diff --git a/src/github/client.ts b/src/github/client.ts
index 8e03e09a..eeef4bd5 100644
--- a/src/github/client.ts
+++ b/src/github/client.ts
@@ -226,6 +226,15 @@ export const githubClient = {
 		};
 	},
 
+	async deletePRComment(owner: string, repo: string, commentId: number): Promise<void> {
+		logger.debug('Deleting PR comment', { owner, repo, commentId });
+		await getClient().issues.deleteComment({
+			owner,
+			repo,
+			comment_id: commentId,
+		});
+	},
+
 	async getPRReviews(owner: string, repo: string, prNumber: number): Promise<PRReview[]> {
 		logger.debug('Fetching PR reviews', { owner, repo, prNumber });
 		const { data } = await getClient().pulls.listReviews({
diff --git a/src/triggers/github/webhook-handler.ts b/src/triggers/github/webhook-handler.ts
index f1de81ae..3c960c2d 100644
--- a/src/triggers/github/webhook-handler.ts
+++ b/src/triggers/github/webhook-handler.ts
@@ -7,7 +7,12 @@ import { getPersonaToken, resolvePersonaIdentities } from '../../github/personas
 import { withPMCredentials } from '../../pm/context.js';
 import { createPMProvider, pmRegistry, withPMProvider } from '../../pm/index.js';
 import { extractGitHubContext, generateAckMessage } from '../../router/ackMessageGenerator.js';
-import type { CascadeConfig, ProjectConfig, TriggerContext } from '../../types/index.js';
+import type {
+	AgentResult,
+	CascadeConfig,
+	ProjectConfig,
+	TriggerContext,
+} from '../../types/index.js';
 import {
 	enqueueWebhook,
 	getQueueLength,
@@ -25,6 +30,35 @@ import { runAgentExecutionPipeline } from '../shared/agent-execution.js';
 import { processNextQueuedWebhook } from '../shared/webhook-queue.js';
 import type { TriggerResult } from '../types.js';
 
+async function deleteProgressCommentOnSuccess(
+	result: TriggerResult,
+	_agentResult: AgentResult,
+): Promise<void> {
+	// Only delete the progress comment for non-implementation agents.
+	// The implementation agent's success is handled via lifecycle (handleSuccess),
+	// which manages the PR comment separately.
+	if (result.agentType === 'implementation') return;
+
+	const input = result.agentInput as { repoFullName?: string };
+	if (!input.repoFullName || !result.prNumber) return;
+
+	let owner: string;
+	let repo: string;
+	try {
+		({ owner, repo } = parseRepoFullName(input.repoFullName));
+	} catch {
+		return;
+	}
+
+	const { initialCommentId } = getSessionState();
+	if (!initialCommentId) return;
+
+	await safeOperation(() => githubClient.deletePRComment(owner, repo, initialCommentId), {
+		action: 'delete progress comment after agent success',
+		prNumber: result.prNumber,
+	});
+}
+
 async function updateInitialCommentWithError(
 	result: TriggerResult,
 	agentResult: { success: boolean; error?: string },
@@ -105,6 +139,7 @@ async function executeGitHubAgent(
 		skipPrepareForAgent: true,
 		skipHandleFailure: true,
 		handleSuccessOnlyForAgentType: 'implementation',
+		onSuccess: deleteProgressCommentOnSuccess,
 		onFailure: updateInitialCommentWithError,
 		logLabel: 'GitHub agent',
 	};
diff --git a/src/triggers/shared/agent-execution.ts b/src/triggers/shared/agent-execution.ts
index 35afd458..a4f24f62 100644
--- a/src/triggers/shared/agent-execution.ts
+++ b/src/triggers/shared/agent-execution.ts
@@ -33,6 +33,12 @@ export interface AgentExecutionConfig {
 	 */
 	handleSuccessOnlyForAgentType?: string;
 
+	/**
+	 * Optional callback invoked when the agent succeeds (after pipeline completes).
+	 * Used by GitHub to delete the progress comment for non-implementation agents.
+	 */
+	onSuccess?: (result: TriggerResult, agentResult: AgentResult) => Promise<void>;
+
 	/**
 	 * Optional callback invoked when the agent fails (after pipeline completes).
 	 * Used by GitHub to update the PR comment with an error message.
@@ -178,7 +184,7 @@ export async function runAgentExecutionPipeline(
 		return;
 	}
 
-	const { skipPrepareForAgent = false, onFailure, logLabel = 'Agent' } = executionConfig;
+	const { skipPrepareForAgent = false, onSuccess, onFailure, logLabel = 'Agent' } = executionConfig;
 
 	const workItemId = result.workItemId;
 
@@ -218,6 +224,10 @@ export async function runAgentExecutionPipeline(
 		runId: agentResult.runId,
 	});
 
+	if (onSuccess && agentResult.success) {
+		await onSuccess(result, agentResult);
+	}
+
 	if (onFailure && !agentResult.success) {
 		await onFailure(result, agentResult);
 	}
diff --git a/tests/unit/github/client.test.ts b/tests/unit/github/client.test.ts
index 9de950f8..7432a9a2 100644
--- a/tests/unit/github/client.test.ts
+++ b/tests/unit/github/client.test.ts
@@ -15,6 +15,7 @@ const mockPulls = {
 const mockIssues = {
 	createComment: vi.fn(),
 	updateComment: vi.fn(),
+	deleteComment: vi.fn(),
 	listComments: vi.fn(),
 };
 
@@ -303,6 +304,20 @@ describe('githubClient', () => {
 		});
 	});
 
+	describe('deletePRComment', () => {
+		it('calls deleteComment with correct params', async () => {
+			mockIssues.deleteComment.mockResolvedValue({});
+
+			await withGitHubToken('test-token', () => githubClient.deletePRComment('owner', 'repo', 200));
+
+			expect(mockIssues.deleteComment).toHaveBeenCalledWith({
+				owner: 'owner',
+				repo: 'repo',
+				comment_id: 200,
+			});
+		});
+	});
+
 	describe('getPRReviews', () => {
 		it('returns mapped reviews', async () => {
 			mockPulls.listReviews.mockResolvedValue({
diff --git a/tests/unit/triggers/agent-execution.test.ts b/tests/unit/triggers/agent-execution.test.ts
index 3003cee4..7fbae5d6 100644
--- a/tests/unit/triggers/agent-execution.test.ts
+++ b/tests/unit/triggers/agent-execution.test.ts
@@ -394,6 +394,36 @@ describe('runAgentExecutionPipeline', () => {
 		});
 	});
 
+	describe('onSuccess callback', () => {
+		it('calls onSuccess when agent succeeds', async () => {
+			const agentResult: AgentResult = {
+				success: true,
+				runId: 'run-1',
+				output: '',
+			};
+			vi.mocked(runAgent).mockResolvedValue(agentResult);
+			const onSuccess = vi.fn().mockResolvedValue(undefined);
+
+			await runAgentExecutionPipeline(mockTriggerResult, mockProject, mockConfig, { onSuccess });
+
+			expect(onSuccess).toHaveBeenCalledWith(mockTriggerResult, agentResult);
+		});
+
+		it('does not call onSuccess when agent fails', async () => {
+			vi.mocked(runAgent).mockResolvedValue({
+				success: false,
+				error: 'Agent error',
+				runId: 'run-1',
+				output: '',
+			});
+			const onSuccess = vi.fn().mockResolvedValue(undefined);
+
+			await runAgentExecutionPipeline(mockTriggerResult, mockProject, mockConfig, { onSuccess });
+
+			expect(onSuccess).not.toHaveBeenCalled();
+		});
+	});
+
 	describe('onFailure callback', () => {
 		it('calls onFailure when agent fails', async () => {
 			const agentResult: AgentResult = {