feat(profiler/behave_shell): emit environmental.locale

Searches ANSI-stripped output for LANG / LC_ALL / LC_CTYPE envvar
substrings emitted by env / locale / printenv. Highest-priority key
wins (LC_ALL > LANG > LC_CTYPE); POSIX value normalised to BCP-47:
en_US.UTF-8 → en-US, pt_BR.UTF-8 → pt-BR, C/POSIX → und. Free-string
registry value emitted directly.

PII discipline: only the parsed locale value enters observations;
surrounding output is read once for matching and dropped.

tests/profiler/behave_shell/test_environmental_locale.py

@@ -0,0 +1,95 @@
+"""Step F.3: ``environmental.locale``."""
+from __future__ import annotations
+
+from decnet.profiler.behave_shell import extract_session
+from decnet.profiler.behave_shell._features.environmental import _to_bcp47
+from decnet.profiler.behave_shell._parse import AsciinemaEvent
+
+
+PRIMITIVE = "environmental.locale"
+
+
+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 = 0.0, dt: float = 0.05) -> list[AsciinemaEvent]:
+    return [(t0 + i * dt, "i", c) for i, c in enumerate(text)]
+
+
+# ── _to_bcp47 ──────────────────────────────────────────────────────────────
+
+
+def test_to_bcp47_lang_region() -> None:
+    assert _to_bcp47("en_US.UTF-8") == "en-US"
+    assert _to_bcp47("pt_BR.UTF-8") == "pt-BR"
+    assert _to_bcp47("de_DE@euro") == "de-DE"
+
+
+def test_to_bcp47_language_only() -> None:
+    assert _to_bcp47("fr") == "fr"
+
+
+def test_to_bcp47_c_posix() -> None:
+    assert _to_bcp47("C") == "und"
+    assert _to_bcp47("POSIX") == "und"
+
+
+def test_to_bcp47_malformed() -> None:
+    assert _to_bcp47("X") is None        # too short
+    assert _to_bcp47("en_99") is None    # non-alpha region
+
+
+# ── feature integration ────────────────────────────────────────────────────
+
+
+def test_no_envvar_dump_no_emission() -> None:
+    events: list[AsciinemaEvent] = [
+        *_typed("ls\r"),
+        (0.20, "o", "file1\nfile2\n"),
+    ]
+    out = list(extract_session(events, sid="loc-none"))
+    assert [o for o in out if o.primitive == PRIMITIVE] == []
+
+
+def test_lang_envvar_dump_emits_bcp47() -> None:
+    events: list[AsciinemaEvent] = [
+        *_typed("env\r"),
+        (0.20, "o", "PATH=/usr/bin\nLANG=en_US.UTF-8\nUSER=anti\n"),
+    ]
+    obs = _of(list(extract_session(events, sid="loc-en")), PRIMITIVE)
+    assert obs.value == "en-US"
+
+
+def test_lc_all_takes_precedence_over_lang() -> None:
+    events: list[AsciinemaEvent] = [
+        *_typed("env\r"),
+        (0.20, "o", "LANG=en_US.UTF-8\nLC_ALL=pt_BR.UTF-8\nUSER=anti\n"),
+    ]
+    obs = _of(list(extract_session(events, sid="loc-prec")), PRIMITIVE)
+    assert obs.value == "pt-BR"
+
+
+def test_c_locale_emits_und() -> None:
+    events: list[AsciinemaEvent] = [
+        *_typed("env\r"),
+        (0.20, "o", "LANG=C\nUSER=anti\n"),
+    ]
+    obs = _of(list(extract_session(events, sid="loc-und")), PRIMITIVE)
+    assert obs.value == "und"
+
+
+def test_pii_locale_value_only_no_surrounding_output() -> None:
+    """Surrounding output isn't leaked — only the parsed BCP-47 value."""
+    events: list[AsciinemaEvent] = [
+        *_typed("env\r"),
+        (0.20, "o", "SECRET_TOKEN=abcdef123\nLANG=en_US.UTF-8\n"),
+    ]
+    out = list(extract_session(events, sid="loc-pii"))
+    obs = _of(out, PRIMITIVE)
+    serialised = obs.model_dump_json()
+    assert "SECRET_TOKEN" not in serialised
+    assert "abcdef123" not in serialised
+    assert "en-US" in serialised