PR #61729: fix(Gateway): strip tool_call and tool_result XML blocks from assistant visible text

• Repository: openclaw/openclaw
• Author: openperf
• State: closed | merged: True
• Link: https://github.com/openclaw/openclaw/pull/61729

Description (problem / solution / changelog)

Summary

• Problem: In Discord and other gateway-managed channels, raw <tool_call> and <tool_result> XML blocks leak into the assistant's visible messages even when verboseDefault: "off" is set. This occurs because the gateway layer sometimes emits tool results wrapped in XML (e.g., <tool_result>...</tool_result> or even mismatched <tool_result>...</tool_call>), and the core message delivery pipeline fails to strip these tags.
• Root Cause: There are two separate sanitization pipelines in the codebase. PR #60619 added stripToolCallXmlTags() to stripAssistantInternalScaffolding() in assistant-visible-text.ts, but this function is only exported for the plugin SDK and is never called in the main message delivery path. The actual delivery pipeline uses sanitizeAssistantText() in pi-embedded-utils.ts, which strips <think> tags, downgraded [Tool Call: ...] text, and Minimax XML, but completely misses standard <tool_call> and <tool_result> XML tags. Furthermore, the TOOL_CALL_TAG_NAMES set did not include tool_result, meaning even if the function was called, <tool_result> blocks would still leak.
• Fix:
  1. Exported stripToolCallXmlTags from assistant-visible-text.ts and integrated it into the core sanitizeAssistantText() pipeline in pi-embedded-utils.ts.
  2. Added tool_result to TOOL_CALL_TAG_NAMES and TOOL_CALL_QUICK_RE so that tool result XML blocks are properly identified and stripped. This ensures that all assistant text is properly sanitized of tool XML before being chunked and delivered to any channel, fixing the root cause of the leak.
• What changed:
  • src/shared/text/assistant-visible-text.ts: Added tool_result to tag names and regex; exported stripToolCallXmlTags.
  • src/agents/pi-embedded-utils.ts: Imported and called stripToolCallXmlTags inside sanitizeAssistantText().
  • src/shared/text/assistant-visible-text.test.ts: Added tests for <tool_result> stripping.
  • src/agents/pi-embedded-utils.test.ts: Added regression tests for <tool_call> and <tool_result> stripping in extractAssistantText.
• What did NOT change (scope boundary): The logic for determining when to emit tool results (the verbose flag logic) remains unchanged. We are strictly fixing the text sanitization pipeline to ensure XML scaffolding never reaches the user-facing text buffer. The stripAssistantInternalScaffolding behavior for plugins remains functionally identical (just with added tool_result support).

Reproduction

1. Set agents.defaults.verboseDefault: "off" in openclaw.json.
2. Use /verbose off in a Discord channel.
3. Send a message that triggers a tool call (e.g., "Read the file test.txt").
4. Observe that the assistant's reply no longer contains raw <tool_call> or <tool_result> XML blocks inline.

Risk / Mitigation

• Risk: Stripping <tool_result> or <tool_call> might accidentally remove legitimate user-facing text if the assistant is trying to teach the user about these XML tags.
• Mitigation: The stripToolCallXmlTags function is already stateful and carefully designed to preserve literal XML-style examples in prose (e.g., when wrapped in backticks or when used as lone mentions). We added comprehensive unit tests in pi-embedded-utils.test.ts to ensure both the stripping of raw blocks and the preservation of legitimate text work as expected.

Change Type (select all)

• Bug fix

Scope (select all touched areas)

• Gateway
• Agents

Linked Issue/PR

Fixes #61688

Changed files

• CHANGELOG.md (modified, +2/-0)
• src/agents/pi-embedded-utils.test.ts (modified, +110/-0)
• src/agents/pi-embedded-utils.ts (modified, +8/-218)
• src/agents/tools/chat-history-text.ts (modified, +3/-13)
• src/agents/tools/sessions.test.ts (modified, +7/-0)
• src/shared/text/assistant-visible-text.test.ts (modified, +55/-1)
• src/shared/text/assistant-visible-text.ts (modified, +220/-4)