Index of all AI-generated media organized by type and date. Each entry contains: path (relative to documents/), type (image/audio/poster/headshot/icon/etc), prompt_summary (brief description), and created_at (ISO date). Updated when any media skill generates output. Enables cross-skill browsing ("show me all my generated images") and history queries ("what did I create last week?"). Skills should APPEND entries when generating new media, not replace the file. Keep entries for 90 days; prune older entries unless user starred them. This is a lightweight index—don't store full prompts or binary data here.