Add scoped Agent-mode pipeline as experimental Classic fork.

Wire specialist waves, Brain consolidation, and Classic-compatible reports so Agent mode can run end-to-end via OpenRouter without changing the default Classic path.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/agents/completeness.py

@@ -0,0 +1,55 @@
+"""Summary-only drawing-set completeness agent."""
+
+import json
+from typing import Dict, List
+
+from backend import config
+from backend.agents.base import AgentResult, AgentScope, AgentUsage, failure
+from backend.agents.prompts import COMPLETENESS_SYSTEM_PROMPT, COMPLETENESS_USER_PROMPT
+from backend.llm import call_json
+from backend.pipeline._stage import collect_list, validate_issue
+
+
+def build_sheet_summaries(sheets: List[Dict]) -> List[Dict]:
+    """Return counts and classifications only; never raw assertions."""
+    return [{
+        "sheet_number": sheet.get("sheet_number"),
+        "sheet_title": sheet.get("sheet_title"),
+        "discipline": sheet.get("discipline"),
+        "drawing_type": sheet.get("drawing_type"),
+        "level": sheet.get("level"),
+        "assertion_count": len(sheet.get("assertions") or []),
+        "unresolved_count": len(sheet.get("unresolved_items") or []),
+    } for sheet in sheets]
+
+
+class CompletenessAgent:
+    name = "completeness"
+
+    def __init__(self, usage: AgentUsage) -> None:
+        self.usage = usage
+
+    def run(self, scope: AgentScope) -> AgentResult:
+        try:
+            instruction = COMPLETENESS_USER_PROMPT
+            for key in ("sheet_index", "sheet_summaries", "cluster_summary"):
+                instruction = instruction.replace(
+                    "{" + key + "}",
+                    json.dumps(scope.payload.get(key) or {}, ensure_ascii=True),
+                )
+            parsed = call_json(
+                system_prompt=COMPLETENESS_SYSTEM_PROMPT,
+                user_text=instruction,
+                max_tokens=config.QAQC_MAX_TOKENS,
+                model=config.AGENT_COMPLETENESS_MODEL,
+                usage_tracker=self.usage,
+                usage_stage="agent.completeness",
+            )
+            findings = collect_list(
+                parsed, "issues", lambda item: validate_issue(item, "qaqc")
+            )
+            for finding in findings:
+                finding.update(agent=self.name, scope_id=scope.scope_id)
+            return AgentResult(scope_id=scope.scope_id, artifacts=findings)
+        except Exception as exc:
+            return failure(scope, exc)