Edits a page by element id WITHOUT re-sending the whole source — the surgical-edit and fix-after-error path. Targets EITHER a live page (page_id) OR a cached draft source (draft_id). Draft sources come from: (a) create_page — failed validation or timed-out network call → patched/committed tree is CREATED as a new page once valid; (b) add_section dry_run or validation/network failure → patched/committed shell is APPENDED to the stored page once valid; (c) update_page or live-page patch_page — timed-out/failed network call → re-committed via updatePageSource. Send only a list of per-element ops; the MCP loads the source, applies them, validates the WHOLE merged tree (blocks on errors), and saves. Ops: {op:'update',id,type?,specials?,styles?:{desktop?,mobile?},config?:{desktop?,mobile?},events?,properties?} (shallow-merges; op defaults to 'update'; `type` fixes a wrong element type; update CANNOT delete an existing/stray key — schema 'additional properties' errors need op:'replace'), {op:'replace',id,element}, {op:'remove',id}, {op:'add',parent_id,element}. EMPTY/OMITTED patches with a draft_id = commit the cached draft as-is (skip apply, still validate, then honor dry_run) — this is the RETRY PATH after a timeout. Use this to fix the elements a failed create_page/update_page/add_section reported instead of rebuilding. DEFAULTS to dry_run=true (loads + merges + validates + previews, no write); dry_run=false to save. Needs WEBCAKE_API_BASE + WEBCAKE_JWT (a draft_id sections-patch only needs creds to actually append; a page_id patch reads the live page so needs creds even on dry_run).