docs(memory): add naming and maintenance guidance

memory/README.md

@@ -47,6 +47,16 @@ When in doubt:
 2. later promote durable truths into `../MEMORY.md`
 3. only create a named note when the topic genuinely needs a long-lived home
 
+Create a named note when:
+- the topic will span multiple sessions
+- it needs to collect evidence, commands, or findings over time
+- it is likely to be reused as a reference later
+
+Prefer the daily note when:
+- it was a one-off conversation
+- it was a tiny fix or validation
+- the note would otherwise become a small orphan file
+
 ## Cleanup guidance
 
 If top-level `memory/` starts filling with non-daily files again: