Problem: AI-created documents could not be handed off as validated, durable
file cards, and binary files could not be read through the text editor route.
Root cause: delivery identity lived only in ordinary tool output, while file
reading, view selection and auxiliary actions lacked a shared preview path.
Fix: add a bounded root-confined reader, Controller and raw-byte preview APIs,
and host-confirmed present_files results projected through live and stored
history. Add lazy PDF, worker CSV and sandboxed HTML viewers, responsive file
cards, type icons, current-file state and accessible shared tooltips. Preserve
dirty drafts while surfacing deletion/revocation and avoid metadata reads per
keystroke. Keep the current workbench request-consumption contract intact.
Verification: root and desktop Go tests, go vet, make lint/check, frontend
typecheck, 498 related tests and production build. Browser checks cover PDF
navigation, CSV literals, menus, request consumption and responsive themes.
The builtin schema inventory grows by 143 measured tokens; boot effect tests
verify stable schemas within a turn for direct and capability-proxy calls.
