feat(profiler/behave_shell): emit cognitive.planning_depth

Distribution of inter-command IATs bucketed against IKI_THINK_MAX_S
(deep) and INTER_CMD_INSTANT_MAX (reactive); fall-through is shallow.
v0.1 thresholds; D.8 re-tunes.

tests/profiler/behave_shell/test_cognitive_planning_depth.py

@@ -0,0 +1,61 @@
+"""Step D.3: ``cognitive.planning_depth``."""
+from __future__ import annotations
+
+from decnet.profiler.behave_shell import extract_session
+from decnet.profiler.behave_shell._parse import AsciinemaEvent
+
+
+def _of(observations: list, primitive: str):
+    obs = [o for o in observations if o.primitive == primitive]
+    assert len(obs) == 1, f"expected exactly one {primitive}, got {len(obs)}"
+    return obs[0]
+
+
+def _commands_at(starts: list[float]) -> list[AsciinemaEvent]:
+    events: list[AsciinemaEvent] = []
+    for s in starts:
+        events.append((s, "i", "x\r"))
+    return events
+
+
+def test_no_inter_cmd_iats_no_emission() -> None:
+    out = list(extract_session(_commands_at([0.0]), sid="pd-empty"))
+    assert [o for o in out if o.primitive == "cognitive.planning_depth"] == []
+
+
+def test_long_pauses_emit_deep() -> None:
+    """Most pauses > 1.5s → deep."""
+    out = list(extract_session(
+        _commands_at([0.0, 3.0, 6.0, 9.0, 12.0, 15.0, 18.0, 21.0]),
+        sid="pd-deep",
+    ))
+    obs = _of(out, "cognitive.planning_depth")
+    assert obs.value == "deep"
+
+
+def test_sub_instant_pauses_emit_reactive() -> None:
+    """Most pauses ≤ INTER_CMD_INSTANT_MAX (0.30s) → reactive."""
+    out = list(extract_session(
+        _commands_at([i * 0.10 for i in range(8)]),
+        sid="pd-react",
+    ))
+    obs = _of(out, "cognitive.planning_depth")
+    assert obs.value == "reactive"
+
+
+def test_typing_speed_pauses_emit_shallow() -> None:
+    """Pauses around 1s — neither deep nor reactive → shallow."""
+    out = list(extract_session(
+        _commands_at([i * 1.0 for i in range(8)]),
+        sid="pd-shallow",
+    ))
+    obs = _of(out, "cognitive.planning_depth")
+    assert obs.value == "shallow"
+
+
+def test_low_sample_count_reduces_confidence() -> None:
+    short = list(extract_session(_commands_at([0.0, 1.0, 2.0]), sid="pd-short"))
+    full = list(extract_session(_commands_at([i * 1.0 for i in range(8)]), sid="pd-full"))
+    s = _of(short, "cognitive.planning_depth")
+    f = _of(full, "cognitive.planning_depth")
+    assert s.confidence < f.confidence