test(cli): cover quiet-mode resume status lines routed to stderr

4 tests: session-not-found in quiet mode -> stderr; in full mode -> stdout
(unchanged); resumed banner in quiet mode -> stderr; has-no-messages in
quiet mode -> stderr.

tests/cli/test_resume_quiet_stderr.py

@@ -0,0 +1,121 @@
+"""Tests for /resume status lines going to stderr in quiet mode (#11793).
+
+The fix in cli._init_agent routes three messages to stderr when
+``tool_progress_mode == "off"`` (set by ``hermes chat --quiet``):
+
+  * "Session not found: ..."
+  * "↻ Resumed session ... (N user messages, M total messages)"
+  * "Session ... found but has no messages. Starting fresh."
+
+Interactive mode (tool_progress_mode == "full") still uses ChatConsole.
+"""
+
+from datetime import datetime
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from cli import HermesCLI
+
+
+def _make_cli(quiet=False, session_id="20260524_111111_xyz", db=None):
+    """Build a minimal HermesCLI bound to only what _init_agent needs for
+    the resume code path: _resumed, _session_db, conversation_history,
+    session_id, and tool_progress_mode."""
+    cli = HermesCLI.__new__(HermesCLI)
+    cli.session_id = session_id
+    cli._resumed = True
+    cli.conversation_history = []
+    cli._session_db = db
+    cli.tool_progress_mode = "off" if quiet else "full"
+    cli.session_start = datetime.now()
+    cli.agent = None
+    # We need _init_agent to reach the resume block (line ~4757) but not
+    # proceed into actual AIAgent construction. _ensure_runtime_credentials
+    # must return True (False returns early at line 4743). _install_tool_callbacks,
+    # _ensure_tirith_security are stubbed; the resume block will either return
+    # False (session-not-found) or reach the eventual AIAgent() call which
+    # we'll let raise — we only check stdout/stderr printed BEFORE that.
+    cli._install_tool_callbacks = lambda: None
+    cli._ensure_tirith_security = lambda: None
+    cli._ensure_runtime_credentials = lambda: True
+    return cli
+
+
+class TestResumeQuietStderr:
+    def test_session_not_found_goes_to_stderr_in_quiet_mode(self, capsys):
+        db = MagicMock()
+        db.get_session.return_value = None
+        cli = _make_cli(quiet=True, db=db)
+
+        with patch("cli._prepare_deferred_agent_startup"):
+            result = cli._init_agent()
+
+        captured = capsys.readouterr()
+        assert result is False
+        # stdout must stay clean
+        assert "Session not found" not in captured.out
+        # the resume status goes to stderr
+        assert "Session not found" in captured.err
+        assert "hermes sessions list" in captured.err
+
+    def test_session_not_found_goes_to_stdout_in_full_mode(self, capsys):
+        db = MagicMock()
+        db.get_session.return_value = None
+        cli = _make_cli(quiet=False, db=db)
+
+        with patch("cli._prepare_deferred_agent_startup"):
+            result = cli._init_agent()
+
+        captured = capsys.readouterr()
+        assert result is False
+        # Interactive mode keeps the existing _cprint path → stdout.
+        assert "Session not found" in captured.out
+
+    def test_resumed_banner_goes_to_stderr_in_quiet_mode(self, capsys):
+        db = MagicMock()
+        db.get_session.return_value = {"id": "20260524_111111_xyz", "title": "demo"}
+        db.resolve_resume_session_id.return_value = "20260524_111111_xyz"
+        db.get_messages_as_conversation.return_value = [
+            {"role": "user", "content": "hi"},
+            {"role": "assistant", "content": "hey"},
+        ]
+        db._conn = MagicMock()  # for the reopen execute() call
+
+        cli = _make_cli(quiet=True, db=db)
+        # Stop _init_agent right after the resume banner: prevent it from
+        # constructing a real AIAgent (the next code path).
+        with patch("cli._prepare_deferred_agent_startup"):
+            try:
+                cli._init_agent()
+            except Exception:
+                # The post-resume agent-init machinery may fail in this
+                # stubbed context (no API key, no real config) — we only
+                # care about the printed banner that comes earlier.
+                pass
+
+        captured = capsys.readouterr()
+        # Banner on stderr — stdout stays clean for automation.
+        assert "↻ Resumed session" not in captured.out
+        assert "↻ Resumed session" in captured.err
+        assert "20260524_111111_xyz" in captured.err
+        assert "demo" in captured.err
+
+    def test_no_messages_goes_to_stderr_in_quiet_mode(self, capsys):
+        db = MagicMock()
+        db.get_session.return_value = {"id": "20260524_111111_xyz"}
+        db.resolve_resume_session_id.return_value = "20260524_111111_xyz"
+        db.get_messages_as_conversation.return_value = []
+        db._conn = MagicMock()
+
+        cli = _make_cli(quiet=True, db=db)
+        with patch("cli._prepare_deferred_agent_startup"):
+            try:
+                cli._init_agent()
+            except Exception:
+                pass
+
+        captured = capsys.readouterr()
+        assert "has no messages" not in captured.out
+        assert "has no messages" in captured.err
+        assert "Starting fresh" in captured.err