Log every finished Hireflix interview to Google Sheets

Build a deterministic code workflow that appends one row to a Google Sheet every time a candidate finishes a Hireflix interview. No LLM reasoning in the flow. The sheet is the durable source of truth for hiring managers who do not log in to Hireflix.

Trigger: a Hireflix webhook on the interview.finished event. The workflow config must expose the Hireflix webhook secret so the incoming request's x-hireflix-signature header (Base64 HMAC-SHA256 of the raw body) is verified before any downstream step runs. Reject invalid signatures with a 401.

Steps, in order:

1. Parse the webhook body and pull out the interview id, position id, candidate name, candidate email, current status, reviewer score (if present), shortlist flag (if present), and the finish timestamp.

2. Call the Hireflix operation Fetch Interview Results using the interview id to enrich the row with the latest position title, latest status, latest reviewer score, and the current shortlist flag. This handles cases where the webhook payload is stale or missing fields.

3. Convert the finish timestamp from Unix epoch milliseconds (Hireflix's standard timestamp format per common_docs) to an ISO 8601 UTC string before writing to the sheet.

4. Build the admin URL for the interview using the pattern https://admin.hireflix.com/en/positions/<positionId>/interviews/<interviewId> so reviewers can click straight through from the sheet.

5. Call the Google Sheets operation Append Values on the configured spreadsheet and tab to write exactly one row. Use valueInputOption USER_ENTERED so timestamps and numbers are typed correctly for filtering and sorting. Default column order: Timestamp (ISO), Position Title, Candidate Name, Candidate Email, Status, Reviewer Score, Shortlisted, Interview URL.

Configuration surface (all editable in workflow config, no code edits required): Google Sheets spreadsheet ID, tab name (default "Hireflix Interviews"), a column-mapping object so users can point at an existing sheet where the header row is in a different order, and the Hireflix webhook secret. Keep the column mapping declarative so a non-technical user can rearrange it.

Rules: strictly deterministic, no model calls. If a field is missing (e.g. no reviewer score yet), write an empty cell rather than failing the run. On Google Sheets 429 responses, retry with exponential backoff (start ~1s, cap ~64s, jitter). On Hireflix errors, log the interview id and the __typename of the returned error and stop; do not silently write a partial row.