chore: import upstream snapshot with attribution

tests/unit/chatcore-semantic-cache-store.test.ts

@@ -0,0 +1,109 @@
+// Characterization of storeSemanticCacheResponse — the Phase 9.1 non-streaming semantic-cache
+// store extracted from handleChatCore (chatCore god-file decomposition, #3501). Deps are injected
+// so the gating logic + signature derivation are observable without the real cache backend.
+// Locks: the 3-way gate (enabled + cacheable-for-write + small-enough), the signature args
+// (messages ?? input, temperature, top_p, apiKeyId), and the `prompt + completion || 0` token count.
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+const { storeSemanticCacheResponse } = await import(
+  "../../open-sse/handlers/chatCore/semanticCacheStore.ts"
+);
+
+type Stored = { sig: unknown; model: string; response: unknown; tokens: number };
+
+function makeDeps(overrides: Record<string, unknown> = {}) {
+  const stored: Stored[] = [];
+  const calls = { cacheable: 0, small: 0, signature: 0 };
+  const deps = {
+    isCacheableForWrite: (..._a: unknown[]) => {
+      calls.cacheable++;
+      return true;
+    },
+    isSmallEnoughForSemanticCache: (..._a: unknown[]) => {
+      calls.small++;
+      return true;
+    },
+    generateSignature: (...a: unknown[]) => {
+      calls.signature++;
+      return `sig:${JSON.stringify(a)}`;
+    },
+    setCachedResponse: (sig: unknown, model: string, response: unknown, tokens: number) => {
+      stored.push({ sig, model, response, tokens });
+    },
+    ...overrides,
+  } as Parameters<typeof storeSemanticCacheResponse>[1];
+  return { deps, stored, calls };
+}
+
+function baseArgs(overrides: Record<string, unknown> = {}) {
+  return {
+    enabled: true,
+    body: { messages: [{ role: "user", content: "hi" }], temperature: 0, top_p: 1 },
+    headers: undefined,
+    translatedResponse: { id: "resp-1" },
+    model: "gpt-x",
+    apiKeyId: "key-1",
+    usage: { prompt_tokens: 10, completion_tokens: 5 },
+    log: undefined,
+    ...overrides,
+  } as Parameters<typeof storeSemanticCacheResponse>[0];
+}
+
+test("happy path → stores under a signature, tokensSaved = prompt + completion", () => {
+  const { deps, stored } = makeDeps();
+  storeSemanticCacheResponse(baseArgs(), deps);
+  assert.equal(stored.length, 1);
+  assert.equal(stored[0].model, "gpt-x");
+  assert.deepEqual(stored[0].response, { id: "resp-1" });
+  assert.equal(stored[0].tokens, 15);
+});
+
+test("disabled → no store, no gate calls past enabled", () => {
+  const { deps, stored, calls } = makeDeps();
+  storeSemanticCacheResponse(baseArgs({ enabled: false }), deps);
+  assert.equal(stored.length, 0);
+  assert.equal(calls.cacheable, 0);
+});
+
+test("not cacheable-for-write → no store", () => {
+  const { deps, stored } = makeDeps({ isCacheableForWrite: () => false });
+  storeSemanticCacheResponse(baseArgs(), deps);
+  assert.equal(stored.length, 0);
+});
+
+test("too large → no store", () => {
+  const { deps, stored } = makeDeps({ isSmallEnoughForSemanticCache: () => false });
+  storeSemanticCacheResponse(baseArgs(), deps);
+  assert.equal(stored.length, 0);
+});
+
+test("signature uses messages when present, with model/temperature/top_p/apiKeyId", () => {
+  const { deps, stored } = makeDeps();
+  storeSemanticCacheResponse(baseArgs(), deps);
+  const sig = stored[0].sig as string;
+  assert.ok(sig.includes("gpt-x"));
+  assert.ok(sig.includes("key-1"));
+});
+
+test("falls back to body.input when messages absent", () => {
+  let captured: unknown[] = [];
+  const { deps } = makeDeps({
+    generateSignature: (...a: unknown[]) => {
+      captured = a;
+      return "sig";
+    },
+  });
+  storeSemanticCacheResponse(
+    baseArgs({ body: { input: "the-input", temperature: 0, top_p: 1 } }),
+    deps
+  );
+  // args: (model, messages ?? input, temperature, top_p, apiKeyId)
+  assert.equal(captured[1], "the-input");
+});
+
+test("missing usage → tokensSaved coerces to 0 (NaN || 0)", () => {
+  const { deps, stored } = makeDeps();
+  storeSemanticCacheResponse(baseArgs({ usage: undefined }), deps);
+  assert.equal(stored[0].tokens, 0);
+});