id	example-pydantic-validation
type	example
title	Validate Untrusted Boundary Payloads
summary	Parse, sanitize, and validate messy external payloads with field normalization and structured error contracts.
lang	en-US
content_version	1
status	reviewed
reviewed_on	2026-09-02

Validate Untrusted Boundary Payloads

External payloads from webhooks, mobile clients, and LLM tool calls are untrusted. They frequently arrive with mixed camelCase and snake_case keys, dirty currency strings, or invalid enum states. A production boundary validator must sanitize valid variations and return structured errors without crashing.

python examples/pydantic-validation/verify.py starter --expect-failure
python examples/pydantic-validation/verify.py solution

The first command reports the expected failures from the naive starter. The second verifies the robust solution. Give TASK.md to a coding agent, ask it to fix only starter/validator.py, and run:

python examples/pydantic-validation/verify.py starter