pub const CREATOR_SOURCE_PREFIX: &str = "creator:source=";Expand description
Tag prefix carrying the originating subsystem (http/mcp/hook/cli).
Why: same labels as ActivitySource for HTTP / MCP / hook; CLI is
a fourth value we accept here because drawers written from the
trusty-memory send-message CLI never travel through the activity
log emit path but still need attribution.
What: lowercase string after the prefix.
Test: creator_info_renders_all_fields.