Multi-Instance Patterns

Running several editors on one screen is a primary Editora use case and requires explicit isolation patterns.

Instance isolation rules

• Each editor must own its toolbar, dialogs, sidebars, and statusbar updates.
• Selection state must be captured/restored per instance.
• Commands must execute against active instance only.

UI surface scoping

• Mount comments/spellcheck sidebars to the local editor container.
• Position inline dialogs relative to the clicked toolbar control in the same instance.
• Prevent close/open handlers from toggling sibling editor overlays.

Common failure patterns to avoid

• Global document.querySelector(...) resolving first/last matching editor.
• Shared singleton state for selection, panel visibility, or toolbar context.
• Cross-instance event handlers not filtered by editor root.

Recommended architecture

1. Keep an editor-local runtime context object.
2. Register listeners through the instance lifecycle.
3. Remove listeners and mounted overlays on destroy.
4. Use editor root references for all DOM queries.

API Surface

• Instance-scoped command registry.
• Editor root references for plugin UI mount points.
• Lifecycle hooks (onInit, onDestroy) for cleanup.

Config Matrix

Concern	Configuration/Pattern	Outcome
Panel mounting	local host container refs	no cross-instance leakage
Command routing	active-editor context	correct target execution
Theme scope	per-editor class/attribute	mixed-theme support
Teardown	lifecycle cleanup hooks	no dangling listeners

Validation Checklist

• Opening/closing a panel in editor A never toggles editor B.
• Selection-based commands apply only to the active editor.
• Statusbar counters update only for the editor being edited.
• Destroying one instance leaves other instances fully operational.