Fill a PDF form using facts found in supporting documents. Emboss reads the answers out of context_text and/or context_urls (public https links to PDFs, Word, spreadsheets, images, or text) and fills the form. Give form_id for a form already in the library, or pdf_url/pdf_base64 for a new one. Give library= from find_form to start from a form Emboss already keeps. policy is safe (write high and medium confidence) or strict (high only). Returns a job_id; poll get_job about every 20 seconds. Billed as one context fill; the first 5 each month are free. Optional retention: ephemeral or account_default (default: the account's own setting); it applies only when this call creates the form (pdf_url, pdf_base64 or library), since an existing form keeps the setting it was created with. Ephemeral processing: source and output documents are deleted 60 to 70 minutes after the last activity on a form.