Add Phase Z placement trace telemetry

- run B1/B2/B4 placement planning in trace-only mode
- record placement_trace per rendered zone in debug output
- preserve existing render output and visual routing behavior

src/phase_z2_pipeline.py

@@ -30,7 +30,7 @@ import re
 import shutil
 import sys
 import time
-from dataclasses import dataclass
+from dataclasses import asdict, dataclass
 from pathlib import Path
 from typing import Optional
 
@@ -46,6 +46,7 @@ from phase_z2_mapper import (
     FitError,
     compute_capacity_fit,
     get_contract,
+    load_frame_contracts,
     map_with_contract,
 )
 from phase_z2_classifier import classify_visual_runtime_check
@@ -57,6 +58,11 @@ from phase_z2_retry import (
 )
 from phase_z2_failure_router import enrich_retry_trace_with_failure_classification
 
+# trace-only runtime 연결 v0 — B1 → B4 chain.
+# final.html / mapper / render path 미영향. debug_zones[i].placement_trace 만 기록.
+from phase_z2_content_extractor import extract_content_objects
+from phase_z2_placement_planner import plan_placement
+
 
 # ─── Constants ──────────────────────────────────────────────────
 
@@ -1051,6 +1057,38 @@ def run_phase_z2_mvp1(mdx_path: Path, run_id: Optional[str] = None) -> Path:
         min_height_px = visual_hints.get("min_height_px", DEFAULT_ZONE_MIN_HEIGHT_PX)
         contract_frame_id = contract.get("frame_id")
 
+        # ─── trace-only runtime 연결 v0 — B1 → B4 chain (final.html 영향 X) ───
+        # B1~B4 의 dormant chain 을 *real MDX runtime data* 로 처음 호출.
+        # 결과 (PlacementPlan) = debug_zones[i].placement_trace 로 *기록만*.
+        # render path / mapper output / final.html 모두 미변경 — B5 baseline SHA 유지.
+        # B4 frame selection = catalog declaration order (V4 evidence 미사용 — 별 axis).
+        content_objects = extract_content_objects(synth_section)
+        placement_plan = plan_placement(
+            content_objects=content_objects,
+            frame_contracts=list(load_frame_contracts().values()),
+            section_id=synth_section.section_id,
+        )
+        mapper_frame_template_id = unit.frame_template_id
+        matches_mapper = (
+            placement_plan.selected_template_id == mapper_frame_template_id
+        )
+        match_note: Optional[str] = None
+        if not matches_mapper:
+            if placement_plan.selected_template_id is None:
+                match_note = "no_frame_covers_content_types"
+            else:
+                match_note = (
+                    f"B4 selected '{placement_plan.selected_template_id}' but "
+                    f"mapper uses '{mapper_frame_template_id}' (composition V4 rank-1)"
+                )
+        placement_trace = {
+            **asdict(placement_plan),
+            "mapper_frame_template_id": mapper_frame_template_id,
+            "frame_selection_matches_mapper": matches_mapper,
+            "frame_selection_match_note": match_note,
+        }
+        # ─── end trace-only runtime 연결 v0 ───
+
         # mapper 시도 — 실패 (FitError) 시 zone 을 adapter_needed 로 표시하고 skip
         try:
             slot_payload = map_mdx_to_slots(synth_section, unit.frame_template_id)
@@ -1102,6 +1140,8 @@ def run_phase_z2_mvp1(mdx_path: Path, run_id: Optional[str] = None) -> Path:
             "content_truncated_count": truncated_count,        # None / N (builder 가 N 개 자름)
             "assets_dir": str(assets_dir.relative_to(run_dir)) if assets_dir else None,
             "content_weight": content_weight,
+            # trace-only runtime 연결 v0 — B1 → B2 → B4 chain 결과 (render 미영향).
+            "placement_trace": placement_trace,
         })
 
     # 6. Build layout CSS — horizontal-2 = dynamic heights (regression preserve), 그 외 = fr default