docs: actions

docs/actions.md

@@ -0,0 +1,62 @@
+# Actions System
+
+Actions are the trigger layer for user-initiated operations. They connect keyboard shortcuts, UI buttons, and context menus to editor functionality.
+
+## Adding a New Action
+
+### 1. Define the action — `src/lib/actions/definitions.ts`
+
+Add an entry to the `ACTIONS` object:
+
+```typescript
+"my-action": {
+    description: "What it does",
+    category: "editing",           // playback | navigation | editing | selection | history | timeline | controls
+    defaultShortcuts: ["ctrl+m"],  // optional
+    args: { someValue: "number" }, // optional, only if it takes args
+},
+```
+
+### 2. Register the handler — `src/hooks/actions/use-editor-actions.ts`
+
+```typescript
+useActionHandler(
+    "my-action",
+    () => {
+        editor.timeline.doSomething();
+    },
+    undefined, // isActive: MutableRefObject<boolean> | boolean | undefined
+);
+```
+
+### 3. Register arg types (if needed) — `src/lib/actions/types.ts`
+
+Only required if your action accepts arguments:
+
+```typescript
+export type TActionArgsMap = {
+    // ...existing actions...
+    "my-action": { someValue: number } | undefined; // | undefined = optional args
+};
+```
+
+## Invoking Actions
+
+Use `invokeAction` for any user-triggered operation (buttons, context menus, etc.):
+
+```typescript
+import { invokeAction } from "@/lib/actions";
+
+invokeAction("my-action");
+invokeAction("seek-forward", { seconds: 5 });
+```
+
+Avoid calling `editor.xxx()` directly from UI components — that bypasses the action layer (toasts, validation feedback, keybinding support).
+
+## The `isActive` parameter
+
+The third argument to `useActionHandler` controls when the handler is active:
+
+- `undefined` — always active
+- `true` / `false` — statically enabled/disabled
+- `MutableRefObject<boolean>` — reactive, toggled at runtime (e.g. only active when a panel is focused)