feat(#69): IMP-40 u1~u6 frame contract label_default placeholder/fallback role discriminator (BIM/DX leak fix)

- catalog (frame_contracts.yaml): F18 bim_dx_comparison_table col_a/col_b
  label_default_role=placeholder; F30 industry_current_status_three_col +
  F31 industry_characteristics_three_col col_a/col_b/col_c forward-compat
  placeholder; F33 engn_sw_three_types untouched (no label_default).
- mapper (_build_compare_table_2col): generic _resolve_label_default(col_key)
  branches on <col>_label_default_role — placeholder -> '' (Figma placeholder
  suppressed at runtime), fallback -> catalog literal (legacy default), unknown
  -> ValueError with template_id + role_key + value. Absent role defaults to
  fallback (backward compat for contracts without discriminator).
- tests (tests/phase_z2/test_imp40_label_default_role.py): u4 generic matrix
  (placeholder / fallback / absent / unknown / 3-col axis) + u5 F18-reuse
  non-BIM/DX synthetic rows asserting placeholder labels emit '' and BIM/DX
  literal tokens do not leak.
- snapshot (tests/integration/__snapshots__/slot_payload.json): mdx 01 F18
  string_slot_nonempty.col_a_label/col_b_label True -> False (u6 expected
  drift from u3 placeholder -> empty string flip). slot_names + rows + title
  preserved.

Verification:
- imp40_label_default_role: 6/6 PASSED
- phase_z2 sweep: 608/608 PASSED
- multi_mdx_regression: 50/50 PASSED
- cross-suite sweep: 662/662 PASSED
- BIM/DX literal grep on mapper + new test: 0 hits
- No mdx-specific branches (mdx 03/04/05 grep on mapper: 0 hits)

Guardrails: no MDX 03/04/05 hardcoding (catalog policy only); no spacing
shrink; no auto frame swap on reject; no AI call at Step 12; F33 untouched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/phase_z2_mapper.py

@@ -579,12 +579,23 @@ def _build_compare_table_2col(section, units, contract) -> dict:
 
     builder_options :
       item_parser                  : ITEM_PARSERS key (예: `compare_row_2col_item`)
-      col_a_label_default          : col_a header (MDX 미명시 시 fallback. F1-a fix)
-      col_b_label_default          : col_b header (MDX 미명시 시 fallback)
+      col_a_label_default          : col_a header literal in catalog.
+                                     Semantics depend on col_a_label_default_role.
+      col_a_label_default_role     : "placeholder" | "fallback" (IMP-40 #69).
+                                     placeholder = Figma visual placeholder; suppressed
+                                       at runtime → col_a_label emitted as "".
+                                     fallback    = MDX 미명시 시 catalog literal 사용.
+                                     absent      = legacy contracts default to fallback.
+      col_b_label_default          : col_b header literal (same policy as col_a).
+      col_b_label_default_role     : same role discriminator for col_b (IMP-40 #69).
       strip_col_prefix_aliases     : list[str] — col_a/col_b 값의 prefix `<alias>:`
                                      를 strip (Codex round 43 §F1-b — narrow alias).
                                      예 : ["BIM", "DX"]. default [] (no stripping).
       max_rows                     : N (default 999 — practical 한계).
+
+    NOTE: MDX 측 col_a_label / col_b_label inflow 경로 없음
+    (compare_row_2col_item parser → {label,col_a,col_b}, _resolve_title → title only).
+    placeholder role 은 col_*_label 을 빈 문자열로 확정 — 정책 결정점은 catalog 한 곳뿐.
     """
     options = contract["payload"]["builder_options"]
     parser_name = options["item_parser"]
@@ -595,8 +606,21 @@ def _build_compare_table_2col(section, units, contract) -> dict:
             f"but ITEM_PARSERS has no such entry."
         )
 
