* feat: persist AI conversations and add chat history
Store transcripts and attachment previews in IndexedDB, separate conversation history from transport lifetime, and add document-aware switching with shared Storybook coverage. Preserve interrupted activity and guard stale writes and async switches.
* test: group chat history tests by domain
* feat: simplify chat history navigation and diagnostics
Use a compact header with searchable document-scoped history and a correctly anchored conversation menu. Move diagnostic copying into the menu with copy-result feedback, and separate Storybook fixtures from composition.
* fix: address chat history review findings
* test: cover harness shutdown and restored chat scrolling
* fix: preserve Portless proxy port in MCP routes
* docs: clarify UI animation conventions
* feat: configure reasoning display and animate disclosure
* fix: separate transcript following from reasoning disclosure
* fix: restore selected chat after document recovery
* refactor: separate chat history persistence and sessions
* style: format reasoning story imports