Recurse terminal autodetection for tmux/screen

Author: japhb

Changes

@@ -1,6 +1,10 @@
 Revision history for Terminal-Capabilities
 
 {{$NEXT}}
+  [Features]
+  - Recursively detect underlying terminal when detecting tmux or screen,
+    forcing disabled any capabilities broken by the multiplexer app
+
 
 0.0.7  2025-10-06T00:24:02-07:00
   [Bug Fix]

bin/terminal-autodetect

@@ -22,6 +22,7 @@ sub show-env() {
     section('Konsole',     < KONSOLE_DBUS_SERVICE KONSOLE_DBUS_SESSION KONSOLE_DBUS_WINDOW >);
     section('MLTerm',      [ 'MLTERM', ]);
     section('Qt',          < D_DISABLE_RT_SCREEN_SCALE QT_SCALE_FACTOR_ROUNDING_POLICY >);
+    section('screen',      < STY WINDOW TERMCAP >);
     section('Terminator',  < TERMINATOR_DBUS_NAME TERMINATOR_DBUS_PATH TERMINATOR_UUID >);
     section('Terminology', < TERMINOLOGY XTERM_256_COLORS >);
     section('tmux',        < TMUX TMUX_PANE >);

lib/Terminal/Capabilities/Autodetect.rakumod

@@ -177,19 +177,41 @@ sub terminal-env-detect() is export {
         $terminal    = 'tmux';
         $version     = %*ENV<TERM_PROGRAM_VERSION>;
 
-        # XXXX: Limited by symbol-set of underlying terminal emulator too
-        $symbol-set  = symbol-set('Full') if $has-utf8;
-
-        # XXXX: Detection of underlying terminal emulator to AND with these?
-        $italic      = True;
-        $emoji-text  = True;
-        $emoji-color = True;
-        $emoji-skin  = True;
-        $emoji-iso   = True;
+        # tmux breaks these, regardless of underlying terminal
+        $color24bit  = False;
         $emoji-reg   = False;
         $emoji-zwj   = False;
+
+        # Try to recurse to detect underlying terminal's capabilities
+        temp %*ENV<TERM> = $term eq 'tmux-256color' ?? 'xterm-256color' !! 'xterm';
+        my ($under-caps, $under-terminal, $under-version) = terminal-env-detect;
+
+        my $caps   = $under-caps.clone(:$color24bit, :$emoji-reg, :$emoji-zwj);
+        $terminal ~= ' on ' ~ $under-terminal;
+        $terminal ~= ' version ' ~ $under-version if $under-version;
+
+        return ($caps, $terminal, $version);
+    }
+    elsif ?$term.starts-with('screen') {
+        $terminal    = 'screen';
+
+        # Screen breaks these, regardless of underlying terminal
+        $italic      = False;
+        $color24bit  = False;
+
+        # Try to recurse to detect underlying terminal's capabilities
+        if $term ~~ /^ 'screen.' (.+) $/ {
+            temp %*ENV<TERM> = ~$0;
+            my ($under-caps, $under-terminal, $under-version) = terminal-env-detect;
+
+            my $caps   = $under-caps.clone(:$italic, :$color24bit);
+            $terminal ~= ' on ' ~ $under-terminal;
+            $terminal ~= ' version ' ~ $under-version if $under-version;
+
+            return ($caps, $terminal, $version);
+        }
     }
-    elsif ?$term.starts-with('screen'|'vt220'|'vt420')
+    elsif ?$term.starts-with('vt220'|'vt420')
        || ?$term.lc.contains('color'|'ansi'|'cygwin'|'linux') {
         $terminal    = $term;
         $color3bit   = True;