fix(stop): an unconfirmed /exit no longer claims a kill-chain fallback (Issue #60, Linux item 2)

An agent that exits on /exit never turns `working`, so send_keys_safe
returns 4 although the stop then ends cleanly. The line now says the
delivery is unconfirmed and that the stop waits for the session to exit;
the kill steps keep their own lines, printed only when they run. Exit
judgement and the kill chain are unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_issue60_linux_fixes.py

@@ -7,14 +7,18 @@
    the sidecars on close; a plain mode=ro open creates missing ones).
 6. `debug paths` (which writes a line to opencode's log) runs once per
    (binary, HOME, XDG_DATA_HOME) in a process.
+2. A graceful stop whose `/exit` worked says so: the agent exits instead of
+   turning `working`, so the delivery is unconfirmed, and no kill step ran.
 """
 
 from __future__ import annotations
 
 import os
 import re
+import json
 import shutil
 import sqlite3
+import subprocess
 import sys
 from pathlib import Path
 
@@ -213,3 +217,63 @@ def test_a_failed_debug_paths_is_not_remembered(tmp_path, monkeypatch):
     default = str(tmp_path / "home" / ".local" / "share" / "opencode" / "opencode.db")
     assert [adapter._resolve_db(ctx) for _ in range(2)] == [default] * 2
     assert log.read_text().splitlines() == ["debug paths"] * 2
+
+
+# ---------------------------------------------------------------------------
+# 2. the stop's words match what happened
+# ---------------------------------------------------------------------------
+SESSION = "i60-stop-opencode"
+
+# A herdr in front of the conftest mock that, like a real opencode 2.x pane
+# (Linux check 3-3), ends the agent on `/exit`: the prompt's wait for
+# `working` then fails because the agent is gone.
+EXITING_HERDR = """#!/usr/bin/env python3
+import json, os, sys
+args = sys.argv[1:]
+if "prompt" in args and "/exit" in args:
+    with open(@STATE@) as f:
+        state = json.load(f)
+    state["agents"].pop(@NAME@, None)
+    state.setdefault("calls", []).append("herdr " + " ".join(args))
+    with open(@STATE@, "w") as f:
+        json.dump(state, f)
+    sys.stderr.write(json.dumps({"error": {"code": "agent_exited", "message": "agent exited"}}) + "\\n")
+    sys.exit(1)
+os.execv(@MOCK@, [@MOCK@] + args)
+"""
+
+
+@pytest.mark.parametrize("exits", [True, False])
+def test_the_graceful_stop_reports_what_happened(mam_sandbox, mock_herdr, mock_agents, monkeypatch, exits):
+    state = json.loads(Path(mock_herdr).read_text())
+    state["agents"][SESSION] = {"status": "running", "agent": "opencode", "agent_status": "idle",
+                                "cwd": str(mam_sandbox), "pid": 12345, "pane_id": "w1:p1",
+                                "command": "opencode", "buffer": "Ask anything"}
+    Path(mock_herdr).write_text(json.dumps(state, indent=2))
+    lib = mam_sandbox / ".agents" / "skills" / "lib.sh"
+    row = ("d['herdr_sessions'] = [{'name': '%s', 'agent': 'opencode', 'status': 'running', "
+           "'pane': {'cwd': '%s', 'pid': 12345, 'cmd': 'opencode'}}]" % (SESSION, mam_sandbox))
+    res = subprocess.run(["bash", "-c", f"source {lib} && atomic_dump_yaml {mam_sandbox / '.mam' / 'agent-sessions.yaml'}"],
+                         input=row, capture_output=True, text=True)
+    assert res.returncode == 0, res.stderr
+    if exits:
+        wrap = mam_sandbox / "exitbin" / "herdr"
+        wrap.parent.mkdir()
+        wrap.write_text(EXITING_HERDR.replace("@STATE@", repr(str(mock_herdr))).replace("@NAME@", repr(SESSION))
+                        .replace("@MOCK@", repr(shutil.which("herdr"))))
+        wrap.chmod(0o755)
+        monkeypatch.setenv("PATH", f"{wrap.parent}:{os.environ['PATH']}")
+    stop = mam_sandbox / ".agents" / "skills" / "multi-agent-mux-stop" / "scripts" / "stop_session.sh"
+    res = subprocess.run(["bash", str(stop), "--session", SESSION, "--agent", "opencode"],
+                         capture_output=True, text=True, timeout=180)
+    out = res.stdout + res.stderr
+    assert res.returncode == 0, out
+    calls = json.loads(Path(mock_herdr).read_text()).get("calls", [])
+    assert any("prompt" in c and "/exit" in c for c in calls), calls
+    assert "falling back to kill chain" not in out
+    if exits:
+        assert "unconfirmed" in out and "graceful: exited cleanly" in out, out
+        assert "kill-session" not in out and not any("kill-session" in c for c in calls), out
+    else:
+        # The kill step runs, so it is named.
+        assert "still alive → kill-session" in out, out