add-feature

A development guide for adding a major new capability to OhMyCode when it does not fit the existing tool or AI-provider extension points.

In plain words
What is it for?
Use it for work such as adding hooks, MCP support, multiple sessions, a plugin system, new command-line features or a new compression method.
Why use it?
It helps plan changes across the project using its architecture, coding rules and testing conventions.

Skill for Claude CodeCodex

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 skills/alphalab-ustc/ohmycode/add-feature
Any agent
npx skills add AlphaLab-USTC/OhMyCode --skill add-feature
Clone the repo
git clone --depth 1 https://github.com/AlphaLab-USTC/OhMyCode

Made for: Claude Code, Codex.

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 937 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00044 $0.00937
Opus 5 $0.00022 $0.00468
Sonnet 5 $0.00009 $0.00187
Haiku 4.5 $0.00004 $0.00094

Measured 3d ago against content hash a695cd13ef83, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

add-feature 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 3d 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.

.agents/skills/add-feature/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Add a New Feature to OhMyCode

Add a major new capability that isn't covered by existing extension points (add-tool, add-provider).

Examples: hook system, MCP support, multi-session management, plugin architecture, new CLI commands, new compression strategy.

When to Use

  • User wants a feature that requires new modules or modifying core modules
  • User says "add hook support", "add MCP", "add plugin system", etc.
  • The feature doesn't fit into the existing tool/provider/config pattern

IMPORTANT: Read First

Before doing anything, read docs/DEVELOPMENT_GUIDE.md — it contains:

  • Project architecture and module dependency graph
  • Code conventions (file size limits, naming, async patterns)
  • Testing conventions
  • Commit conventions

Step-by-Step Guide

Step 1: Understand the Request

Ask the user:

  1. What does the feature do?
  2. Who uses it? (end users via CLI? developers extending OhMyCode? both?)
  3. What existing modules does it interact with?

Step 2: Design the Architecture

Based on docs/DEVELOPMENT_GUIDE.md, determine:

  1. Where does the code go?

    • New module under ohmycode/? (e.g., ohmycode/hooks/)
    • Extends an existing module? (e.g., add to ohmycode/core/)
    • Both?
  2. What interfaces does it expose?

    • New Protocol/ABC?
    • New config options?
    • New CLI commands/flags?
    • New slash commands in REPL?
  3. What existing code needs to change?

    • Check the dependency graph in DEVELOPMENT_GUIDE.md
    • Minimize changes to existing modules
    • Never introduce circular imports
  4. Propose the design to the user before writing code.

Step 3: Implement with TDD

For each component:

  1. Write failing test in tests/<module>/test_<component>.py
  2. Run test to confirm it fails
  3. Implement the minimal code to pass
  4. Run ALL tests to ensure no regressions: python3 -m pytest tests/ -v
  5. Commit incrementally

Step 4: Integrate

If the feature requires changes to existing modules:

  • Keep changes minimal and surgical
  • Prefer adding new functions over modifying existing ones
  • Use feature flags in config if the feature should be optional

Read the full file on GitHub · 117 lines

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. 3d ago First seen · 117 lines · 44 tokens per session scan A a695cd13ef83

Subscribe to this mod's changes

add-feature is a skill published in the GitHub repository AlphaLab-USTC/OhMyCode (131 stars, last pushed 5mo ago), licensed MIT. It adds 44 tokens to every session and 937 once invoked, about $0.0002 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 2026-08-30.

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