Don't send kitty kbd protocol probe until ECHO is disabled

With tmux 3.0 (from 2019) inside SSH, the CSI 5n response is echoed.
I guess with all other terminals we were just lucky.  Move it to
right after where we disable ECHO I guess.

In general, asynchronous requests create a lot of potential for error,
we should try to get away from them.

src/bin/fish_key_reader.rs

@@ -9,19 +9,19 @@
 
 use std::{ops::ControlFlow, os::unix::prelude::OsStrExt};
 
-use libc::{STDIN_FILENO, TCSANOW, VEOF, VINTR};
+use libc::{STDIN_FILENO, STDOUT_FILENO, TCSANOW, VEOF, VINTR};
 
 #[allow(unused_imports)]
 use fish::future::IsSomeAnd;
 use fish::{
     builtins::shared::BUILTIN_ERR_UNKNOWN,
-    common::{shell_modes, str2wcstring, PROGRAM_NAME},
+    common::{shell_modes, str2wcstring, write_loop, PROGRAM_NAME},
     env::env_init,
     eprintf, fprintf,
     input::input_terminfo_get_name,
     input_common::{
         terminal_protocol_hacks, terminal_protocols_enable_ifn, CharEvent, InputEventQueue,
-        InputEventQueuer,
+        InputEventQueuer, KITTY_PROGRESSIVE_ENHANCEMENTS_QUERY,
     },
     key::{char_to_symbol, Key},
     panic::panic_handler,
@@ -137,6 +137,7 @@ fn setup_and_process_keys(continuous_mode: bool, verbose: bool) -> i32 {
     unsafe { libc::tcsetattr(STDIN_FILENO, TCSANOW, &*shell_modes()) };
 
     terminal_protocol_hacks();
+    let _ = write_loop(&STDOUT_FILENO, KITTY_PROGRESSIVE_ENHANCEMENTS_QUERY);
 
     if continuous_mode {
         eprintf!("\n");

src/input_common.rs

@@ -451,6 +451,8 @@ macro_rules! kitty_progressive_enhancements {
     };
 }
 
+pub const KITTY_PROGRESSIVE_ENHANCEMENTS_QUERY: &[u8] = b"\x1b[?u\x1b[5n";
+
 static IS_TMUX: RelaxedAtomicBool = RelaxedAtomicBool::new(false);
 pub static IN_MIDNIGHT_COMMANDER_PRE_CSI_U: RelaxedAtomicBool = RelaxedAtomicBool::new(false);
 static IN_ITERM_PRE_CSI_U: RelaxedAtomicBool = RelaxedAtomicBool::new(false);
@@ -468,8 +470,6 @@ pub fn terminal_protocol_hacks() {
                 version < (3, 5, 6)
             }),
     );
-    // Request kitty progressive enhancement value and primary device attribute.
-    let _ = write_loop(&STDOUT_FILENO, b"\x1b[?u\x1b[5n");
 }
 
 fn parse_version(version: &wstr) -> Option<(i64, i64, i64)> {

src/reader.rs

@@ -82,6 +82,7 @@
 use crate::input_common::InputEventQueuer;
 use crate::input_common::WaitingForCursorPosition;
 use crate::input_common::IN_MIDNIGHT_COMMANDER_PRE_CSI_U;
+use crate::input_common::KITTY_PROGRESSIVE_ENHANCEMENTS_QUERY;
 use crate::input_common::{
     terminal_protocol_hacks, terminal_protocols_enable_ifn, CharEvent, CharInputStyle, InputData,
     ReadlineCmd,
@@ -2083,6 +2084,13 @@ fn readline(&mut self, nchars: Option<NonZeroUsize>) -> Option<WString> {
             }
         }
 
+        static queried: RelaxedAtomicBool = RelaxedAtomicBool::new(false);
+        if !queried.load() {
+            queried.store(true);
+            // Query for kitty keyboard protocol support.
+            let _ = write_loop(&STDOUT_FILENO, KITTY_PROGRESSIVE_ENHANCEMENTS_QUERY);
+        }
+
         // HACK: Don't abandon line for the first prompt, because
         // if we're started with the terminal it might not have settled,
         // so the width is quite likely to be in flight.