chore: import upstream snapshot with attribution

tests/unit/background-task-detector.test.ts

@@ -0,0 +1,151 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+const {
+  isBackgroundTask,
+  getBackgroundTaskReason,
+  getDegradedModel,
+  setBackgroundDegradationConfig,
+  getBackgroundDegradationConfig,
+  getDefaultDegradationMap,
+  getDefaultDetectionPatterns,
+  resetStats,
+} = await import("../../open-sse/services/backgroundTaskDetector.ts");
+
+// ─── isBackgroundTask ───────────────────────────────────────────────────────
+
+test("isBackgroundTask: returns true for title generation pattern", () => {
+  setBackgroundDegradationConfig({ enabled: true });
+  const body = {
+    model: "claude-sonnet-4",
+    messages: [
+      { role: "system", content: "Generate a title for this conversation" },
+      { role: "user", content: "How to deploy a Next.js app" },
+    ],
+  };
+  assert.equal(isBackgroundTask(body), true);
+});
+
+test("isBackgroundTask: returns true for summarize pattern", () => {
+  const body = {
+    model: "claude-sonnet-4",
+    messages: [
+      { role: "system", content: "Summarize this conversation briefly" },
+      { role: "user", content: "We discussed deployment techniques" },
+    ],
+  };
+  assert.equal(isBackgroundTask(body), true);
+});
+
+test("isBackgroundTask: returns false for normal chat", () => {
+  const body = {
+    model: "claude-sonnet-4",
+    messages: [
+      { role: "system", content: "You are a helpful coding assistant" },
+      { role: "user", content: "Help me write a function" },
+    ],
+  };
+  assert.equal(isBackgroundTask(body), false);
+});
+
+test("isBackgroundTask: returns false for many-turn conversations", () => {
+  const messages = [
+    { role: "system", content: "Generate a title" },
+    ...Array.from({ length: 10 }, (_, i) => ({
+      role: i % 2 === 0 ? "user" : "assistant",
+      content: `Message ${i}`,
+    })),
+  ];
+  const body = { model: "claude-sonnet-4", messages };
+  assert.equal(isBackgroundTask(body), false); // Too many turns
+});
+
+test("isBackgroundTask: detects X-Request-Priority header", () => {
+  const body = {
+    model: "claude-sonnet-4",
+    messages: [{ role: "user", content: "hello" }],
+  };
+  const headers = { "x-request-priority": "background" };
+  assert.equal(isBackgroundTask(body, headers), true);
+});
+
+test("isBackgroundTask: detects X-Task-Type header", () => {
+  const body = {
+    model: "claude-sonnet-4",
+    messages: [{ role: "user", content: "hello" }],
+  };
+  const headers = { "x-task-type": "background" };
+  assert.equal(isBackgroundTask(body, headers), true);
+  assert.equal(getBackgroundTaskReason(body, headers), "header_background");
+});
+
+test("isBackgroundTask: detects low max_tokens requests", () => {
+  const body = {
+    model: "claude-sonnet-4",
+    max_tokens: 32,
+    messages: [{ role: "user", content: "hello" }],
+  };
+  assert.equal(isBackgroundTask(body), true);
+  assert.equal(getBackgroundTaskReason(body), "low_max_tokens");
+});
+
+test("isBackgroundTask: returns false for null/undefined body", () => {
+  assert.equal(isBackgroundTask(null), false);
+  assert.equal(isBackgroundTask(undefined), false);
+});
+
+test("isBackgroundTask: returns false for empty messages", () => {
+  assert.equal(isBackgroundTask({ messages: [] }), false);
+});
+
+// ─── getDegradedModel ───────────────────────────────────────────────────────
+
+test("getDegradedModel: returns cheaper model from map", () => {
+  resetStats();
+  assert.equal(getDegradedModel("claude-opus-4-6"), "gemini-3-flash");
+  assert.equal(getDegradedModel("gemini-2.5-pro"), "gemini-3-flash");
+  assert.equal(getDegradedModel("gpt-4o"), "gpt-4o-mini");
+});
+
+test("getDegradedModel: returns original if no mapping exists", () => {
+  assert.equal(getDegradedModel("some-unknown-model"), "some-unknown-model");
+});
+
+test("getDegradedModel: handles null/empty", () => {
+  assert.equal(getDegradedModel(""), "");
+  assert.equal(getDegradedModel(null), null);
+});
+
+test("getDegradedModel: increments stats counter", () => {
+  resetStats();
+  getDegradedModel("claude-opus-4-6"); // known mapping
+  const config = getBackgroundDegradationConfig();
+  assert.equal(config.stats.detected, 1);
+});
+
+// ─── Config Management ──────────────────────────────────────────────────────
+
+test("getBackgroundDegradationConfig: returns config copy", () => {
+  const config = getBackgroundDegradationConfig();
+  assert.ok(typeof config.enabled === "boolean");
+  assert.ok(typeof config.degradationMap === "object");
+  assert.ok(Array.isArray(config.detectionPatterns));
+});
+
+test("setBackgroundDegradationConfig: updates config", () => {
+  setBackgroundDegradationConfig({ enabled: true });
+  assert.equal(getBackgroundDegradationConfig().enabled, true);
+  setBackgroundDegradationConfig({ enabled: false }); // reset
+});
+
+test("getDefaultDegradationMap: returns non-empty map", () => {
+  const map = getDefaultDegradationMap();
+  assert.ok(Object.keys(map).length > 0);
+  assert.ok(map["claude-opus-4-6"]);
+});
+
+test("getDefaultDetectionPatterns: returns non-empty array", () => {
+  const patterns = getDefaultDetectionPatterns();
+  assert.ok(patterns.length > 0);
+  assert.ok(patterns.includes("generate a title"));
+});