feat: unify context compaction

pi-compaction/test/performance.test.ts

@@ -0,0 +1,29 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { performance } from "node:perf_hooks";
+import { DEFAULT_CONFIG } from "../src/config.ts";
+import { SegmentIndex } from "../src/segment-index.ts";
+
+function message(index: number) {
+  return { role: "user", content: `message-${index}`, timestamp: index + 1 };
+}
+
+test("cached projection and append-only delta stay inside the hot-path budget", () => {
+  const index = new SegmentIndex("perf");
+  index.hydrate([], DEFAULT_CONFIG);
+  const messages = Array.from({ length: 10_000 }, (_, value) => message(value));
+  const params = { environmentHash: "env", environmentTokens: 2_000, contextWindow: 300_000 };
+  index.project(messages, params);
+
+  const cacheStart = performance.now();
+  for (let iteration = 0; iteration < 1_000; iteration++) index.project(messages, params);
+  const cacheAverageMs = (performance.now() - cacheStart) / 1_000;
+
+  const appended = [...messages, message(10_000)];
+  const deltaStart = performance.now();
+  index.project(appended, params);
+  const deltaMs = performance.now() - deltaStart;
+
+  assert.ok(cacheAverageMs < 2, `cache-hit average ${cacheAverageMs.toFixed(3)}ms exceeded 2ms`);
+  assert.ok(deltaMs < 10, `delta projection ${deltaMs.toFixed(3)}ms exceeded 10ms`);
+});