Endpoint-Routed Tool Provider (the PagerDuty model)

PagerDuty is the reference implementation. "Endpoint-routed" means the provider has no environment-level credentials: every subscriber registers their own secret (e.g. a PagerDuty Events API v2 routing key) as a channel endpoint, and one trigger fans out to a different external service per subscriber. Grep for pagerduty_service / ENDPOINT_ROUTED_TOOL_PROVIDERS to find every touch point of the reference implementation.

Step 0: Provider discovery gate (mandatory, before any code)

Every invariant and checklist item below encodes a fact from PagerDuty's Events API v2 docs (32-char key regex, us/eu endpoints, dedup_key, 1024-char summary limit). Do not transplant those facts onto another provider. First, read the target provider's official API docs and pin down, with citations:

• Per-recipient secret: name, format (drives the validator regex and DTO @Matches), and scope. It must be issuable per recipient/service.
• Regional endpoints: the region equivalent, or none.
• Idempotency: the dedup_key equivalent and its retry semantics.
• Payload contract: required fields, size limits, allowed actions and severities (drives defaults, RESERVED_OVERRIDE_KEYS, and truncation).
• Auth transport: secret in body vs header.

Then apply the gate:

• Open question that changes the design (secret scope, missing idempotency, OAuth-only auth, ...): ask the user with concrete options. Do not assume.
• An architecture invariant cannot be satisfied (e.g. no per-recipient secret exists): halt. Explain which invariant fails and name the alternatives (credential-routed tool provider, OAuth connection model) instead of forcing this pattern.
• All questions answered: record the findings (they become the validator, provider defaults, and docs content) and proceed to the checklist.

Architecture invariants (do not renegotiate these)

1. Secret lives on the connection, not the endpoint. The wire shape (e.g. { routingKey, region }) is accepted and returned by the API, but persisted encrypted on a dedicated ChannelConnection.auth (1:1 owned by the endpoint). The stored ChannelEndpoint.endpoint document is {}. Read paths re-hydrate the wire shape by decrypting the linked connection.
2. Exactly one endpoint per (environment, subscriber, integration), enforced by a Mongo partial unique index on the endpoint type. Duplicate POST → 409 Conflict; rotation is a PATCH on the existing endpoint.
3. The provider is stateless. Constructor takes no credentials. Routing is resolved inside sendMessage from options.channelData.endpoint, guarded by isChannelDataOfType(channelData, ENDPOINT_TYPES.X). Missing/wrong channelData throws.
4. No endpoint → step is SKIPPED, never errored. The worker send loop checks ENDPOINT_ROUTED_TOOL_PROVIDERS (a Set in send-message-tool.usecase.ts); credential-routed tool providers (tool-webhook, Opsgenie today) still fall back to integration.credentials.
5. Deterministic dedup_key from transactionId + subscriberId + stepId so worker retries update the same incident instead of duplicating it. An explicit override wins.
6. Secrets never leak: not in logs, execution details, or message documents. The routing key is added to SECURE_AUTH_FIELDS in encrypt-channel-connection-auth.ts so it is encrypted at rest.
7. createSubscriberIfMissing (optional boolean on the create-endpoint body) JIT-creates the subscriber via CreateOrUpdateSubscriberUseCase with allowUpdate: false (create-only, never mutates). Without it, unknown subscriberId → 404 whose message names the flag. Connect surfaces are often the user's first Novu touchpoint, so client guides should pass true.

Implementation checklist (slice order matters)

Only start after the discovery gate has passed. Work bottom-up; each slice must build before the next (see Build order below).

A. Foundations (packages/shared, packages/stateless, libs/dal, libs/application-generic)

• Add X_TYPE to ENDPOINT_TYPES + wire shape in ChannelEndpointByType — packages/shared/src/types/channel-endpoint.ts
• Mirror both in packages/stateless/src/lib/provider/channel-data.type.ts; add the XData type to ChannelData and to ENDPOINT_TYPES_REQUIRING_TOKEN
• Partial unique index in libs/dal/src/repositories/channel-endpoint/channel-endpoint.schema.ts ({ _environmentId, subscriberId, integrationIdentifier, type }, partialFilterExpression: { type })
• Add secret field(s) to SECURE_AUTH_FIELDS + ChannelConnectionAuth in libs/application-generic/src/encryption/encrypt-channel-connection-auth.ts (+ spec)
• Validator entry in libs/application-generic/src/schemas/channel-endpoint/channel-endpoint.schema.ts (format-validate the secret, e.g. /^[a-zA-Z0-9]{32}$/, and reject extra keys)

B. Provider (packages/providers, libs/application-generic)

• Stateless provider in packages/providers/src/lib/tool/<provider>/ — resolve routing from channelData, deterministic dedup, reserved-override handling (+ spec)
• Handler in libs/application-generic/src/factories/tool/handlers/ — buildProvider ignores ICredentials
• Empty credentials config in packages/shared/src/consts/providers/credentials/provider-credentials.ts (export const xConfig: IConfigCredential[] = []) with a comment pointing at the channel-endpoints API

