feat(ingest): I3 — D7-speil av ingest (filkatalog/CSV), bygget fra commons-spec alene

Speiler MAF I2 fra shared/ingest-spec.md alene: manifest → CSV-konnektor →
materialisert OKF-bundle, byte-identisk med den delte golden-fasiten.

- ingest.py: ManifestContract (pydantic, fail-fast, file-kilde, verdict-reservasjon
  §3, id-grammatikk, max_rows), CSV-konnektor (boundary-checked fail-closed),
  materialisering (§5-frontmatter eksakt rekkefølge, markdown-tabell m/ escaping,
  LF-only, SHA-256 manifest-stamp), index-generering (§6), replacement §3/§5.
- okf.py: _parse_index_entry — tolererer frontmatterløs index (method-spec §3:
  index rendres via body = summary, ikke som typet concept-fil). Golden var
  spec-konform; D7-okf var strengere enn standarden. Scoped: non-index concept-
  filer krever fortsatt type (honesty-test).
- examples/ingest-golden-file/: repo-lokal golden (byte-frossen kopi av I2s fasit).
- Speiltester (I2s load-bearing-sett, alle detach-bevist røde): golden byte-fasit
  + mutasjonskontroller · provenance/navigability/verdict-reservasjon/re-ingest-safety
  · kontrakt fail-fast/max_rows/boundary/kollisjon · spec-integritet §11.
- docs/2026-07-04-I3-brief.md: brief + de to operatør-avgjorte beslutningene.

Suite 239 passed uten nøkkel/nettverk (189 + 50 nye) · ruff + mypy --strict rene.

[skip-docs] README + docs/extending.md er bevisst utsatt til I7 per sesjonsplan
(programmet batcher ingest-doc der, avgrenset til det D7 faktisk har — CSV nå,
SQL/HTTP senere). Endringen er dokumentert i docs/2026-07-04-I3-brief.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017MM6BWb1hWmJZuXFZ7rjxT

