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.
npx skills add chankov/agent-fleet --skill spec-driven-developmentgit clone --depth 1 https://github.com/chankov/agent-fleetWrote 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/chankov/agent-fleet/spec-driven-development)<a href="https://agentmods.dev/skills/chankov/agent-fleet/spec-driven-development"><img src="https://agentmods.dev/badge/skills/chankov/agent-fleet/spec-driven-development/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/chankov/agent-fleet/spec-driven-development"><img src="https://agentmods.dev/badge/skills/chankov/agent-fleet/spec-driven-development.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 | $0.00050 | $0.02551 |
| Opus 5.5 | $0.00020 | $0.01020 |
| Sonnet 5.5 | $0.00010 | $0.00510 |
| Haiku 4.5 | $0.00005 | $0.00255 |
Grade A, and why
spec-driven-development 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.
This is a copy
83% identical to spec-driven-development — 53 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 246 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spec-Driven Development
Overview
Write a structured specification before writing any code. The spec is the shared source of truth between you and the human engineer — it defines what we're building, why, and how we'll know it's done. Code without a spec is guessing.
When to Use
- Starting a new project or feature
- Requirements are ambiguous or incomplete
- The change touches multiple files or modules
- You're about to make an architectural decision
- The user asks to grill or stress-test a concept/spec before planning
- The task would take more than 30 minutes to implement
When NOT to use: Single-line fixes, typo corrections, or changes where requirements are unambiguous and self-contained.
Output Location
By default, save the spec to docs/prds/{area}/PRD{n}-{topic}.md:
{area}— the functional area of the codebase the change belongs to. Ask the user or infer it from the change (e.g.tournaments,calendar,auth).{n}— the next free PRD number. Scandocs/prds/recursively for the highest existingPRD<number>and add 1; start at1if none exist.{topic}— a short kebab-case slug of the feature.
Match the project's existing docs vs Docs capitalization, and create the directory if it does not exist.
Project overrides: if .ai/agent-fleet-overrides.md has a ## spec-driven-development section, its keys (spec-dir, naming) override these defaults. Absent file or section → use the defaults above. See docs/agent-fleet-setup.md.
The Gated Workflow
Spec-driven development has four phases. Do not advance to the next phase until the current one is validated.
SPECIFY ──→ PLAN ──→ TASKS ──→ IMPLEMENT
│ │ │ │
▼ ▼ ▼ ▼
Human Human Human Human
reviews reviews reviews reviews
Phase 1: Specify
Gather context first. Before writing any spec content, identify and read the sources the spec will build on:
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 · 246 lines · 50 tokens per session scan A 147209ba7a89
spec-driven-development is a skill published in the GitHub repository chankov/agent-fleet (19 stars, last pushed yesterday), licensed MIT. It adds 50 tokens to every session and 2,551 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 83% identical to spec-driven-development, differing in 53 lines, and is treated as a copy.
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