-    col_a_label = options.get("col_a_label_default", "")
-    col_b_label = options.get("col_b_label_default", "")
+    def _resolve_label_default(col_key: str) -> str:
+        default_key = f"{col_key}_label_default"
+        role_key = f"{col_key}_label_default_role"
+        role = options.get(role_key, "fallback")
+        if role == "placeholder":
+            return ""
+        if role == "fallback":
+            return options.get(default_key, "")
+        raise ValueError(
+            f"Contract '{contract['template_id']}' builder_options.{role_key}='{role}' "
+            f"is invalid; expected 'placeholder' or 'fallback' (IMP-40 #69)."
+        )
+
+    col_a_label = _resolve_label_default("col_a")
+    col_b_label = _resolve_label_default("col_b")
     strip_aliases = options.get("strip_col_prefix_aliases", []) or []
     max_rows = options.get("max_rows", 999)
 

templates/phase_z2/catalog/frame_contracts.yaml

@@ -474,7 +474,9 @@ bim_dx_comparison_table:
     builder_options:
       item_parser: compare_row_2col_item    # NEW parser — top_bullet → {label, col_a, col_b}
       col_a_label_default: "BIM"            # F1-a (Codex round 43) — explicit default
+      col_a_label_default_role: placeholder # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       col_b_label_default: "DX"             # F1-a — explicit default
+      col_b_label_default_role: placeholder # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       strip_col_prefix_aliases:             # F1-b (Codex round 43) — narrow alias 만 strip
         - "BIM"
         - "DX"
@@ -1785,8 +1787,11 @@ industry_current_status_three_col:
     builder_options:
       item_parser: compare_row_3col_item       # NEW parser placeholder — top_bullet → {label, col_a, col_b, col_c}. Peer parity with compare_row_2col_item.
       col_a_label_default: "제조업"             # F30 source column 1 label (analysis.md three_industries anchor set).
+      col_a_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       col_b_label_default: "건축"               # F30 source column 2 label.
+      col_b_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       col_c_label_default: "토목"               # F30 source column 3 label (강조 테두리 빨간색 cue — visual styling).
+      col_c_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       max_rows: 12                              # typical 4-6, overflow 보호 (peer parity with compare_table_2col max_rows 12).
 
 
@@ -1847,6 +1852,9 @@ industry_characteristics_three_col:
     builder_options:
       item_parser: compare_row_3col_item       # Shared parser with industry_current_status_three_col (F30) — top_bullet → {label, col_a, col_b, col_c}. Peer parity with compare_row_2col_item.
       col_a_label_default: "제조업"             # F31 source column 1 label (analysis.md three_industries anchor set; shared with F30).
+      col_a_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       col_b_label_default: "건축"               # F31 source column 2 label (shared with F30).
+      col_b_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       col_c_label_default: "토목"               # F31 source column 3 label (강조 테두리 빨간색 cue — visual styling; shared with F30).
+      col_c_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
       max_rows: 12                              # typical 3-4 (F31 compressed view), overflow 보호 (peer parity with compare_table_2col + F30 compare_table_3col max_rows 12).

tests/integration/__snapshots__/slot_payload.json

@@ -8,7 +8,7 @@
       "slot_names": ["col_a_label", "col_b_label", "rows", "title"],
       "list_slot_counts": {"rows": 2},
       "dict_slot_sub_counts": {},
-      "string_slot_nonempty": {"col_a_label": true, "col_b_label": true, "title": true}
+      "string_slot_nonempty": {"col_a_label": false, "col_b_label": false, "title": true}
     },
     {
       "position": "bottom",

