diff --git a/packages/coding-agent/examples/extensions/plan-mode.ts b/packages/coding-agent/examples/extensions/plan-mode.ts
index d0b206026..7d6d2b4b0 100644
--- a/packages/coding-agent/examples/extensions/plan-mode.ts
+++ b/packages/coding-agent/examples/extensions/plan-mode.ts
@@ -426,7 +426,7 @@ Execute each step in order.`,
 
 		// Extract todos from last message
 		const messages = event.messages;
-		const lastAssistant = [...messages].reverse().find(m => m.role === "assistant");
+		const lastAssistant = messages.findLast(m => m.role === "assistant");
 		if (lastAssistant && Array.isArray(lastAssistant.content)) {
 			const textContent = lastAssistant.content
 				.filter(
diff --git a/packages/coding-agent/src/hindsight/state.ts b/packages/coding-agent/src/hindsight/state.ts
index afa3311c6..883e5f714 100644
--- a/packages/coding-agent/src/hindsight/state.ts
+++ b/packages/coding-agent/src/hindsight/state.ts
@@ -346,7 +346,7 @@ export class HindsightSessionState {
 	async maybeRecallOnAgentStart(): Promise<void> {
 		if (!this.config.autoRecall || this.hasRecalledForFirstTurn) return;
 		const messages = extractMessages(this.session.sessionManager);
-		const lastUser = [...messages].reverse().find(m => m.role === "user");
+		const lastUser = messages.findLast(m => m.role === "user");
 		if (!lastUser) return;
 
 		const query = composeRecallQuery(lastUser.content, messages, this.config.recallContextTurns);
@@ -386,7 +386,7 @@ export class HindsightSessionState {
 	}
 
 	async recallForCompaction(messages: HindsightMessage[]): Promise<string | undefined> {
-		const lastUser = [...messages].reverse().find(m => m.role === "user");
+		const lastUser = messages.findLast(m => m.role === "user");
 		if (!lastUser) return undefined;
 
 		const query = composeRecallQuery(lastUser.content, messages, this.config.recallContextTurns);
diff --git a/packages/utils/src/postmortem.ts b/packages/utils/src/postmortem.ts
index bda885683..7e1d0c876 100644
--- a/packages/utils/src/postmortem.ts
+++ b/packages/utils/src/postmortem.ts
@@ -46,8 +46,7 @@ function runCleanup(reason: Reason): Promise<void> {
 
 	// Call .cleanup() for each callback that is still "armed".
 	// Use Promise.try to handle sync/async, but only those armed.
-	// Create a copy to avoid mutating the original array with reverse()
-	const promises = [...callbackList].reverse().map(callback => {
+	const promises = callbackList.toReversed().map(callback => {
 		return Promise.try(() => callback(reason));
 	});