tests/test_ingest.py

@@ -0,0 +1,138 @@
+"""Ingest unit + fail-fast contract tests (ingest-spec §4, §5, §8).
+
+The manifest is schema-validated fail-fast BEFORE any source call (§4, the startup-contract
+discipline). These tests pin the malformed-manifest rejections, the §5 cell-escaping rules,
+and the §8 size cap / fail-closed path resolution / no-overwrite collision.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+from pydantic import ValidationError
+
+from portfolio_optimiser_claude.ingest import (
+    ManifestContract,
+    _escape_cell,
+    load_manifest,
+    materialize,
+)
+
+GOLDEN = Path(__file__).resolve().parents[1] / "examples" / "ingest-golden-file"
+INGESTED_AT = "2026-07-03T12:00:00Z"
+
+
+def _valid() -> dict:
+    return {
+        "manifest_version": 1,
+        "source": {"type": "file", "id": "arkiv", "root": "fixture"},
+        "bundle_summary": "s",
+        "extractions": [
+            {"id": "e", "title": "T", "query": "e.csv", "okf_type": "dataset", "max_rows": 5}
+        ],
+    }
+
+
+def _write_case(tmp_path: Path, manifest: dict, csvs: dict[str, str]) -> Path:
+    case = tmp_path / "case"
+    (case / "fixture").mkdir(parents=True)
+    (case / "manifest.json").write_text(json.dumps(manifest), encoding="utf-8")
+    for name, text in csvs.items():
+        (case / "fixture" / name).write_text(text, encoding="utf-8")
+    return case
+
+
+class TestManifestValidation:
+    """§4: a malformed manifest never starts a run (fail-fast)."""
+
+    def test_valid_manifest_loads_and_stamps(self) -> None:
+        contract = ManifestContract(**_valid())
+        assert contract.manifest_version == 1
+        assert contract.source.id == "arkiv"
+
+    def test_stamp_is_stem_at_sha256_16(self, tmp_path: Path) -> None:
+        case = _write_case(tmp_path, _valid(), {"e.csv": "a\n1\n"})
+        loaded = load_manifest(case / "manifest.json")
+        stem, _, digest = loaded.stamp.partition("@")
+        assert stem == "manifest"
+        assert len(digest) == 16 and all(c in "0123456789abcdef" for c in digest)
+
+    @pytest.mark.parametrize(
+        "mutate",
+        [
+            lambda m: m.pop("manifest_version"),
+            lambda m: m.__setitem__("manifest_version", 2),
+            lambda m: m.pop("source"),
+            lambda m: m.pop("bundle_summary"),
+            lambda m: m.__setitem__("extractions", []),
+            lambda m: m["source"].__setitem__("id", "Bad_Id"),
+            lambda m: m["source"].__setitem__("type", "sql"),
+            lambda m: m["extractions"][0].__setitem__("id", "Bad Id"),
+            lambda m: m["extractions"][0].__setitem__("title", "two\nlines"),
+            lambda m: m["extractions"][0].__setitem__("max_rows", 0),
+            lambda m: m["extractions"][0].__setitem__("max_rows", -1),
+        ],
+    )
+    def test_malformed_manifest_is_rejected(self, mutate) -> None:
+        manifest = _valid()
+        mutate(manifest)
+        with pytest.raises(ValidationError):
+            ManifestContract(**manifest)
+
+    def test_duplicate_extraction_ids_are_rejected(self) -> None:
+        manifest = _valid()
+        manifest["extractions"].append(dict(manifest["extractions"][0]))
+        with pytest.raises(ValidationError):
+            ManifestContract(**manifest)
+
+
+class TestCellEscaping:
+    """§5: text verbatim with backslash → \\\\, pipe → \\|, newline → single space."""
+
+    def test_backslash_then_pipe_order(self) -> None:
+        assert _escape_cell("\\|") == "\\\\\\|"
+
+    def test_pipe_escaped(self) -> None:
+        assert _escape_cell("a|b") == "a\\|b"
+
+    def test_newline_becomes_single_space(self) -> None:
+        assert _escape_cell("x\ny") == "x y"
+        assert _escape_cell("x\r\ny") == "x y"
+
+    def test_plain_text_verbatim(self) -> None:
+        assert _escape_cell("007") == "007"
+        assert _escape_cell("1.50") == "1.50"
+
+
+class TestSecurityFrame:
+    """§8: size cap fail-fast, path resolution fail-closed, curated never overwritten."""
+
+    def test_extraction_exceeding_max_rows_fails(self, tmp_path: Path) -> None:
+        manifest = _valid()
+        manifest["extractions"][0]["max_rows"] = 1
+        case = _write_case(tmp_path, manifest, {"e.csv": "col\n1\n2\n"})  # 2 data rows > 1
+        with pytest.raises(ValueError, match="max_rows"):
+            materialize(case / "manifest.json", tmp_path / "bundle", INGESTED_AT)
+
+    def test_query_escaping_root_is_refused(self, tmp_path: Path) -> None:
+        manifest = _valid()
+        manifest["extractions"][0]["query"] = "../secret.csv"
+        case = _write_case(tmp_path, manifest, {"e.csv": "col\n1\n"})
+        (case / "secret.csv").write_text("col\nx\n", encoding="utf-8")
+        with pytest.raises(ValueError, match="escapes"):
+            materialize(case / "manifest.json", tmp_path / "bundle", INGESTED_AT)
+
+    def test_collision_with_non_ingest_file_fails(self, tmp_path: Path) -> None:
+        case = _write_case(tmp_path, _valid(), {"e.csv": "col\n1\n"})
+        bundle = tmp_path / "bundle"
+        bundle.mkdir()
+        # A curated (non-stamped) file already occupies the generated name.
+        (bundle / "ingest-e.md").write_text(
+            "---\ntype: reference\ntitle: hand\n---\n\nCurated.\n", encoding="utf-8"
+        )
+        with pytest.raises(ValueError, match="collides"):
+            materialize(case / "manifest.json", bundle, INGESTED_AT)
+        # The curated file is untouched — never overwritten.
+        assert "Curated." in (bundle / "ingest-e.md").read_text(encoding="utf-8")

