Add Trigger

Add Trigger

You are an expert at creating webhook and polling triggers for Sim. You understand the trigger system, the generic buildTriggerSubBlocks helper, polling infrastructure, and how triggers connect to blocks.

Your Task

1. Research what webhook events the service supports — if the service lacks reliable webhooks, use polling
2. Create the trigger files using the generic builder (webhook) or manual config (polling)
3. Create a provider handler (webhook) or polling handler (polling)
4. Register triggers and connect them to the block

Hard Rule: No Guessed Webhook Payload Schemas

If the service docs do not clearly show the webhook payload JSON for an event, you MUST tell the user instead of guessing trigger outputs or formatInput mappings.

• Do NOT invent payload field names
• Do NOT guess nested event object paths
• Do NOT infer output fields from the UI or marketing docs
• Do NOT write formatInput against unverified webhook bodies

If the payload shape is unknown, do one of these instead:

1. Ask the user for sample webhook payloads
2. Ask the user for a test webhook source so you can inspect a real event
3. Implement only the event registration/setup portions whose payloads are documented
4. Leave the trigger unimplemented and explicitly say which payload fields are unknown

Directory Structure

apps/sim/triggers/{service}/
├── index.ts              # Barrel exports
├── utils.ts              # Service-specific helpers (options, instructions, extra fields, outputs)
├── {event_a}.ts          # Primary trigger (includes dropdown)
├── {event_b}.ts          # Secondary trigger (no dropdown)
└── webhook.ts            # Generic webhook trigger (optional, for "all events")

apps/sim/lib/webhooks/
├── provider-subscription-utils.ts  # Shared subscription helpers (getProviderConfig, getNotificationUrl)
├── providers/
│   ├── {service}.ts       # Provider handler (auth, formatInput, matchEvent, subscriptions)
│   ├── types.ts           # WebhookProviderHandler interface
│   ├── utils.ts           # Shared helpers (createHmacVerifier, verifyTokenAuth, skipByEventTypes)
│   └── registry.ts        # Handler map + default handler

Step 1: Create utils.ts

This file contains all service-specific helpers used by triggers.

import type { SubBlockConfig } from '@/blocks/types'
import type { TriggerOutput } from '@/triggers/types'

export const {service}TriggerOptions = [
  { label: 'Event A', id: '{service}_event_a' },
  { label: 'Event B', id: '{service}_event_b' },
]

export function {service}SetupInstructions(eventType: string): string {
  const instructions = [
    'Copy the <strong>Webhook URL</strong> above',
    'Go to <strong>{Service} Settings > Webhooks</strong>',
    `Select the <strong>${eventType}</strong> event type`,
    'Paste the webhook URL and save',
    'Click "Save" above to activate your trigger',
  ]
  return instructions
    .map((instruction, index) =>
      `<div class="mb-3"><strong>${index + 1}.</strong> ${instruction}</div>`
    )
    .join('')
}

export function build{Service}ExtraFields(triggerId: string): SubBlockConfig[] {
  return [
    {
      id: 'projectId',
      title: 'Project ID (Optional)',
      type: 'short-input',
      placeholder: 'Leave empty for all projects',
      mode: 'trigger',
      condition: { field: 'selectedTriggerId', value: triggerId },
    },
  ]
}

export function build{Service}Outputs(): Record<string, TriggerOutput> {
  return {
    eventType: { type: 'string', description: 'The type of event' },
    resourceId: { type: 'string', description: 'ID of the affected resource' },
    resource: {
      id: { type: 'string', description: 'Resource ID' },
      name: { type: 'string', description: 'Resource name' },
    },
  }
}

Step 2: Create Trigger Files

Primary trigger — MUST include includeDropdown: true:

import { {Service}Icon } from '@/components/icons'
import { buildTriggerSubBlocks } from '@/triggers'
import { build{Service}ExtraFields, build{Service}Outputs, {service}SetupInstructions, {service}TriggerOptions } from '@/triggers/{service}/utils'
import type { TriggerConfig } from '@/triggers/types'

export const {service}EventATrigger: TriggerConfig = {
  id: '{service}_event_a',
  name: '{Service} Event A',
  provider: '{service}',
  description: 'Trigger workflow when Event A occurs',
  version: '1.0.0',
  icon: {Service}Icon,
  subBlocks: buildTriggerSubBlocks({
    triggerId: '{service}_event_a',
    triggerOptions: {service}TriggerOptions,
    includeDropdown: true,
    setupInstructions: {service}SetupInstructions('Event A'),
    extraFields: build{Service}ExtraFields('{service}_event_a'),
  }),
  outputs: build{Service}Outputs(),
  webhook: { method: 'POST', headers: { 'Content-Type': 'application/json' } },
}

