test(task-33-p3): cross-source default value gate for graph_extraction_window_size (#1933)

Codify Lesson #13 v3 (cross-source default value alignment) as a CI
unit test gate so future task-#30 B3-class drift is caught by
``cicd-push.yml`` lint+unit instead of by reviewers via fix-forward
rounds.

Background — task #30 B3 (PR #1925, merge ``43648f9``) locked
``graph_extraction_window_size`` default to ``2`` across **four**
sources that all need to agree:

1. ``aperag/indexing/graph_extractor.py``
   ``_DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE`` (Python const, runtime
   fallback)
2. ``aperag/schema/common.py``
   ``KnowledgeGraphConfig.graph_extraction_window_size`` Pydantic
   ``Field(examples=[N])`` (OpenAPI / TS schema source)
3. ``web/src/api-v2/schema.d.ts`` JSDoc ``@example N`` (frontend client
   surface — committed to repo, can drift if regen skipped)
4. ``docs/zh-CN/architecture/task-30-graph-chunk-window-spec-v1.md``
   § 3.1.1 line 85 ``**B3 lock default `N`**`` + § 4.2
   ``**`graph_extraction_window_size = N`**`` (architectural source of
   truth that PRs CR against)

PR #1925 itself surfaced the drift class:
- Weston ``msg=1b7d9bef`` BLOCKER 1 caught ``schema.d.ts`` still
  carrying default ``1``
- huangheng ``msg=bf785b12`` NIT 1 caught § 3.1.1 line 85 still saying
  default ``1``
Both required a fix-forward commit (``dae43f5``).

Why a unit test (not a boundary test): ``tests/boundaries/`` is not
currently invoked by ``make test-unit`` / ``test-integration`` /
``cicd-push.yml`` (task #33 Layer 1 audit finding).
``tests/unit_test/`` runs on every push via ``make test-unit``. Per
simple-stable directive (earayu2 ``msg=1224bec8``), the cheapest
reliable gate is a unit test in the existing CI lane, not a new
workflow file.

Scope discipline: pins **default value parity** across four sources
only. Does not pin description text, override-recommendation phrasing,
or rationale wording. If a future change moves the default away from
2, the test fails with a list of all observed values per source plus
the procedural reminder (``≥10 samples + ≥3 models 同时不退步 + PM +
architect + earayu2 三方 confirm``).

Tests:

- ``test_graph_extraction_window_size_default_consistent_across_sources``
  — the main gate (asserts all 4 sources agree)
- ``test_graph_extraction_window_size_default_is_positive_integer`` —
  sanity (window assembler math requires ``>= 1``)
- ``test_individual_source_extractor_does_not_raise[*]`` — separates
  "extractor broken" failures from "values drifted" failures so
  operator immediately knows whether to fix test infra or schema

Local validation:

- 5/5 pass in clean state
- Synthetic drift on each of (Python const / TS schema / spec § 3.1.1 /
  spec § 4.2) caught with clear actionable error message naming the
  drifting source
- Full ``tests/unit_test/contracts/`` 58/58 pass
- ruff format + ruff check clean

Sediment cross-link: this gate is the codified counterpart to
huangheng PR #1932 § 四 Lesson #13 v3 application demo 2 + Lesson #14
application demo (PR #1925 § 3.1.1 multi-iteration cleanup) — that PR
records the drift class as a CR-checklist lesson; this PR enforces it
mechanically so the lesson does not have to be remembered.

task #33 Layer 2 P3 (chenyexuan claim, in_progress) per PM dispatch
``msg=65465f9e``.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: earayu

tests/unit_test/contracts/test_graph_extraction_window_size_default_consistency.py

