wehub-resource-sync
106 lines
4.8 KiB
TypeScript
106 lines
4.8 KiB
TypeScript
/**
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* Tests for #3890: prompt-cache misses when memory injection is enabled.
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*
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* When the client uses prompt caching (cache_control breakpoints), the previous behavior
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* prepended the (per-query, varying) memory message at index 0 — shifting the entire
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* cacheable prefix and forcing a cache miss on every turn. With `cacheSafe`, memory is
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* inserted just before the last user message so the cacheable prefix stays byte-stable.
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*/
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import { describe, it } from "node:test";
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import assert from "node:assert/strict";
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import { injectMemory } from "../../src/lib/memory/injection.ts";
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import type { ChatRequest } from "../../src/lib/memory/injection.ts";
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import type { Memory } from "../../src/lib/memory/types.ts";
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function mem(content: string): Memory {
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return {
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id: `mem-${content}`,
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content,
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type: "factual" as any,
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apiKeyId: "k",
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createdAt: "2026-01-01T00:00:00.000Z",
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updatedAt: "2026-01-01T00:00:00.000Z",
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importance: 0.5,
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};
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}
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function multiTurn(): ChatRequest {
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return {
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model: "anthropic/claude-sonnet-4-6",
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messages: [
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{ role: "system", content: "SYSTEM PROMPT", cache_control: { type: "ephemeral" } } as any,
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{ role: "user", content: "turn 1 question" },
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{ role: "assistant", content: "turn 1 answer" },
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{ role: "user", content: "turn 2 question" },
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],
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};
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}
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describe("injectMemory cache-safe positioning (#3890)", () => {
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it("default (cacheSafe off) prepends memory at index 0 — unchanged legacy behavior", () => {
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const out = injectMemory(multiTurn(), [mem("dark mode")], "anthropic");
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assert.equal(out.messages[0].role, "system");
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assert.ok(out.messages[0].content.includes("Memory context"));
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assert.equal(out.messages[1].content, "SYSTEM PROMPT");
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});
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it("cacheSafe inserts memory just before the last user message, preserving the prefix", () => {
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const req = multiTurn();
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const prefixBefore = JSON.stringify(req.messages.slice(0, 3)); // sys, u1, a1
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const out = injectMemory(req, [mem("dark mode")], "anthropic", { cacheSafe: true });
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// The cacheable prefix (system + prior turns up to the last assistant) is byte-identical.
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assert.equal(JSON.stringify(out.messages.slice(0, 3)), prefixBefore);
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// Memory is injected right before the last user message...
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assert.equal(out.messages[3].role, "system");
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assert.ok(out.messages[3].content.includes("Memory context"));
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// ...and the last user message is preserved at the tail.
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assert.equal(out.messages[4].content, "turn 2 question");
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assert.equal(out.messages.length, 5);
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// Memory must NOT be at index 0 (that is what broke caching).
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assert.notEqual(out.messages[0].content, out.messages[3].content);
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assert.equal(out.messages[0].content, "SYSTEM PROMPT");
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});
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it("cacheSafe keeps the cacheable prefix identical across two turns despite different memories", () => {
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// Turn 1: [sys, u1]; Turn 2: [sys, u1, a1, u2]. Different memories retrieved per query.
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// Same conversation, observed on two consecutive turns.
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const turn1: ChatRequest = {
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model: "anthropic/claude-sonnet-4-6",
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messages: [
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{ role: "system", content: "SYSTEM PROMPT", cache_control: { type: "ephemeral" } } as any,
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{ role: "user", content: "turn 1 question" },
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],
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};
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const turn2 = multiTurn();
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const out1 = injectMemory(turn1, [mem("A")], "anthropic", { cacheSafe: true });
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const out2 = injectMemory(turn2, [mem("B")], "anthropic", { cacheSafe: true });
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// The cache-breakpoint-bearing system message stays at the head, byte-identical, in
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// both turns (and is NOT displaced by the per-query memory) — so the prompt cache
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// created on turn 1 still matches on turn 2. (Memory is inserted before the last user
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// turn: [SYS, MEM_A, u1] and [SYS, u1, a1, MEM_B, u2] respectively.)
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assert.deepEqual(out1.messages[0], out2.messages[0]);
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assert.equal(out1.messages[0].content, "SYSTEM PROMPT");
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assert.equal((out1.messages[0] as any).cache_control?.type, "ephemeral");
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// In turn 2 the earlier turns up to the last assistant are preserved before memory.
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assert.equal(out2.messages[1].content, "turn 1 question");
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assert.equal(out2.messages[2].content, "turn 1 answer");
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assert.ok(out2.messages[3].content.includes("Memory context"));
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assert.equal(out2.messages[4].content, "turn 2 question");
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});
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it("cacheSafe falls back to leading injection when there is no user message", () => {
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const req: ChatRequest = {
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model: "anthropic/claude-sonnet-4-6",
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messages: [{ role: "system", content: "SYS" }],
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};
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const out = injectMemory(req, [mem("x")], "anthropic", { cacheSafe: true });
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assert.equal(out.messages[0].role, "system");
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assert.ok(out.messages[0].content.includes("Memory context"));
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assert.equal(out.messages[1].content, "SYS");
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});
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});
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