fix: run agent in TUI mode so tmux attach shows live progress (#118)

Previously claude was launched with -p (print mode) which produces no
visible TUI.  Attaching to the session with `tmux attach -t issue-NNN`
showed a blank terminal.  Removing -p makes Claude run its interactive
TUI inside the tmux pane, so the session is fully watchable.

Add scripts/test_agent_loop.py covering _start_agent command
construction and state file round-trips.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/test_agent_loop.py

@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+"""Tests for scripts/agent_loop.py."""
+import json
+import unittest
+from pathlib import Path
+from unittest.mock import MagicMock, call, patch
+
+
+class TestStartAgent(unittest.TestCase):
+    """Verify that _start_agent builds the correct tmux / claude command."""
+
+    def _run(self, prompt: str, session_name: str):
+        """Call _start_agent with all subprocess.run calls mocked out."""
+        calls: list = []
+
+        def fake_run(cmd, **kwargs):
+            calls.append(cmd)
+            return MagicMock(returncode=0)
+
+        with (
+            patch("scripts.agent_loop.subprocess.run", side_effect=fake_run),
+            patch("scripts.agent_loop.Path.mkdir"),
+        ):
+            import scripts.agent_loop as al
+            al._start_agent(prompt, session_name)
+
+        return calls
+
+    def _get_shell_cmd(self, calls: list) -> str:
+        """Extract the shell command string from tmux new-session call."""
+        for cmd in calls:
+            if "new-session" in cmd:
+                # last element is the shell_cmd passed to bash -c
+                return cmd[-1]
+        self.fail("tmux new-session call not found")
+
+    def test_no_print_flag(self):
+        calls = self._run("Do something", "issue-1")
+        shell_cmd = self._get_shell_cmd(calls)
+        self.assertNotIn(" -p ", shell_cmd)
+        self.assertNotIn("--print", shell_cmd)
+
+    def test_prompt_included_in_cmd(self):
+        calls = self._run("Fix the bug", "issue-42")
+        shell_cmd = self._get_shell_cmd(calls)
+        self.assertIn("Fix the bug", shell_cmd)
+
+    def test_session_name_in_cmd(self):
+        calls = self._run("task prompt", "issue-99")
+        shell_cmd = self._get_shell_cmd(calls)
+        self.assertIn("issue-99", shell_cmd)
+
+    def test_dangerously_skip_permissions_present(self):
+        calls = self._run("prompt", "ci-fix")
+        shell_cmd = self._get_shell_cmd(calls)
+        self.assertIn("--dangerously-skip-permissions", shell_cmd)
+
+    def test_prompt_with_special_chars_is_quoted(self):
+        prompt = "Fix issue #42; rm -rf /"
+        calls = self._run(prompt, "issue-42")
+        shell_cmd = self._get_shell_cmd(calls)
+        # The dangerous part should be inside quotes, not interpreted by shell
+        self.assertNotIn("; rm -rf /", shell_cmd.split("'")[-1])
+
+    def test_tmux_new_session_is_detached(self):
+        calls = self._run("prompt", "issue-1")
+        new_session_call = next(c for c in calls if "new-session" in c)
+        self.assertIn("-d", new_session_call)
+
+    def test_tmux_new_session_uses_correct_name(self):
+        calls = self._run("prompt", "issue-7")
+        new_session_call = next(c for c in calls if "new-session" in c)
+        self.assertIn("issue-7", new_session_call)
+
+    def test_pipe_pane_called_for_logging(self):
+        calls = self._run("prompt", "issue-1")
+        pipe_pane_calls = [c for c in calls if "pipe-pane" in c]
+        self.assertEqual(len(pipe_pane_calls), 1)
+
+    def test_returns_session_name(self):
+        with (
+            patch("scripts.agent_loop.subprocess.run", return_value=MagicMock(returncode=0)),
+            patch("scripts.agent_loop.Path.mkdir"),
+        ):
+            import scripts.agent_loop as al
+            result = al._start_agent("prompt", "issue-55")
+        self.assertEqual(result, "issue-55")
+
+
+class TestWriteAndReadState(unittest.TestCase):
+    def test_roundtrip(self):
+        import tempfile
+        import scripts.agent_loop as al
+        with tempfile.NamedTemporaryFile(suffix=".json", delete=False) as f:
+            tmp = Path(f.name)
+        original = al.STATE_FILE
+        try:
+            al.STATE_FILE = tmp
+            al._write_state("issue-10", 10, "issue")
+            state = al._read_state()
+            self.assertEqual(state["tmux_session"], "issue-10")
+            self.assertEqual(state["issue"], 10)
+            self.assertEqual(state["type"], "issue")
+        finally:
+            al.STATE_FILE = original
+            tmp.unlink(missing_ok=True)
+
+    def test_read_missing_returns_none(self):
+        import scripts.agent_loop as al
+        original = al.STATE_FILE
+        try:
+            al.STATE_FILE = Path("/nonexistent/state.json")
+            self.assertIsNone(al._read_state())
+        finally:
+            al.STATE_FILE = original
+
+
+if __name__ == "__main__":
+    unittest.main()