Edit Canvas App

# Edit a Canvas App

Make the following changes to the existing Canvas App:

$ARGUMENTS

## Overview

This skill uses two paths depending on edit complexity:

- **Simple edits** (single control/property changes, formula tweaks) — handled inline
- **Complex edits** (multiple screens, new screens, structural changes, new data sources) —
  orchestrated via specialist agents: `canvas-edit-planner` + parallel `canvas-screen-editor`

---

## Phase 0 — Create App Folder

Before syncing or editing, create a subfolder to contain the app's YAML files:

1. Derive a short folder name from `$ARGUMENTS` — extract the app name if present, otherwise
   use a 2–3 word summary of what is being edited
2. Convert to kebab-case (e.g., "Expense Tracker" → `expense-tracker`)
3. Create the folder using `Bash`: `mkdir -p <folder-name>`
4. Resolve its absolute path — this is the **working directory** for all subsequent phases

All file reads, writes, and syncs operate in this folder.

---

## Phase 1 — Sync and Check

**Sync the canvas app:**

Call the `sync_canvas` MCP tool targeting the working directory. This pulls the current app
state from the coauthoring session into local `.pa.yaml` files. Only proceed after
`sync_canvas` completes successfully.

**Check for meaningful content:**

After `sync_canvas` completes, read the synced `.pa.yaml` files and check whether the app
has meaningful content. An app is considered **empty** if:

- No `.pa.yaml` files were written, or
- The only files present contain no screens, or
- Every screen present has no controls (only bare screen-level YAML with no children), or
- Every screen's controls consist solely of containers (e.g., `GroupContainer`) with no
  leaf controls inside them

If the app is empty, **do not proceed with the edit workflow**. Instead, inform the user:

> **The synced app appears to be empty — no existing screens or controls were found.**
> Switching to app generation mode to build the app from scratch.

Then follow the full **generate-canvas-app** workflow, using the user's original request as
the generation requirements.

If the app has meaningful content, proceed to Phase 2.

---

## Phase 2 — Assess Complexity

Read all synced `.pa.yaml` files. Based on `$ARGUMENTS` and the current app state, determine
whether this is a **simple** or **complex** edit:

**Simple** — all of the following are true:
- Changes affect ≤ 2 controls or properties
- Changes are confined to ≤ 1 screen
- No new screens are being added
- No new data sources or connectors are needed
- No structural layout changes (e.g., not changing ManualLayout to AutoLayout)

Examples: change a button color, update label text, fix a formula, adjust a control size.

**Complex** — any of the following are true:
- Changes span multiple screens
- One or more new screens need to be created
- New data sources or connectors are required
- Structural layout changes are involved
- Significant visual redesign of a screen

Examples: add a settings screen, redesign the home screen layout, integrate a new connector,
change the navigation flow across the app.

- If **simple**: proceed to Phase 3a.
- If **complex**: proceed to Phase 3b.

---

## Phase 3a — Simple: Direct Edit

Read `${CLAUDE_PLUGIN_ROOT}/references/TechnicalGuide.md` before making changes.

Apply the changes directly:

1. **Edit** the relevant `.pa.yaml` files with the required changes, following conventions
   from TechnicalGuide.md.

2. **Validate** by calling `compile_canvas` on the working directory after making changes.
   On failure, read the errors, fix with `Edit`, and re-compi