Squashed 'src/pi/' content from commit d981de122

git-subtree-dir: src/pi
git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477

packages/agent/test/harness/branch-summarization.test.ts

@@ -0,0 +1,71 @@
+import type { AgentMessage } from "@earendil-works/pi-agent-core";
+import { describe, expect, it } from "vitest";
+import { collectEntriesForBranchSummary } from "../../src/harness/compaction/branch-summarization.ts";
+import { BACKGROUND_CONTEXT } from "../../src/harness/context.ts";
+import type { Branch, Entry, MessageEntry, Session } from "../../src/harness/session/index.ts";
+
+function message(text: string): AgentMessage {
+	return { role: "user", content: [{ type: "text", text }], timestamp: 1 };
+}
+
+function messageEntry(id: string, parentId: string | null, text: string, seq: number): MessageEntry {
+	return { type: "message", id, parentId, message: message(text), seq, timestamp: seq };
+}
+
+function branchReader(entries: Entry[]): {
+	branch: Pick<Branch, "findEntries">;
+	session: Pick<Session, "getEntry">;
+} {
+	const byId = new Map(entries.map((entry) => [entry.id, entry]));
+	return {
+		session: {
+			async getEntry(id) {
+				return byId.get(id);
+			},
+		},
+		branch: {
+			async findEntries(query = {}) {
+				const path: Entry[] = [];
+				let currentId = query.start ?? null;
+				while (currentId !== null) {
+					const entry = byId.get(currentId);
+					if (!entry) throw new Error(`Unknown entry ${currentId}`);
+					path.push(entry);
+					currentId = entry.parentId;
+				}
+				return path;
+			},
+		},
+	};
+}
+
+describe("v4 branch summarization", () => {
+	it("collects the abandoned side of a branch in chronological order", async () => {
+		const root = messageEntry("root", null, "root", 1);
+		const common = messageEntry("common", root.id, "common", 2);
+		const abandoned1 = messageEntry("abandoned-1", common.id, "abandoned 1", 3);
+		const abandoned2 = messageEntry("abandoned-2", abandoned1.id, "abandoned 2", 4);
+		const target = messageEntry("target", common.id, "target", 5);
+		const { branch, session } = branchReader([root, common, abandoned1, abandoned2, target]);
+
+		const result = await collectEntriesForBranchSummary(
+			branch,
+			session,
+			abandoned2.id,
+			target.id,
+			BACKGROUND_CONTEXT,
+		);
+		expect(result.commonAncestorId).toBe(common.id);
+		expect(result.entries.map((entry) => entry.id)).toEqual([abandoned1.id, abandoned2.id]);
+		expect(result.entries.some((entry) => entry.id === root.id)).toBe(false);
+	});
+
+	it("returns no entries when there was no previous leaf", async () => {
+		const target = messageEntry("target", null, "target", 1);
+		const { branch, session } = branchReader([target]);
+		expect(await collectEntriesForBranchSummary(branch, session, null, target.id, BACKGROUND_CONTEXT)).toEqual({
+			entries: [],
+			commonAncestorId: null,
+		});
+	});
+});