test(FN-4512): complete Step 4 — add parser interop verdict tests

Fusion-Task-Id: FN-4512
Fusion-Task-Lineage: b9d9534b-e623-4748-aa0d-dd65af509fbe

plugins/fusion-plugin-agent-browser/src/__tests__/workflow-steps-verdict.test.ts

@@ -0,0 +1,30 @@
+import { describe, expect, it } from "vitest";
+import { inferWorkflowStepVerdictFromProse, parseWorkflowStepVerdict } from "../../../../packages/engine/src/executor.js";
+import { AGENT_BROWSER_WORKFLOW_STEPS } from "../workflow-steps.js";
+
+describe("browser-evidence-review verdict parsing", () => {
+  it("parses clean trailing JSON output", () => {
+    const output = '{"verdict":"APPROVE","notes":""}';
+    expect(parseWorkflowStepVerdict(output)).toEqual({ verdict: "APPROVE", notes: "" });
+  });
+
+  it("parses fast-bail JSON output", () => {
+    const output = '{"verdict":"APPROVE","notes":"out of scope: no browser-derived evidence in diff"}';
+    expect(parseWorkflowStepVerdict(output)).toEqual({
+      verdict: "APPROVE",
+      notes: "out of scope: no browser-derived evidence in diff",
+    });
+  });
+
+  it("keeps prose fallback for revision requests", () => {
+    const output = "REQUEST REVISION\nclaim about pricing page lacks a screenshot";
+    const inferred = inferWorkflowStepVerdictFromProse(output);
+    expect(inferred?.verdict).toBe("REVISE");
+    expect(inferred?.notes).toContain("claim about pricing page lacks a screenshot");
+  });
+
+  it("template declares structured verdict envelope", () => {
+    const step = AGENT_BROWSER_WORKFLOW_STEPS.find((entry) => entry.stepId === "browser-evidence-review");
+    expect(step?.prompt).toContain('{"verdict":"APPROVE|APPROVE_WITH_NOTES|REVISE","notes":"..."}');
+  });
+});