feat(userspace): programs in /bin w/o .elf; bin manifests (needs = display) so shell runs snake; Ctrl+C kills foreground via terminal interrupt notification; ctrl keys; sleep

docs/ipc.md

@@ -116,12 +116,21 @@ font. Its output side is the log protocol (`types::log`), so a program whose
 log endpoint is the terminal prints there with `println!`: standard output
 is whatever text endpoint a program was given. `READ` (`types::terminal`)
 blocks until a line is typed and returns it in chunks, the last ending in
-`\n`. The desktop is the shell, given the terminal, storage and a spawn
-allowance. A command that is not a built-in runs `name.elf`: the shell
-spawns it, gives it a call-only copy of the terminal (as its log, so its
-output) and a read-only storage grant to the shell's current directory
-(`cd`, `pwd`), writes its arguments page, starts it, waits for its death
-and releases the grant.
+`\n`. Ctrl+C there drops the line. Keys typed while no line is read are
+kept for the next one, except Ctrl+C, which signals the notification its
+first `ON_INTERRUPT` caller gave. `REDRAW` repaints the screen and takes
+input focus back.
+
+The desktop is the shell, given the terminal, storage, the display and a
+spawn allowance. Programs live in `/bin`, without extensions. A command
+that is not a built-in runs `/bin/name`: the shell spawns it, gives it a
+call-only copy of the terminal (as its log, so its output) and a read-only
+storage grant to the shell's current directory (`cd`, `pwd`), writes its
+arguments page, starts it, waits for its death (Ctrl+C kills it) and
+releases the grant. `/bin/name.manifest` (`types::manifest`) asks for more:
+`needs = display` gets the display (`StartArg::display`), with which the
+program takes focus; the shell has the terminal redraw once it is gone. A
+need the shell does not know, it refuses to run.
 
 Only init holds `ProcessCreate`. Everyone else runs programs through init's
 spawn service (`types::spawn`, client `libkos::spawn`), which init serves