feat: unify context compaction

pi-compaction/test/segment-index.test.ts

@@ -0,0 +1,84 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { DEFAULT_CONFIG } from "../src/config.ts";
+import { SegmentIndex, deterministicSummary } from "../src/segment-index.ts";
+
+const assistant = {
+  role: "assistant",
+  content: [{ type: "toolCall", id: "call-1", name: "bash", arguments: { command: "npm test" } }],
+  timestamp: 10,
+};
+const result = {
+  role: "toolResult",
+  toolCallId: "call-1",
+  toolName: "bash",
+  content: [{ type: "text", text: `failure\n${"x".repeat(12_000)}\nstack tail` }],
+  isError: true,
+  timestamp: 11,
+};
+
+test("deterministic summary is bounded and preserves head/tail evidence", () => {
+  const summary = deterministicSummary({
+    toolName: "bash",
+    args: { command: "npm test" },
+    rawText: result.content[0]!.text,
+    isError: true,
+    maxStubTokens: 256,
+  });
+  assert.match(summary, /tool=bash status=error/);
+  assert.match(summary, /failure/);
+  assert.match(summary, /stack tail/);
+  assert.ok(summary.length <= 1_100);
+});
+
+test("projection incrementally replaces tool results and caches identical input", () => {
+  const index = new SegmentIndex("session-1");
+  index.hydrate([], DEFAULT_CONFIG);
+  const records = index.captureTurn(assistant, [result], DEFAULT_CONFIG);
+  assert.equal(records.length, 1);
+
+  const messages = [assistant, result];
+  const first = index.project(messages, {
+    environmentHash: "env",
+    environmentTokens: 100,
+    contextWindow: 300_000,
+  });
+  const second = index.project(messages, {
+    environmentHash: "env",
+    environmentTokens: 100,
+    contextWindow: 300_000,
+  });
+
+  assert.strictEqual(first, second);
+  assert.ok(first.effectiveTokens < first.rawTokens);
+  assert.match(first.messages[1]!.content[0].text, /context_tree_query/);
+
+  const record = records[0]!;
+  assert.ok(index.applySemantic(record.sourceKey, record.sourceHash, "- npm test failed\n- stack tail"));
+  const semantic = index.project(messages, {
+    environmentHash: "env",
+    environmentTokens: 100,
+    contextWindow: 300_000,
+  });
+  assert.notStrictEqual(semantic, first);
+  assert.match(semantic.messages[1]!.content[0].text, /npm test failed/);
+});
+
+test("usage-backed baseline is adjusted only by projected delta", () => {
+  const index = new SegmentIndex("session-2");
+  index.hydrate([], DEFAULT_CONFIG);
+  const initial = index.project([assistant], {
+    environmentHash: "env",
+    environmentTokens: 50,
+    contextWindow: 100_000,
+  });
+  index.recordUsage(1_000, initial.messageEstimate, "env");
+  const next = index.project([assistant, { role: "user", content: "next", timestamp: 12 }], {
+    environmentHash: "env",
+    environmentTokens: 50,
+    contextWindow: 100_000,
+  });
+  assert.equal(next.confidence, "usage-backed");
+  assert.ok(next.effectiveTokens >= 1_000);
+  assert.ok(next.effectiveTokens < 1_100);
+});