Instruction file imported from AIHeart-Professional/MCP_Server (.github/instructions/code-reuse.instructions.md). Copyright stays with the author.

Code Reuse — Pre-Implementation Check (Mandatory)

BLOCKING REQUIREMENT: Before writing any new function, class, method, route, service, use case, database query, or utility, you MUST perform all steps below. This applies to every implementation request without exception.

Step 1 — Read KEYWORDS from Existing Docstrings

Search for any function whose KEYWORDS overlap with what you are about to write:

grep_search("KEYWORDS:.*<domain_term>|KEYWORDS:.*<action_term>", isRegexp=True)

• Extract 3–6 domain/action keywords from the request.
• Any function with 2+ keyword matches is a reuse candidate — read it before proceeding.

Step 2 — Run a Semantic Search

semantic_search("<natural language description of the feature>")

Review the top 5–10 results. Look for exact matches, partial matches, or composable helpers.

Step 3 — Declare Your Finding Before Writing Code

Before any implementation, explicitly state one of:

• ♻️ Reuse: "Function X in path/to/file.py already does this — I will call/extend it."
• 🔀 Compose: "Functions X and Y can be composed to cover this — I will use them."
• 🆕 New: "No existing implementation found after checking KEYWORDS and semantic search. New code is required."

Only proceed to write new code after reaching a 🆕 New conclusion.

Rule Summary

• NEVER write a new function without completing Steps 1–3 first.
• NEVER duplicate logic that already exists in the codebase.
• ALWAYS prefer calling/importing an existing function over reimplementing it.
• ALWAYS prefer composing two existing functions over writing a new one.