Google Docs whoami (signed-in account)
Report which Google account Google Docs/Sheets is signed in as in this browser: display name and email, read from Google's account button. Being signed out is reported as a normal answer (loggedIn false), not an error, so it can be used to check a session before running other Docs or Sheets scripts.
Input
None
Output
loggedIn requiredname optionalemail optionalFAQ
Sheets: new spreadsheet
Create a new Google Spreadsheet in My Drive, optionally with a title. Returns spreadsheetId, url, and firstGid (always 0). The file lands in Drive root (My Drive); moving it elsewhere is a Drive action, not a Sheets one.
Sheets: add tab
Add a tab to a Google Spreadsheet, optionally naming it in the same pass. Returns the new tab's gid and final name. Waits for the editor's save before resolving; needs edit rights.
Sheets: write cells
Write a 2D block of values into one tab of a Google Spreadsheet, top-left at startCell, like the Sheets API: null leaves a cell as it is, "" clears it, anything else replaces it as if typed (dropdown rules and formatting stay; clearing a dropdown cell removes its dropdown). Returns range, rows, cols, saved once every edit is saved. A value the sheet refuses (data validation, outside the grid) stops the run with the sheet's own message. Values are parsed per the spreadsheet locale ("1.5" in a FR sheet becomes 1 May; prefix ' to force text); leading = enters a formula; needs edit rights.
