Update session history with server alignment learnings

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -31,7 +31,7 @@ No known bugs at the moment
 
 ### Version 0.2.0
 
-No changes at the moment.
+No pending tasks at the moment.
 
 ## Technical Stack
 
@@ -202,3 +202,19 @@ When editing CLAUDE.md or other markdown files, follow these rules to avoid lint
 - Empty header values should be treated as missing (null) not empty strings
 - Constructor parameters added: `allowInsecureHttp` for HTTP on non-localhost in dev mode
 - Private IP ranges to block: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 127.0.0.0/8, 169.254.0.0/16, 0.0.0.0/8
+
+### 2026-01-26 - Server Implementation Alignment
+
+**Completed:**
+
+- Verified client implementation against server documentation
+- Updated server docs to use RFC 5869 `hash_hkdf()` for key derivation (matching client)
+- Added recursive key sorting (`sortKeysRecursive()`) to client `ResponseSignature`
+- Client and server now use identical signature algorithms
+
+**Learnings:**
+
+- Server and client must use identical key derivation and JSON canonicalization
+- Recursive key sorting is essential for nested objects like the `license` object in validate responses
+- When updating cryptographic implementations, both client and server documentation must be aligned
+- The remote server documentation URL was 404 - local `docs/server-implementation.md` is the source of truth