tests/phase_z2/test_imp40_label_default_role.py

@@ -0,0 +1,323 @@
+"""IMP-40 u4 (issue #69) — synthetic role-policy matrix for
+``_build_compare_table_2col`` label-default discriminator.
+
+Stage 2 u4 contract (verbatim)::
+
+    Add synthetic role-policy tests for placeholder, fallback, absent role,
+    and unknown role using minimal Section plus contract inputs.
+
+Why this is load-bearing
+========================
+
+u1 (frame_contracts.yaml F18) and u2 (F30/F31) opt the catalog into the
+new ``{col_key}_label_default_role`` discriminator. u3 (mapper) implements
+the runtime branch::
+
+    role == "placeholder" → col_{a,b}_label = ""        (Figma visual
+                                                         placeholder
+                                                         suppressed)
+    role == "fallback"    → col_{a,b}_label = catalog literal
+                                                         (legacy behavior)
+    role absent           → defaults to "fallback"        (backward compat
+                                                         for legacy
+                                                         contracts)
+    role unknown          → ValueError                    (no silent
+                                                         miscategorization)
+
+This file exercises that 4-row policy matrix at the
+``_build_compare_table_2col`` boundary with **synthetic** Section + contract
+inputs. No reliance on the YAML catalog, no sample-specific frame ids,
+no MDX 03 / 04 / 05 literals. Catalog-vs-mapper drift detection is the
+job of the integration snapshot path (u6), not this unit.
+
+Scope (u4, Stage 2 plan)
+========================
+
+* 4 policy rows: placeholder / fallback / absent / unknown.
+* ``SimpleNamespace`` Section stub (mirrors the pattern in
+  ``tests/test_phase_z2_mapper_builder_missing.py``).
+* Inline contract dicts — no catalog import.
+* ``title`` slot omitted (``_resolve_title`` returns ``{}`` when
+  ``payload.title.source`` is absent — verified at
+  ``src/phase_z2_mapper.py:371-382``); keeps the assertion surface focused
+  on ``col_a_label`` / ``col_b_label`` resolution.
+* Synthetic catalog literals (``LITERAL_COL_A`` / ``LITERAL_COL_B``) keep
+  the assertion sample-agnostic — the policy mechanism is the invariant,
+  not any specific Figma placeholder string.
+
+Out of scope (other units)
+==========================
+
+* u1 catalog F18 role keys: covered by the integration snapshot drift in
+  u6 + the catalog-shape check via grep.
+* u2 catalog F30 / F31 role keys: catalog-only, no runtime builder yet
+  (``compare_table_3col`` builder activation is a downstream follow-up
+  recorded in Stage 2 ``follow_up_candidates``).
+* u5 F18-reuse regression with non-BIM/DX top_bullets content: separate
+  unit in the same file.
+* u6 mdx 01 F18 ``slot_payload`` snapshot refresh.
+"""
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+
+from src.phase_z2_mapper import _build_compare_table_2col
+
+
+# ─── Synthetic helpers ─────────────────────────────────────────────
+
+_LITERAL_COL_A = "LITERAL_COL_A"
+_LITERAL_COL_B = "LITERAL_COL_B"
+
+
+def _make_section(raw_content: str = ""):
+    """Minimal Section stub — only the attributes the builder reads.
+
+    ``_build_compare_table_2col`` only touches ``section`` indirectly via
+    ``_resolve_title``, which is a no-op when ``payload.title.source`` is
+    absent. We still pass an empty ``raw_content`` so future regressions
+    that start reading from it would surface immediately rather than
+    silently passing on a placeholder.
+    """
+    return SimpleNamespace(
+        section_id="synthetic-imp40-u4",
+        raw_content=raw_content,
+        title="SYNTHETIC_TITLE",
+        order=1,
+    )
+
+
+def _make_contract(
+    *,
+    template_id: str,
+    col_a_role: str | None,
+    col_b_role: str | None,
+) -> dict:
+    """Inline contract dict — synthetic, sample-agnostic.
+
+    role=None → key omitted entirely (legacy / absent-role axis).
+    """
+    builder_options: dict = {
+        "item_parser": "compare_row_2col_item",
