Subscribes to subagentWatcher's subagent:tool_call events and attributes every
Write/Edit/MultiEdit/NotebookEdit file_path to its agent. Dedupes repeat writes,
classifies by extension (html/image/pdf/document/markdown/text/code/other), bounds
memory (FIFO per-agent + per-index caps), and exposes query-by-agent/session/all.
Metadata only — records paths, never reads/serves contents; guard enforcement stays
in the serving layer. recordExternalArtifact() reserved for image-watcher correlation
of Bash-written screenshots. Load-bearing piece for the Agent Gallery view.
Verified against live w7 transcripts: 8 mockups correctly attributed with write counts.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
