Keep prompt colors when switching local TERM to xterm-256color

Resources/shell-integration/.zshenv

@@ -27,6 +27,20 @@ fi
     # zsh treats unset ZDOTDIR as if it were HOME. We do the same.
     builtin typeset _cmux_file="${ZDOTDIR-$HOME}/.zshenv"
     [[ ! -r "$_cmux_file" ]] || builtin source -- "$_cmux_file"
+
+    if [[ -o interactive \
+       && -z "${ZSH_EXECUTION_STRING:-}" \
+       && "${CMUX_SHELL_INTEGRATION:-1}" != "0" \
+       && -n "${CMUX_SHELL_INTEGRATION_DIR:-}" \
+       && -r "${CMUX_SHELL_INTEGRATION_DIR}/cmux-zsh-integration.zsh" \
+       && "${TERM:-}" == "xterm-256color" \
+       && -z "${CMUX_ZSH_RESTORE_TERM:-}" ]]; then
+        # Keep startup TERM-compatible prompt/theme selection during shell init,
+        # then restore the managed xterm-256color identity before the first
+        # interactive command executes.
+        builtin export CMUX_ZSH_RESTORE_TERM="$TERM"
+        builtin export TERM="xterm-ghostty"
+    fi
 } always {
     if [[ -o interactive ]]; then
         # We overwrote GhosttyKit's injected ZDOTDIR, so manually load Ghostty's

Resources/shell-integration/cmux-zsh-integration.zsh

@@ -981,6 +981,7 @@ _cmux_command_starts_nested_shell() {
 }
 
 _cmux_preexec() {
+    _cmux_restore_terminal_identity_after_startup
     _cmux_tmux_sync_cmux_environment
 
     if [[ -z "$_CMUX_TTY_NAME" ]]; then
@@ -1214,6 +1215,13 @@ _cmux_fix_path() {
     add-zsh-hook -d precmd _cmux_fix_path
 }
 
+_cmux_restore_terminal_identity_after_startup() {
+    if [[ -n "${CMUX_ZSH_RESTORE_TERM:-}" ]]; then
+        builtin export TERM="$CMUX_ZSH_RESTORE_TERM"
+        builtin unset CMUX_ZSH_RESTORE_TERM
+    fi
+}
+
 _cmux_zshexit() {
     _cmux_stop_git_head_watch
     _cmux_stop_pr_poll_loop

Resources/terminfo-overlay/README.md

@@ -1,15 +1,14 @@
 # cmux terminfo overlay
 
-cmux ships Ghostty's `xterm-ghostty` terminfo entry, but the embedded
-renderer in cmux has differed from Ghostty's app renderer in how it treats
-the "bright" SGR 90-97/100-107 sequences.
+cmux ships patched `xterm-ghostty` and `xterm-256color` terminfo entries so
+the embedded renderer keeps the same color behavior even when the reported
+`TERM` changes.
 
-This overlay patches the terminfo capabilities so that `tput setaf 8` (and
+These overlays patch the terminfo capabilities so that `tput setaf 8` (and
 similar "bright" colors) uses 256-color indexed sequences (`38;5;<n>m` /
 `48;5;<n>m`) rather than SGR 90-97/100-107. This avoids relying on bright SGR
 handling and fixes zsh-autosuggestions (default `fg=8`) visibility issues in
-cmux.
+cmux while preserving Ghostty's truecolor capabilities.
 
 The build phase `Copy Ghostty Resources` overlays this directory onto the app
 bundle's `Contents/Resources/terminfo` after copying Ghostty's resources.
-

Sources/GhosttyTerminalView.swift

@@ -3133,15 +3133,14 @@ final class TerminalSurface: Identifiable, ObservableObject {
     private var backgroundSurfaceStartQueued = false
     private var surfaceCallbackContext: Unmanaged<GhosttySurfaceCallbackContext>?
     /// The desired focus state for the Ghostty C surface. May be set before the
-    /// C surface exists (e.g. during layout restoration); `createSurface` seeds
-    /// the initial runtime focus state from this value, then keeps using it as a
-    /// dedup guard to avoid redundant `ghostty_surface_set_focus` calls
+    /// C surface exists (e.g. during layout restoration); `createSurface`
+    /// reapplies this value once the runtime surface exists, then keeps using it
+    /// as a dedup guard to avoid redundant `ghostty_surface_set_focus` calls
     /// (prevents prompt redraws with P10k).
     ///
     /// Start unfocused and only opt into focus when the workspace/AppKit focus
-    /// path explicitly requests it. `createSurface` passes this through as the
-    /// runtime surface's initial focus state so background panes never need a
-    /// synthetic focus-loss transition during creation.
+    /// path explicitly requests it so background panes do not keep a focused
+    /// state unless the workspace focus path requests it.
     private var desiredFocusState: Bool = false
 #if DEBUG
     private var needsConfirmCloseOverrideForTesting: Bool?
@@ -3255,6 +3254,22 @@ final class TerminalSurface: Identifiable, ObservableObject {
         return merged
     }
 
+    static let managedTerminalType = "xterm-256color"
+    static let managedTerminalProgram = "ghostty"
+    static let managedColorTerm = "truecolor"
+
+    static func applyManagedTerminalIdentityEnvironment(
+        to environment: inout [String: String],
+        protectedKeys: inout Set<String>
+    ) {
+        environment["TERM"] = managedTerminalType
+        protectedKeys.insert("TERM")
+        environment["COLORTERM"] = managedColorTerm
+        protectedKeys.insert("COLORTERM")
+        environment["TERM_PROGRAM"] = managedTerminalProgram
+        protectedKeys.insert("TERM_PROGRAM")
+    }
+
     static func mergedStartupEnvironment(
         base: [String: String],
         protectedKeys: Set<String>,
@@ -3769,7 +3784,6 @@ final class TerminalSurface: Identifiable, ObservableObject {
         surfaceCallbackContext?.release()
         surfaceCallbackContext = callbackContext
         surfaceConfig.scale_factor = scaleFactors.layer
-        surfaceConfig.focused = desiredFocusState
         surfaceConfig.context = surfaceContext
 #if DEBUG
         let templateFontText = String(format: "%.2f", surfaceConfig.font_size)
@@ -3790,6 +3804,10 @@ final class TerminalSurface: Identifiable, ObservableObject {
         var env = baseConfig.environmentVariables
 
         var protectedStartupEnvironmentKeys: Set<String> = []
+        Self.applyManagedTerminalIdentityEnvironment(
+            to: &env,
+            protectedKeys: &protectedStartupEnvironmentKeys
+        )
         func setManagedEnvironmentValue(_ key: String, _ value: String) {
             env[key] = value
             protectedStartupEnvironmentKeys.insert(key)

Sources/cmuxApp.swift

@@ -229,11 +229,15 @@ struct cmuxApp: App {
         }
 
         if getenv("TERM") == nil {
-            setenv("TERM", "xterm-ghostty", 1)
+            setenv("TERM", TerminalSurface.managedTerminalType, 1)
+        }
+
+        if getenv("COLORTERM") == nil {
+            setenv("COLORTERM", TerminalSurface.managedColorTerm, 1)
         }
 
         if getenv("TERM_PROGRAM") == nil {
-            setenv("TERM_PROGRAM", "ghostty", 1)
+            setenv("TERM_PROGRAM", TerminalSurface.managedTerminalProgram, 1)
         }
 
         if let resourcesDir = getenv("GHOSTTY_RESOURCES_DIR").flatMap({ String(cString: $0) }) {