diff --git a/packages/coding-agent/src/modes/acp/acp-agent.ts b/packages/coding-agent/src/modes/acp/acp-agent.ts
index 7ff07b073..f57c3736d 100644
--- a/packages/coding-agent/src/modes/acp/acp-agent.ts
+++ b/packages/coding-agent/src/modes/acp/acp-agent.ts
@@ -66,7 +66,11 @@ import {
 import { ACP_BUILTIN_SLASH_COMMANDS, executeAcpBuiltinSlashCommand } from "../../slash-commands/acp-builtins";
 import { parseThinkingLevel } from "../../thinking";
 import { createAcpClientBridge } from "./acp-client-bridge";
-import { mapAgentSessionEventToAcpSessionUpdates, mapToolKind } from "./acp-event-mapper";
+import {
+	buildToolCallStartUpdate,
+	mapAgentSessionEventToAcpSessionUpdates,
+	normalizeReplayToolArguments,
+} from "./acp-event-mapper";
 import { ACP_TERMINAL_AUTH_FLAG } from "./terminal-auth";
 
 const ACP_DEFAULT_MODE_ID = "default";
@@ -1590,7 +1594,7 @@ export class AcpAgent implements Agent {
 
 	#messageToReplayNotifications(sessionId: string, message: ReplayableMessage, cwd: string): SessionNotification[] {
 		if (message.role === "assistant") {
-			return this.#replayAssistantMessage(sessionId, message);
+			return this.#replayAssistantMessage(sessionId, message, cwd);
 		}
 		if (
 			message.role === "user" ||
@@ -1631,7 +1635,7 @@ export class AcpAgent implements Agent {
 		return [];
 	}
 
-	#replayAssistantMessage(sessionId: string, message: ReplayableMessage): SessionNotification[] {
+	#replayAssistantMessage(sessionId: string, message: ReplayableMessage, cwd: string): SessionNotification[] {
 		const notifications: SessionNotification[] = [];
 		const messageId = crypto.randomUUID();
 		if (Array.isArray(message.content)) {
@@ -1673,16 +1677,14 @@ export class AcpAgent implements Agent {
 					"name" in item &&
 					typeof item.name === "string"
 				) {
-					const update: SessionUpdate = {
-						sessionUpdate: "tool_call",
+					const args = normalizeReplayToolArguments("arguments" in item ? item.arguments : undefined).args;
+					const update = buildToolCallStartUpdate({
 						toolCallId: item.id,
-						title: item.name,
-						kind: mapToolKind(item.name),
+						toolName: item.name,
+						args,
 						status: "completed",
-					};
-					if ("arguments" in item && typeof item.arguments === "string") {
-						update.rawInput = item.arguments;
-					}
+						cwd,
+					});
 					notifications.push({ sessionId, update });
 				}
 			}
diff --git a/packages/coding-agent/src/modes/acp/acp-event-mapper.ts b/packages/coding-agent/src/modes/acp/acp-event-mapper.ts
index 37b702a61..63034c8b3 100644
--- a/packages/coding-agent/src/modes/acp/acp-event-mapper.ts
+++ b/packages/coding-agent/src/modes/acp/acp-event-mapper.ts
@@ -335,6 +335,18 @@ export function buildToolCallStartUpdate(input: {
 	return update;
 }
 
+export function normalizeReplayToolArguments(value: unknown): { args: unknown } {
+	if (typeof value !== "string") {
+		return { args: value ?? {} };
+	}
+	try {
+		const parsed: unknown = JSON.parse(value);
+		return { args: parsed };
+	} catch {
+		return { args: value };
+	}
+}
+
 function buildToolStartContent(toolName: string, args: unknown): ToolCallContent[] {
 	if (!isCommandToolName(toolName)) {
 		return [];
diff --git a/packages/coding-agent/test/acp-event-mapper.test.ts b/packages/coding-agent/test/acp-event-mapper.test.ts
index 646abdf59..c30dda7a9 100644
--- a/packages/coding-agent/test/acp-event-mapper.test.ts
+++ b/packages/coding-agent/test/acp-event-mapper.test.ts
@@ -2,7 +2,11 @@ import { describe, expect, it } from "bun:test";
 import path from "node:path";
 import type { SessionNotification } from "@agentclientprotocol/sdk";
 import { zSessionNotification } from "@agentclientprotocol/sdk/dist/schema/zod.gen.js";
-import { mapAgentSessionEventToAcpSessionUpdates } from "../src/modes/acp/acp-event-mapper";
+import {
+	buildToolCallStartUpdate,
+	mapAgentSessionEventToAcpSessionUpdates,
+	normalizeReplayToolArguments,
+} from "../src/modes/acp/acp-event-mapper";
 import type { AgentSessionEvent } from "../src/session/agent-session";
 import { expectAcpStructure, expectAcpStructureRejects } from "./helpers/acp-schema";
 
