Update AGENTS.md

AGENTS.md

@@ -234,7 +234,7 @@ WpAllocator scratch = wpMemArenaAllocatorInitZero(KiB(16));
 
 ## Documentation
 
-Save research notes and implementation plans as markdown in `documents/`:
+Save research notes, implementation plans and session logs as markdown in `documents/`:
 
 ```
 documents/
@@ -248,6 +248,9 @@ documents/
     └── YYYY-MM-DD.md
 ```
 
+At the start of each new session, read the previous session logs to understand what
+we've implemented so far
+
 ## Skills
 
 Domain-specific conventions are stored as skills in `.opencode/skills/<name>/SKILL.md`.