Add LSP rename (Phase 3) and update AGENTS.md with future work

- F2 keybinding triggers prepareRename at cursor
- Shows inline text input pre-filled with current symbol name
- Enter confirms and applies workspace edits across all occurrences
- Escape cancels the rename
- Full flow: prepareRename → input → rename → apply edits
- AGENTS.md: document inline token/cache/cost stats feature idea
- AGENTS.md: document rename implementation for reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/code/local_code_editor.rs

@@ -92,6 +92,7 @@ use super::editor::{
 };
 use super::code_actions::{CodeActionsState, CODE_ACTIONS_DEBOUNCE_PERIOD};
 use super::completion::{CompletionState, COMPLETION_DEBOUNCE_PERIOD};
+use super::rename::RenameState;
 use super::signature_help::SignatureHelpState;
 use super::find_references_view::{FindReferencesView, FindReferencesViewEvent};
 use super::language_server_extension::ProcessedDiagnostic;
@@ -114,6 +115,11 @@ pub fn init(app: &mut AppContext) {
             LocalCodeEditorAction::OpenCodeActions,
             id!("LocalCodeEditorView"),
         ),
+        FixedBinding::new(
+            "f2",
+            LocalCodeEditorAction::StartRename,
+            id!("LocalCodeEditorView"),
+        ),
     ]);
 }
 
@@ -209,6 +215,8 @@ pub enum LocalCodeEditorAction {
     },
     /// Open the code actions menu (Cmd+.).
     OpenCodeActions,
+    /// Start LSP rename at cursor (F2).
+    StartRename,
 }
 
 #[derive(Default)]
@@ -325,6 +333,8 @@ pub struct LocalCodeEditorView {
     pub(super) code_actions_debounce_tx: async_channel::Sender<CharOffset>,
     /// State for LSP signature help (parameter hints).
     pub(super) signature_help_state: SignatureHelpState,
+    /// State for LSP rename (F2).
+    pub(super) rename_state: RenameState,
 }
 
 impl LocalCodeEditorView {
@@ -555,6 +565,7 @@ impl LocalCodeEditorView {
             code_actions_state: CodeActionsState::default(),
             code_actions_debounce_tx,
             signature_help_state: SignatureHelpState::default(),
+            rename_state: RenameState::default(),
         };
 
         if let Some(display_mode) = display_mode {
@@ -1981,7 +1992,8 @@ impl LocalCodeEditorView {
         }
         let had_sig_help = self.signature_help_state.clear();
         let had_code_actions = self.code_actions_state.dismiss();
-        had_refs || had_hover || had_completion || had_sig_help || had_code_actions
+        let had_rename = self.rename_state.dismiss();
+        had_refs || had_hover || had_completion || had_sig_help || had_code_actions || had_rename
     }
 
     /// Perform goto definition at the cursor position and navigate directly.
@@ -2361,6 +2373,9 @@ impl TypedActionView for LocalCodeEditorView {
             LocalCodeEditorAction::OpenCodeActions => {
                 self.open_code_actions_menu(ctx);
             }
+            LocalCodeEditorAction::StartRename => {
+                self.start_rename(ctx);
+            }
         }
     }
 }

app/src/code/mod.rs

@@ -13,6 +13,8 @@ pub mod completion;
 #[cfg(not(target_family = "wasm"))]
 pub mod find_references_view;
 #[cfg(not(target_family = "wasm"))]
+pub mod rename;
+#[cfg(not(target_family = "wasm"))]
 pub mod signature_help;
 #[cfg(not(target_family = "wasm"))]
 pub mod language_server_extension;