Secondary triggers — NO includeDropdown (it's already in the primary):

export const {service}EventBTrigger: TriggerConfig = {
  // Same as above but: id: '{service}_event_b', no includeDropdown
}

Step 3: Register and Wire

apps/sim/triggers/{service}/index.ts

export { {service}EventATrigger } from './event_a'
export { {service}EventBTrigger } from './event_b'

apps/sim/triggers/registry.ts

import { {service}EventATrigger, {service}EventBTrigger } from '@/triggers/{service}'

export const TRIGGER_REGISTRY: TriggerRegistry = {
  // ... existing ...
  {service}_event_a: {service}EventATrigger,
  {service}_event_b: {service}EventBTrigger,
}

Block file (apps/sim/blocks/blocks/{service}.ts)

Wire triggers into the block so the trigger UI appears and generate-docs.ts discovers them. Two changes are needed:

1. Spread trigger subBlocks at the end of the block's subBlocks array
2. Add triggers property after outputs with enabled: true and available: [...]

import { getTrigger } from '@/triggers'

export const {Service}Block: BlockConfig = {
  // ...
  subBlocks: [
    // Regular tool subBlocks first...
    ...getTrigger('{service}_event_a').subBlocks,
    ...getTrigger('{service}_event_b').subBlocks,
  ],
  // ... tools, inputs, outputs ...
  triggers: {
    enabled: true,
    available: ['{service}_event_a', '{service}_event_b'],
  },
}

Versioned blocks (V1 + V2): Many integrations have a hidden V1 block and a visible V2 block. Where you add the trigger wiring depends on how V2 inherits from V1:

• V2 uses ...V1Block spread (e.g., Google Calendar): Add trigger to V1 — V2 inherits both subBlocks and triggers automatically.
• V2 defines its own subBlocks (e.g., Google Sheets): Add trigger to V2 (the visible block). V1 is hidden and doesn't need it.
• Single block, no V2 (e.g., Google Drive): Add trigger directly.

generate-docs.ts deduplicates by base type (first match wins). If V1 is processed first without triggers, the V2 triggers won't appear in integrations.json. Always verify by checking the output after running the script.

Provider Handler

All provider-specific webhook logic lives in a single handler file: apps/sim/lib/webhooks/providers/{service}.ts.

When to Create a Handler

If none apply, you don't need a handler. The default handler provides bearer token auth.

Example Handler

import crypto from 'crypto'
import { createLogger } from '@sim/logger'
import { safeCompare } from '@sim/security/compare'
import type { EventMatchContext, FormatInputContext, FormatInputResult, WebhookProviderHandler } from '@/lib/webhooks/providers/types'
import { createHmacVerifier } from '@/lib/webhooks/providers/utils'

const logger = createLogger('WebhookProvider:{Service}')

function validate{Service}Signature(secret: string, signature: string, body: string): boolean {
  if (!secret || !signature || !body) return false
  const computed = crypto.createHmac('sha256', secret).update(body, 'utf8').digest('hex')
  return safeCompare(computed, signature)
}

export const {service}Handler: WebhookProviderHandler = {
  verifyAuth: createHmacVerifier({
    configKey: 'webhookSecret',
    headerName: 'X-{Service}-Signature',
    validateFn: validate{Service}Signature,
    providerLabel: '{Service}',
  }),

  async matchEvent({ body, requestId, providerConfig }: EventMatchContext) {
    const triggerId = providerConfig.triggerId as string | undefined
    if (triggerId && triggerId !== '{service}_webhook') {
      const { is{Service}EventMatch } = await import('@/triggers/{service}/utils')
      if (!is{Service}EventMatch(triggerId, body as Record<string, unknown>)) return false
    }
    return true
  },

  async formatInput({ body }: FormatInputContext): Promise<FormatInputResult> {
    const b = body as Record<string, unknown>
    return {
      input: {
        eventType: b.type,
        resourceId: (b.data as Record<string, unknown>)?.id ?? null,
        resource: b.data,
      },
    }
  },

  extractIdempotencyId(body: unknown) {
    const obj = body as Record<string, unknown>
    return obj.id && obj.type ? `${obj.type}:${obj.id}` : null
  },
}

