rp-build

name	rp-build
description	Build with RepoPrompt MCP tools context builder plan → implement
repoprompt_managed	true
repoprompt_skills_version	29
repoprompt_variant	mcp

MCP Builder Mode

Task: $ARGUMENTS

Build deep context via context_builder to get a plan, then implement directly. Use follow-up reasoning only when navigating the selected code proves difficult or the plan leaves a concrete gap.

The Workflow

0. Verify workspace – Confirm the target codebase is loaded
1. Quick scan – Understand how the task relates to the codebase
2. Context builder – Call context_builder with a clear prompt to get deep context + an architectural plan
3. Only if needed, ask chat_send – Use it when navigating the selected code is difficult or the plan leaves a concrete unresolved gap
4. Implement directly – Use editing tools to make changes once the plan is clear

---

CRITICAL REQUIREMENT

⚠️ DO NOT START IMPLEMENTATION until you have:

1. Completed Phase 0 (Workspace Verification)
2. Completed Phase 1 (Quick Scan)
3. Called context_builder and received its plan

Skipping context_builder results in shallow implementations that miss architectural patterns, related code, and edge cases. The quick scan alone is NOT sufficient for implementation.

---

Phase 0: Workspace Verification (REQUIRED)

Before any exploration, confirm the target codebase is loaded:

{ "tool": "list_windows", "args": {} }

Check the output:

• If your target root appears in a window → bind to that window with select_window
• If not → the codebase isn't loaded

Bind to the correct window:

{"tool":"select_window","args":{"window_id":<window_id_with_your_root>}}

If the root isn't loaded, find and open the workspace:

{"tool":"manage_workspaces","args":{"action":"list"}}
{"tool":"manage_workspaces","args":{"action":"switch","workspace":"<workspace_name>","open_in_new_window":true}}

---

Phase 1: Quick Scan (LIMITED - 2-3 tool calls max)

⚠️ This phase is intentionally brief. Do NOT do extensive exploration here—that's what context_builder is for.

Start by getting a lay of the land with the file tree:

{ "tool": "get_file_tree", "args": { "type": "files", "mode": "auto" } }

Then use targeted searches to understand how the task maps to the codebase:

{"tool":"file_search","args":{"pattern":"<key term from task>","mode":"path"}}
{"tool":"get_code_structure","args":{"paths":["RootName/likely/relevant/area"]}}

Use what you learn to reformulate the user's prompt with added clarity—reference specific modules, patterns, or terminology from the codebase.

STOP exploring after 2-3 searches. Your goal is orientation, not deep understanding. context_builder will do the heavy lifting.

---

Phase 2: Context Builder

Call context_builder with your informed prompt. Use response_type: "plan" to get an actionable architectural plan.

{
  "tool": "context_builder",
  "args": {
    "instructions": "<reformulated prompt with codebase context>",
    "response_type": "plan"
  }
}

What you get back:

• Smart file selection (automatically curated within token budget)
• Architectural plan grounded in actual code
• chat_id for follow-up conversation

Trust context_builder – it explores deeply, aggregates the relevant context, and selects intelligently. Default to trusting the plan it returns. The chat_send follow-up only reasons over that selected context; it cannot fill coverage gaps on its own.

---

Phase 3: Ask chat_send only if needed

chat_send deep-reasons over the files selected by context_builder. It sees those selected files completely (full content, not summaries), but it only sees what's in the selection — nothing else.

This phase is optional. If the builder's plan is already clear and navigation through the selected code is straightforward, proceed straight to Phase 4.

Bring a follow-up to chat_send only when:

• Navigating the selected code proves difficult even with the builder's plan
• You need cross-file reasoning over the files already selected
• The plan leaves a concrete unresolved gap you cannot close by reading the selected files directly

If the answer depends on files outside the current selection, chat_send cannot answer it from thin air. Do not turn this workflow into manual selection management by default — if coverage is materially wrong, prefer rerunning context_builder with a better prompt.

{
  "tool": "chat_send",
  "args": {
    "chat_id": "<from context_builder>",
    "message": "The plan points me to X and Y, but I'm still having trouble tracing how they connect across these selected files. What am I missing, and what edge cases should I watch for?",
    "mode": "plan",
    "new_chat": false
  }
}

chat_send excels at:

• Deep reasoning over the context_builder output and selected files
• Spotting cross-file connections that piecemeal reading might miss
• Answering targeted "what am I missing in this selected context" questions

Don't expect:

• Knowledge of files outside the selection
• Repository exploration or missing-file discovery — that's context_builder's job
• Implementation — that's your job

---

Phase 4: Direct Implementation

STOP - Before implementing, verify you have:

• A builder result available (chat_id if follow-up is needed)
• An architectural plan grounded in actual code

If a specific point is still unclear, use chat_send to clarify before proceeding.

Implement the plan directly. Do not use chat_send with mode:"edit" – you implement directly.

Primary tools:

// Modify existing files (search/replace)
{"tool":"apply_edits","args":{"path":"Root/File.swift","search":"old","replace":"new","verbose":true}}

// Create new files (auto-added to selection)
{"tool":"file_actions","args":{"action":"create","path":"Root/NewFile.swift","content":"..."}}

// Read specific sections during implementation
{"tool":"read_file","args":{"path":"Root/File.swift","start_line":50,"limit":30}}

Ask chat_send only when navigation or cross-file reasoning is the bottleneck:

{
  "tool": "chat_send",
  "args": {
    "chat_id": "<same chat_id>",
    "message": "I'm implementing X. The plan does not fully explain Y, and reading the selected files still leaves a gap. What pattern or connection am I missing here?",
    "mode": "chat",
    "new_chat": false
  }
}

---

Key Guidelines

Token limit: Stay under ~160k tokens. Check with manage_selection(op:"get") if unsure. Context builder manages this, but be aware if you add files.

Selection coverage:

• context_builder should already have selected the files needed for the plan
• chat_send can reason only over that selected context; it cannot discover missing files on its own
• If a material coverage gap blocks you, prefer rerunning context_builder with a better prompt over hand-curating selection
• Use manage_selection only as a last resort for a very small, targeted addition

chat_send sees only the selection: If the answer depends on files outside the selection, chat_send cannot provide it until coverage changes — and in this workflow, coverage changes should usually come from context_builder, not from manual curation.

---

Anti-patterns to Avoid

• 🚫 Using chat_send with mode:"edit" – implement directly with editing tools
• 🚫 Asking chat_send about files it cannot see in the current selection
• 🚫 Treating Phase 3 as mandatory when the builder's plan is already clear
• 🚫 Reopening or second-guessing the builder's plan by default instead of trusting it
• 🚫 Leaning on manual manage_selection work to patch coverage gaps that should be handled by context_builder
• 🚫 Skipping context_builder and going straight to implementation – you'll miss context
• 🚫 Using manage_selection with op:"clear" – this undoes context_builder's work; only use small targeted additions if absolutely necessary
• 🚫 Exceeding ~160k tokens – use slices if needed
• 🚫 CRITICAL: Doing extensive exploration (5+ tool calls) before calling context_builder – the quick scan should be 2-3 calls max
• 🚫 Reading full file contents during Phase 1 – save that for after context_builder builds context
• 🚫 Convincing yourself you understand enough to skip context_builder – you don't

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Your job: Get a solid plan from context_builder, trust it by default, use chat_send only when navigating the selected code proves difficult or the plan leaves a concrete unresolved gap, then implement directly and completely.