fix(telegram): reuse preview for long text finals (#77658)

* fix(telegram): reuse preview for long text finals

* test(qa): cover long telegram finals

* fix(qa): satisfy extension lint

* fix(qa): keep telegram long final fixture to two chunks

* test(telegram): cover three chunk finals

* fix(telegram): force long final preview boundary

docs/channels/telegram.md

@@ -344,6 +344,7 @@ curl "https://api.telegram.org/bot<bot_token>/getUpdates"
     For text-only replies:
 
     - short DM/group/topic previews: OpenClaw keeps the same preview message and performs a final edit in place, unless a visible non-preview message was sent after the preview appeared
+    - long text finals that split into multiple Telegram messages reuse the existing preview as the first final chunk when possible, then send only the remaining chunks
     - previews followed by visible non-preview output: OpenClaw sends the completed reply as a fresh final message and cleans up the older preview, so the final answer appears after intermediate output
     - previews older than about one minute: OpenClaw sends the completed reply as a fresh final message and then cleans up the preview, so Telegram's visible timestamp reflects completion time instead of the preview creation time
 

docs/concepts/qa-e2e-automation.md

@@ -232,6 +232,8 @@ Scenarios (`extensions/qa-lab/src/live-transports/telegram/telegram-live.runtime
 - `telegram-tools-compact-command`
 - `telegram-whoami-command`
 - `telegram-context-command`
+- `telegram-long-final-reuses-preview`
+- `telegram-long-final-three-chunks`
 
 Output artifacts: