Replace XML tags with markdown formatting in chat prompts by subsy · Pull Request #205 · subsy/ralph-tui

subsy · 2026-01-23T14:16:24Z

Summary

Updated the prompt building logic in ChatEngine to use markdown formatting instead of XML tags for better compatibility with CLI agents that may interpret angle-bracket tags as protocol markers.

Changes

Replaced <system> XML tags with ## Instructions markdown header
Replaced <conversation> XML tags with ## Conversation History markdown header
Added ## Current Request markdown header for the current user message
Removed the explicit Assistant: prompt suffix to allow agents more flexibility in response formatting
Improved overall prompt structure with consistent markdown formatting

Implementation Details

The prompt structure remains logically equivalent, with system instructions, conversation history, and current request clearly separated
Markdown headers provide clear visual separation while avoiding potential conflicts with CLI agent protocol parsing
Conversation history entries maintain the User: and Assistant: prefixes for clarity within the history section
Empty strings are added to parts array to ensure proper line spacing in the final joined output

Summary by CodeRabbit

Refactor
- Prompt assembly now uses Markdown section headers for instructions, conversation history and current request; surrounding spacing adjusted. No change to behaviour or user-facing features.
Tests
- Expanded test coverage to validate the new prompt formatting, section ordering and history limits.

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…t compatibility The chat engine's buildPrompt() method used <system> and <conversation> XML tags to wrap the system prompt and history. This caused OpenCode CLI (and potentially other agents) to timeout when processing the prompt via stdin, as the angle-bracket tags may be interpreted as protocol markers by the CLI tool's input parser. Replace with markdown headers (## Instructions, ## Conversation History, ## Current Request) which matches the format used by the ralph-tui run engine templates that work correctly with all agents. Fixes #204 https://claude.ai/code/session_014bffPdJT7UX84NpCw7zxig

vercel · 2026-01-23T14:16:29Z

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1 Skipped Deployment

Project	Deployment	Review	Updated (UTC)
ralph-tui	Ignored	Preview	Jan 23, 2026 2:32pm

coderabbitai · 2026-01-23T14:16:53Z

Walkthrough

Prompt assembly in the chat engine was reformatted from XML-like tags to Markdown sections (## Instructions, ## Conversation History, ## Current Request). Tests were expanded and a public ChatEngine export was added; no changes to message handling, history slicing, or API interactions.

Changes

Cohort / File(s)	Change Summary
Prompt format & export `src/chat/engine.ts`	Replaced XML-style wrappers (`<system>`, `<conversation>`, trailing `Assistant:`) with Markdown headers (`## Instructions`, `## Conversation History`, `## Current Request`) and adjusted surrounding blank lines; `ChatEngine` is now publicly exported.
Tests & mocking `src/chat/engine.test.ts`	Added/imported `ChatEngine`, introduced `createMockAgent` helper, expanded assertions to verify Markdown section headers, history formatting and limits, and absence of old XML tags.

Sequence Diagram(s)

(omitted — changes are formatting and tests, no new multi-component control flow)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

Improve user story description parsing for multiple LLM formats #200 — Edits prompt-generation formatting in src/chat/engine.ts, similar change from XML-like tags to Markdown headers.

Poem

🐇 I hopped through prompts, tidy and bright,

Swapped tags for headers, made sections light.
Instructions here, history in view,
Current request, crisp and new.
A rabbit’s nod to clean, readable cue.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Replace XML tags with markdown formatting in chat prompts' directly and concisely describes the main change in the changeset — replacing XML-like tags with Markdown headers in the prompt assembly logic.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

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codecov · 2026-01-23T14:17:38Z

Codecov Report

❌ Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 44.88%. Comparing base (e4ccc45) to head (9f66979).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/chat/engine.ts	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #205      +/-   ##
==========================================
+ Coverage   44.23%   44.88%   +0.65%     
==========================================
  Files          84       84              
  Lines       24229    24231       +2     
==========================================
+ Hits        10718    10877     +159     
+ Misses      13511    13354     -157

Files with missing lines	Coverage Δ
src/chat/engine.ts	`63.54% <87.50%> (+53.10%)`	⬆️

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

Adds tests verifying the ChatEngine.buildPrompt() method uses markdown headers instead of XML tags for CLI agent compatibility: - Uses ## Instructions instead of <system> tags - Uses ## Conversation History instead of <conversation> tags - Uses ## Current Request for the user message - Does not end with bare Assistant: marker - Sections appear in correct order - Respects maxHistoryMessages limit - Includes User:/Assistant: role prefixes in history https://claude.ai/code/session_014bffPdJT7UX84NpCw7zxig

…-V8Zcy Replace XML tags with markdown formatting in chat prompts

subsy merged commit eff9228 into main Jan 23, 2026
9 checks passed

subsy deleted the claude/fix-opencode-cli-issue-V8Zcy branch January 23, 2026 14:38

sakaman pushed a commit to sakaman/ralph-tui that referenced this pull request Feb 15, 2026

Merge pull request subsy#205 from subsy/claude/fix-opencode-cli-issue…

ebf646c

…-V8Zcy Replace XML tags with markdown formatting in chat prompts

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Replace XML tags with markdown formatting in chat prompts#205

Replace XML tags with markdown formatting in chat prompts#205
subsy merged 2 commits intomainfrom
claude/fix-opencode-cli-issue-V8Zcy

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