feat: refocus on drawings — code/ADA gated off, drawing-integrity wave, Brain-directed clarification

- ENABLE_CODE_REVIEW flag (default off): skips code/ADA/jurisdiction review
  path in both pipelines; nothing deleted, one env flag to restore.
- Per-sheet Drawing Integrity QA wave (agent + classic, default on):
  dangling refs, on-sheet contradictions, dimension sanity, missing sheet
  essentials, tag hygiene. New DrawingIntegrityAgent + classic stage.
- Broadened conflict critic: intra-sheet + same-discipline contradictions,
  not just cross-discipline.
- Wave 6.5 Brain-directed clarification (bounded hub-and-spoke): Brain names
  uncertain findings, verify_evidence requests route through the wave-5b
  verifier; refuted findings suppressed. One planning call + capped verifies,
  single iteration. Shared _build_verify_scopes across 5b and 6.5.
- Config knobs, .env.example, frontend copy, tests (182 passing).

tests/agents/test_drawing_integrity.py

@@ -0,0 +1,95 @@
+"""Unit tests for the per-sheet DrawingIntegrityAgent and scope builder."""
+
+import backend.agents.integrity_agent as integ
+from backend.agents.base import AgentScope, AgentUsage
+from backend.agents.integrity_agent import (
+    DrawingIntegrityAgent, build_integrity_scopes,
+)
+from backend import config
+
+
+def _sheet(page, sheet_number, n_assertions):
+    return {
+        "sheet_number": sheet_number,
+        "page_number": page,
+        "sheet_title": f"Sheet {sheet_number}",
+        "discipline": "Architectural",
+        "assertions": [
+            {"object_type": "note", "source_text": f"note {i}"}
+            for i in range(n_assertions)
+        ],
+    }
+
+
+def test_build_scopes_skips_sparse_sheets(monkeypatch):
+    monkeypatch.setattr(config, "INTEGRITY_MIN_ASSERTIONS", 3)
+    sheets = [
+        _sheet(1, "A101", 5),   # kept
+        _sheet(2, "A102", 2),   # skipped (too sparse)
+        _sheet(3, "A103", 3),   # kept (== floor)
+    ]
+    page_to_b64 = {1: "IMG1", 2: "IMG2", 3: "IMG3"}
+    page_to_text = {1: "text one", 2: "text two", 3: "text three"}
+    scopes = build_integrity_scopes(sheets, page_to_b64, page_to_text)
+    ids = sorted(s.scope_id for s in scopes)
+    assert ids == ["integrity:1", "integrity:3"]
+    # Each scope carries its own page image + text layer.
+    by_id = {s.scope_id: s for s in scopes}
+    assert by_id["integrity:1"].payload["image_b64"] == "IMG1"
+    assert by_id["integrity:1"].payload["text_layer"] == "text one"
+
+
+def test_agent_parses_and_anchors_sheet(monkeypatch):
+    """Findings with blank sheets get anchored to the scope's sheet number."""
+    captured = {}
+
+    def fake_call_json(**kwargs):
+        captured.update(kwargs)
+        return {"issues": [
+            {"issue_id": "DI-1", "severity": "high", "confidence": "high",
+             "category": "dangling_reference", "sheets": [],
+             "description": "Detail callout 5/A101 has no detail 5 on this sheet",
+             "evidence": [{"sheet": "A101", "source_text": "5/A101"}]},
+        ]}
+
+    monkeypatch.setattr(integ, "call_json", fake_call_json)
+    sheet = _sheet(1, "A101", 5)
+    scope = AgentScope("integrity:1", {
+        "sheet": sheet, "page_number": 1,
+        "image_b64": "IMG1", "text_layer": "the deterministic text layer",
+    })
+    result = DrawingIntegrityAgent(AgentUsage()).run(scope)
+    assert result.error == ""
+    assert len(result.artifacts) == 1
+    finding = result.artifacts[0]
+    assert finding["source_stage"] == "drawing_integrity"
+    assert finding["sheets"] == ["A101"]          # anchored
+    assert finding["agent"] == "drawing_integrity"
+    assert finding["scope_id"] == "integrity:1"
+    # The image + text layer reached the model.
+    assert captured["images_b64"] == ["IMG1"]
+    assert "the deterministic text layer" in captured["user_text"]
+
+
+def test_agent_empty_issues_is_clean(monkeypatch):
+    monkeypatch.setattr(integ, "call_json", lambda **k: {"issues": []})
+    scope = AgentScope("integrity:1", {
+        "sheet": _sheet(1, "A101", 5), "page_number": 1,
+        "image_b64": "IMG1", "text_layer": "t",
+    })
+    result = DrawingIntegrityAgent(AgentUsage()).run(scope)
+    assert result.error == ""
+    assert result.artifacts == []
+
+
+def test_agent_survives_call_failure(monkeypatch):
+    def boom(**kwargs):
+        raise RuntimeError("model exploded")
+    monkeypatch.setattr(integ, "call_json", boom)
+    scope = AgentScope("integrity:1", {
+        "sheet": _sheet(1, "A101", 5), "page_number": 1,
+        "image_b64": "IMG1", "text_layer": "t",
+    })
+    result = DrawingIntegrityAgent(AgentUsage()).run(scope)
+    assert "model exploded" in result.error
+    assert result.artifacts == []