fix(tui_gateway): honor prefill_messages_file on the Desktop agent path

Desktop and TUI agents are built by tui_gateway.server._make_agent, which
never runs the classic CLI bootstrap and passed no prefill_messages to
AIAgent, so a configured prefill_messages_file was silently ignored there.

Resolve it with the CLI's own resolver/loader (env > prefill_messages_file >
legacy agent.prefill_messages_file). The loader takes an optional base_dir so
relative paths resolve against the profile building the agent, not the
launch home.

Co-authored-by: leakedd <66937184+leakedd@users.noreply.github.com>

hermes_cli/cli_config_load.py

@@ -24,14 +24,16 @@ def _cli():
     return cli
 
 
-def _load_prefill_messages(file_path: str) -> List[Dict[str, Any]]:
-    """Load prefill messages (JSON array) from *file_path*; relative to ~/.hermes/; missing/empty -> []."""
-    from cli import _hermes_home
+def _load_prefill_messages(file_path: str, base_dir: Path | None = None) -> List[Dict[str, Any]]:
+    """Load prefill messages (JSON array) from *file_path*; missing/empty -> [].
+
+    Relative paths resolve against *base_dir*, defaulting to the CLI's hermes home.
+    """
     if not file_path:
         return []
     path = Path(file_path).expanduser()
     if not path.is_absolute():
-        path = _hermes_home / path
+        path = (base_dir or _cli()._hermes_home) / path
     if not path.exists():
         logger.warning("Prefill messages file not found: %s", path)
         return []

tests/tui_gateway/test_make_agent_prefill.py

@@ -0,0 +1,55 @@
+"""Desktop/TUI agents honor ``prefill_messages_file`` from the active profile.
+
+Regression for #60456: ``tui_gateway.server._make_agent`` (the Desktop / ``hermes serve`` agent
+factory) never passed ``prefill_messages``, so a configured prefill file only worked in the
+classic CLI and the messaging gateway.
+"""
+
+from __future__ import annotations
+
+import json
+import types
+
+import yaml
+
+from hermes_constants import reset_hermes_home_override, set_hermes_home_override
+from tui_gateway import server
+
+
+def _write_home(root, name: str, content: str):
+    home = root / name
+    home.mkdir()
+    (home / "config.yaml").write_text(yaml.safe_dump({"prefill_messages_file": "prefill.json"}), encoding="utf-8")
+    (home / "prefill.json").write_text(json.dumps([{"role": "user", "content": content}]), encoding="utf-8")
+    return home
+
+
+def _built_prefill(monkeypatch, home):
+    captured = {}
+
+    def fake_agent(**kwargs):
+        captured.update(kwargs)
+        return types.SimpleNamespace(model=kwargs.get("model"))
+
+    monkeypatch.setattr("run_agent.AIAgent", fake_agent)
+    token = set_hermes_home_override(home)
+    try:
+        server._make_agent("sid", "session-key")
+    finally:
+        reset_hermes_home_override(token)
+    return captured["prefill_messages"]
+
+
+def test_make_agent_injects_the_active_profiles_prefill(monkeypatch, tmp_path):
+    monkeypatch.delenv("HERMES_PREFILL_MESSAGES_FILE", raising=False)
+    monkeypatch.setattr(server, "_resolve_agent_model_runtime", lambda *_a: ("test-model", {}))
+    monkeypatch.setattr(server, "_load_enabled_toolsets", lambda *_a, **_kw: None)
+    monkeypatch.setattr(server, "_get_db", lambda: None)
+    monkeypatch.setattr(server, "_agent_cbs", lambda sid: {})
+    home_a = _write_home(tmp_path, "a", "prefill from A")
+    home_b = _write_home(tmp_path, "b", "prefill from B")
+
+    # A -> B -> A: the relative path resolves against whichever profile builds the agent.
+    assert _built_prefill(monkeypatch, home_a) == [{"role": "user", "content": "prefill from A"}]
+    assert _built_prefill(monkeypatch, home_b) == [{"role": "user", "content": "prefill from B"}]
+    assert _built_prefill(monkeypatch, home_a) == [{"role": "user", "content": "prefill from A"}]

tui_gateway/agent_callbacks.py

@@ -330,6 +330,15 @@ def _load_fallback_model():
     return get_fallback_chain(_load_cfg())
 
 
+def _load_prefill_messages() -> list:
+    """Configured prefill messages, resolved like the CLI (env > ``prefill_messages_file`` > legacy
+    ``agent.*``). Desktop/TUI agents never run the CLI bootstrap, so without this the setting was
+    ignored there (#60456). Relative paths resolve against the active profile home, per call."""
+    from hermes_cli.cli_config_load import _load_prefill_messages as _load, _resolve_prefill_messages_file
+    from hermes_constants import get_hermes_home
+    return _load(_resolve_prefill_messages_file(_load_cfg()), get_hermes_home())
+
+
 def _sync_agent_fallback_with_config(sid: str, session: dict) -> None:
     """Adopt ``fallback_providers`` edits into the cached agent at turn start.
 

tui_gateway/server.py

@@ -2548,7 +2548,7 @@ def _make_agent(
         checkpoints_enabled=is_truthy_value(os.environ.get("HERMES_TUI_CHECKPOINTS")),
         pass_session_id=is_truthy_value(os.environ.get("HERMES_TUI_PASS_SESSION_ID")),
         skip_context_files=ignore_rules, skip_memory=ignore_rules, fallback_model=_load_fallback_model(),
-        **_agent_cbs(sid))
+        prefill_messages=_load_prefill_messages() or None, **_agent_cbs(sid))
     if context_cwd_is_launch_artifact is None:
         context_cwd_is_launch_artifact = _context_cwd_is_launch_artifact(session)
     agent._context_cwd_is_launch_artifact = bool(context_cwd_is_launch_artifact)