Save and delete files in an aindrive drive without overwriting another change (#2)

README.md

@@ -27,15 +27,28 @@ that machine runs aindrive; until then they report the folder unavailable.
 
 ## What works
 
-Browsing folders and reading files. aindrive reads a file whole, at most
-8 MiB at a time, so a larger file is refused as unsupported rather than cut
-short. A read is checked against the size the drive reported a moment before,
-so a file that changes in between is a conflict rather than a mix of two
-versions. Names the drive's machine allows but Memona cannot show, such as one
-containing a backslash, are left out of listings.
+Browsing folders, and reading, saving and deleting files. A token generated
+as **Read only** opens the drive read-only.
 
-Saving, creating folders, renaming and deleting are not supported yet, and
-neither is change polling.
+aindrive reads a file whole, at most 8 MiB at a time, so a larger file is
+refused as unsupported rather than cut short. A read is checked against the
+size the drive reported a moment before, so a file that changes in between is
+a conflict rather than a mix of two versions.
+
+A save sends the file whole, up to 1 MiB, the most Memona saves in one
+transfer. It names the revision it was read at, and aindrive compares and
+writes under one lock, so a file someone changed since is reported as a
+conflict instead of being overwritten. A save into a folder that does not
+exist yet creates that folder, as aindrive does.
+
+Deleting takes one file. A folder is refused: aindrive deletes a folder with
+everything in it, and leaves some entries, such as `.git`, out of every
+listing, so a folder cannot be shown to be empty first.
+
+Creating folders, renaming and change polling are not supported, since the
+drive's MCP endpoint offers no tool for them. Names the drive's machine allows
+but Memona cannot show, such as one containing a backslash, are left out of
+listings.
 
 ## Building