chore: import upstream snapshot with attribution

tests/unit/chatcore-compression-usage-receipt.test.ts

@@ -0,0 +1,78 @@
+// tests/unit/chatcore-compression-usage-receipt.test.ts
+// Characterization of attachCompressionUsageReceiptAfterAnalytics — the fire-and-forget compression
+// usage-receipt attachment extracted from handleChatCore (chatCore god-file decomposition, #3501).
+// Uses a real temp DB: inserts a compression_analytics row, attaches a receipt after pendingWrite,
+// and asserts the aggregated realUsage. Also locks the best-effort error swallowing.
+import { test, before, after } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const testDataDir = fs.mkdtempSync(path.join(os.tmpdir(), "omni-compression-receipt-test-"));
+process.env.DATA_DIR = testDataDir;
+
+const coreDb = await import("../../src/lib/db/core.ts");
+const { insertCompressionAnalyticsRow, getCompressionAnalyticsSummary } = await import(
+  "../../src/lib/db/compressionAnalytics.ts"
+);
+const { attachCompressionUsageReceiptAfterAnalytics } = await import(
+  "../../open-sse/handlers/chatCore/compressionUsageReceipt.ts"
+);
+
+const tick = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+before(async () => {
+  await coreDb.ensureDbInitialized();
+});
+
+after(() => {
+  coreDb.resetDbInstance();
+  fs.rmSync(testDataDir, { recursive: true, force: true });
+});
+
+test("attaches the usage receipt only after pendingWrite resolves", async () => {
+  insertCompressionAnalyticsRow({
+    timestamp: new Date().toISOString(),
+    mode: "test",
+    original_tokens: 100,
+    compressed_tokens: 60,
+    tokens_saved: 40,
+    request_id: "req-1",
+  });
+
+  let pendingResolved = false;
+  const pendingWrite = new Promise<void>((res) =>
+    setTimeout(() => {
+      pendingResolved = true;
+      res();
+    }, 20)
+  );
+
+  attachCompressionUsageReceiptAfterAnalytics(
+    { prompt_tokens: 10, completion_tokens: 5, total_tokens: 15 },
+    "provider",
+    { pendingWrite, skillRequestId: "req-1" }
+  );
+
+  await tick(80);
+  assert.equal(pendingResolved, true, "pendingWrite should have resolved first");
+
+  const summary = getCompressionAnalyticsSummary();
+  assert.equal(summary.realUsage.requestsWithReceipts, 1);
+  assert.equal(summary.realUsage.promptTokens, 10);
+  assert.equal(summary.realUsage.completionTokens, 5);
+});
+
+test("swallows the no-matching-row case without throwing or recording a receipt", async () => {
+  assert.doesNotThrow(() =>
+    attachCompressionUsageReceiptAfterAnalytics(
+      { prompt_tokens: 1, total_tokens: 1 },
+      "provider",
+      { pendingWrite: null, skillRequestId: "does-not-exist" }
+    )
+  );
+  await tick(40);
+  const summary = getCompressionAnalyticsSummary();
+  assert.equal(summary.realUsage.requestsWithReceipts, 1);
+});