chore: import upstream snapshot with attribution

tests/unit/compression/progressiveAging.test.ts

@@ -0,0 +1,174 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import { applyAging } from "../../../open-sse/services/compression/progressiveAging.ts";
+import type { AgingThresholds, Summarizer } from "../../../open-sse/services/compression/types.ts";
+
+function makeMessages(
+  count: number,
+  role: string = "user",
+  prefix: string = "Message"
+): Array<{ role: string; content: string }> {
+  return Array.from({ length: count }, (_, i) => ({
+    role: i % 2 === 0 ? "user" : "assistant",
+    content: `${prefix} ${i}: ${"x".repeat(100)}`,
+  }));
+}
+
+describe("applyAging", () => {
+  const defaultThresholds: AgingThresholds = { fullSummary: 5, moderate: 3, light: 2, verbatim: 2 };
+
+  it("returns empty array for empty input", () => {
+    const result = applyAging([]);
+    assert.deepEqual(result.messages, []);
+    assert.equal(result.saved, 0);
+  });
+
+  it("returns single message unchanged (verbatim tier)", () => {
+    const msgs = [{ role: "user", content: "Hello world" }];
+    const result = applyAging(msgs, defaultThresholds);
+    assert.equal(result.messages.length, 1);
+    assert.equal((result.messages[0] as { content: string }).content, "Hello world");
+  });
+
+  it("keeps last 2 messages as verbatim", () => {
+    const msgs = makeMessages(10);
+    const result = applyAging(msgs, defaultThresholds);
+    const last2 = result.messages.slice(-2);
+    for (const msg of last2) {
+      const content =
+        typeof (msg as { content: unknown }).content === "string"
+          ? (msg as { content: string }).content
+          : "";
+      assert.ok(
+        !content.startsWith("[COMPRESSED:aging:"),
+        `Last message should be verbatim, got: ${content.slice(0, 40)}`
+      );
+    }
+  });
+
+  it("applies fullSummary tier to oldest messages", () => {
+    const msgs = makeMessages(10);
+    const result = applyAging(msgs, defaultThresholds);
+    const first = result.messages[0] as { content: string };
+    const content = typeof first.content === "string" ? first.content : "";
+    assert.ok(
+      content.startsWith("[COMPRESSED:aging:fullSummary]"),
+      `Expected fullSummary marker, got: ${content.slice(0, 60)}`
+    );
+  });
+
+  it("skips messages with [COMPRESSED: prefix (idempotent)", () => {
+    const msgs: Array<{ role: string; content: string }> = [
+      { role: "assistant", content: "[COMPRESSED:aging:fullSummary] prior summary" },
+      { role: "user", content: "New message" },
+    ];
+    const result = applyAging(msgs, defaultThresholds);
+    const first = result.messages[0] as { content: string };
+    const content = typeof first.content === "string" ? first.content : "";
+    assert.ok(content.startsWith("[COMPRESSED:aging:fullSummary]"));
+    assert.ok(!content.includes("[COMPRESSED:aging:fullSummary][COMPRESSED:"));
+  });
+
+  it("uses custom thresholds", () => {
+    const customThresholds: AgingThresholds = {
+      fullSummary: 1,
+      moderate: 1,
+      light: 1,
+      verbatim: 1,
+    };
+    const msgs = makeMessages(6);
+    const result = applyAging(msgs, customThresholds);
+    assert.ok(result.messages.length > 0);
+  });
+
+  it("accepts custom summarizer", () => {
+    const customSummarizer: Summarizer = {
+      summarize: () => "[CUSTOM SUMMARY]",
+    };
+    const msgs = makeMessages(10);
+    const result = applyAging(msgs, defaultThresholds, customSummarizer);
+    const fullSummaryMsgs = result.messages.filter((m) => {
+      const content =
+        typeof (m as { content: unknown }).content === "string"
+          ? (m as { content: string }).content
+          : "";
+      return content.includes("[CUSTOM SUMMARY]");
+    });
+    assert.ok(fullSummaryMsgs.length > 0, "Expected at least one message with custom summary");
+  });
+
+  it("computes saved tokens", () => {
+    const msgs = makeMessages(10);
+    const result = applyAging(msgs, defaultThresholds);
+    assert.ok(typeof result.saved === "number");
+  });
+
+  it("handles 2-message conversation (all verbatim)", () => {
+    const msgs = [
+      { role: "user", content: "Hello" },
+      { role: "assistant", content: "Hi there" },
+    ];
+    const result = applyAging(msgs, defaultThresholds);
+    assert.equal(result.messages.length, 2);
+    for (const msg of result.messages) {
+      const content =
+        typeof (msg as { content: unknown }).content === "string"
+          ? (msg as { content: string }).content
+          : "";
+      assert.ok(!content.startsWith("[COMPRESSED:"));
+    }
+  });
+
+  it("handles 5-message conversation with light tier", () => {
+    const msgs = makeMessages(5);
+    const thresholds: AgingThresholds = { fullSummary: 10, moderate: 10, light: 3, verbatim: 1 };
+    const result = applyAging(msgs, thresholds);
+    assert.ok(result.messages.length > 0);
+  });
+
+  it("handles messages with array content", () => {
+    const msgs = [{ role: "user", content: [{ type: "text", text: "Hello from array" }] }];
+    const result = applyAging(msgs, defaultThresholds);
+    assert.equal(result.messages.length, 1);
+  });
+
+  it("does not mutate original messages array", () => {
+    const original = makeMessages(5);
+    const originalCopy = JSON.parse(JSON.stringify(original));
+    applyAging(original, defaultThresholds);
+    assert.deepEqual(original, originalCopy);
+  });
+
+  it("handles all-assistant messages", () => {
+    const msgs = Array.from({ length: 8 }, (_, i) => ({
+      role: "assistant" as const,
+      content: `Response ${i}: ${"y".repeat(100)}`,
+    }));
+    const result = applyAging(msgs, defaultThresholds);
+    assert.ok(result.messages.length > 0);
+  });
+
+  it("handles mixed user/assistant/tool messages", () => {
+    const msgs = [
+      { role: "user", content: "Fix the bug" },
+      { role: "assistant", content: "I'll fix it" },
+      { role: "tool", content: "Result: fixed" },
+      { role: "assistant", content: "Done" },
+    ];
+    const result = applyAging(msgs, defaultThresholds);
+    assert.ok(result.messages.length > 0);
+  });
+
+  it("idempotent — running twice produces same output", () => {
+    const msgs = makeMessages(10);
+    const first = applyAging(msgs, defaultThresholds);
+    const second = applyAging(first.messages, defaultThresholds);
+    const firstContent = JSON.stringify(
+      first.messages.map((m) => (m as { content: string }).content)
+    );
+    const secondContent = JSON.stringify(
+      second.messages.map((m) => (m as { content: string }).content)
+    );
+    assert.equal(firstContent, secondContent);
+  });
+});