fix(workbench): stabilize investigation presentation rendering

Keep investigation graphs stable during updates, defer expensive chart rendering, and prevent stale results when switching tasks. Adopt reference annotations and consolidate frontend documentation.

src/features/workbench/utils/investigation-diagram-reference.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from "vitest";
+import { investigationDiagramSchema } from "../api/investigation-report";
+import { styleInvestigationDiagram } from "./investigation-diagram-style";
+
+describe("investigation diagrams as process references", () => {
+  it("reads a legacy running node as a neutral reference without suggesting live execution", () => {
+    const diagram = investigationDiagramSchema.parse({ title: "流程参考", mermaid: "flowchart TD\nA[核查]",
+      node_refs: [{ node_id: "A", label: "核查", status: "running" }] });
+    const styled = styleInvestigationDiagram(diagram);
+    expect(styled).toContain("class A tjReference;");
+    expect(diagram.node_refs[0].status).toBe("reference");
+    expect(styled).not.toContain("class A tjRunning;");
+    expect(styled).not.toContain("class A tjRecordedRunning;");
+  });
+
+  it("distinguishes a recorded finding from task completion and preserves failed paths", () => {
+    const diagram = investigationDiagramSchema.parse({ title: "调查脉络", mermaid: "flowchart TD\nA[原尝试] --> B[替代路线]",
+      node_refs: [{ node_id: "A", label: "原尝试", status: "failed", detail: "接口超时" },
+        { node_id: "B", label: "替代路线", status: "recorded" }] });
+    const styled = styleInvestigationDiagram(diagram);
+    expect(styled).toContain("class A tjFailed;");
+    expect(styled).toContain("class B tjRecorded;");
+    expect(styled.startsWith(diagram.mermaid)).toBe(true);
+    expect(diagram.node_refs[0].detail).toBe("接口超时");
+  });
+});