live_diff: add live_diff.enabled_on_startup config option

crates/fresh-editor/plugins/config-schema.json

@@ -161,6 +161,13 @@
         "shell": null
       }
     },
+    "live_diff": {
+      "description": "Live Diff plugin settings.\nControls the inline-diff view rendered against a git reference.",
+      "$ref": "#/$defs/LiveDiffConfig",
+      "default": {
+        "enabled_on_startup": false
+      }
+    },
     "keybindings": {
       "description": "Custom keybindings (overrides for the active map)",
       "type": "array",
@@ -1053,6 +1060,17 @@
         "command"
       ]
     },
+    "LiveDiffConfig": {
+      "description": "Live Diff plugin configuration.\n\nThe Live Diff plugin renders a unified-diff view directly inside the\neditable buffer (gutter glyphs, virtual deletion lines, change\nhighlights) against a git reference. By default it is opt-in: the\nuser toggles it on via the `Live Diff: Toggle (Global)` command.\nThis struct exposes settings that take effect at startup, before\nany toggle command has been issued.",
+      "type": "object",
+      "properties": {
+        "enabled_on_startup": {
+          "description": "Enable the Live Diff view globally when Fresh starts.\nWhen `true`, the editor begins each session with Live Diff on\n— equivalent to invoking `Live Diff: Toggle (Global)` once\nfrom the command palette. The user can still toggle it off\nfor the current session; the next startup re-enables it.\nDefault: false (opt-in via command palette).",
+          "type": "boolean",
+          "default": false
+        }
+      }
+    },
     "Keybinding": {
       "description": "Keybinding definition",
       "type": "object",

crates/fresh-editor/plugins/live_diff.ts

@@ -1236,13 +1236,15 @@ registerHandler("live_diff_set_default", live_diff_set_default);
 // =============================================================================
 
 editor.on("after_file_open", (args) => {
+  applyStartupConfigOnce();
   const state = ensureState(args.buffer_id);
   if (!state) return true;
   recompute(args.buffer_id).catch((e) => editor.error(`live-diff: ${e}`));
   return true;
 });
 
 editor.on("buffer_activated", (args) => {
+  applyStartupConfigOnce();
   const state = ensureState(args.buffer_id);
   if (!state) return true;
   // Indicators stick around across activations; only repaint if we never
@@ -1345,8 +1347,31 @@ editor.exportPluginApi("live-diff", {
 // Initialization
 // =============================================================================
 
+// Honor `live_diff.enabled_on_startup` from user config: if the user has
+// opted in, force the global toggle on at the start of every session,
+// regardless of the persisted value. The user can still toggle off
+// mid-session via the command palette; the next startup re-enables it.
+//
+// The check is one-shot per session, gated by `startupConfigApplied`. It
+// runs lazily — on the first buffer event (open, activate) or the first
+// recompute — rather than at plugin load. `editor.getConfig()` reads
+// from a snapshot the editor refreshes between ticks, so it can return
+// `{}` if the plugin loads before the snapshot has been populated; the
+// lazy check guarantees we look after the editor has settled.
+let startupConfigApplied = false;
+function applyStartupConfigOnce(): void {
+  if (startupConfigApplied) return;
+  startupConfigApplied = true;
+  const config = editor.getConfig() as Record<string, unknown> | null;
+  const section = (config?.live_diff as Record<string, unknown> | undefined) ?? undefined;
+  if (section?.enabled_on_startup === true && !isGlobalEnabled()) {
+    setGlobalEnabled(true);
+  }
+}
+
 const initBid = editor.getActiveBufferId();
 if (initBid !== 0) {
+  applyStartupConfigOnce();
   const state = ensureState(initBid);
   if (state) {
     recompute(initBid).catch((e) => editor.error(`live-diff: ${e}`));

crates/fresh-editor/src/config.rs

@@ -362,6 +362,11 @@ pub struct Config {
     #[serde(default)]
     pub terminal: TerminalConfig,
 
+    /// Live Diff plugin settings.
+    /// Controls the inline-diff view rendered against a git reference.
+    #[serde(default)]
+    pub live_diff: LiveDiffConfig,
+
     /// Custom keybindings (overrides for the active map)
     #[serde(default)]
     pub keybindings: Vec<Keybinding>,
@@ -1854,6 +1859,34 @@ pub struct TerminalShellConfig {
     pub args: Vec<String>,
 }
 