Register the Handler

In apps/sim/lib/webhooks/providers/registry.ts:

import { {service}Handler } from '@/lib/webhooks/providers/{service}'

const PROVIDER_HANDLERS: Record<string, WebhookProviderHandler> = {
  // ... existing (alphabetical) ...
  {service}: {service}Handler,
}

Output Alignment (Critical)

There are two sources of truth that MUST be aligned:

1. Trigger outputs — schema defining what fields SHOULD be available (UI tag dropdown)
2. formatInput on the handler — implementation that transforms raw payload into actual data

If they differ: the tag dropdown shows fields that don't exist, or actual data has fields users can't discover.

Rules for formatInput:

• Return { input: { ... } } where inner keys match trigger outputs exactly
• Return { input: ..., skip: { message: '...' } } to skip execution
• No wrapper objects or duplication
• Use null for missing optional data

Automatic Webhook Registration

If the service API supports programmatic webhook creation, implement createSubscription and deleteSubscription on the handler. The orchestration layer calls these automatically — no code touches route.ts, provider-subscriptions.ts, or deploy.ts.

import { getNotificationUrl, getProviderConfig } from '@/lib/webhooks/provider-subscription-utils'
import type { DeleteSubscriptionContext, SubscriptionContext, SubscriptionResult } from '@/lib/webhooks/providers/types'

export const {service}Handler: WebhookProviderHandler = {
  async createSubscription(ctx: SubscriptionContext): Promise<SubscriptionResult | undefined> {
    const config = getProviderConfig(ctx.webhook)
    const apiKey = config.apiKey as string
    if (!apiKey) throw new Error('{Service} API Key is required.')

    const res = await fetch('https://api.{service}.com/webhooks', {
      method: 'POST',
      headers: { Authorization: `Bearer ${apiKey}`, 'Content-Type': 'application/json' },
      body: JSON.stringify({ url: getNotificationUrl(ctx.webhook) }),
    })

    if (!res.ok) throw new Error(`{Service} error: ${res.status}`)
    const { id } = (await res.json()) as { id: string }
    return { providerConfigUpdates: { externalId: id } }
  },

  async deleteSubscription(ctx: DeleteSubscriptionContext): Promise<void> {
    const config = getProviderConfig(ctx.webhook)
    const { apiKey, externalId } = config as { apiKey?: string; externalId?: string }
    if (!apiKey || !externalId) return
    await fetch(`https://api.{service}.com/webhooks/${externalId}`, {
      method: 'DELETE',
      headers: { Authorization: `Bearer ${apiKey}` },
    }).catch(() => {})
  },
}

Key points:

• Throw from createSubscription — orchestration rolls back the DB webhook
• Never throw from deleteSubscription — log non-fatally
• Return { providerConfigUpdates: { externalId } } — orchestration merges into providerConfig
• Add apiKey field to build{Service}ExtraFields with password: true

Trigger Outputs Schema

Trigger outputs use the same schema as block outputs (NOT tool outputs).

Supported: type + description for leaf fields, nested objects for complex data. NOT supported: optional: true, items (those are tool-output-only features).

export function buildOutputs(): Record<string, TriggerOutput> {
  return {
    eventType: { type: 'string', description: 'Event type' },
    timestamp: { type: 'string', description: 'When it occurred' },
    payload: { type: 'json', description: 'Full event payload' },
    resource: {
      id: { type: 'string', description: 'Resource ID' },
      name: { type: 'string', description: 'Resource name' },
    },
  }
}

Polling Triggers

Use polling when the service lacks reliable webhooks (e.g., Google Sheets, Google Drive, Google Calendar, Gmail, RSS, IMAP). Polling triggers do NOT use buildTriggerSubBlocks — they define subBlocks manually.

