From bf862656aee5fb46d1398ec7298124c6eb35a147 Mon Sep 17 00:00:00 2001
From: GRayHook <s@marinkevich.ru>
Date: Wed, 17 Jun 2026 11:47:27 +0700
Subject: [PATCH] =?UTF-8?q?Phase=206:=20add=20compaction=20coexistence=20h?=
 =?UTF-8?q?int=20=E2=80=94=20one-time=20notify=20when=20both=20compactors?=
 =?UTF-8?q?=20run.?=
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Shows ui.notify once when pi-auto-compact is detected while Pi compaction.enabled stays true.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 src/auto-compact.ts       | 57 ++++++++++++++++++++++++++++++++++++++-
 src/state.ts              |  3 +++
 test/auto-compact.test.ts | 53 ++++++++++++++++++++++++++++++++++++
 3 files changed, 112 insertions(+), 1 deletion(-)

diff --git a/src/auto-compact.ts b/src/auto-compact.ts
index a80df6b..5981d02 100644
--- a/src/auto-compact.ts
+++ b/src/auto-compact.ts
@@ -1,4 +1,5 @@
-import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
+import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
+import { SettingsManager, getAgentDir } from "@earendil-works/pi-coding-agent";
 import {
 	effectiveIntegration,
 	type ReinjectDeliveryMode,
@@ -33,3 +34,57 @@ export const PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES = [
 	"Emergency auto-compact ran.",
 	"Auto-compact ran on session resume.",
 ] as const;
+
+const PI_DEFAULT_COMPACTION_ENABLED = true;
+
+function readCompactionEnabled(settings: object): boolean | undefined {
+	const compaction = (settings as Record<string, unknown>).compaction;
+	if (!compaction || typeof compaction !== "object" || Array.isArray(compaction)) {
+		return undefined;
+	}
+	const enabled = (compaction as Record<string, unknown>).enabled;
+	return typeof enabled === "boolean" ? enabled : undefined;
+}
+
+/** Merged Pi compaction.enabled with project-over-global semantics (SPEC §16.7). */
+export function resolvePiDefaultCompactionEnabled(
+	globalSettings: object,
+	projectSettings: object,
+): boolean {
+	return (
+		readCompactionEnabled(projectSettings) ??
+		readCompactionEnabled(globalSettings) ??
+		PI_DEFAULT_COMPACTION_ENABLED
+	);
+}
+
+export function isPiDefaultCompactionEnabled(ctx: ExtensionContext): boolean {
+	const manager = SettingsManager.create(ctx.cwd, getAgentDir(), {
+		projectTrusted: ctx.isProjectTrusted(),
+	});
+	return resolvePiDefaultCompactionEnabled(
+		manager.getGlobalSettings(),
+		manager.getProjectSettings(),
+	);
+}
+
+/** One-time ui.notify when Pi default compaction and pi-auto-compact are both active (SPEC §16.7). */
+export function maybeNotifyCompactionCoexistenceHint(
+	ctx: ExtensionContext,
+	runtime: RuntimeFlags,
+	piDefaultCompactionEnabled = isPiDefaultCompactionEnabled(ctx),
+): void {
+	if (runtime.compactionCoexistenceHintShown || !runtime.autoCompactDetected) {
+		return;
+	}
+	if (!piDefaultCompactionEnabled) {
+		return;
+	}
+	if (ctx.hasUI) {
+		ctx.ui.notify(
+			"Pi built-in auto-compaction and pi-auto-compact are both enabled. Consider setting compaction.enabled to false in settings.json.",
+			"info",
+		);
+	}
+	runtime.compactionCoexistenceHintShown = true;
+}
diff --git a/src/state.ts b/src/state.ts
index 89d7bb0..e38fd26 100644
--- a/src/state.ts
+++ b/src/state.ts
@@ -31,6 +31,8 @@ export interface ExtensionState {
 export interface RuntimeFlags {
 	autoCompactDetected: boolean;
 	autoCompactIntegration: AutoCompactIntegration;
+	/** One-time hint when Pi default compaction coexists with pi-auto-compact (SPEC §16.7). */
+	compactionCoexistenceHintShown: boolean;
 }
 
 export const STATE_ENTRY_TYPE = "skill-reinject:state";
@@ -84,6 +86,7 @@ export function createRuntimeFlags(): RuntimeFlags {
 	return {
 		autoCompactDetected: false,
 		autoCompactIntegration: "auto",
+		compactionCoexistenceHintShown: false,
 	};
 }
 
diff --git a/test/auto-compact.test.ts b/test/auto-compact.test.ts
index a106621..0a0d1ad 100644
--- a/test/auto-compact.test.ts
+++ b/test/auto-compact.test.ts
@@ -2,8 +2,10 @@ import { describe, expect, it } from "vitest";
 import {
 	detectAndCachePiAutoCompact,
 	detectPiAutoCompact,
+	maybeNotifyCompactionCoexistenceHint,
 	PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES,
 	resolveDeliveryMode,
+	resolvePiDefaultCompactionEnabled,
 } from "../src/auto-compact";
 import { createDefaultSettings } from "../src/settings";
 import { createRuntimeFlags } from "../src/state";
@@ -53,3 +55,54 @@ describe("PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES", () => {
 		]);
 	});
 });
+
+describe("resolvePiDefaultCompactionEnabled", () => {
+	it("defaults to enabled when compaction settings are absent", () => {
+		expect(resolvePiDefaultCompactionEnabled({}, {})).toBe(true);
+	});
+
+	it("lets project override global compaction.enabled", () => {
+		expect(
+			resolvePiDefaultCompactionEnabled(
+				{ compaction: { enabled: true } },
+				{ compaction: { enabled: false } },
+			),
+		).toBe(false);
+	});
+});
+
+describe("maybeNotifyCompactionCoexistenceHint", () => {
+	it("notifies once when pi-auto-compact and Pi compaction are both active", () => {
+		const runtime = createRuntimeFlags();
+		runtime.autoCompactDetected = true;
+		const notifications: string[] = [];
+		const ctx = {
+			hasUI: true,
+			ui: {
+				notify: (message: string) => {
+					notifications.push(message);
+				},
+			},
+		};
+
+		maybeNotifyCompactionCoexistenceHint(ctx as never, runtime, true);
+		maybeNotifyCompactionCoexistenceHint(ctx as never, runtime, true);
+
+		expect(notifications).toHaveLength(1);
+		expect(runtime.compactionCoexistenceHintShown).toBe(true);
+	});
+
+	it("skips notify when pi-auto-compact is not detected", () => {
+		const runtime = createRuntimeFlags();
+		const notifications: string[] = [];
+		const ctx = {
+			hasUI: true,
+			ui: { notify: (message: string) => notifications.push(message) },
+		};
+
+		maybeNotifyCompactionCoexistenceHint(ctx as never, runtime, true);
+
+		expect(notifications).toHaveLength(0);
+		expect(runtime.compactionCoexistenceHintShown).toBe(false);
+	});
+});