Tensorlake Webhooks Skill

Tensorlake signs every webhook delivery with Svix, following Standard Webhooks with the svix-* header names. Each delivery is an HTTP POST with a signed JSON body and three headers: svix-id, svix-timestamp, and svix-signature. Webhooks are scoped to one project and report sandbox, application and application-request lifecycle changes. The body is a versioned envelope: { "event_id": "evt_...", "event_type": "tensorlake.sandbox.failed", "event_version": 1, "occurred_at": "...", "project_id": "...", "source_id": "...", "source_revision": "81247", "source_ordinal": 0, "data": { ... } }. event_id is stable across retries (the deduplication key). Order related events from the same source_id by source_revision (a numeric string) and then source_ordinal.

When to Use This Skill

• How do I receive Tensorlake webhooks?
• How do I verify Tensorlake webhook signatures (svix-signature)?
• How do I handle tensorlake.sandbox.failed, tensorlake.sandbox.running or tensorlake.application.request.completed events?
• How do I react to a failed sandbox or a failed application request?
• Why is my Tensorlake webhook signature verification failing, or rejecting Hookdeck retries?

Verification (core)

Signed content is {svix-id}.{svix-timestamp}.{raw body}. Svix signs it with HMAC-SHA256 using the base64-decoded secret (the part after whsec_), base64-encodes the result, and sends one or more space-separated v1,<signature> entries. Use the official svix library, which compares in constant time. Read the svix-* headers, and when svix-id is absent fall back to the webhook-* headers (webhook-id, webhook-timestamp, webhook-signature), as Hookdeck does.

import { Webhook } from 'svix'; // svix 2.x is ESM-only

const prefix = req.headers['svix-id'] ? 'svix' : 'webhook';
const id = req.headers[`${prefix}-id`];
const timestamp = req.headers[`${prefix}-timestamp`];
const signature = req.headers[`${prefix}-signature`];
// rawBody: the raw Buffer/string, never re-serialized JSON
new Webhook(process.env.TENSORLAKE_WEBHOOK_SECRET).verify(rawBody, {
  'svix-id': id, 'svix-timestamp': timestamp, 'svix-signature': signature,
  'webhook-id': id, 'webhook-timestamp': timestamp, 'webhook-signature': signature,
}); // throws on a bad signature or a timestamp outside the window
const event = JSON.parse(rawBody.toString('utf8')); // parse only after verify passes

from svix.webhooks import Webhook, WebhookVerificationError

wh = Webhook(os.environ["TENSORLAKE_WEBHOOK_SECRET"])  # "whsec_..."
wh.verify(raw_body, {"svix-id": id, "svix-timestamp": ts, "svix-signature": sig,
                     "webhook-id": id, "webhook-timestamp": ts, "webhook-signature": sig})

For complete handlers with tests, see examples/express/, examples/nextjs/, examples/fastapi/.

Each destination has its own signing secret: open the project's Webhooks page in Tensorlake Cloud, open the destination, and copy the value under Signing secret. It begins with whsec_. Keep the full value in TENSORLAKE_WEBHOOK_SECRET. Handlers fail closed: with the variable unset (or not a whsec_ value) they return 500 instead of accepting anything. Tensorlake points at Svix's libraries and manual procedure; the svix library used here reads either header set, so no mapping is needed beyond the fallback shown.

Hookdeck retries and replays hit the 5-minute window

The svix and standardwebhooks libraries always enforce a fixed 5-minute timestamp window, and it can't be configured. Hookdeck retries and replays resend the original svix-timestamp, so the library rejects any retry or replay that happens more than 5 minutes after the original delivery. If you verify behind Hookdeck (or replay old events), use the manual verifier in references/verification.md, where the window can be dropped or widened. Deduplicate on event_id instead of relying on the timestamp.

Common Event Types

12 events are documented (the list may not be exhaustive). The name is event_type in the JSON body, and the examples handle all of them:

See references/overview.md for the full catalog and payload shapes.

Environment Variables

# Signing secret of the webhook endpoint (Svix format, starts with whsec_)
TENSORLAKE_WEBHOOK_SECRET=whsec_xxxxx

Local Development

# Start tunnel (no account needed)
npx hookdeck-cli listen 3000 tensorlake --path /webhooks/tensorlake

Register the tunnel URL as a destination on the project's Webhooks page in Tensorlake Cloud, then send a synthetic event with Test webhook on the destination's page.

Reference Materials

• references/overview.md - Tensorlake webhook concepts, events, payload shapes, delivery
• references/setup.md - Create a destination, get the secret, send a test event
• references/verification.md - Svix verification details, header fallback, manual verifier, timestamp window