feat(profiler/behave_shell): emit cognitive.error_resilience.fallback_to_man

For each errored command, check whether the next command's
first_token_hash is in {man, help, info} (precomputed at module
load). At least one match → present, else absent. The --help / -h
flag forms aren't first tokens; v0.2 will reconsider once arg-token
hashing is justified by corpus.

tests/profiler/behave_shell/test_cognitive_error_resilience_fallback_to_man.py

@@ -0,0 +1,72 @@
+"""Step D.7: ``cognitive.error_resilience.fallback_to_man``."""
+from __future__ import annotations
+
+from decnet.profiler.behave_shell import extract_session
+from decnet.profiler.behave_shell._parse import AsciinemaEvent
+
+
+PRIMITIVE = "cognitive.error_resilience.fallback_to_man"
+
+
+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 _typed(text: str, t0: float, dt: float = 0.05) -> list[AsciinemaEvent]:
+    return [(t0 + i * dt, "i", c) for i, c in enumerate(text)]
+
+
+def _err_then(token: str, response: str, t0: float) -> list[AsciinemaEvent]:
+    events = _typed(f"{token}\r", t0=t0)
+    cmd_end = t0 + len(token) * 0.05
+    events.append((cmd_end + 0.10, "o", f"bash: {token}: command not found\n"))
+    events.extend(_typed(f"{response}\r", t0=t0 + 1.5))
+    return events
+
+
+def test_no_errors_no_emission() -> None:
+    events = _typed("ls\r", t0=0.0) + [(0.5, "o", "file1\n")]
+    out = list(extract_session(events, sid="ftm-clean"))
+    assert [o for o in out if o.primitive == PRIMITIVE] == []
+
+
+def test_help_after_error_emits_present() -> None:
+    """At least one fallback to a help-family token → present."""
+    events: list[AsciinemaEvent] = []
+    for i in range(5):
+        events.extend(_err_then("foo", "man", t0=i * 3.0))
+    out = list(extract_session(events, sid="ftm-present"))
+    obs = _of(out, PRIMITIVE)
+    assert obs.value == "present"
+
+
+def test_pivot_unrelated_emits_absent() -> None:
+    """Errors followed by non-help tools → absent."""
+    events: list[AsciinemaEvent] = []
+    for i in range(5):
+        events.extend(_err_then("foo", "ls", t0=i * 3.0))
+    out = list(extract_session(events, sid="ftm-absent"))
+    obs = _of(out, PRIMITIVE)
+    assert obs.value == "absent"
+
+
+def test_info_token_also_counts() -> None:
+    events: list[AsciinemaEvent] = []
+    for i in range(5):
+        events.extend(_err_then("foo", "info", t0=i * 3.0))
+    out = list(extract_session(events, sid="ftm-info"))
+    assert _of(out, PRIMITIVE).value == "present"
+
+
+def test_low_error_count_reduces_confidence() -> None:
+    short_events: list[AsciinemaEvent] = []
+    for i in range(2):
+        short_events.extend(_err_then("foo", "man", t0=i * 3.0))
+    full_events: list[AsciinemaEvent] = []
+    for i in range(6):
+        full_events.extend(_err_then("foo", "man", t0=i * 3.0))
+    s = _of(list(extract_session(short_events, sid="ftm-short")), PRIMITIVE)
+    f = _of(list(extract_session(full_events, sid="ftm-full")), PRIMITIVE)
+    assert s.confidence < f.confidence