Read chat logs incrementally and drain retention (Refs #62)

docs/guides/native-hosts.md

@@ -76,7 +76,19 @@ successful monitoring and file-read records. The default is one day; zero keeps
 them indefinitely. Actions, failures, negative checks, and unresolved operations
 are retained. Agent 1.4.9 also cleans up successful routine journal records after
 the controller confirms their final receipt. Older unconfirmed journal entries
-remain until a replay supplies that confirmation. Cleanup runs in bounded batches.
+remain until a replay supplies that confirmation. Controller cleanup runs every
+five minutes and drains eligible records in batches, yielding between batches.
+
+Log-read operation history stores metadata only. The waiting reader receives the
+log content directly; saved match chat remains with its match. Background cleanup
+also removes log bodies left in controller history by earlier versions.
+
+Agent 1.8.5 adds incremental game-log reads for chat collection. After the initial
+tail, the controller requests only appended bytes, handles rotation and truncation,
+and buffers incomplete lines. Unchanged logs need no content transfer or chat
+parsing. Background collection skips offline hosts, stopped servers and known
+empty servers, with one final read after players leave. Opening chat still reads
+on demand. Older agents use tail reads until they update.
 
 ### New game files and cached versions