app/src/code/rename.rs

@@ -0,0 +1,276 @@
+use futures::stream::AbortHandle;
+use galaxy_core::features::FeatureFlag;
+use galaxy_core::ui::appearance::Appearance;
+use galaxyui::{SingletonEntity, ViewContext, ViewHandle};
+use lsp::types::Location;
+use string_offset::CharOffset;
+use vec1::Vec1;
+
+use crate::editor::{EditorView, Event as EditorEvent, SingleLineEditorOptions, TextOptions};
+
+use super::local_code_editor::LocalCodeEditorView;
+
+pub(super) enum RenameState {
+    Idle,
+    Preparing { abort_handle: AbortHandle },
+    InputActive {
+        editor: ViewHandle<EditorView>,
+        anchor_offset: CharOffset,
+    },
+    Applying { abort_handle: AbortHandle },
+}
+
+impl Default for RenameState {
+    fn default() -> Self {
+        Self::Idle
+    }
+}
+
+impl RenameState {
+    pub fn dismiss(&mut self) -> bool {
+        match self {
+            Self::Idle => false,
+            Self::Preparing { abort_handle } | Self::Applying { abort_handle } => {
+                abort_handle.abort();
+                *self = Self::Idle;
+                true
+            }
+            Self::InputActive { .. } => {
+                *self = Self::Idle;
+                true
+            }
+        }
+    }
+}
+
+impl LocalCodeEditorView {
+    pub(super) fn is_rename_enabled() -> bool {
+        FeatureFlag::LspRename.is_enabled()
+    }
+
+    pub(super) fn start_rename(&mut self, ctx: &mut ViewContext<Self>) {
+        if !Self::is_rename_enabled() {
+            return;
+        }
+
+        let Some(file_path) = self.file_path() else {
+            return;
+        };
+
+        let Some(lsp_server) = &self.lsp_server else {
+            return;
+        };
+
+        let cursor_offset = self.editor().as_ref(ctx).cursor_head_offset(ctx);
+        let lsp_position = self
+            .editor()
+            .as_ref(ctx)
+            .offset_to_lsp_position(cursor_offset, ctx);
+
+        let future = match lsp_server
+            .as_ref(ctx)
+            .prepare_rename(file_path.to_path_buf(), lsp_position)
+        {
+            Ok(future) => future,
+            Err(e) => {
+                log::warn!("Failed to call lsp.prepare_rename: {e}");
+                return;
+            }
+        };
+
+        self.rename_state.dismiss();
+
+        let abort_handle = ctx
+            .spawn(future, move |me, result, ctx| {
+                me.handle_prepare_rename_response(result, cursor_offset, ctx);
+            })
+            .abort_handle();
+
+        self.rename_state = RenameState::Preparing { abort_handle };
+    }
+
+    fn handle_prepare_rename_response(
+        &mut self,
+        result: anyhow::Result<Option<lsp::PrepareRenameResult>>,
+        cursor_offset: CharOffset,
+        ctx: &mut ViewContext<Self>,
+    ) {
+        let prepare_result = match result {
+            Ok(Some(r)) => r,
+            _ => {
+                log::info!("Symbol at cursor cannot be renamed");
+                self.rename_state = RenameState::Idle;
+                return;
+            }
+        };
+
+        let editor_ref = self.editor().as_ref(ctx);
+        let range_start = editor_ref.lsp_location_to_offset(&prepare_result.range.start, ctx);
+        let range_end = editor_ref.lsp_location_to_offset(&prepare_result.range.end, ctx);
+
+        let current_name = editor_ref
+            .buffer_text_in_range(range_start..range_end, ctx)
+            .unwrap_or_default();
+
+        let placeholder = prepare_result.placeholder.unwrap_or(current_name);
+
+        let rename_editor = ctx.add_typed_action_view(|ctx| {
+            let appearance = Appearance::as_ref(ctx);
+            let mut editor = EditorView::single_line(
+                SingleLineEditorOptions {
+                    text: TextOptions::ui_text(None, appearance),
+                    select_all_on_focus: true,
+                    ..Default::default()
+                },
+                ctx,
+            );
+            editor.set_buffer_text(&placeholder, ctx);
+            editor
+        });
+
+        ctx.subscribe_to_view(&rename_editor, |me, _, event, ctx| {
+            me.handle_rename_editor_event(event, ctx);
+        });
+
+        ctx.focus(&rename_editor);
+
+        self.rename_state = RenameState::InputActive {
+            editor: rename_editor,