tests/test_ingest_golden.py

@@ -0,0 +1,86 @@
+"""Ingest golden regression (ingest-spec §11) — the shared byte-for-byte fasit.
+
+D7 mirror of MAF I2. Consumes the repo-local ``examples/ingest-golden-file/``
+(a byte-frozen copy of MAF I2's golden — the SAME shared extraction, so this test
+proves D7's independent implementation reproduces MAF's exact bytes from the shared
+spec alone). ``expected-bundle/`` is compared file by file, byte for byte.
+
+The mutation controls prove the net is taut: one changed determinism input (a CSV
+cell, the timestamp, the manifest bytes) must diverge from the golden bytes.
+"""
+
+from __future__ import annotations
+
+import shutil
+from pathlib import Path
+
+from portfolio_optimiser_claude.ingest import materialize
+
+GOLDEN = Path(__file__).resolve().parents[1] / "examples" / "ingest-golden-file"
+
+
+def _ingested_at() -> str:
+    return (GOLDEN / "ingested-at.txt").read_text(encoding="utf-8").strip()
+
+
+def test_materializes_golden_byte_for_byte(tmp_path: Path) -> None:
+    bundle = tmp_path / "bundle"
+    bundle.mkdir()
+    materialize(GOLDEN / "manifest.json", bundle, _ingested_at())
+
+    expected = GOLDEN / "expected-bundle"
+    expected_names = sorted(p.name for p in expected.iterdir())
+    produced_names = sorted(p.name for p in bundle.iterdir())
+    assert produced_names == expected_names  # no missing, no extra files
+    for name in expected_names:
+        assert (bundle / name).read_bytes() == (expected / name).read_bytes(), name
+
+
+def test_reingest_is_idempotent(tmp_path: Path) -> None:
+    # ingest-spec §10: same source content, manifest, ingested_at → byte-identical,
+    # repeated runs idempotent.
+    bundle = tmp_path / "bundle"
+    bundle.mkdir()
+    materialize(GOLDEN / "manifest.json", bundle, _ingested_at())
+    first = {p.name: p.read_bytes() for p in bundle.iterdir()}
+    materialize(GOLDEN / "manifest.json", bundle, _ingested_at())
+    second = {p.name: p.read_bytes() for p in bundle.iterdir()}
+    assert first == second
+
+
+class TestMutationControl:
+    """One changed determinism input → divergence from the golden bytes."""
+
+    def _case(self, tmp_path: Path) -> Path:
+        case = tmp_path / "case"
+        shutil.copytree(GOLDEN, case)
+        return case
+
+    def test_changed_cell_diverges(self, tmp_path: Path) -> None:
+        case = self._case(tmp_path)
+        csv = case / "fixture" / "costs.csv"
+        csv.write_bytes(csv.read_bytes().replace(b"120000", b"999999"))
+        bundle = tmp_path / "bundle"
+        bundle.mkdir()
+        materialize(case / "manifest.json", bundle, _ingested_at())
+        golden_bytes = (GOLDEN / "expected-bundle" / "ingest-costs.md").read_bytes()
+        assert (bundle / "ingest-costs.md").read_bytes() != golden_bytes
+
+    def test_changed_timestamp_diverges(self, tmp_path: Path) -> None:
+        bundle = tmp_path / "bundle"
+        bundle.mkdir()
+        materialize(GOLDEN / "manifest.json", bundle, "2099-01-01T00:00:00Z")
+        golden_bytes = (GOLDEN / "expected-bundle" / "ingest-costs.md").read_bytes()
+        assert (bundle / "ingest-costs.md").read_bytes() != golden_bytes
+
+    def test_changed_manifest_bytes_change_the_stamp(self, tmp_path: Path) -> None:
+        # The ingest_manifest stamp is SHA-256 of the manifest's raw bytes (§5) —
+        # a whitespace-only edit still re-stamps every generated file.
+        case = self._case(tmp_path)
+        manifest = case / "manifest.json"
+        manifest.write_bytes(manifest.read_bytes() + b"\n")
+        bundle = tmp_path / "bundle"
+        bundle.mkdir()
+        materialize(manifest, bundle, _ingested_at())
+        golden_bytes = (GOLDEN / "expected-bundle" / "ingest-costs.md").read_bytes()
+        assert (bundle / "ingest-costs.md").read_bytes() != golden_bytes

