The temporary namespace is no longer a note

Two left: one path length both implementations agree on, and a bound on
directory entries that keeps every one of them nameable as a parent.

NOTES.md

@@ -2,25 +2,6 @@
 
 Temporary notes from the SBFS v2 and CosmOS review, in priority order.
 
-## Protect the temporary-file namespace
-
-Whole-file saves and streamed writes use the fixed names `sbfs.part` and `sbfs.out`.
-Starting another operation deletes an existing entry with the corresponding name as stale
-temporary output, but these are otherwise legal user filenames. A real user file with one
-of those names can therefore be deleted.
-
-Possible resolutions:
-
-- Reserve these names and refuse ordinary creation under them.
-- Use a spare descriptor flag to identify temporary entries, and clean up by identity
-  rather than by name.
-- Move temporary artifacts into a defined `/tmp` policy where appropriate. A stream's
-  temporary currently needs to be in the destination directory because rename changes a
-  name but not a parent, so `/tmp` alone may require adding a move operation.
-
-Whatever rule is chosen should be enforced in both SplitDisk and the native SBFS code and
-documented as part of the format or CosmOS policy.
-
 ## Establish one portable path-length limit
 
 SplitDisk carries paths up to 511 characters, while the native path machinery appears to