Log incoming webhook events to Google Sheets

An operations team describes their process like this: "Whenever our payment processor
sends a webhook for a completed transaction, I want a new row added to a Google Sheet
with the date, customer email, amount, and transaction ID, so finance has a running
log without needing processor dashboard access."

AVAILABLE TOOLS: [Payment processor webhook (trigger), Uncanny Automator, Google
Sheets]

Turn this into an implementation-ready automation recipe, thinking through what the
plain description leaves ambiguous:
1. Trigger: the exact webhook event type to listen for, distinguishing a genuinely
   completed transaction from a "payment.succeeded" event that's later followed by a
   "charge.refunded" event for the same transaction ID, since the sheet needs to
   reflect the refund, not just silently keep the original row as if nothing changed.
2. Conditions: state the exact dedup logic against transaction ID, since payment
   processors are known to redeliver the same webhook multiple times if their retry
   logic doesn't get a fast enough acknowledgment, and a naive append-only recipe
   would create duplicate rows for the same transaction.
3. Actions in order: look up the transaction ID in the sheet first, update the
   existing row if a refund event arrives for it, otherwise append a new row, then
   format the amount as currency and the date in a consistent timezone rather than
   whatever the webhook payload happens to use.
4. Failure handling: if Google Sheets' API rate limit is hit during a burst of
   transactions, should events queue and retry, and how do you guarantee ordering
   isn't scrambled when the retry catches up out of sequence.
5. One edge case specific to this exact workflow: a webhook payload missing the
   customer email field due to a guest checkout with only a phone number on file.
   Decide what placeholder or fallback value the recipe writes instead of leaving the
   cell blank in a way that breaks a later VLOOKUP.

Replace the workflow description and available tools with your own.