tests/test_ingest_loadbearing.py

@@ -0,0 +1,178 @@
+"""Load-bearing ingest seams (ingest-spec §11) — D7 mirror of MAF I2's set.
+
+Each test must go RED when its seam is detached (the method-spec §11 regime): a
+grønn-men-død test is the failure mode the rule exists for. The seams mirrored here:
+
+- Provenance stamping — a generated file carries the §7 provenance layer, in order.
+- Navigability — the generated bundle is consumable by the UNCHANGED ``okf`` navigation
+  (index links included), incl. the frontmatter-less generated index.
+- Verdict reservation — a manifest mapping to ``type: verdict`` is rejected fail-fast,
+  before any source call.
+- Re-ingest layer safety — re-materialization over a bundle carrying a promoted verdict
+  preserves the verdict file AND its index link (curated content always survives).
+"""
+
+from __future__ import annotations
+
+import json
+import shutil
+from pathlib import Path
+
+import pytest
+from pydantic import ValidationError
+
+from portfolio_optimiser_claude import okf
+from portfolio_optimiser_claude.ingest import ManifestContract, load_manifest, materialize
+
+GOLDEN = Path(__file__).resolve().parents[1] / "examples" / "ingest-golden-file"
+INGESTED_AT = (GOLDEN / "ingested-at.txt").read_text(encoding="utf-8").strip()
+
+_PROVENANCE_KEYS = ("source_system", "source_query", "ingested_at", "ingest_manifest", "generated")
+
+
+def _materialized(tmp_path: Path) -> Path:
+    bundle = tmp_path / "bundle"
+    bundle.mkdir()
+    materialize(GOLDEN / "manifest.json", bundle, INGESTED_AT)
+    return bundle
+
+
+class TestProvenanceStamping:
+    """Seam: a generated file carries the §7 provenance layer (RED if it stops)."""
+
+    def test_generated_file_carries_the_provenance_layer(self, tmp_path: Path) -> None:
+        bundle = _materialized(tmp_path)
+        concept = okf.parse_concept_file(bundle / "ingest-costs.md")
+        for key in _PROVENANCE_KEYS:
+            assert key in concept.frontmatter, f"provenance key {key} detached"
+        assert concept.frontmatter["source_system"] == "prosjekt-arkiv"
+        assert concept.frontmatter["ingested_at"] == INGESTED_AT
+        assert concept.frontmatter["generated"] == "true"
+        stamp = load_manifest(GOLDEN / "manifest.json").stamp
+        assert concept.frontmatter["ingest_manifest"] == stamp
+
+    def test_provenance_keys_are_in_the_spec_order(self, tmp_path: Path) -> None:
+        # §5: exactly these keys, in exactly this order — the chain is a contract.
+        bundle = _materialized(tmp_path)
+        lines = (bundle / "ingest-costs.md").read_text(encoding="utf-8").splitlines()
+        keys = [ln.split(":", 1)[0] for ln in lines[1 : lines.index("---", 1)]]
+        assert keys == [
+            "type",
+            "title",
+            "source_system",
+            "source_query",
+            "ingested_at",
+            "ingest_manifest",
+            "generated",
+        ]
+
+
+class TestNavigability:
+    """Seam: the generated bundle is consumable by the UNCHANGED okf navigation."""
+
+    def test_generated_bundle_navigates_via_unchanged_okf(self, tmp_path: Path) -> None:
+        bundle = _materialized(tmp_path)
+        names = [c.path.name for c in okf.navigate_bundle(bundle)]
+        # Every generated ingest file must be REACHABLE via index cross-links — an
+        # unlinked generated file is unreachable (RED if index linking detaches).
+        assert names == ["index.md", "ingest-costs.md", "ingest-edge.md"]
+
+    def test_generated_context_renders_the_extracted_rows(self, tmp_path: Path) -> None:
+        bundle = _materialized(tmp_path)
+        context = okf.bundle_context(bundle)
+        assert "led-retrofit" in context and "requires vendor quote" in context
+
+    def test_generated_index_is_frontmatterless_and_still_navigates(self, tmp_path: Path) -> None:
+        # The generated index carries no frontmatter (§6 shape) — navigation must
+        # still work, exercising the okf entry-point relaxation end to end.
+        bundle = _materialized(tmp_path)
+        assert not (bundle / "index.md").read_text(encoding="utf-8").startswith("---")
+        assert okf.navigate_bundle(bundle)[0].path.name == "index.md"
+
+
+class TestVerdictReservation:
+    """Seam: an ingest mapping to the verdict layer is rejected fail-fast (§3)."""
+