@@ -273,6 +277,91 @@ describe("ACP event mapper", () => {
 		expect(update.content).toEqual([{ type: "content", content: { type: "text", text: "$ npm run check" } }]);
 	});
 
+	it("builds replayed bash tool calls from JSON string arguments", () => {
+		const replayArgs = normalizeReplayToolArguments(JSON.stringify({ command: "npm test", cwd: "/repo" }));
+		const update = buildToolCallStartUpdate({
+			toolCallId: "toolu_replay_1",
+			toolName: "bash",
+			args: replayArgs.args,
+			status: "completed",
+		});
+
+		expectAcpStructure(zSessionNotification, { sessionId: "session-1", update });
+		expect(update).toMatchObject({
+			sessionUpdate: "tool_call",
+			toolCallId: "toolu_replay_1",
+			title: "bash: npm test",
+			kind: "execute",
+			status: "completed",
+			rawInput: { command: "npm test", cwd: "/repo" },
+			content: [{ type: "content", content: { type: "text", text: "$ npm test" } }],
+		});
+	});
+
+	it("builds replayed read tool-call locations against the replay cwd", () => {
+		const replayArgs = normalizeReplayToolArguments(JSON.stringify({ path: "src/foo.ts" }));
+		const update = buildToolCallStartUpdate({
+			toolCallId: "toolu_replay_read",
+			toolName: "read",
+			args: replayArgs.args,
+			cwd: path.resolve("/repo"),
+			status: "completed",
+		});
+
+		expectAcpStructure(zSessionNotification, { sessionId: "session-1", update });
+		expect(update).toMatchObject({
+			sessionUpdate: "tool_call",
+			toolCallId: "toolu_replay_read",
+			title: "read: src/foo.ts",
+			kind: "read",
+			status: "completed",
+			rawInput: { path: "src/foo.ts" },
+			locations: [{ path: path.resolve("/repo", "src/foo.ts") }],
+		});
+		expect("content" in update).toBe(false);
+	});
+
+	it("keeps malformed replay arguments as raw input without command content", () => {
+		const replayArgs = normalizeReplayToolArguments("{not json");
+		const update = buildToolCallStartUpdate({
+			toolCallId: "toolu_replay_bad",
+			toolName: "bash",
+			args: replayArgs.args,
+			status: "completed",
+		});
+
+		expectAcpStructure(zSessionNotification, { sessionId: "session-1", update });
+		expect(update).toMatchObject({
+			sessionUpdate: "tool_call",
+			toolCallId: "toolu_replay_bad",
+			title: "bash",
+			kind: "execute",
+			status: "completed",
+			rawInput: "{not json",
+		});
+		expect("content" in update).toBe(false);
+	});
+
+	it("keeps object replay arguments unchanged and builds command content", () => {
+		const rawArgs = { command: "bun test", cwd: "/repo" };
+		const replayArgs = normalizeReplayToolArguments(rawArgs);
+		const update = buildToolCallStartUpdate({
+			toolCallId: "toolu_replay_object",
+			toolName: "bash",
+			args: replayArgs.args,
+			status: "completed",
+		});
+
+		expect(replayArgs.args).toBe(rawArgs);
+		expectAcpStructure(zSessionNotification, { sessionId: "session-1", update });
+		expect(update).toMatchObject({
+			title: "bash: bun test",
+			status: "completed",
+			rawInput: rawArgs,
+			content: [{ type: "content", content: { type: "text", text: "$ bun test" } }],
+		});
+	});
+
 	it("does not add command text content to non-command tool starts", () => {
 		const updates = mapAgentSessionEventToAcpSessionUpdates(
 			{