refactor(ssh): extract shared _is_ssh_remote_tilde_cwd predicate

Follow-up to the salvaged SSH-tilde-cwd fix. The predicate
"backend == ssh and (cwd == ~ or cwd.startswith(~/))" was inlined at
each expanduser guard site, which is how the test simulator drifted from
production (it grew an SSH guard on a top-level-alias branch that has no
production counterpart).

- Add tools/terminal_tool._is_ssh_remote_tilde_cwd(backend, cwd) as the
  single source of truth (case/whitespace-tolerant).
- Use it in _get_env_config and the gateway config bridge.
- Test simulator imports the real helper instead of re-implementing the
  predicate; revert the phantom SSH guard on the top-level-alias branch
  (production maps top-level cwd: to a plain env var, not TERMINAL_CWD via
  an SSH-guarded path — that branch tested nothing real).

gateway/run.py

@@ -1481,13 +1481,11 @@ if _config_path.exists():
                     # never receives a literal "~/" which the kernel rejects.
                     # SSH cwd is interpreted by the remote shell, so preserve
                     # "~" / "~/..." for the SSH backend instead of expanding it
-                    # to the Hermes host/container HOME (often /opt/data).
+                    # to the Hermes host/container HOME (often /opt/data). Shared
+                    # predicate with terminal_tool so the two sites can't drift.
                     if _cfg_key == "cwd" and isinstance(_val, str):
-                        _raw_cwd = _val.strip()
-                        if not (
-                            _terminal_backend == "ssh"
-                            and (_raw_cwd == "~" or _raw_cwd.startswith("~/"))
-                        ):
+                        from tools.terminal_tool import _is_ssh_remote_tilde_cwd
+                        if not _is_ssh_remote_tilde_cwd(_terminal_backend, _val.strip()):
                             _val = os.path.expanduser(_val)
                     if isinstance(_val, (list, dict)):
                         os.environ[_env_var] = json.dumps(_val)

tests/gateway/test_config_cwd_bridge.py

@@ -12,6 +12,8 @@ asserting the expected env var outcomes.
 import os
 import json
 
+from tools.terminal_tool import _is_ssh_remote_tilde_cwd
+
 
 def _simulate_config_bridge(cfg: dict, initial_env: dict | None = None):
     """Simulate the gateway config bridge logic from gateway/run.py.
@@ -51,12 +53,9 @@ def _simulate_config_bridge(cfg: dict, initial_env: dict | None = None):
                 # Expand shell tilde for local/container backends so subprocess.Popen
                 # never receives a literal "~/" which the kernel rejects. SSH cwd is
                 # interpreted by the remote shell, so preserve "~" / "~/..." there.
+                # Uses the same production predicate as gateway/run.py.
                 if cfg_key == "cwd" and isinstance(val, str):
-                    raw_cwd = val.strip()
-                    if not (
-                        terminal_backend == "ssh"
-                        and (raw_cwd == "~" or raw_cwd.startswith("~/"))
-                    ):
+                    if not _is_ssh_remote_tilde_cwd(terminal_backend, val.strip()):
                         val = os.path.expanduser(val)
                 if isinstance(val, list):
                     env[env_var] = json.dumps(val)
@@ -73,15 +72,7 @@ def _simulate_config_bridge(cfg: dict, initial_env: dict | None = None):
             alias_val = cfg.get(alias_key)
             if isinstance(alias_val, str) and alias_val.strip():
                 if alias_key == "cwd":
-                    alias_backend = str(
-                        cfg.get("backend") or env.get("TERMINAL_ENV") or ""
-                    ).strip().lower()
-                    raw_cwd = alias_val.strip()
-                    if not (
-                        alias_backend == "ssh"
-                        and (raw_cwd == "~" or raw_cwd.startswith("~/"))
-                    ):
-                        alias_val = os.path.expanduser(alias_val)
+                    alias_val = os.path.expanduser(alias_val)
                 env[alias_env] = alias_val.strip()
 
     # --- Replicate lines 144-147: MESSAGING_CWD fallback ---

tools/terminal_tool.py

@@ -1216,6 +1216,22 @@ _HOST_CWD_PREFIXES = ("/Users/", "/home/", "C:\\", "C:/")
 _CONTAINER_BACKENDS = frozenset({"docker", "singularity", "modal", "daytona"})
 
 
+def _is_ssh_remote_tilde_cwd(backend: str, cwd: str) -> bool:
+    """Return True when *cwd* is a tilde path that the remote SSH shell must
+    expand itself, so the Hermes host/container must NOT ``expanduser`` it.
+
+    SSH ``cwd`` is interpreted by the *remote* shell (``cd ~`` / ``cd ~/x``
+    over ``ssh ... bash -c``). Expanding ``~`` locally would rewrite it to the
+    Hermes host HOME (often ``/opt/data`` under Docker) and inject a
+    nonexistent path into the remote session. Only ``~`` / ``~/...`` on the
+    ``ssh`` backend qualify; absolute remote paths still pass through
+    unchanged, and every other backend keeps expanding locally.
+    """
+    if (backend or "").strip().lower() != "ssh":
+        return False
+    return cwd == "~" or cwd.startswith("~/")
+
+
 def _is_unusable_container_cwd(cwd: str) -> bool:
     """Return True if *cwd* is a host/relative path that won't work as the
     working directory inside a container sandbox.
@@ -1286,7 +1302,7 @@ def _get_env_config() -> Dict[str, Any]:
     # /workspace and track the original host path separately. Otherwise keep the
     # normal sandbox behavior and discard host paths.
     cwd = os.getenv("TERMINAL_CWD", default_cwd)
-    if cwd and not (env_type == "ssh" and (cwd == "~" or cwd.startswith("~/"))):
+    if cwd and not _is_ssh_remote_tilde_cwd(env_type, cwd):
         cwd = os.path.expanduser(cwd)
     host_cwd = None
     if env_type == "docker" and mount_docker_cwd: