[gohabereg]

Why

There is no way to tear an editor down. Neither Core nor EditorJS has a destroy(), so unmounting an editor (route change, component unmount, several editors on one page, React StrictMode) leaks the editor DOM, the document-wide selectionchange listener, the collaboration WebSocket, timers, and every tool and plugin instance. Several plugins already implement destroy(), and the core/sdk specs already say it's called on teardown, but nothing calls it.

Board card: Clean up (Core APIs).

What Changes

This PR is the OpenSpec change only (openspec/changes/editor-destroy). Implementation follows in stacked PRs.

• Core#destroy() / EditorJS#destroy(): synchronous, idempotent. Tears down plugins in reverse construction order (unregistering their public APIs), then UndoRedoManager, SelectionManager, BlockRenderer (each block's tool instance and adapter), then the adapter plugin. A throwing step is logged and teardown continues. The model is never mutated, so nothing reaches undo history or collaboration. use()/initialize() throw afterwards.
• Interrupted initialization: destroy() during a pending initialize() makes it reject with a DOMException named AbortError (the platform convention, as with fetch). The bundle handles its own ready promise: AbortError is ignored, other init errors are logged, so neither is reported as an unhandled rejection; awaiting isReady still rejects.
• Tools: optional destroy() on BlockTool/InlineTool, called once per instance the editor creates.
• Adapter plugin: destroy() becomes required on EditorJSAdapterPlugin.
• Repo-wide listener rule (architecture spec): every component releases listeners through one AbortController; unsubscribe functions returned by onUpdate/onCaretUpdate are tied to its abort event. SDK base classes (BlockToolAdapter) own the controller and expose a protected signal to subclasses.
• Shared selectionchange watcher: reference-counted, so several editors can be destroyed independently.
• UI: teardown for every UI plugin is covered by fix(ui): remove blocks holder listeners and detach it on destroy #174, so this change has no UI plugin implementation. The only UI piece kept here is InlineToolbarUI destroying the inline tool instances it creates, done after fix(ui): remove blocks holder listeners and detach it on destroy #174 lands.

Modified capabilities: architecture, core, sdk, dom-adapters, editorjs-bundle. Supersedes the "Core currently does not expose a global destroy()" note in docs/plugins.md (docs are updated in the implementation PR).

Stack

1. This PR: spec
2. feat(core): add editor destroy lifecycle #196 — lifecycle and API changes: Core/EditorJS destroy(), core services, tool contracts, BlockToolAdapter controller (targets this branch)
3. feat: implement destroy() in adapters and plugins #207 — adapters, plugins, e2e tests and the archive (stacked on feat(core): add editor destroy lifecycle #196)

Verification

• openspec validate editor-destroy --type change passes.
• tasks.md is intentionally unchecked here; implementation PRs check off their tasks.

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