Treat user-account bot comments as innocent in triage

src/github/bots.ts

@@ -0,0 +1,23 @@
+/**
+ * Bot-account detection for webhook payloads.
+ *
+ * GitHub reports GitHub App accounts with `user.type === 'Bot'`, and that is
+ * the only signal the router needs for them. Classic bots that run on plain
+ * user accounts — for example withastro's astrobot-houston comment bot — are
+ * typed `User` and are otherwise indistinguishable from humans in a webhook,
+ * so they need an explicit list.
+ *
+ * The `[bot]` login suffix is GitHub's own convention for app accounts; it is
+ * checked here as a belt-and-braces fallback for payloads that omit the type
+ * field, and it costs nothing because GitHub reserves the suffix for apps.
+ */
+
+export const KNOWN_USER_TYPE_BOT_LOGINS: ReadonlySet<string> = new Set([
+	'astrobot-houston',
+]);
+
+/** True when the author is a bot: a `[bot]` app account or a known bot login. */
+export function isBotAuthor(login: string | undefined): boolean {
+	if (!login) return false;
+	return login.endsWith('[bot]') || KNOWN_USER_TYPE_BOT_LOGINS.has(login);
+}

src/github/issues.ts

@@ -6,6 +6,7 @@
 
 import * as v from 'valibot';
 import type { LabelAppearance } from '../triage/labels.ts';
+import { isBotAuthor } from './bots.ts';
 import type { InstallationClient } from './client.ts';
 import { isGitHubStatus } from './content.ts';
 
@@ -73,7 +74,8 @@ export async function fetchIssueDetails(
 		createdAt: issue.data.created_at,
 		comments: comments.map((comment) => ({
 			author: { login: comment.user?.login ?? '' },
-			authorIsBot: comment.user?.type === 'Bot',
+			authorIsBot:
+				comment.user?.type === 'Bot' || isBotAuthor(comment.user?.login),
 			authorAssociation: comment.author_association,
 			body: comment.body ?? '',
 			createdAt: comment.created_at,

src/router.ts

@@ -12,9 +12,14 @@
  * - `issue_comment.created`           → triage, unless the comment is on a
  *                                        pull request or written by a bot
  *                                        (bot filtering prevents self-trigger
- *                                        loops)
+ *                                        loops). Bot filtering covers GitHub
+ *                                        App accounts (`user.type === 'Bot'`)
+ *                                        and known user-account bots such as
+ *                                        astrobot-houston, so another bot's
+ *                                        comment can never start a triage.
  */
 
+import { isBotAuthor } from './github/bots.ts';
 import { RELEASE_SECURITY_CHECK_NAMES } from './release-security/checks.ts';
 import {
 	RELEASE_BRANCH_PREFIX,
@@ -184,10 +189,11 @@ export function routeDelivery(
 				reason: 'The comment is on a pull request, not an issue.',
 			};
 		}
-		if (payload.comment?.user?.type === 'Bot') {
+		const commentAuthor = payload.comment?.user?.login;
+		if (payload.comment?.user?.type === 'Bot' || isBotAuthor(commentAuthor)) {
 			return {
 				kind: 'none',
-				reason: `Comment from bot (${payload.comment.user.login ?? 'unknown'}).`,
+				reason: `Comment from bot (${commentAuthor ?? 'unknown'}).`,
 			};
 		}
 		return {

src/triage/workflow.ts

@@ -11,6 +11,7 @@ import {
 	type TriageConfig,
 } from '../config.ts';
 import type { WorkerEnv } from '../env.ts';
+import { isBotAuthor } from '../github/bots.ts';
 import {
 	createInstallationClient,
 	createScopedInstallationToken,
@@ -1538,17 +1539,23 @@ async function loadAndRoute(
 		params.repo,
 		params.issueNumber,
 	);
-	const action = route(
-		{
-			action: params.issueAction,
-			// Read from the issue rather than inferred from the action: the
-			// delivery only says what happened, and the issue may have moved on
-			// while the delivery waited its turn in the per-issue queue.
-			issueState: normalizeIssueState(details.state),
-			issueLabels: details.labels,
-		},
-		config.triage.labels,
-	);
+	const action =
+		params.issueAction === 'comment' && isBotAuthor(params.commentAuthor)
+			? {
+					type: 'skip' as const,
+					reason: `Comment from bot (${params.commentAuthor}).`,
+				}
+			: route(
+					{
+						action: params.issueAction,
+						// Read from the issue rather than inferred from the action: the
+						// delivery only says what happened, and the issue may have moved on
+						// while the delivery waited its turn in the per-issue queue.
+						issueState: normalizeIssueState(details.state),
+						issueLabels: details.labels,
+					},
+					config.triage.labels,
+				);
 
 	const conversation = details.comments
 		.slice(-MAX_CONVERSATION_ENTRIES)

tests/bots.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from 'vitest';
+import { isBotAuthor, KNOWN_USER_TYPE_BOT_LOGINS } from '../src/github/bots.ts';
+
+describe('isBotAuthor', () => {
+	it('flags GitHub App account logins by their [bot] suffix', () => {
+		expect(isBotAuthor('factory[bot]')).toBe(true);
+		expect(isBotAuthor('astro-build[bot]')).toBe(true);
+		expect(isBotAuthor('github-actions[bot]')).toBe(true);
+	});
+
+	it('flags known user-account bots that GitHub types as User', () => {
+		expect(isBotAuthor('astrobot-houston')).toBe(true);
+		expect(KNOWN_USER_TYPE_BOT_LOGINS.has('astrobot-houston')).toBe(true);
+	});
+
+	it('does not flag human logins', () => {
+		expect(isBotAuthor('matthewp')).toBe(false);
+		expect(isBotAuthor('ilovesusu')).toBe(false);
+		expect(isBotAuthor('someone[bot]ish')).toBe(false);
+	});
+
+	it('is safe for missing logins', () => {
+		expect(isBotAuthor(undefined)).toBe(false);
+		expect(isBotAuthor('')).toBe(false);
+	});
+});

tests/router.test.ts

@@ -229,6 +229,42 @@ describe('webhook dispatch router', () => {
 		});
 	});
 
+	it('ignores comments from user-account bots like astrobot-houston', () => {
+		// GitHub reports classic bots that run on user accounts as `type:
+		// User`, so the type check alone misses them (issue #17991: Houston's
+		// comment triggered a retriage that dropped "needs reproduction").
+		const dispatch = routeDelivery(
+			'issue_comment',
+			{
+				action: 'created',
+				installation,
+				repository,
+				issue: { number: 42 },
+				comment: { user: { login: 'astrobot-houston', type: 'User' } },
+			},
+			'delivery-5b',
+		);
+		expect(dispatch).toEqual({
+			kind: 'none',
+			reason: 'Comment from bot (astrobot-houston).',
+		});
+	});
+
+	it('ignores [bot]-suffixed accounts even when the type field is missing', () => {
+		const dispatch = routeDelivery(
+			'issue_comment',
+			{
+				action: 'created',
+				installation,
+				repository,
+				issue: { number: 42 },
+				comment: { user: { login: 'some-app[bot]' } },
+			},
+			'delivery-5c',
+		);
+		expect(dispatch.kind).toBe('none');
+	});
+
 	it('routes private repositories to triage with the private flag set', () => {
 		const dispatch = routeDelivery(
 			'issues',