Excalidraw Scripting - How to Automate On-File-Open Actions in Obsidian

Excalidraw Automate can trigger Excalidraw actions automatically when a drawing opens in Obsidian—such as switching to the hand tool on mobile or running an “autodraw for pen” style script—by wiring Excalidraw’s API hooks into Obsidian startup automation. The key move is using Excalidraw Automate’s on-file-open hook, then installing that hook at Obsidian launch so it’s ready before any drawing is opened.

The walkthrough starts with Obsidian’s developer console (Ctrl+Shift+I / Cmd+Option+I) and Excalidraw Automate’s shorthand variable (EA = ExcalidrawAutomate). Once the script attaches to the active drawing via EA.setView, the Excalidraw API becomes the control panel. From there, the process becomes a repeatable pattern: fetch the API (EA.getExcalidrawAPI), list available functions, and locate the one needed—such as setActiveTool. Because the API doesn’t make argument values obvious, the method relies on two “find it yourself” tricks: search the Excalidraw GitHub repository for setActiveTool usage to see the expected object shape, and query the current application state (API.getAppState) to confirm tool types (type: hand vs type: rectangle).

With the hand-tool behavior confirmed, the guide shifts to making it run automatically. In Excalidraw’s markdown front matter, an unload script can call EA.getExcalidrawAPI and then setActiveTool with {type: 'hand'}. To target mobile only, the script checks Obsidian’s app.mobile flag: if app.isMobile (or app.mobile in the transcript’s naming) is true, it switches tools; otherwise it can run a desktop alternative. Testing is done by opening the drawing from markdown view and verifying that the active tool changes immediately.

To avoid repeating this per drawing, the same logic is inserted into an Excalidraw template configured in Excalidraw’s plugin settings. New drawings inherit the front matter and therefore the unload script automatically. The transcript also warns about a common template pitfall: the template field can look filled due to a faint placeholder hint, so users should verify they can actually select the text before assuming the template file is truly applied.

For pen automation, the guide expands beyond unload scripts. It shows two ways to run Excalidraw scripts: (1) call them through Obsidian’s command system using app.commands.executeCommandById with the script’s command ID, and (2) use Excalidraw Automate’s on-file-open hook, which receives a data object and can execute logic whenever a file opens. A quick console.log test confirms the hook fires and provides file metadata.

The final step is making the hook persistent across restarts. Instead of relying on per-file front matter, the guide uses Templator to install the on-file-open hook at Obsidian startup. A startup template creates a script that waits for Excalidraw Automate to become available (a watchdog loop with up to 50 retries and short delays) to prevent race conditions. After restart, the developer console message confirms installation, and opening a drawing triggers the desired automation automatically—without manual setup each time.