diff --git a/packages/coding-agent/src/core/agent-session.ts b/packages/coding-agent/src/core/agent-session.ts
index 8b330d555d0f..bb9210e82634 100644
--- a/packages/coding-agent/src/core/agent-session.ts
+++ b/packages/coding-agent/src/core/agent-session.ts
@@ -31,7 +31,7 @@ import {
 	runToolCall,
 	type ThinkingLevel,
 } from "@earendil-works/pi-agent-core";
-import { contentText, getCurrentSystemMessage, retryDelayMs } from "@earendil-works/pi-ai";
+import { contentText, getCurrentSystemMessage, jitteredRetryDelayMs } from "@earendil-works/pi-ai";
 import type {
 	AssistantMessage,
 	AuthResult,
@@ -3803,7 +3803,7 @@ export class AgentSession {
 			return false;
 		}
 
-		const delayMs = retryDelayMs(settings, this._retryAttempt);
+		const delayMs = jitteredRetryDelayMs(settings, this._retryAttempt);
 
 		this._emit({
 			type: "auto_retry_start",
@@ -3816,7 +3816,7 @@ export class AgentSession {
 		// Keep the failed attempt in raw history while durably omitting it from model projection.
 		this._omitRecoveryAttempt(message);
 
-		// Wait with exponential backoff (abortable)
+		// Wait with jittered exponential backoff (abortable)
 		this._retryAbortController = new AbortController();
 		try {
 			await sleep(delayMs, this._retryAbortController.signal);
diff --git a/packages/coding-agent/test/agent-session-retry.test.ts b/packages/coding-agent/test/agent-session-retry.test.ts
index 206b25b6048a..89e67e02344f 100644
--- a/packages/coding-agent/test/agent-session-retry.test.ts
+++ b/packages/coding-agent/test/agent-session-retry.test.ts
@@ -4,7 +4,7 @@ import { join } from "node:path";
 import { Agent, type AgentEvent, type AgentTool } from "@earendil-works/pi-agent-core";
 import { type AssistantMessage, createAssistantMessageEventStream, getModel } from "@earendil-works/pi-ai/compat";
 import { Type } from "typebox";
-import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { AgentSession } from "../src/core/agent-session.ts";
 import { AuthStorage } from "../src/core/auth-storage.ts";
 import { SessionManager } from "../src/core/session-manager.ts";
@@ -47,6 +47,7 @@ describe("AgentSession retry", () => {
 	});
 
 	afterEach(() => {
+		vi.restoreAllMocks();
 		if (session) {
 			session.dispose();
 		}
@@ -155,7 +156,8 @@ describe("AgentSession retry", () => {
 	});
 
 	it("caps agent retry delay", async () => {
-		// Regression for #8826.
+		// Regression for #8826. The top of the jitter range is the unjittered delay.
+		vi.spyOn(Math, "random").mockReturnValue(1);
 		const created = await createSession({ failCount: 4, maxRetries: 5, maxAgentDelayMs: 5 });
 		const delays: number[] = [];
 		created.session.subscribe((event) => {