search-with-proof: feed the control signal back to the agent (served-root hint)

When a path demo does not serve ${served_root}, the keystone control fails
(SideRecord.control_observed False) but the search only reported a generic
inconclusive, so the agent kept making the same wiring mistake. The pilot now
surfaces the affected side's control_observed in the verify result, and the
coordinator appends one advisory, deduplicated "served-root" hint (visible in the
board snapshot the agent reads) telling it to set the served-directory config to the
${served_root} placeholder. Advisory only: verdicts, _end, the oracle, the differential
and the demo validator are unchanged; the hint fires only when control_observed is False.

Tests: coordinator + pilot_run suites 78 passed; ruff clean; mypy unchanged (pre-existing
benchmarks errors only). Host-side change, no image rebuild.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

benchmarks/search/pilot_run.py

@@ -328,7 +328,13 @@ class Pilot:
                 if result.outcome != "demonstrated":
                     self.failure("verify", "no_consistent_differential" if result.outcome == "inconclusive" else result.outcome)
                 end = result.outcome
-                return dict(status="ok", outcome=result.outcome, evidence_refs=["verify:owned"], cost_usd=0)
+                return dict(
+                    status="ok",
+                    outcome=result.outcome,
+                    evidence_refs=["verify:owned"],
+                    cost_usd=0,
+                    control_observed=result.sides[0].control_observed if result.sides else None,
+                )
             if task.step == "explore":
                 if self.args.dry_run:
                     self.worker.executor = InProcessExecutor(self.sides[0 if self.args.side == "vulnerable" else 1].checkout)