Document accepted keys for spend-request --line-item

[pejmanjohn]

Summary

link-cli spend-request create --help documents --line-item as "Line item (repeatable, key:value format)", but it does not show which keys are accepted. As an agent integrating against the CLI, I tried a natural key (amount) and got a runtime validation error.

Repro

link-cli spend-request create \
  --payment-method-id '<payment-method-id>' \
  --credential-type card \
  --amount 2644 \
  --currency usd \
  --merchant-name 'Olympia Coffee Roasting Company' \
  --merchant-url 'https://www.olympiacoffee.com/products/big-truck' \
  --context 'Purchase one 12 oz bag of Olympia Coffee Big Truck whole bean coffee for Pejman Pour-Moezzi, including USPS Ground Advantage shipping to the Mercer Island home address.' \
  --line-item 'name:Big Truck whole bean coffee,quantity:1,amount:1950' \
  --format json

Actual result

{
  "code": "UNKNOWN",
  "message": "Line item: Unrecognized key: \"amount\""
}

Expected / request

Please make the accepted line-item schema discoverable from the CLI. A few options that would help agents:

• Include allowed keys directly in spend-request create --help
• Include at least one valid --line-item example
• Improve the validation error to say something like: Unrecognized key "amount". Allowed keys: ...
• Expose the schema through --schema in a way that clearly shows allowed line-item keys

Why this matters

Agents will infer common ecommerce field names (amount, price, unit_amount, etc.) unless the CLI tells them otherwise. Runtime trial-and-error is avoidable here, and it makes an otherwise clean flow feel brittle.

Environment

link-cli 0.4.0 (build 1)