Research-update mode

Creates, extends, or re-verifies one or more pages’ research evidence file on its own, independent of a rewrite. No draft is written and no review is produced.

1. For each page path the user gave, check whether <source-directory>/_ak/<document-key>/research.md exists, and whether <source-directory>/_ak/<document-key>/research-context.md exists and is newer than it.
2. Choose the mode per page under the researcher brief: create when no file exists; otherwise extend (a new question or topic), reverify (re-check cited sources, optional topic), or rebuild. Infer it from the user’s words and ask once only when it is unclear. An existing file is never replaced without rebuild and an explicit yes for that page. When the context is newer than the file, offer an extend with no topic.
3. Delegate to the researcher one page at a time, never in parallel. Wait for the returned handoff before the next page; the synchronous-delegation rule of Iterate mode applies.
4. Report, per page: the research file path, a one-line summary of findings and gaps, and the one-line research summary. If the handoff lists contested points, offer each as an Open questions entry for research-context.md, never as a [decision] placeholder, and say a later extend with no topic records their resolution once they decide. Say you will add the entries to research-context.md if they ask (Context files); add nothing otherwise. Do not draft, review, or touch a source document or content-quality-ledger.json.

The pipeline router owns mode selection. The researcher brief owns the delegation and its acceptance. The shared output layout owns generated paths.