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/construct_agent.py

@@ -0,0 +1,70 @@
+"""Zone/cluster-scoped constructability agents."""
+
+from typing import Dict, List
+
+from backend import config
+from backend.agents.base import AgentResult, AgentScope, AgentUsage, failure
+from backend.llm import call_json
+from backend.pipeline._serialize import dumps, slim_clusters
+from backend.pipeline._stage import collect_list, validate_issue
+from backend.prompts import (
+    CONSTRUCTABILITY_SYSTEM_PROMPT,
+    CONSTRUCTABILITY_USER_INSTRUCTION,
+)
+
+
+def build_construct_scopes(
+    clusters: List[Dict], conflict_findings: List[Dict]
+) -> List[AgentScope]:
+    scopes = []
+    for index, cluster in enumerate(clusters):
+        related = [
+            finding for finding in conflict_findings
+            if finding.get("scope_id") == f"conflict:{cluster.get('key')}"
+            or finding.get("location") == cluster.get("location")
+        ]
+        scopes.append(AgentScope(
+            scope_id=f"construct:{index + 1}",
+            payload={"cluster": cluster, "conflicts": related},
+        ))
+    return scopes
+
+
+class ConstructabilityAgent:
+    name = "constructability"
+
+    def __init__(self, usage: AgentUsage) -> None:
+        self.usage = usage
+
+    def run(self, scope: AgentScope) -> AgentResult:
+        try:
+            cluster = dict(scope.payload["cluster"])
+            cluster["assertions"] = (
+                cluster.get("assertions") or []
+            )[:config.AGENT_CLUSTER_MAX_ASSERTIONS]
+            instruction = CONSTRUCTABILITY_USER_INSTRUCTION
+            substitutions = {
+                "assertions": dumps(cluster["assertions"]),
+                "clusters": dumps(slim_clusters([cluster])),
+                "conflicts": dumps(scope.payload.get("conflicts") or []),
+            }
+            for key, value in substitutions.items():
+                instruction = instruction.replace("{" + key + "}", value)
+            parsed = call_json(
+                system_prompt=CONSTRUCTABILITY_SYSTEM_PROMPT,
+                user_text=instruction,
+                max_tokens=config.CONSTRUCT_MAX_TOKENS,
+                model=config.AGENT_CONSTRUCT_MODEL,
+                usage_tracker=self.usage,
+                usage_stage="agent.constructability",
+            )
+            findings = collect_list(
+                parsed,
+                "issues",
+                lambda item: validate_issue(item, "constructability"),
+            )
+            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)