+/// Live Diff plugin configuration.
+///
+/// The Live Diff plugin renders a unified-diff view directly inside the
+/// editable buffer (gutter glyphs, virtual deletion lines, change
+/// highlights) against a git reference. By default it is opt-in: the
+/// user toggles it on via the `Live Diff: Toggle (Global)` command.
+/// This struct exposes settings that take effect at startup, before
+/// any toggle command has been issued.
+#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
+pub struct LiveDiffConfig {
+    /// Enable the Live Diff view globally when Fresh starts.
+    /// When `true`, the editor begins each session with Live Diff on
+    /// — equivalent to invoking `Live Diff: Toggle (Global)` once
+    /// from the command palette. The user can still toggle it off
+    /// for the current session; the next startup re-enables it.
+    /// Default: false (opt-in via command palette).
+    #[serde(default = "default_false")]
+    pub enabled_on_startup: bool,
+}
+
+impl Default for LiveDiffConfig {
+    fn default() -> Self {
+        Self {
+            enabled_on_startup: false,
+        }
+    }
+}
+
 /// Warning notification configuration
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
 pub struct WarningsConfig {
@@ -2417,6 +2450,7 @@ impl Default for Config {
             file_browser: FileBrowserConfig::default(),
             clipboard: ClipboardConfig::default(),
             terminal: TerminalConfig::default(),
+            live_diff: LiveDiffConfig::default(),
             keybindings: vec![], // User customizations only; defaults come from active_keybinding_map
             keybinding_maps: HashMap::new(), // User-defined maps go here
             active_keybinding_map: default_keybinding_map_name(),

crates/fresh-editor/src/partial_config.rs

@@ -5,8 +5,8 @@
 
 use crate::config::{
     ClipboardConfig, CursorStyle, FileBrowserConfig, FileExplorerConfig, FormatterConfig,
-    Keybinding, KeybindingMapName, KeymapConfig, LanguageConfig, LineEndingOption, OnSaveAction,
-    PluginConfig, TerminalConfig, ThemeName, WarningsConfig,
+    Keybinding, KeybindingMapName, KeymapConfig, LanguageConfig, LineEndingOption, LiveDiffConfig,
+    OnSaveAction, PluginConfig, TerminalConfig, ThemeName, WarningsConfig,
 };
 use crate::types::LspLanguageConfig;
 use serde::{Deserialize, Serialize};
@@ -82,6 +82,7 @@ pub struct PartialConfig {
     pub file_browser: Option<PartialFileBrowserConfig>,
     pub clipboard: Option<PartialClipboardConfig>,
     pub terminal: Option<PartialTerminalConfig>,
+    pub live_diff: Option<PartialLiveDiffConfig>,
     pub keybindings: Option<Vec<Keybinding>>,
     pub keybinding_maps: Option<HashMap<String, KeymapConfig>>,
     pub active_keybinding_map: Option<KeybindingMapName>,
@@ -107,6 +108,7 @@ impl Merge for PartialConfig {
         merge_partial(&mut self.file_browser, &other.file_browser);
         merge_partial(&mut self.clipboard, &other.clipboard);
         merge_partial(&mut self.terminal, &other.terminal);
+        merge_partial(&mut self.live_diff, &other.live_diff);
         merge_partial(&mut self.warnings, &other.warnings);
         merge_partial(&mut self.packages, &other.packages);
 
@@ -414,6 +416,20 @@ impl Merge for PartialTerminalConfig {
     }
 }
 
+/// Partial Live Diff plugin configuration.
+#[derive(Debug, Clone, Default, Deserialize, Serialize)]
+#[serde(default)]
+pub struct PartialLiveDiffConfig {
+    pub enabled_on_startup: Option<bool>,
+}
+
+impl Merge for PartialLiveDiffConfig {
+    fn merge_from(&mut self, other: &Self) {
+        self.enabled_on_startup
+            .merge_from(&other.enabled_on_startup);
+    }
+}
+
 /// Partial warnings configuration.
 #[derive(Debug, Clone, Default, Deserialize, Serialize)]
 #[serde(default)]
@@ -859,6 +875,24 @@ impl PartialTerminalConfig {
     }
 }
 
