From 2e6d36a85544c7b71a79414d7cd2cb7b26ec165e Mon Sep 17 00:00:00 2001
From: GRayHook <s@marinkevich.ru>
Date: Wed, 17 Jun 2026 11:46:38 +0700
Subject: [PATCH] =?UTF-8?q?Phase=206:=20add=20PI=5FAUTO=5FCOMPACT=5FFOLLOW?=
 =?UTF-8?q?=5FUP=5FPREFIXES=20=E2=80=94=20document=20pi-auto-compact=20phr?=
 =?UTF-8?q?ases.?=
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Constants match SPEC §16.9 for tests and docs; runtime v1 does not match follow-up text.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 src/auto-compact.ts       |  8 ++++++
 test/auto-compact.test.ts | 55 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 test/auto-compact.test.ts

diff --git a/src/auto-compact.ts b/src/auto-compact.ts
index a4ae915..a80df6b 100644
--- a/src/auto-compact.ts
+++ b/src/auto-compact.ts
@@ -25,3 +25,11 @@ export function resolveDeliveryMode(
 ): ReinjectDeliveryMode {
 	return effectiveIntegration(settings, runtime.autoCompactDetected, sessionIntegrationOverride);
 }
+
+/** pi-auto-compact follow-up message prefixes (SPEC §16.9); documentation/tests only, not runtime v1. */
+export const PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES = [
+	"Auto-compact ran before this turn.",
+	"Auto-compact ran mid-turn.",
+	"Emergency auto-compact ran.",
+	"Auto-compact ran on session resume.",
+] as const;
diff --git a/test/auto-compact.test.ts b/test/auto-compact.test.ts
new file mode 100644
index 0000000..a106621
--- /dev/null
+++ b/test/auto-compact.test.ts
@@ -0,0 +1,55 @@
+import { describe, expect, it } from "vitest";
+import {
+	detectAndCachePiAutoCompact,
+	detectPiAutoCompact,
+	PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES,
+	resolveDeliveryMode,
+} from "../src/auto-compact";
+import { createDefaultSettings } from "../src/settings";
+import { createRuntimeFlags } from "../src/state";
+
+describe("detectPiAutoCompact", () => {
+	it("returns true when auto-compact command is registered", () => {
+		const pi = {
+			getCommands: () => [{ name: "auto-compact" }],
+		};
+		expect(detectPiAutoCompact(pi as never)).toBe(true);
+	});
+
+	it("returns false when auto-compact command is absent", () => {
+		const pi = {
+			getCommands: () => [{ name: "skill-reinject" }],
+		};
+		expect(detectPiAutoCompact(pi as never)).toBe(false);
+	});
+});
+
+describe("detectAndCachePiAutoCompact", () => {
+	it("writes detect result into runtime flags", () => {
+		const runtime = createRuntimeFlags();
+		const pi = {
+			getCommands: () => [{ name: "auto-compact" }],
+		};
+		expect(detectAndCachePiAutoCompact(pi as never, runtime)).toBe(true);
+		expect(runtime.autoCompactDetected).toBe(true);
+	});
+});
+
+describe("resolveDeliveryMode", () => {
+	it("defers when pi-auto-compact is cached as detected", () => {
+		const runtime = createRuntimeFlags();
+		runtime.autoCompactDetected = true;
+		expect(resolveDeliveryMode(createDefaultSettings(), runtime)).toBe("defer");
+	});
+});
+
+describe("PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES", () => {
+	it("documents pi-auto-compact follow-up phrases from SPEC §16.9", () => {
+		expect([...PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES]).toEqual([
+			"Auto-compact ran before this turn.",
+			"Auto-compact ran mid-turn.",
+			"Emergency auto-compact ran.",
+			"Auto-compact ran on session resume.",
+		]);
+	});
+});