[opencode-agent]

Summary

• Expose session.list on both Promise and Effect plugin contexts, matching the session API's filters and cursor pagination.
• Share the session-list cursor contract between the server and plugin host so filters, ordering, and pagination use the same cursors.
• Document the new read and test filtered pagination and invalid cursors. Neither session.active nor the experimental session export is added to plugin context.

Validation

• bun test test/plugin/session-list.test.ts (packages/core; 2 pass)
• GOMAXPROCS=2 bun typecheck (packages/core and packages/plugin; rerun after removing active)
• Prettier check and git diff --check
• Initial validation also passed the protocol cursor test, schema/protocol typechecks, website typecheck, and root lint (existing warnings, no errors).

The initial repository-wide typecheck hit the Host's resource limit during an unrelated stats-app task; the affected packages passed individually. The website build rendered the plugin docs but failed during Cloudflare Miniflare teardown (Server is not running). Generated OpenAPI checks are stale on the base branch from unrelated API/schema differences; no generated files are included here.

Requested by: @Brendonovich (Brendan via Slack)