Extension API 0.2.0 migration

API 0.2.0 removes the APIs already deprecated in published package version 0.43.1. The API version stays 0.2.0 because these removals belong to the same unreleased breaking release. See API versioning.

Migrate extension callers on the published SDK and UI 0.43.1 first. Keep that extension PR separate from the platform removal PR. Update the host only after its installed extensions use the replacements.

Removed API	Replacement
ctx.sessions.list(), listByWorkspace()	ctx.sessions.query(), or query({ workspaceId }); follow every nextCursor. Results are newest first. Set includeArchived: true when history includes archived sessions.
ctx.workspaces.archive(), provider archive, capability archive, workspace.archived event	Workspace delete operation, provider delete, capability delete, and workspace.deleted. Session archive operations remain available.
defineStatuses, StatusContribution, WorkflowStatus, StatusActionDefinition, StatusRef, statuses contributions, status.v1	Extension-owned workflow records and settings, query enum options, and boardColumnConfigs.
Kanban attribute kind status	enum with query-owned options. Keep stored attribute and option IDs.
Kanban ordering, flat filters, defaultFilters	sorts, structured filter, and defaultFilter.
Kanban onReorder	onMove, which applies grouping changes and manual order together.
Saved view isDefault, including UI CollectionSavedView.isDefault	Collection defaultActiveViewId and the shared saved-view default.
SDK client projects.listActivity()	No project activity route remains. Read the supported domain APIs needed by the caller.
Chat onOpenFile props on MessagePartsRenderer, ToolInvocationTimeline, and TimelineFromJSON	linkHandler.open, with the shared file-link request.

The generated workspace migration removes stored capability archive keys. If a row has no delete value, it copies the old archive value; an existing delete value takes precedence. Historical board migration code still reads older stored filters and ordering. New API requests use only structured filters and sorts.

Storage KV and collection APIs deprecated only on the current development branch remain available for their normal deprecation window.

Project settings contributions use workbenchSlots.projectSettings (project.settings). Commands from webviews receive the placement resource and a slot with the current project and panel. Command calls return the same response envelope in the dashboard, workbench, and testbench, including structured rejection details.