feat: add multi-channel Devii sessions with docs search mode and channel-aware conversation persistence

README.md

@@ -201,6 +201,17 @@ prose pages are curated markdown rendered through the shared content renderer (m
 highlight.js) with the current host and, when logged in, your own API key and username
 filled in.
 
+`/docs/search.html` search method is admin-configurable (`docs_search_mode` on
+`/admin/settings`, default `agent`). In **agent** mode it is **Docii**, a documentation-only
+assistant: an in-page chat (`<dp-docs-chat>`) rendered in the docs style where you ask
+questions in plain language and Docii repeatedly searches the documentation, reading the
+matching sections and refining its query until it has a grounded answer, with links to the
+relevant pages. Docii is the Devii engine on a dedicated `docs` conversation channel, but
+restricted to a single tool (documentation search) and driven by its own system prompt, so it
+cannot perform platform actions - it only reads the docs. In **bm25** mode it is the classic
+keyword results list. Either way, a viewer who has exceeded their daily AI limit (or a guest
+when Devii is disabled) falls back to keyword (BM25) search automatically.
+
 Every other endpoint is documented from a single source of truth, the `API_GROUPS` registry
 in `devplacepy/docs_api.py`. Each group becomes a reference page listing its endpoints with
 copy-paste cURL, JavaScript, and Python examples and an interactive "try it" panel