+impl From<&LiveDiffConfig> for PartialLiveDiffConfig {
+    fn from(cfg: &LiveDiffConfig) -> Self {
+        Self {
+            enabled_on_startup: Some(cfg.enabled_on_startup),
+        }
+    }
+}
+
+impl PartialLiveDiffConfig {
+    pub fn resolve(self, defaults: &LiveDiffConfig) -> LiveDiffConfig {
+        LiveDiffConfig {
+            enabled_on_startup: self
+                .enabled_on_startup
+                .unwrap_or(defaults.enabled_on_startup),
+        }
+    }
+}
+
 impl From<&WarningsConfig> for PartialWarningsConfig {
     fn from(cfg: &WarningsConfig) -> Self {
         Self {
@@ -988,6 +1022,7 @@ impl From<&crate::config::Config> for PartialConfig {
             file_browser: Some(PartialFileBrowserConfig::from(&cfg.file_browser)),
             clipboard: Some(PartialClipboardConfig::from(&cfg.clipboard)),
             terminal: Some(PartialTerminalConfig::from(&cfg.terminal)),
+            live_diff: Some(PartialLiveDiffConfig::from(&cfg.live_diff)),
             keybindings: Some(cfg.keybindings.clone()),
             keybinding_maps: Some(cfg.keybinding_maps.clone()),
             active_keybinding_map: Some(cfg.active_keybinding_map.clone()),
@@ -1188,6 +1223,10 @@ impl PartialConfig {
                 .terminal
                 .map(|e| e.resolve(&defaults.terminal))
                 .unwrap_or_else(|| defaults.terminal.clone()),
+            live_diff: self
+                .live_diff
+                .map(|e| e.resolve(&defaults.live_diff))
+                .unwrap_or_else(|| defaults.live_diff.clone()),
             keybindings: self
                 .keybindings
                 .unwrap_or_else(|| defaults.keybindings.clone()),

crates/fresh-editor/tests/e2e/plugins/live_diff.rs

@@ -74,6 +74,51 @@ fn enable_live_diff_globally(harness: &mut EditorTestHarness) {
 // Tests
 // =============================================================================
 
+/// `live_diff.enabled_on_startup = true` in the user config replaces the
+/// usual "open command palette, run Toggle (Global)" handshake — the
+/// plugin force-enables the global toggle on init, so a modified file
+/// shows diff decorations on first render with no user input. Regression
+/// guard for the `enabled_on_startup` config field added in
+/// fresh#1950.
+#[test]
+#[cfg_attr(target_os = "windows", ignore)]
+fn test_live_diff_enabled_on_startup_config_renders_without_manual_toggle() {
+    let repo = GitTestRepo::new();
+    repo.setup_typical_project();
+    repo.setup_live_diff_plugin();
+
+    let original_dir = repo.change_to_repo_dir();
+    let _guard = DirGuard::new(original_dir);
+
+    // Same diff shape as the "added line" test below, but we never
+    // invoke `Live Diff: Toggle (Global)`. If the config wiring is
+    // broken the gutter stays empty and `wait_until` will block until
+    // the external test timeout fires.
+    repo.modify_file(
+        "src/utils.rs",
+        r#"// brand new top line added by the agent
+pub fn format_output(msg: &str) -> String {
+    format!("[INFO] {}", msg)
+}
+
+pub fn validate_config(config: &Config) -> bool {
+    config.port > 0 && !config.host.is_empty()
+}
+"#,
+    );
+
+    let mut config = Config::default();
+    config.live_diff.enabled_on_startup = true;
+    let mut harness =
+        EditorTestHarness::with_config_and_working_dir(120, 40, config, repo.path.clone()).unwrap();
+
+    open_file(&mut harness, &repo.path, "src/utils.rs");
+
+    harness
+        .wait_until(|h| has_glyph(&h.screen_to_string(), '+'))
+        .unwrap();
+}
+
 /// vs HEAD: an added line shows `+` in the gutter once the file is opened.
 /// Live-diff fetches `git show HEAD:<path>` and diffs against the on-disk
 /// content (which has one new line vs HEAD), so the new line should be