Dedupe response-tool prompt clause and document reasoning revert intent

Drop duplicate plain-text-invalid clause from response_tool_tips (covered by communication.md). Note reasoning-to-thoughts revert (77e55152) as maintainer UX call in response_stream_end DOX.

extensions/python/response_stream_end/AGENTS.md

@@ -12,6 +12,7 @@
 
 - Preserve final masking before response content is considered complete.
 - Keep log state consistent with streamed chunks and final response text.
+- Do not auto-promote native reasoning summaries into `thoughts` when explicit planning fields are absent; reasoning and `thoughts` are intentionally separate channels. Auto-population was removed (77e55152) as a maintainer UX call, not a bug fix — re-adding it requires an explicit maintainer decision.
 
 ## Work Guidance
 

prompts/agent.system.response_tool_tips.md

@@ -1,2 +1,2 @@
-always deliver the final user-facing answer through this `response` tool's `text` arg; plain-text output without a tool call is invalid and never reaches the user
+always deliver the final user-facing answer through this `response` tool's `text` arg
 for long existing text, use `§§include(path)` instead of rewriting