fix: preserve inter-session input provenance (thanks @anbecker)

src/agents/pi-embedded-runner.sanitize-session-history.test.ts

@@ -112,6 +112,36 @@ describe("sanitizeSessionHistory", () => {
     );
   });
 
+  it("annotates inter-session user messages before context sanitization", async () => {
+    vi.mocked(helpers.isGoogleModelApi).mockReturnValue(false);
+
+    const messages: AgentMessage[] = [
+      {
+        role: "user",
+        content: "forwarded instruction",
+        provenance: {
+          kind: "inter_session",
+          sourceSessionKey: "agent:main:req",
+          sourceTool: "sessions_send",
+        },
+      } as unknown as AgentMessage,
+    ];
+
+    const result = await sanitizeSessionHistory({
+      messages,
+      modelApi: "openai-responses",
+      provider: "openai",
+      sessionManager: mockSessionManager,
+      sessionId: "test-session",
+    });
+
+    const first = result[0] as Extract<AgentMessage, { role: "user" }>;
+    expect(first.role).toBe("user");
+    expect(typeof first.content).toBe("string");
+    expect(first.content as string).toContain("[Inter-session message]");
+    expect(first.content as string).toContain("sourceSession=agent:main:req");
+  });
+
   it("keeps reasoning-only assistant messages for openai-responses", async () => {
     vi.mocked(helpers.isGoogleModelApi).mockReturnValue(false);