fix(okf): fail-closed ingest-stempel-sjekk paa YAML-1.1-sannhetsformer [skip-docs]

_carries_complete_ingest_stamp sammenlignet generated kun mot literalen "true" og
feilet AAPENT: en pinnet ingest-writer som skrev "yes"/"on" ville sluppet det
komplette eierskaps-stempelet forbi write_concept_file uten en eneste lokal diff.
_YAML_TRUE_LITERALS ({"true","yes","on"}, case-insensitivt) er naa ENESTE vokabular,
malt mot PyYAML sin safe_load-resolver; "1"/bare "y"/"n" er bevisst utelatt siden en
YAML-leser aldri leser dem som bool. Halv-stempel forblir lovlig.

RED-foerst (tests/test_ingest_stamp_fail_closed_loadbearing.py), fire mutasjoner
alle roede mot hele suiten (904 passed/5 skipped): revert til literalen "true"
(2 roede) - over-widen til aa inkludere 1/y (1 roed) - and->or paa halv-stempel
(4 roede) - detach gaten helt (4 roede).

Ordre: 20260821T152153Z-432035430-from-portfolio-optimiser

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhxZ7XNjAFHFenWX5j9pev

tests/test_ingest_stamp_fail_closed_loadbearing.py

@@ -0,0 +1,77 @@
+"""RED-FIRST: the ingest ownership stamp check must be FAIL-CLOSED on the *value*, not just on
+field presence. Before this fix ``_carries_complete_ingest_stamp`` compared ``generated`` against
+the single literal string ``"true"`` — a YAML-1.1 truthy form such as ``yes``/``on`` slipped the
+gate open even though a real YAML reader reads it as boolean ``True`` (measured with PyYAML's
+``safe_load`` core-schema resolver, the same resolver family ``ruamel``/most YAML tooling ships:
+``yes``/``no``/``true``/``false``/``on``/``off``, any case, are read as bool; bare ``y``/``n`` and
+``1``/``0`` are NOT — they resolve to string/int). ``okf.py`` stays a hand-rolled, PyYAML-free
+line parser (D7 constraint), so the vocabulary is a plain literal set, not a real parser call."""
+
+import pytest
+
+from portfolio_optimiser import okf
+
+
+def test_yaml_truthy_form_yes_is_recognized_as_the_stamp(tmp_path) -> None:
+    """``generated: yes`` is read as boolean True by a real YAML reader, so it is the SAME stamp
+    as ``generated: true`` and must be refused identically."""
+    fm = {"type": "reference", "generated": "yes", "ingest_manifest": "bygg@0123456789abcdef"}
+    with pytest.raises(okf.IngestStampError):
+        okf.write_concept_file(str(tmp_path), "forged.md", fm, "body\n")
+    assert not (tmp_path / "forged.md").exists()  # refused, not silently repaired
+
+
+def test_yaml_truthy_form_on_mixed_case_is_recognized_as_the_stamp(tmp_path) -> None:
+    """Case-insensitivity must hold for every truthy form, not only ``true``/``True``/``TRUE``."""
+    fm = {"type": "reference", "generated": "On", "ingest_manifest": "bygg@0123456789abcdef"}
+    with pytest.raises(okf.IngestStampError):
+        okf.write_concept_file(str(tmp_path), "forged.md", fm, "body\n")
+    assert not (tmp_path / "forged.md").exists()
+
+
+def test_literal_true_still_refused_control(tmp_path) -> None:
+    """Control: the literal the gate has always recognized must still raise — otherwise the two
+    assertions above could pass against a gate that raises unconditionally, proving nothing."""
+    fm = {"type": "reference", "generated": "true", "ingest_manifest": "bygg@0123456789abcdef"}
+    with pytest.raises(okf.IngestStampError):
+        okf.write_concept_file(str(tmp_path), "forged.md", fm, "body\n")
+    assert not (tmp_path / "forged.md").exists()
+
+
+def test_non_yaml_boolean_forms_are_not_treated_as_the_stamp(tmp_path) -> None:
+    """``1`` and bare ``y`` are NOT read as boolean True by a real YAML reader (measured: PyYAML
+    resolves them to int ``1`` and string ``"y"``, never bool) — widening the true-vocabulary to
+    include them would over-block curated content no ingest pipeline ever produces, and no YAML
+    reader would read as the stamp either. Both write through unchanged, same as any other
+    unrecognized ``generated`` value paired with a manifest."""
+    for value in ("1", "y", "maybe"):
+        name = f"curated-{value}.md"
+        okf.write_concept_file(
+            str(tmp_path),
+            name,
+            {"type": "reference", "generated": value, "ingest_manifest": "bygg@0123456789abcdef"},
+            "body\n",
+        )
+        assert (tmp_path / name).exists()
+
+
+def test_half_stamp_remains_legal_generated_alone(tmp_path) -> None:
+    """CLAUDE.md's ingest-stamp invariant: either half of the stamp alone is still legal curated
+    content — even when that half is written in a non-``true`` truthy form."""
+    okf.write_concept_file(str(tmp_path), "a.md", {"type": "reference", "generated": "yes"}, "b\n")
+    assert (tmp_path / "a.md").exists()
+
+
+def test_half_stamp_remains_legal_manifest_alone(tmp_path) -> None:
+    okf.write_concept_file(
+        str(tmp_path),
+        "b.md",
+        {"type": "reference", "ingest_manifest": "bygg@0123456789abcdef"},
+        "c\n",
+    )
+    assert (tmp_path / "b.md").exists()
+
+
+def test_unstamped_file_written_as_before(tmp_path) -> None:
+    okf.write_concept_file(str(tmp_path), "c.md", {"type": "reference"}, "d\n")
+    assert (tmp_path / "c.md").exists()