feat: stop and rename a session from its tmux window

Add "stop" and "rename" to the Alt+p tool palette so a session can be
managed from inside its own harness window, mirroring the TUI's s/r keys:

- stop kills the harness window (stop_session_for_window).
- rename prompts for a nickname, pre-filled with the current one. The
  name is read from /dev/tty via readline (the fzf pipe leaves our stdin
  spent) and never passes through tmux's command parser, so there's
  nothing to quote-escape.

Extract require_session_id_for_window as the shared resolve-or-raise
guard behind the tool/stop/rename branches, dropping the duplicated
"not an hqt session window" check.

Also removes the now-shipped feature plans and specs under docs/.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_cli.py

@@ -75,6 +75,102 @@ def test_tool_cmd_clone_dispatches_to_clone(monkeypatch, tmp_path):
     assert calls["clone"] == "hqt-5"
 
 
+def test_tool_cmd_stop_dispatches_to_stop(monkeypatch, tmp_path):
+    monkeypatch.setattr(
+        "hqt.config.get_settings", lambda: Settings(db_path=tmp_path / "t.db")
+    )
+    calls = {}
+
+    async def fake_stop(self, window):
+        calls["stop"] = window
+
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.stop_session_for_window", fake_stop
+    )
+
+    result = CliRunner().invoke(cli.main, ["tool", "stop", "hqt-5"])
+
+    assert result.exit_code == 0, result.output
+    assert calls["stop"] == "hqt-5"
+
+
+def test_tool_cmd_rename_applies_new_nickname(monkeypatch, tmp_path):
+    from types import SimpleNamespace
+
+    monkeypatch.setattr(
+        "hqt.config.get_settings", lambda: Settings(db_path=tmp_path / "t.db")
+    )
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.session_id_for_window",
+        lambda self, window: 5,
+    )
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.get_session",
+        lambda self, sid: SimpleNamespace(nickname="old"),
+    )
+    # Prefill the prompt with the current nickname; user edits to "new".
+    seen = {}
+
+    def fake_read(prompt, prefill=""):
+        seen["prefill"] = prefill
+        return "new"
+
+    monkeypatch.setattr(cli, "_read_line_from_tty", fake_read)
+    calls = {}
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.rename_session",
+        lambda self, sid, nickname: calls.setdefault("args", (sid, nickname)),
+    )
+
+    result = CliRunner().invoke(cli.main, ["tool", "rename", "hqt-5"])
+
+    assert result.exit_code == 0, result.output
+    assert seen["prefill"] == "old"
+    assert calls["args"] == (5, "new")
+
+
+def test_tool_cmd_rename_aborted_leaves_name(monkeypatch, tmp_path):
+    from types import SimpleNamespace
+
+    monkeypatch.setattr(
+        "hqt.config.get_settings", lambda: Settings(db_path=tmp_path / "t.db")
+    )
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.session_id_for_window",
+        lambda self, window: 5,
+    )
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.get_session",
+        lambda self, sid: SimpleNamespace(nickname="old"),
+    )
+    monkeypatch.setattr(cli, "_read_line_from_tty", lambda prompt, prefill="": None)
+    calls = {}
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.rename_session",
+        lambda self, sid, nickname: calls.setdefault("args", (sid, nickname)),
+    )
+
+    result = CliRunner().invoke(cli.main, ["tool", "rename", "hqt-5"])
+
+    assert result.exit_code == 0, result.output
+    assert "args" not in calls  # None return = aborted, no DB write
+
+
+def test_tool_cmd_rename_unknown_window_raises(monkeypatch, tmp_path):
+    monkeypatch.setattr(
+        "hqt.config.get_settings", lambda: Settings(db_path=tmp_path / "t.db")
+    )
+    monkeypatch.setattr(
+        "hqt.sessions.service.SessionService.session_id_for_window",
+        lambda self, window: None,
+    )
+
+    result = CliRunner().invoke(cli.main, ["tool", "rename", "hqt-5"])
+
+    assert result.exit_code == 1
+    assert "not an hqt session window" in result.output
+
+
 def test_tool_cmd_reset_windows_dispatches_to_manager(monkeypatch, tmp_path):
     monkeypatch.setattr(
         "hqt.config.get_settings", lambda: Settings(db_path=tmp_path / "t.db")
@@ -150,6 +246,8 @@ def test_palette_cmd_shows_popup_for_session_window(monkeypatch, tmp_path):
     popup_cmd = argv[-1]
     assert "fzf" in popup_cmd
     assert "nvim" in popup_cmd and "clone" in popup_cmd
+    assert "stop" in popup_cmd
+    assert "rename" in popup_cmd
     assert "reset-windows" in popup_cmd
     # the window is baked into the command for `hqt tool {} <window>`
     assert "hqt-5" in popup_cmd