Preserve conversation excerpts and deduplicate case evidence

docs/guides/moderation.md

@@ -149,10 +149,19 @@ the required permission and reason, including after a case closes. Reopening a
 case also leaves its restrictions in place. Check enforcement coverage after
 applying or revoking a restriction.
 
-Staff notes are explicitly labeled as notes. Selecting archived chat when opening
-a case, or attaching a match ID and exact message within an existing case, verifies
-the target GUID and original message against the recorded match and saves an
-independent snapshot, including the original timing context. Unknown or estimated
+Staff notes are explicitly labeled as notes. In match chat, select up to 100
+messages and choose **Attach to case** to open a case or add them to an existing
+case for the selected subject. Select at least one message from that subject;
+messages from other participants can be selected alongside it. Each attachment
+preserves selected messages and, by default, three surrounding messages on either side, with
+names, GUIDs, original timing, and highlighted subject messages. The selection
+preview shows the excerpt before saving. Server verification uses stable archived
+message identifiers; repeated text remains separate occurrences, and attaching
+the same selected messages again does not duplicate evidence. Exact-text
+attachments remain available and include every matching occurrence, without the
+former ten-occurrence limit.
+
+Snapshots remain readable after source-match cleanup. Unknown or estimated
 timestamps remain such; the snapshot does not turn them into exact observations.
 Unarchived or already deleted chat cannot be attached as verified evidence.