fix(tui): save TUI /save snapshots under Hermes home with system prompt (#38251)

* fix(tui): save TUI /save snapshots under Hermes home with system prompt

The TUI gateway's session.save RPC wrote hermes_conversation_<ts>.json to
the workspace/project CWD via os.path.abspath(...) and only exported model
and messages. This diverged from the classic CLI /save (which writes under
the Hermes profile home) and from the dashboard save (which includes the
system prompt).

Write the snapshot under get_hermes_home()/sessions/saved/ and include
system_prompt, session_id, and session_start so the TUI export matches the
CLI and dashboard behavior.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(tui): prefer agent.session_start for /save export; assert it in test

Address review feedback: derive session_start from the agent's session_start
datetime (matching the classic CLI export) and fall back to the gateway
session's created_at only when unavailable. Assert session_start in the
regression test.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_tui_gateway_server.py

@@ -4,6 +4,7 @@ import sys
 import threading
 import time
 import types
+from datetime import datetime
 from pathlib import Path
 from unittest.mock import patch
 
@@ -5473,3 +5474,62 @@ def test_notification_poller_requeues_when_busy(monkeypatch):
         assert requeued["session_id"] == "proc_busy_test"
     finally:
         server._sessions.pop("sid_busy", None)
+
+
+def test_session_save_writes_under_hermes_home_with_system_prompt(monkeypatch, tmp_path):
+    """TUI /save (session.save RPC) must snapshot under the Hermes profile
+    home — not the project/workspace CWD — and include the system prompt,
+    mirroring the classic CLI /save and the dashboard save export.
+
+    Regression: the gateway handler wrote ``hermes_conversation_*.json`` to
+    ``os.path.abspath(...)`` (the workspace CWD) and only exported ``model``
+    and ``messages``, so ``system_prompt`` was missing.
+    """
+    home = tmp_path / ".hermes"
+    home.mkdir()
+    monkeypatch.setenv("HERMES_HOME", str(home))
+
+    # Run from a different CWD to prove the snapshot does NOT leak there.
+    work = tmp_path / "workspace"
+    work.mkdir()
+    monkeypatch.chdir(work)
+
+    sid = "save-sid"
+    agent = types.SimpleNamespace(
+        model="hermes-test",
+        session_id="20260101_120000_abc123",
+        session_start=datetime(2026, 1, 1, 12, 0, 0),
+        _cached_system_prompt="You are Hermes.",
+    )
+    history = [
+        {"role": "user", "content": "hi"},
+        {"role": "assistant", "content": "hello"},
+    ]
+    server._sessions[sid] = {
+        "agent": agent,
+        "session_key": "save-key",
+        "history": history,
+        "history_lock": threading.Lock(),
+        "created_at": 1735732800.0,
+    }
+    try:
+        resp = server._methods["session.save"]("1", {"session_id": sid})
+    finally:
+        server._sessions.pop(sid, None)
+
+    assert "result" in resp, resp
+    saved_file = Path(resp["result"]["file"])
+
+    # Must NOT leak into the workspace/project CWD.
+    assert not list(work.glob("hermes_conversation_*.json"))
+
+    saved_dir = home / "sessions" / "saved"
+    assert saved_file.parent == saved_dir
+    assert saved_file.exists()
+
+    payload = json.loads(saved_file.read_text())
+    assert payload["model"] == "hermes-test"
+    assert payload["session_id"] == "20260101_120000_abc123"
+    assert payload["session_start"] == "2026-01-01T12:00:00"
+    assert payload["system_prompt"] == "You are Hermes."
+    assert payload["messages"] == history

tui_gateway/server.py

@@ -3485,23 +3485,52 @@ def _(rid, params: dict) -> dict:
     session, err = _sess(params, rid)
     if err:
         return err
-    import time as _time
 
-    filename = os.path.abspath(
-        f"hermes_conversation_{_time.strftime('%Y%m%d_%H%M%S')}.json"
-    )
+    agent = session["agent"]
+    # Mirror the classic CLI /save: snapshot under the Hermes profile home
+    # (~/.hermes/sessions/saved/) rather than the project/workspace CWD, and
+    # include the system prompt so the export matches the dashboard save.
+    saved_dir = get_hermes_home() / "sessions" / "saved"
     try:
-        with open(filename, "w", encoding="utf-8") as f:
+        saved_dir.mkdir(parents=True, exist_ok=True)
+    except Exception as e:
+        return _err(rid, 5011, f"failed to create save directory {saved_dir}: {e}")
+
+    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
+    path = saved_dir / f"hermes_conversation_{timestamp}.json"
+
+    with session["history_lock"]:
+        messages = list(session.get("history", []))
+
+    session_id = getattr(agent, "session_id", None) or session.get("session_key") or ""
+    # Prefer the agent's session_start datetime (matches the classic CLI export);
+    # fall back to the gateway session's created_at timestamp.
+    agent_start = getattr(agent, "session_start", None)
+    if isinstance(agent_start, datetime):
+        session_start = agent_start.isoformat()
+    else:
+        created_at = session.get("created_at")
+        session_start = (
+            datetime.fromtimestamp(created_at).isoformat()
+            if isinstance(created_at, (int, float))
+            else ""
+        )
+
+    try:
+        with open(path, "w", encoding="utf-8") as f:
             json.dump(
                 {
-                    "model": getattr(session["agent"], "model", ""),
-                    "messages": session.get("history", []),
+                    "model": getattr(agent, "model", ""),
+                    "session_id": session_id,
+                    "session_start": session_start,
+                    "system_prompt": getattr(agent, "_cached_system_prompt", "") or "",
+                    "messages": messages,
                 },
                 f,
                 indent=2,
                 ensure_ascii=False,
             )
-        return _ok(rid, {"file": filename})
+        return _ok(rid, {"file": str(path)})
     except Exception as e:
         return _err(rid, 5011, str(e))