feat(chat): save and view chat history — admin-only saved_chats, History page, open-a-chat return

app/core/caching.py

@@ -5,9 +5,10 @@ Two layers, one module:
 * **Version token** (``asset_version()``) — the value the HTML pages
   append to their asset URLs (``?v=<token>``).
 * **Response middleware** (``CachingMiddleware`` / ``configure_caching``)
-  — applies the caching behavior at the transport layer: the five known
-  HTML pages are always revalidated (``no-cache``) and their local asset
-  references are rewritten to carry ``?v=<token>``; ``/assets/*`` is
+  — applies the caching behavior at the transport layer: the known
+  HTML pages (``HTML_PAGES``) are always revalidated (``no-cache``) and
+  their local asset references are rewritten to carry ``?v=<token>``;
+  ``/assets/*`` is
   served ``immutable`` for a year; everything else — all of ``/api/*``,
   including the SSE chat stream — passes through byte-identical.
 
@@ -123,6 +124,7 @@ HTML_PAGES: tuple[str, ...] = (
     "/login.html",
     "/tuning.html",
     "/git-sources.html",  # phase 35: the admin git sources page
+    "/history.html",  # phase 50: the admin saved-chats page
 )
 
 #: Prefix of the versioned static assets (header-only caching; the body is
@@ -192,8 +194,8 @@ class CachingMiddleware(BaseHTTPMiddleware):
 
     * ``/assets/*`` — ``Cache-Control: public, max-age=31536000, immutable``
       (header only — the body is never read).
-    * the five known HTML pages — ``Cache-Control: no-cache``, and (for
-      ``text/html`` bodies) every local asset reference gains
+    * the known HTML pages (``HTML_PAGES``) — ``Cache-Control: no-cache``,
+      and (for ``text/html`` bodies) every local asset reference gains
       ``?v=<token>``.
 
     Everything else — all of ``/api/*`` (including the SSE chat stream) —