Convex React App Optimistic Updates Planner: Instant UI with Sonner Toasts

You are an expert React developer and UX specialist with deep expertise in Convex backend, shadcn/ui (including Sonner toasts), TanStack Query, and optimistic UI patterns for seamless user experiences.

Your goal is to analyze the provided app codebase and generate a comprehensive, actionable plan to add optimistic updates to EVERY Convex mutation. This will make the UI feel instant and responsive: changes appear immediately in the UI, with a success toast from Sonner on confirmation, and automatic reversion on errors.

Key principles:
- Use Convex's built-in optimistic updates where possible (e.g., via useOptimisticUpdate or manual query patching with useQuery).
- For mutations: Optimistically update local state/queries before the mutation resolves.
- On success: Invalidate/revalidate relevant queries and show a success toast (e.g., 'Todo created!').
- On error: Revert optimistic changes, show error toast (e.g., 'Failed to create todo.').
- Ensure no loading spinners block the UI; everything feels immediate.
- Prioritize UX: Reduce perceived latency to <50ms for common actions.

Steps to follow:
1. SCAN the entire provided codebase for all Convex mutations (e.g., useMutation, mutate calls, useConvex mutation hooks).
2. For each mutation, note:
   - File/component location.
   - Action performed (e.g., createPost, updateUser).
   - Affected queries/state (e.g., useQuery('getPosts'), local todos array).
   - Current implementation issues (e.g., no optimistic update).
3. Propose implementation:
   - Code snippet for optimistic update (using useOptimistic or query.setQueryData).
   - Error handling with reversion.
   - Sonner toast integration (assume Sonner is set up; import { toast } from 'sonner').
4. Identify global improvements: e.g., custom mutation hooks, query client setup.

Provided codebase/repo details:
[REPO_CODE_OR_KEY_FILES]

App context/description:
[APP_DESCRIPTION]

Target areas (optional):
[SPECIFIC_MUTATIONS_OR_COMPONENTS]

Output in this exact structured format:

## Summary
- Total mutations found: X
- High-impact UX wins: [list]

## Mutations Plan
1. **File: [path] - [Mutation name] ([action])**
   - Affected: [queries/state]
   - Current: [brief]
   - Optimistic code:
     ```tsx
     [code snippet]
     ```
   - Toasts: Success: '[message]', Error: '[message]'

(Repeat for all)

## Global Changes
- [e.g., Convex config, query client wrappers]

## Next Steps
- Prioritized file list to implement.
- Testing checklist for UX (e.g., network throttling).