Raw system/internal XML tags leak into TUI assistant message output #20148

Description

When system prompts or MCP wrapper tools inject XML-like tags into LLM context (e.g. <system-reminder>, <dcp-message-id>, <dcp-system-reminder>, <!-- OMO_INTERNAL_INITIATOR -->), the model sometimes echoes them back in its response text. These raw tags render as visible text in the TUI TextPart component, cluttering the output.

The TextPart function in routes/session/index.tsx passes props.part.text.trim() directly to the <markdown> or <code> renderer without stripping these injected tags.

Plugins

MCP servers (e.g. Firebase MCP) — but the issue is in core text rendering, not plugin-specific.

OpenCode version

1.3.0

Steps to reproduce

1. Use opencode with a system prompt or wrapper that injects <system-reminder> tags
2. Have the LLM echo back those tags in its response
3. Observe raw XML tags rendering as visible text in the TUI

Operating System

macOS (Apple Silicon)

Terminal

Ghostty