Add UX enhancements: modals for env vars and instructions, global env vars, taskbar icon fix

- Fix Windows taskbar icon by loading icon.ico instead of icon.png (ICO contains
  multiple sizes native to Windows taskbar/title bar/alt-tab)
- Add "Container must be stopped to change settings" warning banner in config panel
- Move per-project Environment Variables and Claude Instructions into modal dialogs
  for more editing space, with buttons in the config panel to open them
- Move global Claude Instructions into a modal in Settings panel
- Add default global Claude instruction recommending git initialization
- Add global environment variables support (full stack: Rust model, TS types,
  container creation with merge logic where project overrides global for same key,
  fingerprinting for recreation checks, and Settings UI with modal)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src-tauri/src/commands/project_commands.rs

@@ -170,6 +170,7 @@ pub async fn start_project_container(
                     &existing_id,
                     &project,
                     settings.global_claude_instructions.as_deref(),
+                    &settings.global_custom_env_vars,
                 )
                 .await
                 .unwrap_or(false);
@@ -185,6 +186,7 @@ pub async fn start_project_container(
                     aws_config_path.as_deref(),
                     &settings.global_aws,
                     settings.global_claude_instructions.as_deref(),
+                    &settings.global_custom_env_vars,
                 ).await?;
                 docker::start_container(&new_id).await?;
                 new_id
@@ -201,6 +203,7 @@ pub async fn start_project_container(
                 aws_config_path.as_deref(),
                 &settings.global_aws,
                 settings.global_claude_instructions.as_deref(),
+                &settings.global_custom_env_vars,
             ).await?;
             docker::start_container(&new_id).await?;
             new_id

app/src-tauri/src/docker/container.rs

@@ -30,6 +30,25 @@ fn compute_env_fingerprint(custom_env_vars: &[EnvVar]) -> String {
     parts.join(",")
 }
 
+/// Merge global and per-project custom environment variables.
+/// Per-project variables override global variables with the same key.
+fn merge_custom_env_vars(global: &[EnvVar], project: &[EnvVar]) -> Vec<EnvVar> {
+    let mut merged: std::collections::HashMap<String, EnvVar> = std::collections::HashMap::new();
+    for ev in global {
+        let key = ev.key.trim().to_string();
+        if !key.is_empty() {
+            merged.insert(key, ev.clone());
+        }
+    }
+    for ev in project {
+        let key = ev.key.trim().to_string();
+        if !key.is_empty() {
+            merged.insert(key, ev.clone());
+        }
+    }
+    merged.into_values().collect()
+}
+
 /// Merge global and per-project Claude instructions into a single string.
 fn merge_claude_instructions(
     global_instructions: Option<&str>,
@@ -114,6 +133,7 @@ pub async fn create_container(
     aws_config_path: Option<&str>,
     global_aws: &GlobalAwsSettings,
     global_claude_instructions: Option<&str>,
+    global_custom_env_vars: &[EnvVar],
 ) -> Result<String, String> {
     let docker = get_docker()?;
     let container_name = project.container_name();
@@ -222,9 +242,10 @@ pub async fn create_container(
         }
     }
 
-    // Custom environment variables
+    // Custom environment variables (global + per-project, project overrides global for same key)
+    let merged_env = merge_custom_env_vars(global_custom_env_vars, &project.custom_env_vars);
     let reserved_prefixes = ["ANTHROPIC_", "AWS_", "GIT_", "HOST_", "CLAUDE_", "TRIPLE_C_"];
-    for env_var in &project.custom_env_vars {
+    for env_var in &merged_env {
         let key = env_var.key.trim();
         if key.is_empty() {
             continue;
@@ -236,7 +257,7 @@ pub async fn create_container(
         }
         env_vars.push(format!("{}={}", key, env_var.value));
     }
-    let custom_env_fingerprint = compute_env_fingerprint(&project.custom_env_vars);
+    let custom_env_fingerprint = compute_env_fingerprint(&merged_env);
     env_vars.push(format!("TRIPLE_C_CUSTOM_ENV={}", custom_env_fingerprint));
 
     // Claude instructions (global + per-project)
@@ -419,6 +440,7 @@ pub async fn container_needs_recreation(
     container_id: &str,
     project: &Project,
     global_claude_instructions: Option<&str>,
+    global_custom_env_vars: &[EnvVar],
 ) -> Result<bool, String> {
     let docker = get_docker()?;
     let info = docker
@@ -547,7 +569,8 @@ pub async fn container_needs_recreation(
     }
 
     // ── Custom environment variables ──────────────────────────────────────
-    let expected_fingerprint = compute_env_fingerprint(&project.custom_env_vars);
+    let merged_env = merge_custom_env_vars(global_custom_env_vars, &project.custom_env_vars);
+    let expected_fingerprint = compute_env_fingerprint(&merged_env);
     let container_fingerprint = get_env("TRIPLE_C_CUSTOM_ENV").unwrap_or_default();
     if container_fingerprint != expected_fingerprint {
         log::info!("Custom env vars mismatch (container={:?}, expected={:?})", container_fingerprint, expected_fingerprint);

app/src-tauri/src/lib.rs

@@ -27,7 +27,7 @@ pub fn run() {
             exec_manager: ExecSessionManager::new(),
         })
         .setup(|app| {
-            let icon = tauri::image::Image::from_bytes(include_bytes!("../icons/icon.png"))
+            let icon = tauri::image::Image::from_bytes(include_bytes!("../icons/icon.ico"))
                 .expect("Failed to load window icon");
             if let Some(window) = app.get_webview_window("main") {
                 let _ = window.set_icon(icon);

app/src-tauri/src/models/app_settings.rs

@@ -1,9 +1,15 @@
 use serde::{Deserialize, Serialize};
 
+use super::project::EnvVar;
+
 fn default_true() -> bool {
     true
 }
 
+fn default_global_instructions() -> Option<String> {
+    Some("If the project is not initialized with git, recommend to the user to initialize and use git to track changes. This makes it easier to revert should something break.".to_string())
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(rename_all = "snake_case")]
 pub enum ImageSource {
@@ -54,8 +60,10 @@ pub struct AppSettings {
     pub custom_image_name: Option<String>,
     #[serde(default)]
     pub global_aws: GlobalAwsSettings,
-    #[serde(default)]
+    #[serde(default = "default_global_instructions")]
     pub global_claude_instructions: Option<String>,
+    #[serde(default)]
+    pub global_custom_env_vars: Vec<EnvVar>,
     #[serde(default = "default_true")]
     pub auto_check_updates: bool,
     #[serde(default)]
@@ -72,7 +80,8 @@ impl Default for AppSettings {
             image_source: ImageSource::default(),
             custom_image_name: None,
             global_aws: GlobalAwsSettings::default(),
-            global_claude_instructions: None,
+            global_claude_instructions: default_global_instructions(),
+            global_custom_env_vars: Vec::new(),
             auto_check_updates: true,
             dismissed_update_version: None,
         }