fix(reply): honour explicit [[reply_to_*]] tags when replyToMode is off (#16174)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 778fc2559a
Co-authored-by: aldoeliacim <17973757+aldoeliacim@users.noreply.github.com>
Co-authored-by: steipete <58493+steipete@users.noreply.github.com>
Reviewed-by: @steipete

docs/channels/discord.md

@@ -273,6 +273,8 @@ See [Slash commands](/tools/slash-commands) for command catalog and behavior.
     - `first`
     - `all`
 
+    Note: `off` disables implicit reply threading. Explicit `[[reply_to_*]]` tags are still honored.
+
     Message IDs are surfaced in context/history so agents can target specific messages.
 
   </Accordion>

docs/channels/slack.md

@@ -233,6 +233,8 @@ Manual reply tags are supported:
 - `[[reply_to_current]]`
 - `[[reply_to:<id>]]`
 
+Note: `replyToMode="off"` disables implicit reply threading. Explicit `[[reply_to_*]]` tags are still honored.
+
 ## Media, chunking, and delivery
 
 <AccordionGroup>

docs/channels/telegram.md

@@ -416,6 +416,8 @@ curl "https://api.telegram.org/bot<bot_token>/getUpdates"
     - `first`
     - `all`
 
+    Note: `off` disables implicit reply threading. Explicit `[[reply_to_*]]` tags are still honored.
+
   </Accordion>
 
   <Accordion title="Forum topics and thread behavior">