feat(ipc): saved replies: SaveReply/ReplySaved (8 per thread, released on thread death, unforgeable); terminal READ saved until Enter (line.rs editor, reader queue), now pinged

crates/types/src/bounded.rs

@@ -3,6 +3,8 @@ use crate::macros::bounded;
 // Kani runs the real kernel with tiny tables; see kernel/src/proofs.
 bounded!(CapSlot, u8, 0, if cfg!(kani) { 3 } else { 63 });
 bounded!(Priority, u8, 0, 31);
+// A caller a server thread saved to answer later; a thread keeps up to 8.
+bounded!(SavedReply, u8, 0, 7);
 // Up to a process's whole address window (32 MiB): one request may be big (a
 // KDF's memory); budgets bound how much anyone gets.
 bounded!(PageCount, u16, 1, 8192);

crates/types/src/syscall_abi.rs

@@ -43,6 +43,8 @@ pub const SYS_MAP_REGION: usize = 34;
 pub const SYS_REGION_ADDRESS: usize = 35;
 pub const SYS_WATCH_DEATH: usize = 36;
 pub const SYS_SET_TIMER: usize = 37;
+pub const SYS_SAVE_REPLY: usize = 39;
+pub const SYS_REPLY_SAVED: usize = 40;
 
 /// `PagePerms` in a register.
 pub const PERMS_READ_ONLY: usize = 0;