Directory Structure

apps/sim/triggers/{service}/
├── index.ts              # Barrel export
└── poller.ts             # TriggerConfig with polling: true

apps/sim/lib/webhooks/polling/
└── {service}.ts           # PollingProviderHandler implementation

Polling Handler (apps/sim/lib/webhooks/polling/{service}.ts)

import { pollingIdempotency } from '@/lib/core/idempotency/service'
import type { PollingProviderHandler, PollWebhookContext } from '@/lib/webhooks/polling/types'
import { markWebhookFailed, markWebhookSuccess, resolveOAuthCredential, updateWebhookProviderConfig } from '@/lib/webhooks/polling/utils'
import { processPolledWebhookEvent } from '@/lib/webhooks/processor'

export const {service}PollingHandler: PollingProviderHandler = {
  provider: '{service}',
  label: '{Service}',

  async pollWebhook(ctx: PollWebhookContext): Promise<'success' | 'failure'> {
    const { webhookData, workflowData, requestId, logger } = ctx
    const webhookId = webhookData.id

    try {
      // For OAuth services:
      const accessToken = await resolveOAuthCredential(webhookData, '{service}', requestId)
      const config = webhookData.providerConfig as unknown as {Service}WebhookConfig

      // First poll: seed state, emit nothing
      if (!config.lastCheckedTimestamp) {
        await updateWebhookProviderConfig(webhookId, { lastCheckedTimestamp: new Date().toISOString() }, logger)
        await markWebhookSuccess(webhookId, logger)
        return 'success'
      }

      // Fetch changes since last poll, process with idempotency
      // ...

      await markWebhookSuccess(webhookId, logger)
      return 'success'
    } catch (error) {
      logger.error(`[${requestId}] Error processing {service} webhook ${webhookId}:`, error)
      await markWebhookFailed(webhookId, logger)
      return 'failure'
    }
  },
}

Key patterns:

• First poll seeds state and emits nothing (avoids flooding with existing data)
• Use pollingIdempotency.executeWithIdempotency(provider, key, callback) for dedup
• Use processPolledWebhookEvent(webhookData, workflowData, payload, requestId) to fire the workflow
• Use updateWebhookProviderConfig(webhookId, partialConfig, logger) for read-merge-write on state
• Use the latest server-side timestamp from API responses (not wall clock) to avoid clock skew

Trigger Config (apps/sim/triggers/{service}/poller.ts)

import { {Service}Icon } from '@/components/icons'
import type { TriggerConfig } from '@/triggers/types'

export const {service}PollingTrigger: TriggerConfig = {
  id: '{service}_poller',
  name: '{Service} Trigger',
  provider: '{service}',
  description: 'Triggers when ...',
  version: '1.0.0',
  icon: {Service}Icon,
  polling: true,               // REQUIRED — routes to polling infrastructure

  subBlocks: [
    { id: 'triggerCredentials', type: 'oauth-input', title: 'Credentials', serviceId: '{service}', requiredScopes: [], required: true, mode: 'trigger' },
    // ... service-specific config fields (dropdowns, inputs, switches) ...
    { id: 'triggerInstructions', type: 'text', title: 'Setup Instructions', hideFromPreview: true, mode: 'trigger', defaultValue: '...' },
  ],

  outputs: {
    // Must match the payload shape from processPolledWebhookEvent
  },
}

Registration (3 places)

1. apps/sim/triggers/constants.ts — add provider to POLLING_PROVIDERS Set
2. apps/sim/lib/webhooks/polling/registry.ts — import handler, add to POLLING_HANDLERS
3. apps/sim/triggers/registry.ts — import trigger config, add to TRIGGER_REGISTRY

Helm Cron Job

Add to helm/sim/values.yaml under the existing polling cron jobs:

{service}WebhookPoll:
  enabled: true
  name: {service}-webhook-poll
  schedule: "*/1 * * * *"
  path: "/api/webhooks/poll/{service}"
  concurrencyPolicy: Forbid
  successfulJobsHistoryLimit: 3
  failedJobsHistoryLimit: 1

Mirror the existing rssWebhookPoll entry.

Reference Implementations

• Simple: apps/sim/lib/webhooks/polling/rss.ts + apps/sim/triggers/rss/poller.ts
• Complex (OAuth, attachments): apps/sim/lib/webhooks/polling/gmail.ts + apps/sim/triggers/gmail/poller.ts
• Cursor-based (changes API): apps/sim/lib/webhooks/polling/google-drive.ts
• Timestamp-based: apps/sim/lib/webhooks/polling/google-calendar.ts

Option Lists: selectorKey or options, never a per-block fetcher

A sub-block gets its choices from exactly one of two places. There is no third.

selectorKey — every remote list. Use the add-selector skill to add the key to the browser-safe manifest and attach its provider behavior on the server. All remote selectors execute through selectors.execute; never add a client provider module or selector-only fetch route.

