fix(runner): count prior unavailable candidate turns in eval limits

Deduplicate unavailable turns against measured receipts and retain unknown aggregate usage across mixed turns, so a later measured response cannot hide earlier calls or imply complete cost coverage.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/paperclip-runner/src/cli/eval-session-contract.test.ts

@@ -305,6 +305,33 @@ describe("eval-session usage", () => {
     })).toThrow("agent turn limit exceeded");
   });
 
+  it("counts prior unavailable candidate turns alongside a later measured turn without claiming a complete total", () => {
+    const parsed = parseEvalSessionRequest(request({
+      provider: "acpx", acpxAgent: "cursor", model: "gpt-5.6-sol",
+    }), { candidateProfile: "cursor" });
+    const unavailable = {
+      turnId: "prior-turn", attemptId: "attempt-1", agent: "cursor" as const,
+      reason: "provider_did_not_report_usage" as const,
+      tokenUsage: null, costNanodollars: null, observedAt: "2026-09-28T19:18:10.000Z",
+    };
+    const snapshot = {
+      config: { provider: "acpx", acpxAgent: "cursor" },
+      usageUnavailable: [unavailable, { ...unavailable }],
+      usageLedger: [{
+        receiptId: "measured-receipt", turnId: "measured-turn", providerCalls: 1,
+        providerRequests: 1, inputTokens: 100, outputTokens: 10,
+        cachedInputTokens: 0, reasoningTokens: 0, costNanodollars: 0,
+      }],
+    } as unknown as CapabilityLiveSessionSnapshot;
+    const turn = { turnId: "measured-turn", status: "completed" as const, assistantText: "Done", snapshot };
+    expect(() => boundedEvalSessionUsage(parsed, turn)).toThrow("agent turn limit exceeded");
+    expect(boundedEvalSessionUsage({ ...parsed, limits: { ...parsed.limits, maxAgentTurns: 2 } }, turn)).toBeNull();
+    expect(boundedEvalSessionUsage(parsed, {
+      ...turn,
+      snapshot: { ...snapshot, usageUnavailable: [{ ...unavailable, turnId: "measured-turn" }] },
+    })).toMatchObject({ agentTurns: 1, inputTokens: 100, outputTokens: 10 });
+  });
+
   it("deduplicates receipts and applies the versioned model price", () => {
     const receipt = {
       receiptId: "receipt-1",

packages/paperclip-runner/src/cli/eval-session.ts

@@ -250,19 +250,23 @@ export function boundedEvalSessionUsage(
   if (turn.status !== "completed") {
     return usageIfAvailable(request, turn.snapshot);
   }
-  const unavailable = request.provider === "acpx"
+  const candidate = request.provider === "acpx"
     && request.acpxAgent !== undefined
     && ["pi", "cursor", "copilot"].includes(request.acpxAgent)
     && turn.snapshot.config.provider === "acpx"
-    && turn.snapshot.config.acpxAgent === request.acpxAgent
-    && turn.snapshot.usageUnavailable?.some((entry) => entry.turnId === turn.turnId
-      && entry.agent === request.acpxAgent && entry.reason === "provider_did_not_report_usage");
-  const usage = unavailable
+    && turn.snapshot.config.acpxAgent === request.acpxAgent;
+  const measuredTurns = new Set(turn.snapshot.usageLedger?.map((entry) => entry.turnId));
+  const unavailableTurnIds = new Set(candidate
+    ? turn.snapshot.usageUnavailable?.filter((entry) => entry.agent === request.acpxAgent
+      && entry.reason === "provider_did_not_report_usage"
+      && entry.tokenUsage === null && entry.costNanodollars === null
+      && !measuredTurns.has(entry.turnId)).map((entry) => entry.turnId)
+    : []);
+  const unavailable = unavailableTurnIds.size > 0;
+  const usage = unavailable && (unavailableTurnIds.has(turn.turnId) || turn.snapshot.usageLedger?.length)
     ? usageIfAvailable(request, turn.snapshot)
     : evalSessionUsage(request.model, turn.snapshot);
-  const unavailableTurns = unavailable
-    ? new Set(turn.snapshot.usageUnavailable?.map((entry) => entry.turnId)).size
-    : 0;
+  const unavailableTurns = unavailableTurnIds.size;
   if ((usage?.agentTurns ?? 0) + unavailableTurns > request.limits.maxAgentTurns) {
     throw new Error("agent turn limit exceeded");
   }