@@ -0,0 +1,251 @@
+"""Cross-source default value gate for ``graph_extraction_window_size`` (task #33 P3).
+
+Background — task #30 B3 (PR #1925, merge ``43648f9``) locked
+``graph_extraction_window_size`` default to ``2`` (sweet spot) per
+``earayu2`` directive ``msg=adb0c366``. The lock landed in **four**
+independent sources that all need to agree:
+
+1. **Python const** — ``aperag/indexing/graph_extractor.py``
+   ``_DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE``: the runtime fallback the
+   extractor actually uses when a collection does not override the
+   value.
+2. **Pydantic Field** — ``aperag/schema/common.py``
+   ``KnowledgeGraphConfig.graph_extraction_window_size``: the API
+   schema's user-facing default (surfaced via the Field's ``examples``
+   tuple and the description text).
+3. **TS schema** — ``web/src/api-v2/schema.d.ts``: the auto-generated
+   typed client schema's ``@example`` tag, consumed by frontend code.
+4. **Spec doc** — ``docs/zh-CN/architecture/task-30-graph-chunk-window-spec-v1.md``
+   § 3.1.1 + § 4.2 lock declaration: the architectural source of truth
+   that PRs CR against.
+
+PR #1925 itself surfaced the cross-source drift risk: the initial
+commit only updated source 1 + 2 + 4. ``Weston`` ``msg=1b7d9bef``
+BLOCKER 1 caught that ``schema.d.ts`` still carried the old default
+``1``; ``huangheng`` ``msg=bf785b12`` NIT 1 caught § 3.1.1 line 85
+still saying default ``1``. Both required a fix-forward commit. This
+test gate exists so that next time only ``cicd-push`` lint+unit needs
+to fail the PR — no manual cross-source inspection required, no
+fix-forward round trip with reviewers acting as drift detectors.
+
+Why a unit test (not a boundary test): ``tests/boundaries/`` is not
+currently invoked by ``make test-unit`` / ``test-integration`` /
+``cicd-push.yml`` (audit task #33 Layer 1 finding). ``tests/unit_test/``
+runs on every push. Per simple-stable directive (earayu2
+``msg=1224bec8``), the cheapest reliable gate is a unit test that runs
+in the existing CI lane, not a new workflow file.
+
+Scope discipline: this test pins the **default value parity** across
+four sources only. It does not pin description text, override-recommendation
+phrasing, or rationale wording — those evolve. If a future change
+moves the default away from 2, this test will fail; the fix is to
+update the Python const, Pydantic ``examples``, TS schema ``@example``,
+and spec doc § 3.1.1 + § 4.2 in the same PR. The failure message
+spells out which sources disagree so the operator does not have to
+guess.
+
+Sediment alignment: Lesson #13 v3 (cross-source default value
+alignment, ``docs/zh-CN/architecture/task-17-cr-review-checklist.md``
+§ 四) — this test is the codified gate Lesson #13 v3 was waiting for.
+"""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[3]
+GRAPH_EXTRACTOR_PATH = REPO_ROOT / "aperag" / "indexing" / "graph_extractor.py"
+SCHEMA_COMMON_PATH = REPO_ROOT / "aperag" / "schema" / "common.py"
+TS_SCHEMA_PATH = REPO_ROOT / "web" / "src" / "api-v2" / "schema.d.ts"
+SPEC_DOC_PATH = REPO_ROOT / "docs" / "zh-CN" / "architecture" / "task-30-graph-chunk-window-spec-v1.md"
+
+
+def _python_const_default() -> int:
+    """Read ``_DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE`` from ``graph_extractor.py``.
+
+    Imports the module so the value matches what runtime actually uses;
+    catches the case where the constant is shadowed / re-bound at import
+    time.
+    """
+    from aperag.indexing.graph_extractor import (
+        _DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE,
+    )
+
+    return _DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE
+
+
+def _pydantic_field_default() -> int:
