fix(issue-30): review ad3d8206 - a prompt glyph inside a draft is draft text; the R4 regression test tells the defect apart

- input_region: in the prompt-line shape the input box starts only at a
  column-0 prompt (codex indents a draft's continuation lines), and the
  prompt and the (whole-line) placeholder are stripped from the box's first
  non-blank line only, so `› Explain this terminal prompt:\n  ›` is not empty.
- test_r4 runs with S=40 again: the defective code nudged ~30 s after a
  missed transition, which S=10 could not tell from the fixed ~10 s.

Both new checks fail against the defective versions (stall_watch.py at
47e4274 -> 30.24 s < 40; input_region.py at bf0f5c1 -> nudge sent) and pass
now, each with its passing twin.

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

.agents/skills/lib_py/agents/input_region.py

@@ -11,12 +11,13 @@ def extract_input_region(pane_text: str, agent_name: str) -> str:
       1. an `input_block_prefix` -> the last contiguous block of lines starting
          with it, prefix removed, cut at the first `input_stop_pattern` line;
       2. two or more `input_rule_pattern` rules -> the lines between the last two;
-      3. an `input_prompt` -> from the last line starting with the prompt to
+      3. an `input_prompt` -> from the last line starting (column 0) with the prompt to
          the end of the pane, minus a last non-blank line matching
          `input_stop_pattern` (the status footer). Every other line below the
          prompt line is input: a multi-line draft is never cut to its first line.
 
-    Then `input_frame_chars`, the prompt and the placeholder are stripped. There
+    Then `input_frame_chars` are stripped, and the prompt and the placeholder
+    (whole-line) are stripped from the box's first non-blank line only. There
     is no whole-pane fallback: a pane with none of these shapes has no input
     region and yields a non-empty "unknown" result rather than a guess.
     Raises ValueError for agents without input area facts (like hermes' peers).
@@ -52,7 +53,10 @@ def extract_input_region(pane_text: str, agent_name: str) -> str:
             region_lines = lines[rule_indices[-2] + 1:rule_indices[-1]]
 
     if region_lines is None:
-        starts = [i for i, line in enumerate(lines) if line.lstrip().startswith(prompt)]
+        # The composer's prompt sits at column 0; a draft's continuation lines
+        # are indented, so an indented prompt character is draft text (review
+        # ad3d8206), never the start of the input box.
+        starts = [i for i, line in enumerate(lines) if line.startswith(prompt)]
         if starts:
             region_lines = [line for line in lines[starts[-1]:]]
             while region_lines and not region_lines[-1].strip():
@@ -68,11 +72,15 @@ def extract_input_region(pane_text: str, agent_name: str) -> str:
     if frame:
         region_lines = [line.strip().strip(frame) for line in region_lines]
 
-    region_text = "\n".join(region_lines)
-    region_text = re.sub(r'^\s*' + re.escape(prompt) + r'\s*', '', region_text, flags=re.MULTILINE)
+    # The prompt and the placeholder belong to the box's first line only: the
+    # same characters further down are what the user typed.
+    region_lines = list(region_lines)
+    first = next((i for i, line in enumerate(region_lines) if line.strip()), None)
+    if first is not None:
+        head = re.sub(r'^\s*' + re.escape(prompt) + r'\s*', '', region_lines[first], count=1)
+        placeholder = adapter.input_placeholder
+        if placeholder and head.strip() == placeholder:
+            head = ''
+        region_lines[first] = head
 
-    placeholder = adapter.input_placeholder
-    if placeholder:
-        region_text = region_text.replace(placeholder, '')
-
-    return region_text.strip()
+    return "\n".join(region_lines).strip()

tests/test_issue30_stall_watch.py

@@ -676,7 +676,7 @@ def test_r4_a_missed_transition_restarts_the_idle_window(mam_sandbox, mock_herdr
     wait mock. process-info retains its measured nested result shape.
     """
     reg = mam_sandbox / ".mam" / "jobs"
-    env = _env(mam_sandbox, MAM_STALL_IDLE_S=10)
+    env = _env(mam_sandbox, MAM_STALL_IDLE_S=40)
     jid = _job(env, reg)
     agent = _proc("exec sleep 300")
     observed = mam_sandbox / "observed.json"
@@ -729,7 +729,10 @@ def test_r4_a_missed_transition_restarts_the_idle_window(mam_sandbox, mock_herdr
         w.terminate()
         w.communicate(timeout=10)
         idle_time = times['prompted'] - times.get('changed', times['started'])
-        assert idle_time >= 10, {'continuous_idle_seconds': idle_time, 'threshold': 10}
+        # S must exceed the 30 s re-judgement interval: with the old code the nudge came
+        # ~30 s after the missed transition, which only fails the assertion when S > 30
+        # (review ad3d8206; S=10 passed on the defective code too).
+        assert idle_time >= 40, {'continuous_idle_seconds': idle_time, 'threshold': 40}
     finally:
         if w is not None and w.poll() is None:
             w.terminate()
@@ -745,3 +748,42 @@ def test_r1_the_codex_extractor_keeps_every_line_under_the_prompt():
     assert extract_input_region(draft, "codex") == "draft on the second input line"
     no_footer = "\n".join(idle.splitlines()[:-1]).replace("› Ask Codex to do anything", "›\n  a · b · c")
     assert extract_input_region(no_footer, "codex") != "", "only the last line may be the footer"
+
+
+
+# Review ad3d8206 (planner-reviewer-codex-01): a prompt glyph inside the draft
+# is draft text, not the start of the input box (the reviewer's reproduction).
+@pytest.mark.parametrize("draft", [False, True])
+def test_r1b_a_draft_containing_the_prompt_glyph_is_not_empty(mam_sandbox, mock_herdr, draft):
+    reg = mam_sandbox / ".mam" / "jobs"
+    env = _env(mam_sandbox, MAM_STALL_IDLE_S=1)
+    jid = _job(env, reg)
+    agent = _proc("exec sleep 300")
+    w = None
+    try:
+        pane = _pane("codex")
+        if draft:
+            pane = pane.replace("› Ask Codex to do anything", "› Explain this terminal prompt:\n  ›")
+        _agent(mock_herdr, "reviewer-codex-t", "codex", agent.pid, "idle", pane)
+        w = _watch(env, reg, jid, "reviewer-codex-t", "codex")
+        if draft:
+            time.sleep(5)
+        else:
+            assert _until(lambda: _prompts(mock_herdr))
+        prompts = _prompts(mock_herdr)
+        _finish(env, reg, jid, w)
+        assert len(prompts) == (0 if draft else 1), prompts
+    finally:
+        if w is not None and w.poll() is None:
+            w.terminate()
+            w.communicate(timeout=10)
+        _kill(agent)
+
+
+def test_r1b_the_extractor_strips_the_prompt_from_the_first_line_only():
+    from lib_py.agents.input_region import extract_input_region
+    idle = _pane("codex")
+    for draft in ("› Explain this terminal prompt:\n  ›", "›\n  ›", "› Ask Codex to do anything\n  more"):
+        assert extract_input_region(idle.replace("› Ask Codex to do anything", draft), "codex") != "", draft
+    typed = re.sub(r"^❯\s*$", "❯ x\n  ❯", _pane("claude"), count=1, flags=re.M)
+    assert typed != _pane("claude") and extract_input_region(typed, "claude") != ""