fix(tcsh): escape special characters correctly

src/prompt/engine.go

@@ -108,17 +108,19 @@ func (e *Engine) pwd() {
 }
 
 func (e *Engine) getNewline() string {
-	// WARP terminal will remove \n from the prompt, so we hack a newline in.
+	if e.Plain || e.Env.Flags().Debug {
+		return "\n"
+	}
+
+	// Warp terminal will remove a newline character ('\n') from the prompt, so we hack it in.
 	// For Elvish, we do this to prevent cutting off a right-aligned block.
 	if e.isWarp() || e.Env.Shell() == shell.ELVISH {
 		return terminal.LineBreak()
 	}
 
-	// TCSH needs a space before the LITERAL newline character or it will not render correctly
-	// don't ask why, it be like that sometimes.
-	// https://unix.stackexchange.com/questions/99101/properly-defining-a-multi-line-prompt-in-tcsh#comment1342462_322189
+	// To avoid improper translations in Tcsh, we use an invisible word joiner character (U+2060) to separate a newline from possible preceding escape sequences.
 	if e.Env.Shell() == shell.TCSH {
-		return ` \n`
+		return "\u2060\\n"
 	}
 
 	return "\n"

src/shell/formats.go

@@ -73,6 +73,9 @@ func GetFormats(shell string) *Formats {
 			ITermPromptMark:       "%{$(iterm2_prompt_mark)%}",
 			ITermCurrentDir:       "%%{\x1b]1337;CurrentDir=%s\x07%%}",
 			ITermRemoteHost:       "%%{\x1b]1337;RemoteHost=%s@%s\x07%%}",
+			EscapeSequences: map[rune]string{
+				'%': "%%",
+			},
 		}
 	default:
 		formats = &Formats{
@@ -98,10 +101,9 @@ func GetFormats(shell string) *Formats {
 		}
 	}
 
-	if shell == ZSH {
-		formats.EscapeSequences = map[rune]string{
-			'%': "%%",
-		}
+	if shell == TCSH {
+		formats.EscapeSequences['\\'] = `\\`
+		formats.EscapeSequences['!'] = `\!`
 	}
 
 	return formats