fix(segmentation): hash the extracted text and let the plan key fire

tests/test_segmented_inbox.py

@@ -35,7 +35,12 @@ from llm_ingestion_okf.errors import SegmentationError
 from llm_ingestion_okf.extract import extract_text
 from llm_ingestion_okf.inbox import GateDecision, process_inbox
 from llm_ingestion_okf.profiles import DEFAULT, SEGMENTED_V1
-from llm_ingestion_okf.segmentation import SegmentationPlan, parse_segmentation_plan
+from llm_ingestion_okf.segmentation import (
+    STDLIB_EXTRACTOR_VERSION,
+    SegmentationPlan,
+    observed_extractor_version,
+    parse_segmentation_plan,
+)
 
 INGESTED_AT = "2026-07-25T12:00:00Z"
 PLAN_AT = "2026-08-30T09:00:00Z"
@@ -90,8 +95,9 @@ def build_plan(
     payload: dict[str, Any] = {
         "version": "1",
         "source_sha256": hashlib.sha256(source_bytes).hexdigest(),
+        "text_sha256": hashlib.sha256(text.encode("utf-8")).hexdigest(),
         "extractor_id": extractor_id,
-        "extractor_version": "1.0.0",
+        "extractor_version": observed_extractor_version(extractor_id),
         "adjudicated_at": "2026-08-30T08:00:00Z",
         "entries": [
             {
@@ -441,3 +447,55 @@ def test_without_the_capability_an_unmatched_plan_is_still_the_earlier_refusal(
     with pytest.raises(SegmentationError) as excinfo:
         run(tmp_path, plan=plan, profile=DEFAULT, values={})
     assert excinfo.value.code == "segmentation_unsupported_profile"
+
+
+# --- S5b: the cache key can actually fail ----------------------------------
+#
+# Both halves below were decorative before Step 11. The proposer hashed SOURCE
+# BYTES only, so a converter that reshaped the extracted text left the hash
+# identical and every offset moved under a key that still matched; and the run
+# path passed `plan.extractor_version` straight back into `assert_plan_applies`,
+# comparing the plan's value with itself. Two guards that could never fire, in
+# the one place where a false pass produces a bundle nobody adjudicated and no
+# downstream test can catch -- every span still lands on real text.
+
+
+def test_a_plan_whose_extracted_text_hash_moved_is_refused(tmp_path: Path) -> None:
+    """The signal a source-bytes hash cannot carry.
+
+    Same bytes on disk, same extractor id, same extractor version -- and a
+    different canonical text, which is what the offsets index. Simulated by
+    moving the hash rather than the converter, because the property under test
+    is that the component is COMPARED at all.
+    """
+    source = drop(tmp_path / "round", "n500.md", DOCUMENT)
+    plan = build_plan(source.read_bytes(), DOCUMENT, text_sha256="0" * 64)
+    result = run(tmp_path, plan=plan)
+    assert {entry.error.code for entry in result.failed} == {"segmentation_extractor_mismatch"}
+    assert "text_sha256" in str(result.failed[0].error)
+    assert tree(tmp_path / "bundle") == {}
+
+
+def test_a_plan_whose_extractor_version_moved_is_refused(tmp_path: Path) -> None:
+    """The half of S5b that compared a value with itself."""
+    source = drop(tmp_path / "round", "n500.md", DOCUMENT)
+    plan = build_plan(source.read_bytes(), DOCUMENT, extractor_version="not-the-one-that-ran")
+    result = run(tmp_path, plan=plan)
+    assert {entry.error.code for entry in result.failed} == {"segmentation_extractor_mismatch"}
+    assert "extractor_version" in str(result.failed[0].error)
+    assert tree(tmp_path / "bundle") == {}
+
+
+def test_the_observed_extractor_version_is_not_the_proposers_own(tmp_path: Path) -> None:
+    """Defect (b): the proposer wrote ITS version into the extractor's field.
+
+    A stdlib row names this package's own literal because there is no third
+    party to name; a converter row names the pinned converter. What matters is
+    that the two are DIFFERENT values from different sources -- one tool
+    version standing in for both is exactly what made the field unable to move.
+    """
+    assert observed_extractor_version("md") == STDLIB_EXTRACTOR_VERSION
+    assert observed_extractor_version("docx") != STDLIB_EXTRACTOR_VERSION
+    with pytest.raises(SegmentationError) as excinfo:
+        observed_extractor_version("nothing-registers-this")
+    assert excinfo.value.code == "segmentation_extractor_mismatch"