diff --git a/openspec/specs/architecture.md b/openspec/specs/architecture.md
index ff71f5e..fc95f6b 100644
--- a/openspec/specs/architecture.md
+++ b/openspec/specs/architecture.md
@@ -33,3 +33,11 @@ Implementation notes
 
 Decisions
 - <record cross‑cutting decisions here>
+
+Client platform decisions
+- Web: Next.js (SSR).
+  Rationale: semantic HTML, SEO, CWV, and ecosystem maturity.
+  Notes: App Router, server actions; sitemap, RSS for blog/resources.
+
+Decisions
+- 2025-11-17 — Web stack: Next.js (SSR).