{ id: 'triggerCredentials', type: 'oauth-input', canonicalParamId: 'oauthCredential', mode: 'trigger' },
{ id: 'labelIds', type: 'dropdown', multiSelect: true,
  selectorKey: 'gmail.labels', dependsOn: ['triggerCredentials'], mode: 'trigger' },
{ id: 'manualLabelIds', type: 'short-input', mode: 'trigger-advanced' },

canonicalParamId: 'oauthCredential' on the credential sub-block is the line people forget. The shared context builder uses trigger mode and projects only active dependsOn values under their canonical ids. Exact {{KEY}} environment references remain unresolved until the authorized server executor. The builder does not infer a credential from type: 'oauth-input'; only the legacy ids credential / botCredential / customBotCredential / manualBotCredential are aliased. Give the field canonicalParamId: 'oauthCredential', or declare a manifest sourceFields alias when a legacy source id must be retained.

options — everything else. A static array, or a pure function of the block's own values for a list that narrows to a sibling's selection. No I/O.

options: (params) => {
  const model = params?.values.model
  return typeof model === 'string' ? effortsFor(model) : DEFAULT_EFFORTS
}

Never fetch inside options, and never reach into the stores from a block definition. A fetcher that resolves its credential with readSubBlockValue(blockId, ...) only works on the canvas — every surface that is not the editor gets an empty list. fetchOptions/fetchOptionById were removed for exactly this reason.

Two rules the checks enforce:

• Selector query keys contain no dependency values. Credential IDs, secrets, unresolved references, and their hashes stay out of browser cache identities.
• A sub-block that dependsOn a credential / knowledge-base / table selector must be reconfigurable at fork-sync time — a selectorKey, a canonical pair whose basic member is a selector, or a short-input/long-input. bun run check:fork-dependent-coverage fails otherwise, because a fork sync clears those fields on every push and an unofferable one can never be set anywhere that sticks.

Checklist

Webhook and polling routes are legitimate external ingress boundaries. They must not call this Sim app's own API routes to reuse provider or business logic. Extract the shared provider operation or authorized application use case and call it directly from the trigger handler and any other server adapter. HTTP is reserved for an actual cross-process/capability boundary. Tool work uses a registered InternalToolConfig.operation; a directExecution property fails bun run check:tool-request-boundary.

Trigger Definition

• Created utils.ts with options, instructions, extra fields, and output builders
• Primary trigger has includeDropdown: true; secondary triggers do NOT
• All triggers use buildTriggerSubBlocks helper
• Created index.ts barrel export

Registration

• All triggers in triggers/registry.ts → TRIGGER_REGISTRY
• Block has triggers.enabled: true and lists all trigger IDs in triggers.available
• Block spreads all trigger subBlocks: ...getTrigger('id').subBlocks

Provider Handler (if needed)

• Handler file at apps/sim/lib/webhooks/providers/{service}.ts
• Registered in providers/registry.ts (alphabetical)
• Signature validator is a private function inside the handler file
• formatInput output keys match trigger outputs exactly
• Event matching uses dynamic await import() for trigger utils

Auto Registration (if supported)

• createSubscription and deleteSubscription on the handler
• NO changes to route.ts, provider-subscriptions.ts, or deploy.ts
• API key field uses password: true

Polling Trigger (if applicable)

• Handler implements PollingProviderHandler at lib/webhooks/polling/{service}.ts
• Trigger config has polling: true and defines subBlocks manually (no buildTriggerSubBlocks)
• Provider string matches across: trigger config, handler, POLLING_PROVIDERS, polling registry
• First poll seeds state and emits nothing
• Added provider to POLLING_PROVIDERS in triggers/constants.ts
• Added handler to POLLING_HANDLERS in lib/webhooks/polling/registry.ts
• Added cron job to helm/sim/values.yaml
• Payload shape matches trigger outputs schema

Testing

• bun run type-check passes
• Manually verify output keys match trigger outputs keys
• Trigger UI shows correctly in the block
• Ran bun run scripts/generate-docs.ts and committed the refreshed pages — trigger sections render into the owning integration's docs page, and CI's bun run docs:check fails on stale pages