diff --git a/docs/architecture/c4/l3-frontend-3b-document-workflows.puml b/docs/architecture/c4/l3-frontend-3b-document-workflows.puml
index cf8663a7..71407f27 100644
--- a/docs/architecture/c4/l3-frontend-3b-document-workflows.puml
+++ b/docs/architecture/c4/l3-frontend-3b-document-workflows.puml
@@ -8,8 +8,8 @@ Container(backend, "API Backend", "Spring Boot")
 
 System_Boundary(frontend, "Web Frontend (SvelteKit / SSR)") {
     Component(homePage, "/ (Home / Search)", "SvelteKit Route", "Loader: parses URL params (q, from, to, senderId, receiverId, tags), fetches /api/documents/search and /api/persons. Renders search form with full-text, date range, sender/receiver typeahead, and tag filters.")
-    Component(docsListPageTs, "/documents/+page.ts", "SvelteKit Client Loader", "Client-side load gated by matchMedia('(min-width: 640px)') and ?view query. Fetches /api/documents/density only on tablet/desktop and outside calendar view; degrades to empty buckets on network failure.")
-    Component(timelineFilter, "TimelineDensityFilter.svelte", "Svelte Component", "Per-month density bars above the document list. Click selects a single month, emits onchange({from, to}) using YYYY-MM-DD boundaries. Hidden on mobile and in calendar view.")
+    Component(docsListPageTs, "/documents/+page.ts", "SvelteKit Client Loader", "Client-side load gated by matchMedia('(min-width: 1024px)') and ?view query. Fetches /api/documents/density only on desktop (Tailwind lg breakpoint) and outside calendar view; degrades to empty buckets on network failure.")
+    Component(timelineFilter, "TimelineDensityFilter.svelte", "Svelte Component", "Per-month density bars above the document list. Click selects a single month, emits onchange({from, to}) using YYYY-MM-DD boundaries. Hidden on mobile and tablet (below lg, 1024px) and in calendar view.")
     Component(docDetail, "/documents/[id]", "SvelteKit Route", "Loader: GET /api/documents/{id}. Page: metadata panel, inline file viewer, transcription editor, annotation layer, and comment thread.")
     Component(docEdit, "/documents/[id]/edit", "SvelteKit Route", "Edit form with PersonTypeahead, TagInput, date/location fields. Form action: PUT /api/documents/{id}.")
     Component(docNew, "/documents/new", "SvelteKit Route", "Upload form for a new document. Loader: GET /api/persons. Form action: POST /api/documents with multipart file.")
@@ -23,7 +23,7 @@ System_Boundary(frontend, "Web Frontend (SvelteKit / SSR)") {
 
 Rel(user, homePage, "Searches and browses", "HTTPS / Browser")
 Rel(homePage, backend, "GET /api/documents/search, GET /api/persons", "HTTP / JSON")
-Rel(docsListPageTs, backend, "GET /api/documents/density (tablet/desktop only)", "HTTP / JSON")
+Rel(docsListPageTs, backend, "GET /api/documents/density (desktop only, ≥1024px)", "HTTP / JSON")
 Rel(homePage, timelineFilter, "Mounts above the result list")
 Rel(docsListPageTs, timelineFilter, "Provides density / minDate / maxDate props")
 Rel(docDetail, backend, "GET /api/documents/{id}, GET /api/documents/{id}/file", "HTTP / JSON + Binary")