess.STDOUT,
             text=True,
             executable="/bin/bash",
+            cwd=WORKSPACE,
         )
         self._reader = threading.Thread(target=self._read_loop, daemon=True)
         self._reader.start()
@@ -256,6 +260,7 @@ async def _dispatch(name: str, args: dict) -> dict:
             r = subprocess.run(
                 cmd, shell=True, capture_output=True, text=True,
                 timeout=timeout, executable="/bin/bash",
+                cwd=WORKSPACE,
             )
             return {"stdout": r.stdout, "stderr": r.stderr, "exit_code": r.returncode}
         except subprocess.TimeoutExpired: