diff --git a/tests/helpers/factories.ts b/tests/helpers/factories.ts
index a965d048..b2d91358 100644
--- a/tests/helpers/factories.ts
+++ b/tests/helpers/factories.ts
@@ -1,4 +1,6 @@
 import type { TRPCContext, TRPCUser } from '../../src/api/trpc.js';
+import type { TrelloCard } from '../../src/trello/client.js';
+import type { TrelloWebhookPayload } from '../../src/triggers/trello/types.js';
 import type { ProjectConfig, TriggerContext } from '../../src/types/index.js';
 
 // ---------------------------------------------------------------------------
@@ -116,3 +118,220 @@ export function createTriggerContext(overrides?: Partial<TriggerContext>): Trigg
 		...overrides,
 	} as TriggerContext;
 }
+
+// ---------------------------------------------------------------------------
+// Trello payload factories
+// ---------------------------------------------------------------------------
+
+/**
+ * Creates a mock Trello webhook action payload.
+ *
+ * Builds the `{ model, action }` shape used across 27+ trigger test occurrences.
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ *
+ * @example
+ * createTrelloActionPayload({ action: { data: { listAfter: { id: 'todo-list-id', name: 'Todo' } } } })
+ */
+export function createTrelloActionPayload(
+	overrides?: Partial<TrelloWebhookPayload>,
+): TrelloWebhookPayload {
+	return {
+		model: { id: 'board123', name: 'Board' },
+		action: {
+			id: 'action1',
+			idMemberCreator: 'member1',
+			type: 'updateCard',
+			date: '2024-01-01',
+			data: {
+				card: { id: 'card1', name: 'Test Card', idShort: 1, shortLink: 'abc' },
+				listBefore: { id: 'other-list', name: 'Other' },
+				listAfter: { id: 'splitting-list-id', name: 'Splitting' },
+			},
+		},
+		...overrides,
+	};
+}
+
+/**
+ * Creates a mock Trello card object for `trelloClient.getCard()` return values.
+ *
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ */
+export function createTrelloCard(overrides?: Partial<TrelloCard>): TrelloCard {
+	return {
+		id: 'card1',
+		name: 'Test Card',
+		desc: 'Test card description',
+		url: 'https://trello.com/c/abc/test-card',
+		shortUrl: 'https://trello.com/c/abc',
+		idList: 'todo-list-id',
+		labels: [],
+		...overrides,
+	};
+}
+
+/**
+ * Creates a mock Trello trigger context combining project + Trello payload.
+ *
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ */
+export function createTrelloTriggerContext(overrides?: Partial<TriggerContext>): TriggerContext {
+	return {
+		project: createMockProject(),
+		source: 'trello',
+		payload: createTrelloActionPayload(),
+		...overrides,
+	} as TriggerContext;
+}
+
+// ---------------------------------------------------------------------------
+// GitHub payload factories
+// ---------------------------------------------------------------------------
+
+/**
+ * Shape of a GitHub pull request object as used in webhook payloads.
+ */
+export interface MockPR {
+	number: number;
+	title: string;
+	body: string | null;
+	html_url: string;
+	state: string;
+	draft: boolean;
+	head: { ref: string; sha: string };
+	base: { ref: string };
+	user: { login: string };
+}
+
+/**
+ * Creates a mock GitHub PR object used in webhook payloads.
+ *
+ * Matches the `pull_request` shape used 80+ times inline across trigger tests.
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ */
+export function createMockPR(overrides?: Partial<MockPR>): MockPR {
+	return {
+		number: 42,
+		title: 'Test PR',
+		body: 'https://trello.com/c/abc123/card-name',
+		html_url: 'https://github.com/owner/repo/pull/42',
+		state: 'open',
+		draft: false,
+		head: { ref: 'feature/test', sha: 'sha123' },
+		base: { ref: 'main' },
+		user: { login: 'author' },
+		...overrides,
+	};
+}
+
+/**
+ * Shape of a GitHub check suite webhook payload.
+ */
+export interface CheckSuitePayload {
+	action: string;
+	check_suite: {
+		id: number;
+		status: string;
+		conclusion: string;
+		head_sha: string;
+		pull_requests: Array<{ number: number; head: { ref: string; sha: string } }>;
+	};
+	repository: { full_name: string; html_url: string };
+	sender: { login: string };
+}
+
+/**
+ * Creates a mock GitHub check suite webhook payload.
+ *
+ * Based on the local `makeCheckSuitePayload` pattern from `check-suite-success.test.ts`.
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ */
+export function createCheckSuitePayload(overrides?: Partial<CheckSuitePayload>): CheckSuitePayload {
+	return {
+		action: 'completed',
+		check_suite: {
+			id: 1,
+			status: 'completed',
+			conclusion: 'success',
+			head_sha: 'sha123',
+			pull_requests: [{ number: 42, head: { ref: 'feature/test', sha: 'sha123' } }],
+		},
+		repository: { full_name: 'owner/repo', html_url: 'https://github.com/owner/repo' },
+		sender: { login: 'github-actions' },
+		...overrides,
+	};
+}
+
+/**
+ * Shape of a GitHub pull request review webhook payload.
+ */
+export interface ReviewPayload {
+	action: string;
+	review: {
+		id: number;
+		state: string;
+		body: string | null;
+		html_url: string;
+		user: { login: string };
+	};
+	pull_request: {
+		number: number;
+		title: string;
+		body: string | null;
+		html_url: string;
+		head: { ref: string; sha: string };
+		base: { ref: string };
+	};
+	repository: { full_name: string; html_url: string };
+	sender: { login: string };
+}
+
+/**
+ * Creates a mock GitHub PR review webhook payload.
+ *
+ * Builds the `{ action, review, pull_request, repository, sender }` shape.
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ */
+export function createReviewPayload(overrides?: Partial<ReviewPayload>): ReviewPayload {
+	return {
+		action: 'submitted',
+		review: {
+			id: 100,
+			state: 'changes_requested',
+			body: 'Please fix the bug',
+			html_url: 'https://github.com/owner/repo/pull/42#pullrequestreview-100',
+			user: { login: 'cascade-reviewer' },
+		},
+		pull_request: {
+			number: 42,
+			title: 'Test PR',
+			body: 'https://trello.com/c/abc123/card-name',
+			html_url: 'https://github.com/owner/repo/pull/42',
+			head: { ref: 'feature/test', sha: 'sha123' },
+			base: { ref: 'main' },
+		},
+		repository: { full_name: 'owner/repo', html_url: 'https://github.com/owner/repo' },
+		sender: { login: 'cascade-reviewer' },
+		...overrides,
+	};
+}
+
+/**
+ * Creates a mock GitHub trigger context combining project + GitHub payload.
+ *
+ * Pass overrides (shallow-merged) for test-specific customisation.
+ */
+export function createGitHubTriggerContext(overrides?: Partial<TriggerContext>): TriggerContext {
+	return {
+		project: createMockProject(),
+		source: 'github',
+		payload: {
+			action: 'opened',
+			number: 42,
+			pull_request: createMockPR(),
+			repository: { full_name: 'owner/repo', html_url: 'https://github.com/owner/repo' },
+			sender: { login: 'author' },
+		},
+		...overrides,
+	} as TriggerContext;
+}