diff --git a/CHANGELOG.md b/CHANGELOG.md
index a81197383e2..1b6b6c64371 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -88,6 +88,7 @@ Docs: https://docs.openclaw.ai
 - Diagnostics/Memory: prune stale diagnostic session state entries and cap tracked session states to prevent unbounded in-memory growth on long-running gateways. (#5136) Thanks @coygeek and @vignesh07.
 - Gateway/Memory: clean up `agentRunSeq` tracking on run completion/abort and enforce maintenance-time cap pruning to prevent unbounded sequence-map growth over long uptimes. (#6036) Thanks @coygeek and @vignesh07.
 - Auto-reply/Memory: bound `ABORT_MEMORY` growth by evicting oldest entries and deleting reset (`false`) flags so abort state tracking cannot grow unbounded over long uptimes. (#6629) Thanks @coygeek and @vignesh07.
+- Slack/Memory: bound thread-starter cache growth with TTL + max-size pruning to prevent long-running Slack gateways from accumulating unbounded thread cache state. (#5258) Thanks @coygeek and @vignesh07.
 - Security/Slack: compute command authorization for DM slash commands even when `dmPolicy=open`, preventing unauthorized users from running privileged commands via DM. Thanks @christos-eth.
 - Security/Nostr: require loopback source and block cross-origin profile mutation/import attempts. Thanks @vincentkoc.
 - Security/Archive: enforce archive extraction entry/size limits to prevent resource exhaustion from high-expansion ZIP/TAR archives. Thanks @vincentkoc.