+    def _manifest(self, okf_type: str) -> dict:
+        return {
+            "manifest_version": 1,
+            "source": {"type": "file", "id": "x", "root": "fixture"},
+            "bundle_summary": "s",
+            "extractions": [
+                {"id": "e", "title": "T", "query": "e.csv", "okf_type": okf_type, "max_rows": 1}
+            ],
+        }
+
+    def test_verdict_okf_type_is_rejected(self) -> None:
+        with pytest.raises(ValidationError):
+            ManifestContract(**self._manifest("verdict"))
+
+    def test_verdict_reservation_is_case_insensitive(self) -> None:
+        with pytest.raises(ValidationError):
+            ManifestContract(**self._manifest("Verdict"))
+
+    def test_rejection_is_fail_fast_before_any_source_call(self, tmp_path: Path) -> None:
+        # A verdict manifest never touches the source: no bundle is written.
+        manifest = tmp_path / "manifest.json"
+        manifest.write_text(json.dumps(self._manifest("verdict")), encoding="utf-8")
+        bundle = tmp_path / "bundle"
+        with pytest.raises(ValidationError):
+            materialize(manifest, bundle, INGESTED_AT)
+        assert not bundle.exists() or not any(bundle.iterdir())
+
+
+class TestReingestLayerSafety:
+    """Seam: re-ingest preserves a promoted verdict AND its index link (§3, §6)."""
+
+    def _promote(self, bundle: Path) -> None:
+        # Simulate the promotion gate writing a verdict file + its (neutral) index link,
+        # plus a curated file + link. Neither carries the ingest stamp.
+        (bundle / "promoted-verdict-led.md").write_text(
+            "---\ntype: verdict\ndecision: approved\ndescription: LED holds up.\n---\n\nBody.\n",
+            encoding="utf-8",
+        )
+        (bundle / "curated-note.md").write_text(
+            "---\ntype: reference\ntitle: Curated\n---\n\nHand-written.\n", encoding="utf-8"
+        )
+        index = bundle / "index.md"
+        index.write_text(
+            index.read_text(encoding="utf-8")
+            + "- [promoted](promoted-verdict-led.md)\n"
+            + "- [Curated](curated-note.md)\n",
+            encoding="utf-8",
+        )
+
+    def test_promoted_verdict_and_curated_survive_reingest(self, tmp_path: Path) -> None:
+        bundle = _materialized(tmp_path)
+        self._promote(bundle)
+        materialize(GOLDEN / "manifest.json", bundle, INGESTED_AT)  # re-ingest
+
+        assert (bundle / "promoted-verdict-led.md").is_file()  # verdict file survives
+        assert (bundle / "curated-note.md").is_file()  # curated file survives
+        index_text = (bundle / "index.md").read_text(encoding="utf-8")
+        assert "- [promoted](promoted-verdict-led.md)" in index_text  # verdict link survives
+        assert "- [Curated](curated-note.md)" in index_text  # curated link survives
+        # ...and the ingest files were still refreshed.
+        assert (bundle / "ingest-costs.md").is_file()
+        assert "](ingest-costs.md)" in index_text
+
+    def test_reingest_drops_a_stale_ingest_file_and_its_link(self, tmp_path: Path) -> None:
+        # A manifest that no longer generates ingest-edge → the stale file AND its index
+        # link are removed; the promoted/curated content is untouched (RED if replacement
+        # over-reaches or under-reaches).
+        bundle = _materialized(tmp_path)
+        self._promote(bundle)
+        # The shrunk manifest must sit beside its own fixture/ (root resolves relative to
+        # the manifest dir), so copy the golden case and rewrite the manifest there.
+        case = tmp_path / "case"
+        shutil.copytree(GOLDEN, case)
+        shrunk = json.loads((case / "manifest.json").read_text(encoding="utf-8"))
+        shrunk["extractions"] = [e for e in shrunk["extractions"] if e["id"] == "costs"]
+        (case / "manifest.json").write_text(json.dumps(shrunk), encoding="utf-8")
+        materialize(case / "manifest.json", bundle, INGESTED_AT)
+
+        assert not (bundle / "ingest-edge.md").exists()  # stale ingest file removed
+        index_text = (bundle / "index.md").read_text(encoding="utf-8")
+        assert "](ingest-edge.md)" not in index_text  # stale ingest link removed
+        assert "- [promoted](promoted-verdict-led.md)" in index_text  # promoted survives
+        assert (bundle / "ingest-costs.md").is_file()  # kept extraction survives

tests/test_ingest_spec_loadbearing.py

@@ -0,0 +1,70 @@
+"""Spec-integrity seam for the ingest spec (ingest-spec §11).
+
+The D7 analog of MAF's I1 framework-guard: this repo consumes ``shared/ingest-spec.md``
+UNCHANGED from commons, and this test keeps the contract honest — it goes RED when the
+spec goes missing, names a concrete agent toolkit (the framework-neutrality rule), or
+stops documenting a contract field. It is the load-bearing guard the ingest layer relies
+on to keep being implementable "from this spec alone".
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+SPEC = Path(__file__).resolve().parents[1] / "shared" / "ingest-spec.md"
+
+# Concrete agent toolkits / vendor stacks the framework-neutral spec MUST NOT name.
+_FORBIDDEN_TOOLKITS = (
+    "claude",
+    "anthropic",
+    "openai",
+    "gpt",
+    "gemini",
+    "llama",
+    "langchain",
+    "autogen",
+    "crewai",
+    "semantic kernel",
+    "microsoft agent framework",
+    "agent sdk",
+    "bedrock",
+    "vertex",
+    "foundry",
+    "maf",
+)
+
+# Every field of the machine-readable contracts the D7 implementation depends on — the
+# spec's §12 cross-check table must keep documenting each (spec-integrity).
+_CONTRACT_FIELDS = (
+    "manifest_version",
+    "source",
+    "bundle_summary",
+    "extractions",
+    "source_system",
+    "source_query",
+    "ingested_at",
+    "ingest_manifest",
+    "generated",
+    "okf_type",
+    "max_rows",
+    "root",
+)
+
+
+def test_spec_is_present() -> None:
+    # RED if the spec goes missing (the layer stops being implementable from spec alone).
+    assert SPEC.is_file(), "ingest-spec.md missing — subtree pull the commons contract"
+
+
+def test_spec_names_no_agent_toolkit() -> None:
+    text = SPEC.read_text(encoding="utf-8").lower()
+    present = [tok for tok in _FORBIDDEN_TOOLKITS if tok in text]
+    assert not present, f"framework-neutral spec names a concrete toolkit: {present}"
+
+
+@pytest.mark.parametrize("field", _CONTRACT_FIELDS)
+def test_spec_documents_contract_field(field: str) -> None:
+    text = SPEC.read_text(encoding="utf-8")
+    assert field in text, f"contract field {field!r} is no longer documented in the spec"

tests/test_okf.py

@@ -54,6 +54,32 @@ class TestNavigation:
         names = [c.path.name for c in navigate_bundle(bundle)]
         assert names == ["index.md", "b.md", "a.md"]
 
+    def test_frontmatterless_index_navigates(self, tmp_path: Path) -> None:
+        # method-spec §3 Step 1: the index contributes "the index body (the summary)"
+        # and is NOT a "non-index concept file" rendered as a `## {type}: {title}`
+        # section — so a generated index carrying only the summary + links (ingest
+        # spec §6 shape, frozen in the ingest golden) is valid. The index MAY omit
+        # frontmatter; okf must navigate it via its body, never raise.
+        _write(tmp_path / "index.md", "Summary line.\n- [A](a.md)\n")
+        _write(tmp_path / "a.md", "---\ntype: project\ntitle: A\n---\nBody A.")
+        concepts = navigate_bundle(tmp_path)
+        assert [c.path.name for c in concepts] == ["index.md", "a.md"]
+        index = concepts[0]
+        assert index.type == "index"  # default type, no KeyError for downstream .type reads
+        assert index.body == "Summary line.\n- [A](a.md)"  # body = the whole file
+        # The summary flows into the read-context as the leading section.
+        assert bundle_context(tmp_path).startswith("Summary line.")
+
+    def test_frontmatterless_tolerance_is_scoped_to_the_index(self, tmp_path: Path) -> None:
+        # LOAD-BEARING (honesty): the relaxation is for the index ENTRY POINT only.
+        # A NON-index concept file without frontmatter is still malformed and MUST
+        # raise — else the relaxation has silently weakened the `type`-required rule
+        # for concept files (method-spec §3 Step 1). RED if the tolerance leaks.
+        _write(tmp_path / "index.md", "Summary.\n- [A](a.md)\n")
+        _write(tmp_path / "a.md", "no frontmatter here\n")
+        with pytest.raises(ValueError, match="frontmatter"):
+            navigate_bundle(tmp_path)
+
     def test_out_of_bundle_and_escaping_targets_are_skipped(self, tmp_path: Path) -> None:
         # A target containing a path separator is out-of-bundle — skipped, never
         # raised; ../-escapes never resolve outside the bundle (fail-closed).