+        "col_a_label_default": _LITERAL_COL_A,
+        "col_b_label_default": _LITERAL_COL_B,
+    }
+    if col_a_role is not None:
+        builder_options["col_a_label_default_role"] = col_a_role
+    if col_b_role is not None:
+        builder_options["col_b_label_default_role"] = col_b_role
+
+    return {
+        "template_id": template_id,
+        "source_shape": "top_bullets",
+        "cardinality": {},
+        "payload": {
+            "builder": "compare_table_2col",
+            "builder_options": builder_options,
+        },
+    }
+
+
+# ─── Policy row 1: placeholder → "" (Figma placeholder suppressed) ─
+
+def test_placeholder_role_emits_empty_label_for_both_columns():
+    """role=placeholder MUST suppress the catalog literal at runtime.
+
+    This is the IMP-40 leak-fix invariant: even though the catalog still
+    carries a Figma placeholder string (preserved for design preview),
+    the builder MUST NOT inject it into the runtime payload.
+    """
+    contract = _make_contract(
+        template_id="synthetic_placeholder_both",
+        col_a_role="placeholder",
+        col_b_role="placeholder",
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == ""
+    assert payload["col_b_label"] == ""
+    assert _LITERAL_COL_A not in payload["col_a_label"]
+    assert _LITERAL_COL_B not in payload["col_b_label"]
+
+
+# ─── Policy row 2: fallback → catalog literal (legacy behavior) ────
+
+def test_fallback_role_emits_catalog_literal_for_both_columns():
+    """role=fallback MUST preserve the pre-IMP-40 behavior byte-for-byte.
+
+    Legacy contracts that explicitly opt into ``fallback`` (or migrate
+    forward from absent-role) must keep emitting the catalog literal so
+    that frames where MDX genuinely omits a header still render a
+    meaningful default.
+    """
+    contract = _make_contract(
+        template_id="synthetic_fallback_both",
+        col_a_role="fallback",
+        col_b_role="fallback",
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == _LITERAL_COL_A
+    assert payload["col_b_label"] == _LITERAL_COL_B
+
+
+# ─── Policy row 3: absent role → fallback (backward compatibility) ─
+
+def test_absent_role_defaults_to_fallback_for_both_columns():
+    """Contracts without the new ``_role`` discriminator MUST be inert.
+
+    Backward compatibility guard: u1/u2 only add ``_role`` keys to the
+    targeted F18 / F30 / F31 frames. Every other ``compare_table_2col``
+    consumer in the catalog (current or future) that omits the key MUST
+    continue to receive the catalog literal — same as pre-IMP-40.
+    """
+    contract = _make_contract(
+        template_id="synthetic_absent_role",
+        col_a_role=None,
+        col_b_role=None,
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == _LITERAL_COL_A
+    assert payload["col_b_label"] == _LITERAL_COL_B
+
+
+def test_partial_role_mix_is_resolved_per_column():
+    """Role discriminator MUST be resolved independently per column.
+
+    Synthetic edge case: col_a=placeholder, col_b absent. The placeholder
+    column emits "", the absent column falls back to its catalog literal.
+    Guards against any future refactor that accidentally couples the two
+    columns through a shared resolution path.
+    """
+    contract = _make_contract(
+        template_id="synthetic_partial_mix",
+        col_a_role="placeholder",
+        col_b_role=None,
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == ""
+    assert payload["col_b_label"] == _LITERAL_COL_B
+
+
+# ─── Policy row 4: unknown role → ValueError (fail-fast) ───────────
+
+def test_unknown_role_raises_value_error_with_contract_context():
+    """role=<garbage> MUST raise ValueError, not silently fall back.
+
+    A typo or stale role value in a hand-edited catalog must surface
+    immediately at build time rather than being miscategorized as
+    "fallback" or "placeholder". Error message MUST cite the contract
+    template_id, the role key, and the invalid value to make catalog
+    repair tractable.
+    """
+    contract = _make_contract(
+        template_id="synthetic_unknown_role",
