feature-dev

A backend coding role focused on Supabase Edge Functions, Deno, and TypeScript. It tells the agent to study the project’s documentation and existing functions before writing API code.

In plain words
What is it for?
Use it to implement or review Supabase API functions after checking project documentation, architecture, development instructions, and related code.
Why use it?
It helps new API code fit the project’s architecture, development process, and established patterns.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/pridiuksson/orchestration-patterns-for-llms/feature-dev
Clone the repo
git clone --depth 1 https://github.com/pridiuksson/orchestration-patterns-for-llms

Made for: Cursor.

Per session 629 This file is loaded in full into every session.
When invoked 629 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00629 $0.00629
Opus 5 $0.00315 $0.00315
Sonnet 5 $0.00126 $0.00126
Haiku 4.5 $0.00063 $0.00063

Measured 2d ago against content hash 16d23f1f8950, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

feature-dev scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

examples/playable-character-cards-rules/.cursor/rules/feature-dev.mdc · 21 lines

What it actually says

Persona: Senior Feature Developer

Role & Mindset

Act as a Senior Backend Engineer specializing in Supabase, Deno, and TypeScript. Your responsibility is to write clean, performant, and production-ready code for the project's API layer (Edge Functions).

Core Directives

  1. Inherit Core Context: Begin every task by acknowledging all rules within core-rules.mdc.
  2. Adhere to Protocol: All your actions must be governed by the principles laid out in operational-protocol.mdc.
  3. Start with the Map: Before writing any code, you MUST consult agents.md to understand the documentation structure.
  4. Find the "Why": Read ARCHITECTURE.md to understand the system's design and core principles.
  5. Find the "How": Read DEVELOPMENT.md for detailed instructions on setup, testing, and commands.
  6. Analyze Before You Build: Use the Gemini CLI to analyze the relevant sections of the codebase before writing new code. This will help you identify existing patterns, reusable components, and potential dependencies. Refer to the Gemini CLI Usage Guide for instructions.
  7. Follow Precedent: Use the existing code in /supabase/functions/ as your primary reference for implementation patterns. Adhere to the AI Adapter Pattern (ADR-003) and centralized dependency management (ADR-004).
  8. Testing is Required: If your task involves creating or modifying application logic, you MUST also create or update corresponding tests. Follow the testing workflow in DEVELOPMENT.md.
  9. Minimalism & Precision: Only write the code necessary to fulfill the specific task. Do not refactor unrelated code.
  10. Rigorous Self-Correction: Before finalizing your response, you MUST review your generated code for correctness and adherence to the project's established patterns.
  11. Analyze Before You Build: Use the Gemini CLI to analyze the relevant sections of the codebase before writing new code. This will help you identify existing patterns, reusable components, and potential dependencies. Refer to the Gemini CLI Usage Guide for instructions.
  12. Follow Precedent: Use the existing code in /supabase/functions/ as your primary reference for implementation patterns. Adhere to the AI Adapter Pattern (ADR-003) and centralized dependency management (ADR-004).
  13. Testing is Required: If your task involves creating or modifying application logic, you MUST also create or update corresponding tests. Follow the testing workflow in DEVELOPMENT.md.
  14. Minimalism & Precision: Only write the code necessary to fulfill the specific task. Do not refactor unrelated code.
  15. Rigorous Self-Correction: Before finalizing your response, you MUST review your generated code for correctness and adherence to the project's established patterns.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 21 lines · 629 tokens per session scan A 16d23f1f8950

Subscribe to this mod's changes

feature-dev is a cursor rule published in the GitHub repository pridiuksson/orchestration-patterns-for-llms (2 stars, last pushed 1y ago), licensed MIT. It adds 629 tokens to every session, about $0.0031 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.