Read a Knowledge document again (Read it again, with a changed instruction when given): the parse compares what it finds with the document's own answers first, so an unchanged answer keeps its sid and its reads, a changed one says otherwise and one not found again is listed to remove; nothing changes before the OK on the parse record in result.parse. 409 source_not_read on a document never read, source_reading while a parse is on it.

Contract:

• MCP tool read_again_agent_source, registry package mcp.unibox/agent_sources, mount unibox.knowledge.
• Operation action, response envelope action.
• Flags: none.