fix: gate skills reminders in headless sessions (#987)

src/tests/headless/skills-reminder.test.ts

@@ -0,0 +1,83 @@
+import { describe, expect, test } from "bun:test";
+import type { MessageCreate } from "@letta-ai/letta-client/resources/agents/agents";
+import type { Line } from "../../cli/helpers/accumulator";
+import {
+  prependSkillsReminderToContent,
+  shouldReinjectSkillsAfterCompaction,
+} from "../../headless";
+
+describe("headless skills reminder helpers", () => {
+  test("prepends reminder to string user content", () => {
+    const result = prependSkillsReminderToContent(
+      "hello",
+      "<skills>demo</skills>",
+    );
+    expect(result).toBe("<skills>demo</skills>\n\nhello");
+  });
+
+  test("prepends reminder as a text part for multimodal user content", () => {
+    const multimodal = [
+      { type: "text", text: "what is in this image?" },
+      {
+        type: "image",
+        source: { type: "base64", media_type: "image/png", data: "abc" },
+      },
+    ] as unknown as Exclude<MessageCreate["content"], string>;
+
+    const result = prependSkillsReminderToContent(
+      multimodal as MessageCreate["content"],
+      "<skills>demo</skills>",
+    );
+
+    expect(Array.isArray(result)).toBe(true);
+    if (!Array.isArray(result)) return;
+    expect(result[0]).toEqual({
+      type: "text",
+      text: "<skills>demo</skills>\n\n",
+    });
+    expect(result[1]).toEqual(multimodal[0]);
+    expect(result[2]).toEqual(multimodal[1]);
+  });
+
+  test("does not reinject on compaction start event", () => {
+    const lines: Line[] = [
+      {
+        kind: "event",
+        id: "evt-1",
+        eventType: "compaction",
+        eventData: {},
+        phase: "running",
+      },
+    ];
+    expect(shouldReinjectSkillsAfterCompaction(lines)).toBe(false);
+  });
+
+  test("reinjection triggers after compaction completion", () => {
+    const withSummary: Line[] = [
+      {
+        kind: "event",
+        id: "evt-2",
+        eventType: "compaction",
+        eventData: {},
+        phase: "finished",
+        summary: "Compacted old messages",
+      },
+    ];
+    expect(shouldReinjectSkillsAfterCompaction(withSummary)).toBe(true);
+
+    const withStatsOnly: Line[] = [
+      {
+        kind: "event",
+        id: "evt-3",
+        eventType: "compaction",
+        eventData: {},
+        phase: "finished",
+        stats: {
+          contextTokensBefore: 12000,
+          contextTokensAfter: 7000,
+        },
+      },
+    ];
+    expect(shouldReinjectSkillsAfterCompaction(withStatsOnly)).toBe(true);
+  });
+});