+    """Read the ``examples`` value of ``KnowledgeGraphConfig.graph_extraction_window_size``.
+
+    Pydantic ``Field(examples=[N])`` is the canonical default surfaced
+    in OpenAPI + ``schema.d.ts`` ``@example`` generation, so it must
+    match the Python const.
+    """
+    from aperag.schema.common import KnowledgeGraphConfig
+
+    field = KnowledgeGraphConfig.model_fields["graph_extraction_window_size"]
+    examples = field.examples
+    assert examples, (
+        "KnowledgeGraphConfig.graph_extraction_window_size Field is missing "
+        "examples=[...]; the OpenAPI / TS schema default-value annotation "
+        "depends on this. Add examples=[<canonical default>] in "
+        "aperag/schema/common.py."
+    )
+    return int(examples[0])
+
+
+_TS_SCHEMA_BLOCK_RE = re.compile(
+    # Match the JSDoc block immediately preceding `graph_extraction_window_size?:`,
+    # then capture the @example value inside that block.
+    r"@example\s+(\d+)\s*\*/\s*\n\s*graph_extraction_window_size\?:",
+    re.MULTILINE,
+)
+
+
+def _ts_schema_default() -> int:
+    """Extract the ``@example`` integer attached to ``graph_extraction_window_size`` in ``schema.d.ts``.
+
+    The TS schema is auto-generated from the Pydantic ``examples`` field,
+    but it is committed to the repo (frontend imports it directly), so
+    a stale regen drifts silently. This regex pins the lookup to the
+    JSDoc block that immediately precedes the field declaration so we
+    do not match the same ``@example 2`` in some other field block.
+    """
+    text = TS_SCHEMA_PATH.read_text(encoding="utf-8")
+    match = _TS_SCHEMA_BLOCK_RE.search(text)
+    assert match, (
+        f"Could not locate JSDoc @example for graph_extraction_window_size in "
+        f"{TS_SCHEMA_PATH}. Either the schema regen is missing the field, the "
+        f"field name was renamed, or the JSDoc layout changed. Re-run the "
+        f"OpenAPI -> TS schema regen and re-check this test."
+    )
+    return int(match.group(1))
+
+
+_SPEC_LOCK_LINE_RE = re.compile(
+    # Section 4.2 canonical lock declaration: **`graph_extraction_window_size = 2`**
+    r"\*\*`graph_extraction_window_size\s*=\s*(\d+)`\*\*",
+)
+_SPEC_311_LINE_RE = re.compile(
+    # Section 3.1.1 enumeration: **B3 lock default `2`**
+    r"\*\*B3 lock default\s*`(\d+)`\*\*",
+)
+
+
+def _spec_doc_defaults() -> dict[str, int]:
+    """Extract every locked default value from the task #30 spec doc.
+
+    Two canonical lock sites in the spec:
+
+    * § 3.1.1 — ``**B3 lock default `N`**`` in the schema-path enumeration
+    * § 4.2  — ``**`graph_extraction_window_size = N`**`` in the lock
+      chapter title line
+
+    Both lines are part of the spec's locked-value contract. If either
+    drifts away from the runtime default, ``CR 必对照架构文档`` (per
+    earayu2 ``msg=f19f9fc5``) breaks down.
+    """
+    text = SPEC_DOC_PATH.read_text(encoding="utf-8")
+
+    section_42_match = _SPEC_LOCK_LINE_RE.search(text)
+    section_311_match = _SPEC_311_LINE_RE.search(text)
+
+    assert section_42_match, (
+        f"Could not locate § 4.2 lock line `**`graph_extraction_window_size = N`**` "
+        f"in {SPEC_DOC_PATH}. Either the lock chapter was renamed/removed or the "
+        f"markdown emphasis style changed. Restore the canonical lock line or "
+        f"update this regex."
+    )
+    assert section_311_match, (
+        f"Could not locate § 3.1.1 lock line `**B3 lock default `N`**` in "
+        f"{SPEC_DOC_PATH}. Either § 3.1.1 was rewritten or the lock-shorthand "
+        f"phrasing changed. Restore the canonical phrasing or update this regex."
+    )
+
+    return {
+        "section_4_2_lock": int(section_42_match.group(1)),
+        "section_3_1_1_enumeration": int(section_311_match.group(1)),
