feat(profiler/behave_shell): emit cognitive.exploration_style

Two-axis classification over the first_token_hash sequence:
repetition_rate (drilling) vs backtrack_rate (jumping among prior
tools). chaotic/targeted/methodical buckets. v0.1 thresholds; D.8
re-tunes.

tests/profiler/behave_shell/test_cognitive_exploration_style.py

@@ -0,0 +1,74 @@
+"""Step D.2: ``cognitive.exploration_style``."""
+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 _cmds(tokens: list[str]) -> list[AsciinemaEvent]:
+    """One command per token, evenly spaced one second apart."""
+    events: list[AsciinemaEvent] = []
+    for i, tok in enumerate(tokens):
+        t0 = i * 1.0
+        for j, c in enumerate(tok):
+            events.append((t0 + j * 0.05, "i", c))
+        events.append((t0 + len(tok) * 0.05, "i", "\r"))
+    return events
+
+
+def test_no_commands_no_emission() -> None:
+    out = list(extract_session([(0.0, "i", "x")], sid="es-empty"))
+    assert [o for o in out if o.primitive == "cognitive.exploration_style"] == []
+
+
+def test_all_unique_tools_emits_methodical() -> None:
+    """Linear progression through new tools: low R, low J → methodical."""
+    out = list(extract_session(
+        _cmds(["ls", "ps", "id", "uname", "whoami", "pwd", "env", "date"]),
+        sid="es-meth",
+    ))
+    obs = _of(out, "cognitive.exploration_style")
+    assert obs.value == "methodical"
+
+
+def test_drilling_one_tool_emits_targeted() -> None:
+    """Same tool repeated → high R, low J → targeted."""
+    out = list(extract_session(
+        _cmds(["curl", "curl", "curl", "curl", "curl", "curl", "curl", "curl"]),
+        sid="es-tgt",
+    ))
+    obs = _of(out, "cognitive.exploration_style")
+    assert obs.value == "targeted"
+
+
+def test_jumping_among_old_tools_emits_chaotic() -> None:
+    """Backtracking among prior tools → high J → chaotic."""
+    out = list(extract_session(
+        _cmds(["a", "b", "c", "a", "c", "b", "a", "b"]),
+        sid="es-chaos",
+    ))
+    obs = _of(out, "cognitive.exploration_style")
+    assert obs.value == "chaotic"
+
+
+def test_low_sample_count_reduces_confidence() -> None:
+    short = list(extract_session(_cmds(["a", "b", "c"]), sid="es-short"))
+    full = list(extract_session(_cmds(["a", "b", "c", "d", "e", "f"]), sid="es-full"))
+    s = _of(short, "cognitive.exploration_style")
+    f = _of(full, "cognitive.exploration_style")
+    assert s.confidence < f.confidence
+
+
+def test_pii_no_command_bodies_in_observation() -> None:
+    out = list(extract_session(
+        _cmds(["secret_payload"] * 6),
+        sid="es-pii",
+    ))
+    obs = _of(out, "cognitive.exploration_style")
+    assert "secret_payload" not in obs.model_dump_json()