Borrowing it
Nothing to install: this file belongs to AmanKtyr/Tailor. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/AmanKtyr/Tailor/main/.agents/skills/spec-driven-dev/SKILL.mdgit clone --depth 1 https://github.com/AmanKtyr/TailorWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/amanktyr/tailor/spec-driven-dev)<a href="https://agentmods.dev/skills/amanktyr/tailor/spec-driven-dev"><img src="https://agentmods.dev/badge/skills/amanktyr/tailor/spec-driven-dev/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/amanktyr/tailor/spec-driven-dev"><img src="https://agentmods.dev/badge/skills/amanktyr/tailor/spec-driven-dev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00035 | $0.01173 |
| Opus 5.5 | $0.00014 | $0.00469 |
| Sonnet 5.5 | $0.00007 | $0.00235 |
| Haiku 4.5 | $0.00003 | $0.00117 |
Grade A, and why
spec-driven-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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spec-Driven Development (SDD) Skill
Activate this skill when creating non-trivial features, refactoring major subsystems, building multi-file modules, or executing structured engineering workflows.
Operational Axiom: The specification is the contract. Reuse is the law. Code is the verifiable artifact.
1. The Spec-Driven Lifecycle
┌────────────────────────────────────────────────────────┐
│ 1. CONSTITUTION: .ai/CONSTITUTION.md │
│ Project non-negotiables, intensity, guardrails │
└───────────────────────────┬────────────────────────────┘
│
┌───────────────────────────▼────────────────────────────┐
│ 2. SPECIFICATION: specs/<id>-<name>/spec.md │
│ User stories, functional requirements, edge cases │
└───────────────────────────┬────────────────────────────┘
│
┌───────────────────────────▼────────────────────────────┐
│ 3. TECHNICAL PLAN: specs/<id>-<name>/plan.md │
│ AST REUSE AUDIT + file layout + 0-dep verification │
└───────────────────────────┬────────────────────────────┘
│
┌───────────────────────────▼────────────────────────────┐
│ 4. TASK CHECKLIST: specs/<id>-<name>/tasks.md │
│ Granular task ordering (TRIVIAL -> CRITICAL) │
└───────────────────────────┬────────────────────────────┘
│
┌───────────────────────────▼────────────────────────────┐
│ 5. IMPLEMENTATION & VERIFICATION │
│ Atomic changes + unit tests (Exit code: 0) │
└────────────────────────────────────────────────────────┘
2. Command Reference & Artifact Standards
A. /constitution (.ai/CONSTITUTION.md)
Establishes project-wide architectural principles, intensity mode (lite, balanced, ultra, strict), testing requirements, and forbidden patterns.
B. /spec-new <feature-name> (specs/<id>-<name>/spec.md)
Defines the problem domain and user acceptance criteria:
# Feature: [Feature Name]
**ID:** [001] | **Status:** Draft | Proposed | Approved
## 1. Problem Statement & User Value
Clear explanation of what problem this solves and for whom.
## 2. User Stories & Acceptance Criteria
- As a [role], I want [action] so that [outcome].
- [ ] Given [precondition], when [action], then [expected result].
## 3. Scope Boundaries
- **In-Scope:** Specific capabilities included in this release.
- **Out-of-Scope:** Explicitly deferred or rejected capabilities.
## 4. Edge Cases & Error Handling
- Network timeouts, missing permissions, invalid payloads, race conditions.
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.
- 1mo ago First seen · 115 lines · 35 tokens per session scan A 5f2c87959c60
spec-driven-dev is a skill published in the GitHub repository AmanKtyr/Tailor (6 stars, last pushed 11d ago), licensed MIT. It adds 35 tokens to every session and 1,173 once invoked, about $0.0001 per session on Opus 5.5. 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.
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