+    }
+
+
+def test_graph_extraction_window_size_default_consistent_across_sources():
+    """All four sources of ``graph_extraction_window_size`` default must agree.
+
+    Runs on every push via ``cicd-push.yml`` -> ``make test-unit``.
+
+    This is the codified Lesson #13 v3 gate. It catches the same drift
+    class that required two BLOCKER fix-forward rounds on PR #1925
+    (Weston ``msg=1b7d9bef`` BLOCKER 1 + huangheng ``msg=bf785b12`` NIT
+    1) — schema.d.ts and spec § 3.1.1 still carrying ``default 1`` while
+    Python + Pydantic moved to ``2``.
+    """
+    python_const = _python_const_default()
+    pydantic_examples = _pydantic_field_default()
+    ts_example = _ts_schema_default()
+    spec_defaults = _spec_doc_defaults()
+
+    sources: dict[str, int] = {
+        "python_const (aperag/indexing/graph_extractor.py)": python_const,
+        "pydantic_examples (aperag/schema/common.py)": pydantic_examples,
+        "ts_schema_example (web/src/api-v2/schema.d.ts)": ts_example,
+        **{
+            f"spec_doc § {k.replace('_', '.').replace('section.', '')} "
+            f"(docs/zh-CN/architecture/task-30-graph-chunk-window-spec-v1.md)": v
+            for k, v in spec_defaults.items()
+        },
+    }
+
+    distinct = set(sources.values())
+    assert len(distinct) == 1, (
+        "graph_extraction_window_size default has drifted across sources.\n"
+        "All four sources must declare the same integer (currently locked to 2 "
+        "per task #30 B3 / earayu2 msg=adb0c366).\n"
+        "Update ALL of the following in the same PR:\n"
+        "  1. aperag/indexing/graph_extractor.py: _DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE\n"
+        "  2. aperag/schema/common.py: KnowledgeGraphConfig.graph_extraction_window_size Field examples=[N]\n"
+        "  3. web/src/api-v2/schema.d.ts: @example N (regenerate via OpenAPI -> TS pipeline)\n"
+        "  4. docs/zh-CN/architecture/task-30-graph-chunk-window-spec-v1.md: § 3.1.1 + § 4.2 lock lines\n"
+        "Future-default-change procedure (per spec § 4.2): ≥10 samples + ≥3 models "
+        "no regression + PM + architect + earayu2 三方 confirm.\n"
+        "\nObserved values per source:\n" + "\n".join(f"  - {name}: {value}" for name, value in sources.items())
+    )
+
+
+def test_graph_extraction_window_size_default_is_positive_integer():
+    """Sanity check — the locked default must be a positive integer.
+
+    ``window_size <= 0`` would break the assembler's ``len(chunks) //
+    window_size`` math and the bootstrap formula; ``window_size`` is a
+    chunk count, fractional values are not meaningful.
+    """
+    value = _python_const_default()
+    assert isinstance(value, int) and value >= 1, (
+        f"_DEFAULT_GRAPH_EXTRACTION_WINDOW_SIZE must be a positive integer, "
+        f"got {value!r}. Negative or zero values break the window assembler "
+        f"in aperag/indexing/graph_extractor.py."
+    )
+
+
+@pytest.mark.parametrize(
+    "source_name, getter",
+    [
+        ("python_const", _python_const_default),
+        ("pydantic_examples", _pydantic_field_default),
+        ("ts_schema_example", _ts_schema_default),
+    ],
+)
+def test_individual_source_extractor_does_not_raise(source_name, getter):
+    """Each individual source extractor must succeed (no missing file / regex
+    drift / Pydantic field rename).
+
+    This separates "extractor broken" failures from "values drifted" failures
+    so when CI turns red the operator immediately knows whether to update the
+    test infrastructure or the schema.
+    """
+    value = getter()
+    assert isinstance(value, int), (
+        f"{source_name} extractor returned non-int {value!r}; the source format may have changed."
+    )