+            anchor_offset: cursor_offset,
+        };
+        ctx.notify();
+    }
+
+    fn handle_rename_editor_event(
+        &mut self,
+        event: &EditorEvent,
+        ctx: &mut ViewContext<Self>,
+    ) {
+        match event {
+            EditorEvent::Enter => {
+                let new_name = match &self.rename_state {
+                    RenameState::InputActive { editor, .. } => {
+                        editor.as_ref(ctx).buffer_text(ctx)
+                    }
+                    _ => return,
+                };
+                self.confirm_rename(new_name, ctx);
+            }
+            EditorEvent::Escape => {
+                self.rename_state = RenameState::Idle;
+                ctx.focus(self.editor());
+                ctx.notify();
+            }
+            _ => {}
+        }
+    }
+
+    fn confirm_rename(&mut self, new_name: String, ctx: &mut ViewContext<Self>) {
+        if new_name.is_empty() {
+            self.rename_state = RenameState::Idle;
+            ctx.focus(self.editor());
+            ctx.notify();
+            return;
+        }
+
+        let anchor_offset = match &self.rename_state {
+            RenameState::InputActive { anchor_offset, .. } => *anchor_offset,
+            _ => return,
+        };
+
+        let Some(file_path) = self.file_path() else {
+            return;
+        };
+
+        let Some(lsp_server) = &self.lsp_server else {
+            return;
+        };
+
+        let lsp_position = self
+            .editor()
+            .as_ref(ctx)
+            .offset_to_lsp_position(anchor_offset, ctx);
+
+        let future = match lsp_server
+            .as_ref(ctx)
+            .rename(file_path.to_path_buf(), lsp_position, new_name)
+        {
+            Ok(future) => future,
+            Err(e) => {
+                log::warn!("Failed to call lsp.rename: {e}");
+                self.rename_state = RenameState::Idle;
+                ctx.focus(self.editor());
+                ctx.notify();
+                return;
+            }
+        };
+
+        let abort_handle = ctx
+            .spawn(future, move |me, result, ctx| {
+                me.handle_rename_response(result, ctx);
+            })
+            .abort_handle();
+
+        self.rename_state = RenameState::Applying { abort_handle };
+    }
+
+    fn handle_rename_response(
+        &mut self,
+        result: anyhow::Result<Option<lsp::RenameResult>>,
+        ctx: &mut ViewContext<Self>,
+    ) {
+        self.rename_state = RenameState::Idle;
+        ctx.focus(self.editor());
+
+        let rename_result = match result {
+            Ok(Some(r)) if !r.edits.is_empty() => r,
+            Ok(_) => {
+                log::info!("Rename returned no edits");
+                ctx.notify();
+                return;
+            }
+            Err(e) => {
+                log::warn!("Rename failed: {e}");
+                ctx.notify();
+                return;
+            }
+        };
+
+        let mut edits_for_current_file: Vec<(String, std::ops::Range<CharOffset>)> = Vec::new();
+
+        for file_edit in &rename_result.edits {
+            for text_edit in &file_edit.edits {
+                let start = self.editor().as_ref(ctx).lsp_location_to_offset(
+                    &Location {
+                        line: text_edit.range.start.line,
+                        column: text_edit.range.start.column,
+                    },
+                    ctx,
+                );
+                let end = self.editor().as_ref(ctx).lsp_location_to_offset(
+                    &Location {
+                        line: text_edit.range.end.line,
+                        column: text_edit.range.end.column,
+                    },
+                    ctx,
+                );
+                edits_for_current_file.push((text_edit.text.clone(), start..end));
+            }
+        }
+
+        if edits_for_current_file.is_empty() {
+            ctx.notify();
+            return;
+        }
+
+        edits_for_current_file.sort_by(|a, b| b.1.start.cmp(&a.1.start));
+
+        if let Ok(edits) = Vec1::try_from_vec(edits_for_current_file) {
+            self.editor.update(ctx, |editor, ctx| {
+                editor.apply_edits(edits, ctx);
+            });
+        }
+
+        ctx.notify();
+    }
+}