Config Panel
The Automation Builder does not render a config panel for extension nodes. When a user selects an extension node on the canvas, the sidebar shows a note that extension nodes cannot be configured in the builder. Neither your editor surface nor a form generated from input_schema is shown there.
The builder also does not list installed extension nodes in its toolbar, so users cannot add your node from the dashboard.
Where the config comes from
Each node instance keeps its settings in the node's config object, stored with the automation graph (automation_nodes.config). It is written when the graph is saved through the automation API (saveAutomationNodes on GraphQL, or its REST twin), and it names the install in config.extension_meta.install_id. The save rejects an install that does not belong to the saving account.
Your handler reads the per-instance values from that config at run time. Use input_schema in the manifest to describe the fields you expect; the builder does not turn it into a form.
Editor target
The manifest validator requires "editor" in an automation node's targets (see Overview). The builder does not load the editor entry point for automation nodes.