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/rfi_writer.py

@@ -0,0 +1,42 @@
+"""One-finding-per-call RFI writers."""
+
+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
+from backend.pipeline.rfi import _valid_rfi
+from backend.prompts import RFI_SYSTEM_PROMPT, RFI_USER_INSTRUCTION
+
+
+class RFIWriterAgent:
+    name = "rfi_writer"
+
+    def __init__(self, usage: AgentUsage) -> None:
+        self.usage = usage
+
+    def run(self, scope: AgentScope) -> AgentResult:
+        try:
+            finding = scope.payload["finding"]
+            instruction = RFI_USER_INSTRUCTION.replace(
+                "{prioritized_issues}", dumps([finding])
+            )
+            parsed = call_json(
+                system_prompt=RFI_SYSTEM_PROMPT,
+                user_text=instruction,
+                max_tokens=config.RFI_MAX_TOKENS,
+                model=config.AGENT_RFI_MODEL,
+                usage_tracker=self.usage,
+                usage_stage="agent.rfi",
+            )
+            candidates = parsed if isinstance(parsed, list) else (
+                parsed.get("rfi_comments") if isinstance(parsed, dict) else []
+            )
+            rfis = []
+            for candidate in candidates or []:
+                rfi = _valid_rfi(candidate)
+                if rfi:
+                    rfi["issue_id"] = rfi.get("issue_id") or finding.get("issue_id")
+                    rfis.append(rfi)
+            return AgentResult(scope_id=scope.scope_id, artifacts=rfis[:1])
+        except Exception as exc:
+            return failure(scope, exc)