feat: add brief apply formatting instructions to agent/plan, current file description update

[RomneyDa]

Description

• Agent and plan modes need to have simple codeblock instructions to be able to format codeblocks that won't NOT work with apply, but also be instructed that they should avoid using codeblocks unless for demonstrative purposes
• Also tweaks current file tool to be a bit more use-happy

CON-3422
CON-2393
CON-2392

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Summary by cubic

Adds brief apply-formatting guidance to Agent and Plan system messages to reduce noisy code blocks and guide proper edit flow. Addresses CON-3422 by aligning code suggestions with apply tooling.

• New Features
  • Use short placeholders for unchanged parts of large code blocks (e.g., // ... existing code ...).
  • Updated Agent and Plan messages to include this guidance.
  • Clarified usage: code blocks are for suggestions only; Agent uses edit tools; Plan asks to switch to Agent for changes.

[github-actions]

The PR introduces a new constant BRIEF_LAZY_INSTRUCTIONS to encourage use of placeholders for unmodified code sections and integrates it into the default system messages. While the intent is good, there are several issues with the implementation that need to be addressed.

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[github-actions]

Code Review Summary

✅ Strengths

• Code Organization: The introduction of BRIEF_LAZY_INSTRUCTIONS as a separate constant improves code reusability and maintains DRY principles
• Clear Intent: The changes clearly differentiate between showing code examples (in codeblocks) and actually making changes (using edit tools)
• Consistency: The lazy placeholder pattern is consistently applied across different system message modes

⚠️ Issues Found

Medium

• Syntax Error: There's a stray semicolon and quote in BRIEF_LAZY_INSTRUCTIONS that will cause a syntax error: '// ... existing code ...'"; should be '// ... existing code ...'
• Redundant Instructions: The PR removes EDIT_CODE_INSTRUCTIONS from agent and plan modes but adds similar functionality through BRIEF_LAZY_INSTRUCTIONS. This creates some overlap since EDIT_CODE_INSTRUCTIONS already contains comprehensive lazy placeholder guidance

Low

• Formatting Inconsistency: Extra blank line after ${BRIEF_LAZY_INSTRUCTIONS} in agent mode system message creates inconsistent spacing compared to other sections

💡 Suggestions

• Consider Consolidation: Since EDIT_CODE_INSTRUCTIONS already contains detailed instructions about using placeholders like // ... existing code ..., consider whether BRIEF_LAZY_INSTRUCTIONS is necessary or if it should be integrated into the existing constant
• Clarify Tool Usage: The instruction "For making changes, use the edit tools" in agent mode could be more specific about which tools to use
• Documentation: Consider adding a comment explaining why EDIT_CODE_INSTRUCTIONS was removed from agent and plan modes, as this represents a significant behavior change

🚀 Overall Assessment

REQUEST_CHANGES

The PR has a clear goal of improving how the system handles code suggestions versus actual edits, but the syntax error must be fixed before merging. Additionally, addressing the redundancy between the two instruction sets would improve code clarity.

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[cubic-dev-ai]

1 issue found across 1 file

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