feat(coding-agent): refactored eager todo messaging for cleaner categorization

- Changed eager todo reminder message role from 'developer' to 'custom' with customType field for better message categorization.
- Removed userRequest parameter from eager todo prelude generation to simplify prompt template rendering.
- Updated eager todo prompt to avoid redundant todo_write calls unless task state materially changed.
- Modified eager todo reminder message to use string content with display: false property instead of array format.

packages/coding-agent/CHANGELOG.md

@@ -1,7 +1,6 @@
 # Changelog
 
 ## [Unreleased]
-
 ### Added
 
 - Added `assignment` field to task progress and result objects to track the raw per-task assignment text separately from the full templated task
@@ -14,6 +13,8 @@
 
 ### Changed
 
+- Modified eager todo prelude to use hidden custom message type instead of visible developer message, preventing duplicate prompt text in session history
+- Updated eager todo prompt to remove dynamic user request injection, simplifying the template and preventing request repetition in displayed messages
 - Modified eager todo enforcement to prepend the todo reminder to the first user turn instead of executing it as a separate synthetic turn, reducing unnecessary prompt calls
 - Updated task rendering to display assignment text instead of full task template when available, reducing noise in progress and result displays
 - Modified task section rendering to show trimmed assignment text without stripping context blocks, simplifying the display logic

packages/coding-agent/src/prompts/system/eager-todo.md

@@ -1,11 +1,6 @@
 <system-reminder>
 Before doing substantive work on the upcoming user request, create a comprehensive phased todo first.
 
-The todo **MUST** cover this request:
-<user-request>
-{{userRequest}}
-</user-request>
-
 You **MUST** call `todo_write` first in this turn.
 You **MUST** initialize the todo list with a single `replace` op.
 You **MUST** cover the entire request from investigation through implementation and verification — not just the next immediate step.
@@ -14,4 +9,5 @@ You **MUST** keep task `content` to a short label (5-10 words). Put file paths,
 You **MUST** keep exactly one task `in_progress` and all later tasks `pending`.
 
 After the initial `todo_write` call succeeds, continue with the user's request in the same turn.
+Do not emit another `todo_write` call unless task state materially changed.
 </system-reminder>

packages/coding-agent/src/session/agent-session.ts

@@ -1959,7 +1959,7 @@ export class AgentSession {
 			return;
 		}
 
-		const eagerTodoPrelude = !options?.synthetic ? this.#createEagerTodoPrelude(expandedText) : undefined;
+		const eagerTodoPrelude = !options?.synthetic ? this.#createEagerTodoPrelude() : undefined;
 
 		const userContent: (TextContent | ImageContent)[] = [{ type: "text", text: expandedText }];
 		if (options?.images) {
@@ -3515,7 +3515,7 @@ export class AgentSession {
 		}
 	}
 
-	#createEagerTodoPrelude(userRequest: string): { message: AgentMessage; toolChoice: ToolChoice } | undefined {
+	#createEagerTodoPrelude(): { message: AgentMessage; toolChoice: ToolChoice } | undefined {
 		const eagerTodosEnabled = this.settings.get("todo.eager");
 		const todosEnabled = this.settings.get("todo.enabled");
 		if (!eagerTodosEnabled || !todosEnabled) {
@@ -3545,14 +3545,14 @@ export class AgentSession {
 			return undefined;
 		}
 
-		const eagerTodoReminder = renderPromptTemplate(eagerTodoPrompt, {
-			userRequest,
-		});
+		const eagerTodoReminder = renderPromptTemplate(eagerTodoPrompt);
 
 		return {
 			message: {
-				role: "developer",
-				content: [{ type: "text", text: eagerTodoReminder }],
+				role: "custom",
+				customType: "eager-todo-prelude",
+				content: eagerTodoReminder,
+				display: false,
 				attribution: "agent",
 				timestamp: Date.now(),
 			},

packages/coding-agent/test/agent-session-eager-todo.test.ts

@@ -20,6 +20,7 @@ type ObservedPromptCall = {
 	toolChoice: string | undefined;
 	toolNames: string[];
 	messageRoles: AgentMessage["role"][];
+	messageTexts: string[];
 	lastMessageRole: AgentMessage["role"];
 	lastMessageText: string;
 };
@@ -164,6 +165,7 @@ describe("AgentSession eager todo enforcement", () => {
 					toolChoice: getToolChoiceName(options?.toolChoice),
 					toolNames: (context.tools ?? []).map(tool => tool.name),
 					messageRoles: context.messages.map(message => message.role),
+					messageTexts: context.messages.map(message => getMessageText(message)),
 					lastMessageRole: lastMessage.role,
 					lastMessageText: getMessageText(lastMessage),
 				});
@@ -200,21 +202,24 @@ describe("AgentSession eager todo enforcement", () => {
 		tempDir.removeSync();
 	});
 
-	it("prepends the eager todo reminder to the first real user turn", async () => {
+	it("prepends a hidden eager todo reminder without repeating the prompt text", async () => {
 		await session.prompt("list all work trees");
 
-		const dumpText = session.formatSessionAsText();
-
 		expect(observedCalls).toHaveLength(1);
 		expect(observedCalls[0]).toEqual({
 			toolChoice: "todo_write",
 			toolNames: ["todo_write", "bash"],
-			messageRoles: ["developer", "user"],
+			messageRoles: ["user", "user"],
+			messageTexts: [
+				expect.stringContaining("Before doing substantive work on the upcoming user request"),
+				"list all work trees",
+			],
 			lastMessageRole: "user",
 			lastMessageText: "list all work trees",
 		});
-		expect(dumpText).toContain("## Developer");
-		expect(dumpText).toContain("Before doing substantive work on the upcoming user request");
+		expect(observedCalls[0]?.messageTexts.filter(text => text.includes("list all work trees"))).toHaveLength(1);
+		expect(observedCalls[0]?.messageTexts[0]).not.toContain("list all work trees");
+		expect(session.formatSessionAsText()).not.toContain("<user-request>");
 	});
 
 	it("initializes todos once, then continues within the same user turn", async () => {
@@ -242,7 +247,11 @@ describe("AgentSession eager todo enforcement", () => {
 		expect(observedCalls[0]).toEqual({
 			toolChoice: "todo_write",
 			toolNames: ["todo_write", "bash"],
-			messageRoles: ["developer", "user"],
+			messageRoles: ["user", "user"],
+			messageTexts: [
+				expect.stringContaining("Before doing substantive work on the upcoming user request"),
+				"list all work trees",
+			],
 			lastMessageRole: "user",
 			lastMessageText: "list all work trees",
 		});