C. API (apps/api/src/app/channel-endpoints)

• Endpoint DTO in dtos/endpoint-types.dto.ts (regex-validate the secret) + Create<X>EndpointDto in dtos/create-channel-endpoint-variants.dto.ts
• Controller: @ApiExtraModels + oneOf + discriminator mapping for the new DTO
• Create usecase: connection-first then endpoint, compensating delete on failure, duplicate-key → 409; update usecase rotates on the connection; delete cascades the connection; get/list hydrate the wire shape (batch $in for list)
• e2e in e2e/create-channel-endpoint.e2e.ts: happy path, 409, rotation, createSubscriberIfMissing (404 hint / JIT create / no-mutation)

D. Worker (apps/worker/src/app/workflow/usecases/send-message)

• resolve-channel-endpoints.usecase.ts: extract + decrypt the secret from the connection into channelData.endpoint
• send-message-tool.usecase.ts: add the provider id to ENDPOINT_ROUTED_TOOL_PROVIDERS; verify SKIPPED + execution detail on missing endpoint (+ spec for the predicate)

E. Surface (dashboard, docs, playground)

• Provider const in packages/shared/src/consts/providers/channels/tool.ts with docReference → https://docs.novu.co/platform/integrations/tool/<provider> (rebuild @novu/shared after)
• Docs guide docs/platform/integrations/tool/<provider>.mdx + register in the Tool group of docs/docs.json — see reference.md for the required page structure
• Playground demo under playground/nextjs mirroring the PagerDuty trio: src/lib/<provider>-endpoint-connect.ts, src/pages/api/<provider>-endpoint.ts, src/components/<provider>-end-user-connect.tsx + Clerk-gated page + SideNav entry

For per-file code patterns (index definition, provider skeleton, usecase transaction shape, DTO union, worker extraction, playground helper contract), see reference.md.

Opsgenie refactor note

Opsgenie is credential-routed today (env-level apiKey). Refactoring it to this model = running the checklist with opsgenie_* as the endpoint type and removing it from the credential-routed fallback: empty opsgenieConfig, drop the API-key read in opsgenie.handler.ts, add it to ENDPOINT_ROUTED_TOOL_PROVIDERS. PagerDuty was never released so it had no migration; Opsgenie may need one — check for existing integrations with credentials before deleting the old path. The discovery gate still applies: confirm Opsgenie's Alert API supports per-recipient API keys and idempotent alert deduplication before assuming parity with PagerDuty.

Build order & verification

# types flow stateless → providers → application-generic; skipping a step
# yields phantom TS errors (missing channelData on IToolOptions, etc.)
pnpm --filter @novu/shared build
pnpm --filter @novu/stateless build
pnpm --filter @novu/providers build
pnpm --filter @novu/application-generic build

# provider unit tests
CI=true pnpm --filter @novu/providers exec vitest run src/lib/tool/<provider>

# channel-endpoints e2e (from apps/api)
pnpm exec cross-env NODE_ENV=test CI_EE_TEST=true CLERK_ENABLED=true \
  NODE_OPTIONS=--max_old_space_size=8192 mocha --timeout 30000 --retries 3 \
  --grep '#novu-v2' --require ./swc-register.js --exit --file e2e/setup.ts \
  'src/**/create-channel-endpoint.e2e{,-ee}.ts'

Gotchas learned the hard way

• Module DI: JIT subscriber creation needs SharedModule + CreateOrUpdateSubscriberUseCase + UpdateSubscriber + UpdateSubscriberChannel as providers in channel-endpoints.module.ts (mirror channel-connections.module.ts).
• Worker/app-generic specs need STORE_ENCRYPTION_KEY (32 chars) in the env or encryptChannelConnectionAuth throws a Buffer TypeError.
• @novu/api SDK lags: until the OpenAPI regen runs, the internal SDK's create-endpoint union won't include the new DTO — playground/demo code calls the raw REST endpoint (novuFetch pattern) and swaps to the SDK later. Never edit libs/internal-sdk by hand.
• Dashboard View Guide CTA: zero-credential providers skip the credentials accordion; the docs CTA in integration-settings.tsx must live outside the providerCredentials.length > 0 block or it never renders.
• Dashboard gating: the Tool channel is behind the IS_TOOL_CHANNEL_ENABLED LaunchDarkly flag — check it before debugging a "missing provider" in the integration store.
• Secrets in reads: Novu returns secrets on read and masks client-side (last 4 chars, ••••XXXX) — follow that convention, don't invent server-side masking.
• Writing style: no em dashes (—) in this feature's docs/UI copy; use periods, colons, or parentheses.