fix(mastra): use Mastra span id as Braintrust row id for logFeedback

.changeset/mastra-logfeedback-row-id.md

@@ -0,0 +1,5 @@
+---
+"braintrust": patch
+---
+
+fix(mastra): Use the Mastra span id as the Braintrust row id so `logFeedback` attaches to the right row instead of landing as a stray. Matches the upstream `@mastra/braintrust` fix (mastra-ai/mastra#11927).

js/src/wrappers/mastra.test.ts

@@ -0,0 +1,81 @@
+import {
+  afterEach,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  test,
+} from "vitest";
+import { configureNode } from "../node/config";
+import { _exportsForTestingOnly, initLogger } from "../logger";
+import { BraintrustObservabilityExporter } from "./mastra";
+
+try {
+  configureNode();
+} catch {
+  // Best-effort initialization for test environments.
+}
+
+type ExportedSpan = Parameters<
+  BraintrustObservabilityExporter["exportTracingEvent"]
+>[0]["exportedSpan"];
+
+const span = (overrides: Partial<ExportedSpan>): ExportedSpan => ({
+  id: "span-1",
+  traceId: "trace-1",
+  name: "agent run",
+  type: "agent_run",
+  startTime: 1_000_000,
+  ...overrides,
+});
+
+describe("BraintrustObservabilityExporter", () => {
+  let backgroundLogger: ReturnType<
+    typeof _exportsForTestingOnly.useTestBackgroundLogger
+  >;
+  let logger: ReturnType<typeof initLogger>;
+
+  beforeAll(async () => {
+    await _exportsForTestingOnly.simulateLoginForTests();
+  });
+
+  beforeEach(() => {
+    backgroundLogger = _exportsForTestingOnly.useTestBackgroundLogger();
+    logger = initLogger({
+      projectId: "test-project-id",
+      projectName: "mastra.test.ts",
+    });
+  });
+
+  afterEach(() => {
+    _exportsForTestingOnly.clearTestBackgroundLogger();
+  });
+
+  test("logFeedback keyed on the Mastra span id merges into the span row", async () => {
+    const exporter = new BraintrustObservabilityExporter();
+    const id = "mastra-span-123";
+
+    await exporter.exportTracingEvent({
+      type: "span_started",
+      exportedSpan: span({ id }),
+    });
+    await exporter.exportTracingEvent({
+      type: "span_ended",
+      exportedSpan: span({ id, endTime: 1_000_001 }),
+    });
+    // A Mastra user (or Mastra's score-event bus) knows only the Mastra span id.
+    logger.logFeedback({ id, scores: { quality: 0.9 }, source: "external" });
+
+    await backgroundLogger.flush();
+    const rows = (await backgroundLogger.drain()) as any[];
+
+    // The exporter aliases the row id to the Mastra span id, so the feedback
+    // merge row keys onto the span row and `mergeRowBatch` collapses them into a
+    // single row carrying both the span and the score. Without the aliasing the
+    // feedback would land as a separate orphan row.
+    const merged = rows.filter((r) => r.id === id);
+    expect(merged).toHaveLength(1);
+    expect(merged[0].span_attributes?.name).toBe("agent run");
+    expect(merged[0].scores?.quality).toBe(0.9);
+  });
+});

js/src/wrappers/mastra.ts

@@ -272,6 +272,12 @@ export class BraintrustObservabilityExporter implements MastraObservabilityExpor
       name: exported.name,
       spanAttributes: { type: spanTypeFor(exported.type) },
       startTime: epochSeconds(exported.startTime),
+      // Use the Mastra span id as the Braintrust row id so that
+      // `logFeedback({ id: <mastra span id> })` (and Mastra's score events)
+      // attach to the right row. Without this, `SpanImpl` auto-generates a
+      // row id (`this._id = eventId ?? idGenerator.getSpanId()`) that no
+      // external caller could know.
+      event: { id: exported.id },
     };
 
     const parentRecord = exported.parentSpanId