diff --git a/packages/coding-agent/test/agent-session-handoff.test.ts b/packages/coding-agent/test/agent-session-handoff.test.ts
index 52251ec70..d8e82aa54 100644
--- a/packages/coding-agent/test/agent-session-handoff.test.ts
+++ b/packages/coding-agent/test/agent-session-handoff.test.ts
@@ -17,6 +17,7 @@ import { TempDir } from "@oh-my-pi/pi-utils";
 import * as snapcompact from "@oh-my-pi/snapcompact";
 
 const HANDOFF_SECRET = "HANDOFF_SECRET_TOKEN_12345";
+const UNRENDERABLE_SNAPCOMPACT_TEXT = "\uE000\uE001\uE002\uE003\uE004\uE005\uE006\uE007\uE008\uE009";
 
 describe("AgentSession handoff", () => {
 	// Immutable across the whole file: the model registry's synchronous bundled-model
@@ -451,7 +452,7 @@ describe("AgentSession handoff", () => {
 		const fixedPreparation: compactionModule.CompactionPreparation = {
 			firstKeptEntryId: lastEntryId,
 			messagesToSummarize: [
-				{ role: "user", content: [{ type: "text", text: "中文内容".repeat(100) }], timestamp: 1 },
+				{ role: "user", content: [{ type: "text", text: UNRENDERABLE_SNAPCOMPACT_TEXT.repeat(100) }], timestamp: 1 },
 			],
 			turnPrefixMessages: [],
 			recentMessages: [],
@@ -478,7 +479,7 @@ describe("AgentSession handoff", () => {
 		const fixedPreparation: compactionModule.CompactionPreparation = {
 			firstKeptEntryId: lastEntryId,
 			messagesToSummarize: [
-				{ role: "user", content: [{ type: "text", text: "中文内容".repeat(100) }], timestamp: 1 },
+				{ role: "user", content: [{ type: "text", text: UNRENDERABLE_SNAPCOMPACT_TEXT.repeat(100) }], timestamp: 1 },
 			],
 			turnPrefixMessages: [],
 			recentMessages: [],
diff --git a/packages/coding-agent/test/agent-session-snapcompact-auto-fallback.test.ts b/packages/coding-agent/test/agent-session-snapcompact-auto-fallback.test.ts
index 3a3a4ef38..0a9af2702 100644
--- a/packages/coding-agent/test/agent-session-snapcompact-auto-fallback.test.ts
+++ b/packages/coding-agent/test/agent-session-snapcompact-auto-fallback.test.ts
@@ -11,6 +11,8 @@ import { AuthStorage } from "@oh-my-pi/pi-coding-agent/session/auth-storage";
 import { SessionManager } from "@oh-my-pi/pi-coding-agent/session/session-manager";
 import { TempDir } from "@oh-my-pi/pi-utils";
 
+const UNRENDERABLE_SNAPCOMPACT_TEXT = "\uE000\uE001\uE002\uE003\uE004\uE005\uE006\uE007\uE008\uE009";
+
 interface Harness {
 	session: AgentSession;
 	sessionManager: SessionManager;
@@ -42,7 +44,7 @@ async function createHarness(tempDir: TempDir, authStorage: AuthStorage, options
 	const settings = Settings.isolated({
 		"compaction.strategy": "snapcompact",
 		// Force a 1-token recent window so the post-turn cut always splits off the
-		// last turn and summarizes the seeded (CJK) history. With the default
+		// last turn and summarizes the seeded unrenderable history. With the default
 		// 20k window the cut keeps both tiny messages, leaving nothing for
 		// snapcompact's renderability preflight to scan.
 		"compaction.keepRecentTokens": 1,
@@ -153,7 +155,7 @@ describe("AgentSession auto-snapcompact local-blocker fallback", () => {
 			seedMessages: [
 				{
 					role: "user",
-					content: "你好,请帮我审查这段代码。它的逻辑似乎有问题,我无法理解为何返回空结果。",
+					content: UNRENDERABLE_SNAPCOMPACT_TEXT.repeat(10),
 					timestamp: Date.now(),
 				},
 			],