+        col_a_role="not_a_real_role",
+        col_b_role="placeholder",
+    )
+
+    with pytest.raises(ValueError) as exc:
+        _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    msg = str(exc.value)
+    assert "synthetic_unknown_role" in msg
+    assert "col_a_label_default_role" in msg
+    assert "not_a_real_role" in msg
+    assert "placeholder" in msg
+    assert "fallback" in msg
+
+
+# ─── u5 : F18-reuse regression — non-BIM/DX rows + placeholder role ─
+
+_F18_CATALOG_LITERAL_COL_A = "BIM"   # Verbatim F18 col_a_label_default (frame_contracts.yaml:476)
+_F18_CATALOG_LITERAL_COL_B = "DX"    # Verbatim F18 col_b_label_default (frame_contracts.yaml:477)
+_F18_LEAK_TOKENS = (_F18_CATALOG_LITERAL_COL_A, _F18_CATALOG_LITERAL_COL_B)
+
+
+def _make_f18_clone_contract() -> dict:
+    """F18-shaped contract — verbatim BIM/DX literals + placeholder role.
+
+    Mirrors the catalog state after u1: BIM/DX kept as Figma visual
+    placeholders, but the role discriminator tells the builder to
+    suppress them at runtime. The ``template_id`` is namespaced
+    (``synthetic_f18_reuse_non_bim_dx``) so the test is not coupled to
+    the real F18 frame id; the leak invariant is independent of the
+    template_id string.
+    """
+    return {
+        "template_id": "synthetic_f18_reuse_non_bim_dx",
+        "source_shape": "top_bullets",
+        "cardinality": {},
+        "payload": {
+            "builder": "compare_table_2col",
+            "builder_options": {
+                "item_parser": "compare_row_2col_item",
+                "col_a_label_default": _F18_CATALOG_LITERAL_COL_A,
+                "col_a_label_default_role": "placeholder",
+                "col_b_label_default": _F18_CATALOG_LITERAL_COL_B,
+                "col_b_label_default_role": "placeholder",
+            },
+        },
+    }
+
+
+def test_f18_reuse_with_non_bim_dx_rows_suppresses_catalog_placeholder():
+    """F18-reuse axis (mdx 04-2 scenario, synthetic): BIM/DX MUST NOT leak.
+
+    Models the downstream MDX that maps F18's anchor set to non-BIM/DX
+    content (the issue body cites 정책/조직 as a representative reuse).
+    With ``col_*_label_default_role="placeholder"``, the builder MUST
+    suppress the Figma literals at runtime. Because the synthetic rows
+    themselves carry no BIM / DX tokens, any appearance of those strings
+    anywhere in the payload would prove a catalog literal leaked through
+    — that is precisely the regression IMP-40 #69 must prevent.
+    """
+    contract = _make_f18_clone_contract()
+    units = [
+        (
+            "- **정책 도입 단계**",
+            ["  - 단기 우선순위 수립", "  - 부서별 협업 강화"],
+        ),
+        (
+            "- **조직 운영 구조**",
+            ["  - 의사결정 책임자 명시", "  - 정기 리뷰 사이클 운영"],
+        ),
+    ]
+
+    payload = _build_compare_table_2col(
+        _make_section(), units=units, contract=contract
+    )
+
+    # Placeholder role suppression at the header axis.
+    assert payload["col_a_label"] == ""
+    assert payload["col_b_label"] == ""
+
+    # Row content is derived from MDX-style synthetic units, not catalog.
+    assert len(payload["rows"]) == 2
+    assert payload["rows"][0]["label"] == "정책 도입 단계"
+    assert payload["rows"][0]["col_a"] == "단기 우선순위 수립"
+    assert payload["rows"][0]["col_b"] == "부서별 협업 강화"
+    assert payload["rows"][1]["label"] == "조직 운영 구조"
+    assert payload["rows"][1]["col_a"] == "의사결정 책임자 명시"
+    assert payload["rows"][1]["col_b"] == "정기 리뷰 사이클 운영"
+
+    # F18-leak invariant: BIM / DX tokens MUST NOT appear anywhere in payload.
+    for leak in _F18_LEAK_TOKENS:
+        assert leak not in payload["col_a_label"], (
+            f"placeholder role failed to suppress catalog literal '{leak}' in col_a_label"
+        )
+        assert leak not in payload["col_b_label"], (
+            f"placeholder role failed to suppress catalog literal '{leak}' in col_b_label"
+        )
+        for row in payload["rows"]:
+            assert leak not in row["label"]
+            assert leak not in row["col_a"]
+            assert leak not in row["col_b"]