Wire up completion keyboard navigation and add AGENTS.md

- Tab/Enter confirms the selected completion item
- Up/Down arrows navigate the completion menu
- Escape dismisses the menu (via existing dismiss_lsp_overlays)
- Editor intercepts keys via completion_intercept_keys flag when menu is showing
- Add AGENTS.md with LLM-powered predictive autocomplete idea

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

app/src/code/editor/view.rs

@@ -153,6 +153,12 @@ pub enum CodeEditorEvent {
     VimGotoDefinition,
     VimFindReferences,
     VimShowHover,
+    /// Emitted when Up is pressed and completion_intercept_keys is active.
+    CompletionNavigateUp,
+    /// Emitted when Down is pressed and completion_intercept_keys is active.
+    CompletionNavigateDown,
+    /// Emitted when Tab/Enter is pressed and completion_intercept_keys is active.
+    CompletionConfirm,
 }
 
 /// Store all states related to displaying the editor content.
@@ -284,6 +290,9 @@ pub struct CodeEditorView {
     /// The offset where find references card is anchored (if showing).
     find_references_anchor_offset: Option<CharOffset>,
     window_id: WindowId,
+    /// When true, Up/Down/Tab/Enter are redirected to completion events instead of
+    /// normal editor behavior. Set by the parent when a completion menu is visible.
+    pub completion_intercept_keys: bool,
 }
 
 impl CodeEditorView {
@@ -427,6 +436,7 @@ impl CodeEditorView {
             show_find_references_provider: render_options.show_find_references_provider,
             find_references_anchor_offset: None,
             window_id: ctx.window_id(),
+            completion_intercept_keys: false,
         }
     }
 

app/src/code/editor/view/actions.rs

@@ -805,6 +805,28 @@ impl TypedActionView for CodeEditorView {
             return;
         }
 
+        // When completion menu is active, redirect navigation/confirm keys to the parent.
+        if self.completion_intercept_keys {
+            match action {
+                MoveUp => {
+                    ctx.emit(super::CodeEditorEvent::CompletionNavigateUp);
+                    return;
+                }
+                MoveDown => {
+                    ctx.emit(super::CodeEditorEvent::CompletionNavigateDown);
+                    return;
+                }
+                Tab | Enter => {
+                    ctx.emit(super::CodeEditorEvent::CompletionConfirm);
+                    return;
+                }
+                Escape => {
+                    // Let escape fall through to normal handling (which emits EscapePressed)
+                }
+                _ => {}
+            }
+        }
+
         match action {
             UserTyped(content) => self.user_insert(content, ctx),
             VimUserTyped(content) => {