Add customizable keyboard shortcuts

Drive app shortcuts from a central keybindings store (defaults +
localStorage overrides). In the Info panel's Shortcuts tab: click a
shortcut to rebind, right-click to reset, Esc to cancel; combos
already in use are rejected.

src/lib/keybindings.ts

@@ -0,0 +1,163 @@
+import { writable } from "svelte/store";
+
+// A single key combination. `mod` means Ctrl on Windows/Linux and Cmd on macOS.
+// `code` is a KeyboardEvent.code value (layout-independent), e.g. "KeyN",
+// "Backslash", "ArrowLeft", "F11".
+export interface Binding {
+  mod?: boolean;
+  shift?: boolean;
+  alt?: boolean;
+  code: string;
+}
+
+export interface ActionDef {
+  id: string;
+  label: string;
+  group: "General" | "Interface" | "Navigation";
+  default: Binding;
+}
+
+// Every customizable action and its factory-default binding. These mirror the
+// handlers in AppLayout.handleKeydown and the rows in InfoPanel's Shortcuts tab.
+export const ACTIONS: ActionDef[] = [
+  { id: "new-note", label: "New note", group: "General", default: { mod: true, code: "KeyN" } },
+  { id: "save", label: "Save", group: "General", default: { mod: true, code: "KeyS" } },
+  { id: "quick-open", label: "Quick open", group: "General", default: { mod: true, code: "KeyP" } },
+  { id: "find-in-note", label: "Find in note", group: "General", default: { mod: true, code: "KeyF" } },
+  { id: "search-vault", label: "Search vault", group: "General", default: { mod: true, shift: true, code: "KeyF" } },
+  { id: "open-new-window", label: "Open note in new window", group: "General", default: { mod: true, shift: true, code: "KeyW" } },
+
+  { id: "toggle-sidebar", label: "Toggle sidebar", group: "Interface", default: { mod: true, code: "Backslash" } },
+  { id: "toggle-theme", label: "Toggle dark / light theme", group: "Interface", default: { mod: true, shift: true, code: "KeyN" } },
+  { id: "toggle-focus", label: "Toggle focus mode", group: "Interface", default: { mod: true, shift: true, code: "KeyE" } },
+  { id: "toggle-readonly", label: "Toggle read-only", group: "Interface", default: { mod: true, shift: true, code: "KeyR" } },
+  { id: "toggle-source", label: "Toggle source / WYSIWYG", group: "Interface", default: { mod: true, shift: true, code: "KeyM" } },
+  { id: "fullscreen", label: "Toggle fullscreen", group: "Interface", default: { code: "F11" } },
+
+  { id: "nav-back", label: "Go back", group: "Navigation", default: { alt: true, code: "ArrowLeft" } },
+  { id: "nav-forward", label: "Go forward", group: "Navigation", default: { alt: true, code: "ArrowRight" } },
+];
+
+export const DEFAULT_BINDINGS: Record<string, Binding> = Object.fromEntries(
+  ACTIONS.map((a) => [a.id, a.default]),
+);
+
+const STORAGE_KEY = "helix-keybindings";
+
+function loadBindings(): Record<string, Binding> {
+  const merged: Record<string, Binding> = { ...DEFAULT_BINDINGS };
+  try {
+    const raw = typeof localStorage !== "undefined" && localStorage.getItem(STORAGE_KEY);
+    if (raw) {
+      const stored = JSON.parse(raw) as Record<string, Binding>;
+      for (const id of Object.keys(merged)) {
+        if (stored[id]) merged[id] = stored[id];
+      }
+    }
+  } catch {
+    // Corrupt storage - fall back to defaults.
+  }
+  return merged;
+}
+
+export const keybindings = writable<Record<string, Binding>>(loadBindings());
+
+keybindings.subscribe((map) => {
+  try {
+    if (typeof localStorage !== "undefined") {
+      localStorage.setItem(STORAGE_KEY, JSON.stringify(map));
+    }
+  } catch {
+    // Ignore quota / unavailable storage.
+  }
+});
+
+export function setBinding(id: string, binding: Binding) {
+  keybindings.update((m) => ({ ...m, [id]: binding }));
+}
+
+export function resetBinding(id: string) {
+  keybindings.update((m) => ({ ...m, [id]: DEFAULT_BINDINGS[id] }));
+}
+
+// True when the keyboard event matches the given binding exactly. Modifier
+// state must match precisely so e.g. Mod+Shift+F never also triggers Mod+F.
+export function matchBinding(e: KeyboardEvent, b: Binding | undefined): boolean {
+  if (!b) return false;
+  const mod = e.ctrlKey || e.metaKey;
+  return (
+    !!b.mod === mod &&
+    !!b.shift === e.shiftKey &&
+    !!b.alt === e.altKey &&
+    e.code === b.code
+  );
+}
+
+// Returns the id of the first action whose binding matches the event, or null.
+export function matchAction(e: KeyboardEvent, map: Record<string, Binding>): string | null {
+  for (const id of Object.keys(map)) {
+    if (matchBinding(e, map[id])) return id;
+  }
+  return null;
+}
+
+// Build a Binding from a captured keydown event. Returns null for events that
+// are only modifier keys (no real key pressed yet).
+const MODIFIER_CODES = new Set([
+  "ControlLeft", "ControlRight", "MetaLeft", "MetaRight",
+  "ShiftLeft", "ShiftRight", "AltLeft", "AltRight",
+]);
+
+export function bindingFromEvent(e: KeyboardEvent): Binding | null {
+  if (MODIFIER_CODES.has(e.code) || !e.code) return null;
+  return {
+    mod: e.ctrlKey || e.metaKey,
+    shift: e.shiftKey,
+    alt: e.altKey,
+    code: e.code,
+  };
+}
+
+export function bindingsEqual(a: Binding, b: Binding): boolean {
+  return !!a.mod === !!b.mod && !!a.shift === !!b.shift && !!a.alt === !!b.alt && a.code === b.code;
+}
+
+const isMac = typeof navigator !== "undefined" && navigator.platform.startsWith("Mac");
+
+const CODE_LABELS: Record<string, string> = {
+  Backslash: "\\",
+  BracketLeft: "[",
+  BracketRight: "]",
+  Comma: ",",
+  Period: ".",
+  Slash: "/",
+  Semicolon: ";",
+  Quote: "'",
+  Backquote: "`",
+  Minus: "-",
+  Equal: "=",
+  Space: "Space",
+  Enter: "Enter",
+  Tab: "Tab",
+  ArrowLeft: "←",
+  ArrowRight: "→",
+  ArrowUp: "↑",
+  ArrowDown: "↓",
+};
+
+function codeToLabel(code: string): string {
+  if (code.startsWith("Key")) return code.slice(3);
+  if (code.startsWith("Digit")) return code.slice(5);
+  if (code.startsWith("Numpad")) return code.slice(6);
+  return CODE_LABELS[code] ?? code;
+}
+
+// Ordered list of key labels for rendering, e.g. ["Ctrl", "Shift", "N"].
+export function bindingToKeys(b: Binding): string[] {
+  const keys: string[] = [];
+  if (b.mod) keys.push(isMac ? "⌘" : "Ctrl");
+  if (b.alt) keys.push(isMac ? "⌥" : "Alt");
+  if (b.shift) keys.push(isMac ? "⇧" : "Shift");
+  keys.push(codeToLabel(b.code));
+  return keys;
+}