chini-007-payment-webhook

Payment Webhook Receiver

Accept inbound webhooks. Never lose one. Never double-process one.

Source: Classic system-design interview corpus (Stripe / Shopify webhook ingest)

Prompt

Design a webhook-receiver service for a payment processor.

Functional:
- POST /webhook accepts JSON events from Stripe-like upstream providers.
- Each event has a unique id; processing must be idempotent (no double charges).
- Downstream consumers (ledger, email, fulfillment) read processed events.

Non-functional:
- A 3x burst of events during a sale must not lose any.
- If a downstream consumer is slow or down, the receive path must keep accepting webhooks (the upstream will give up and stop retrying if you 5xx for too long).
- Retries from the upstream must be deduped, not double-processed.

Return a Chinilla CanvasState. A durable queue between accept and consumers is almost certainly required, plus dedup storage.

Constraints

Max components: 11
Required behaviors: queue, storage, retry
Monthly budget: $600

Stress scenarios

Baseline events

baseline

Steady webhook volume.

3x sale burst

spike

Black Friday sale triples webhook volume.

Consumer outage

outage

A downstream consumer is offline. Receive path must still accept events.

Pass criteria (overall)

Min stability score: 70
Max drop rate: 4.0%
Min delivery rate: 92.0%
Max errors: 4

Submit your run

Submissions go through the chini-bench CLI. It calls your model with your key, scores the result locally, and posts to the leaderboard. Nothing leaves your machine except the canvas it produces.

End-to-end:

pip install git+https://github.com/collapseindex/chini-bench-cli.git
export OPENROUTER_API_KEY=...

chini-bench run chini-007-payment-webhook \
  --provider openrouter --model google/gemini-2.0-flash-001 \
  --as alice --x alice --linkedin alice-builds

Or inspect the prompt first:

chini-bench prompt chini-007-payment-webhook

Providers: openai · anthropic · google · openrouter · ollama

Leaderboard

Rank	Submitter	Model	Score	Stability	Delivery	Design	Pass	Links
#1	alex default	O openai/gpt-5.4	88	70.0	100.0	100.0	✓	X
#2	alex default	A anthropic/claude-sonnet-4.6	80	84.0	67.0	100.0	✗	X
#3	alex default	G google/gemini-3.1-pro-preview	80	84.0	67.0	100.0	✗	X
#4	alex default	X x-ai/grok-4.20	73	65.0	67.0	100.0	✗	X

Per-scenario breakdown of the top run

Scenario	Health	Drop rate	Delivered	Pass
baseline	71.0	0.0%	332	✓
sale-burst	70.0	0.0%	993	✓
consumer-down	68.0	0.0%	15	✓

How is this scored? →