fix: manage Surplus multiplier offers

supplier/src/surplus/client.ts

@@ -381,7 +381,10 @@ function parseOffer(value: unknown, index: number): SurplusOffer {
   return {
     id: offerId(item, `Surplus offer ${index}`),
     model: string(item.model, `Surplus offer ${index}.model`),
-    sellerBaseUrl: string(item.seller_base_url, `Surplus offer ${index}.seller_base_url`),
+    sellerBaseUrl: string(
+      item.seller_base_url ?? item.base_url,
+      `Surplus offer ${index}.base_url`,
+    ),
     status,
     capDailyUsd: optionalNonNegativeNumber(item.cap_daily_usd, `Surplus offer ${index}.cap_daily_usd`),
     costMultiplierPpm: optionalMultiplierPpm(

supplier/src/surplus/controller.ts

@@ -359,44 +359,40 @@ export class SurplusSellerController {
     const pending = this.state;
     const offers = await this.client.listAllOffers();
     const active = offers.filter((offer) => offer.status === "active");
-    const matches = active
+    const activeMatches = active
       .filter((offer) =>
         offer.model === pending.intent.model &&
         normalizeUrl(offer.sellerBaseUrl) ===
           normalizeUrl(this.config.providerBaseUrl)
       )
       .sort((left, right) => left.id.localeCompare(right.id));
-    if (matches.length === 0) {
-      const inactiveMatch = offers.some((offer) =>
+    const inactiveMatches = offers
+      .filter((offer) =>
         offer.status === "inactive" &&
         offer.model === pending.intent.model &&
         normalizeUrl(offer.sellerBaseUrl) ===
           normalizeUrl(this.config.providerBaseUrl)
-      );
-      if (inactiveMatch && active.length === 0) {
-        const selecting: SurplusControllerState = {
-          version: 1,
-          phase: "selecting",
-        };
-        await this.stateStore.save(selecting);
-        this.state = selecting;
-        this.markSuccess("suspended", null, null);
-        return;
-      }
+      )
+      .sort((left, right) => left.id.localeCompare(right.id));
+    const primary = activeMatches[0] ?? inactiveMatches[0];
+    if (!primary) {
       if (active.length > 0) await this.pauseOffers(active);
       throw new Error(
         "Create result is ambiguous and no matching offer is visible; refusing another POST",
       );
     }
-    const primary = matches[0];
     await this.pauseOffers(active.filter((offer) => offer.id !== primary.id));
     const confirmedOffers = await this.client.listAllOffers();
     const confirmedActive = confirmedOffers.filter(
       (offer) => offer.status === "active",
     );
-    if (confirmedActive.length !== 1 || confirmedActive[0].id !== primary.id) {
+    const expectedActive = primary.status === "active" ? 1 : 0;
+    if (
+      confirmedActive.length !== expectedActive ||
+      (expectedActive === 1 && confirmedActive[0].id !== primary.id)
+    ) {
       await this.pauseOffers(confirmedActive);
-      throw new Error("Adopted Surplus create did not reconcile to one active offer");
+      throw new Error("Adopted Surplus create did not reconcile safely");
     }
     const adopted: SurplusControllerState = {
       version: 1,
@@ -413,6 +409,10 @@ export class SurplusSellerController {
       throw error;
     }
     this.state = adopted;
+    if (primary.status === "inactive") {
+      await this.manageActiveOffer();
+      return;
+    }
     this.markSuccess("active", null, {
       intent: adopted.intent,
       offerId: adopted.offerId,
@@ -492,7 +492,8 @@ export class SurplusSellerController {
       outputMicroUsdPer1m: quote.outputMicroUsdPer1m,
     };
     const priceChanged =
-      managed.costMultiplierPpm !== quote.costMultiplierPpm ||
+      managed.costMultiplierPpm === null ||
+      Math.abs(managed.costMultiplierPpm - quote.costMultiplierPpm) > 1 ||
       managed.capDailyUsd !== Number(this.config.perOfferCapUsd);
     if (this.config.live && priceChanged) {
       await this.client.updateOffer(currentState.offerId, {

tests/unit/surplus-controller.test.ts

@@ -260,6 +260,42 @@ describe("SurplusSellerController", () => {
     await restarted.stop();
   });
 
+  it("adopts and resumes an inactive offer after an ambiguous create", async () => {
+    const client = new FakeSurplusClient();
+    client.offer = {
+      id: "managed-offer",
+      model: "beta-model",
+      sellerBaseUrl: "https://openrouter.ai/api/v1",
+      status: "inactive",
+      capDailyUsd: 1,
+      costMultiplierPpm: 49_950,
+      inputMicroUsdPer1m: 3_972,
+      outputMicroUsdPer1m: 7_944,
+    };
+    const store = new MemoryStateStore();
+    store.state = {
+      version: 1,
+      phase: "create_pending",
+      intent: {
+        model: "beta-model",
+        providerModelId: "vendor/beta-model",
+        costMultiplierPpm: 49_950,
+        inputMicroUsdPer1m: 3_972,
+        outputMicroUsdPer1m: 7_944,
+        dailyCapUsd: 1,
+        idempotencyKey: "create-1",
+        createdAt: "2026-08-27T10:00:00.000Z",
+        baselineTrades24h: 0,
+      },
+    };
+
+    await controller(client, store).runOnce();
+
+    expect(client.createCalls).toBe(0);
+    expect(client.offer.status).toBe("active");
+    expect(store.state.phase).toBe("active");
+  });
+
   it("never retries an ambiguous create when no matching offer is visible", async () => {
     const client = new FakeSurplusClient();
     client.createError = new SurplusHttpError("network lost", null);