feature-dev

A staged workflow for taking a software feature from an early idea through investigation, design, coding, testing, and review. It uses checkpoints between phases instead of moving straight to implementation.

In plain words
What is it for?
Use it to explore an existing codebase, ask design-changing questions, compare architectures, implement a feature, and verify it with tests and review.
Why use it?
It reduces the risk of coding before the goal, codebase, security needs, and design are understood. The checkpoints make important decisions visible before they become expensive to change.

Command for Claude Code

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 commands/webhook-co/webhook/feature-dev
Clone the repo
git clone --depth 1 https://github.com/webhook-co/webhook

Made for: Claude Code.

Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 757 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 $0.00000 $0.00757
Opus 5 $0.00000 $0.00378
Sonnet 5 $0.00000 $0.00151
Haiku 4.5 $0.00000 $0.00076

Measured yesterday against content hash 64919c500871, 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 yesterday.

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.

.claude/commands/feature-dev.md · 60 lines

How it starts

The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/feature-dev

Take a feature from a rough idea to reviewed, tested implementation through explicit phases. Don't jump straight to code — move through the phases in order and check in at the gates.

Phase 1 — discovery

Restate the goal in one line: who it's for, which surface(s) (CLI / API / web / MCP), and the outcome they want. If the ask is vague, run the brainstorming skill / /brainstorming first and come back with an agreed brief.

Phase 2 — codebase exploration

Understand before changing. Find where this lives: the relevant apps/* and packages/*, the shared/ types, existing patterns for the same capability on other surfaces, and the tests that cover the area. Note constraints discovered (DO ownership, RLS, the container-delivery seam). Use the Explore subagent for broad searches when useful.

Phase 3 — clarifying questions

Before designing, ask the questions whose answers would change the design — auth/tenant context, data sensitivity (PII/PHI, raw payloads in R2), parity scope, ordering/performance needs, and which non-negotiables apply. Ask rather than assume. Wait for answers on anything load-bearing.

Phase 4 — architecture design (multiple approaches)

Present two or three viable approaches with concrete tradeoffs (complexity, parity cost, performance, blast radius, how cleanly each respects the non-negotiables). Recommend one and say why — have a point of view. Get agreement before implementing. Design for parity from the start: a capability added to one surface is considered for all four, with shared shared/ types.

Phase 5 — implementation

Implement the agreed approach under TDD (failing test first → minimum code → refactor; see the test-driven-development skill). Workers handlers stay thin (validate → delegate → respond); retries via DO Alarms; delivery idempotent and dedup-by-event-id; Standard-Webhooks-native signing only; open-core code must not import from ee/. For new MCP surface work, use the build-mcp-server skill.

Read the full file on GitHub · 60 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. yesterday First seen · 60 lines · 0 tokens per session scan A 64919c500871

Subscribe to this mod's changes

feature-dev is a command published in the GitHub repository webhook-co/webhook (0 stars, last pushed 6d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 757 tokens. 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.