Add feature for GHCP Desktop App for user to add self-created Canvases as but...

Add feature for GHCP Desktop App for user to add self-created Canvases as buttons/side panel items. Would be awesome. Asking GHCP App to open canvas is slightly cumbersome.

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| Field | Value |
| --- | --- |
| App version | 1.1.12 |
| OS | macOS 26.6.2 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 12 |

Start by locating the desktop app's canvas and side-panel navigation entry points, then review how users currently open canvases. Define the expected button or panel behavior for self-created canvases and confirm the interaction in the /chat path. Done means users can access their canvases directly from the app without reopening them manually.

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