spec-driven-development

spec-driven-development is a skill for Claude Code, Codex from Plazmodium/odin-workflow. It costs 20 tokens per session (336 once invoked), scanned A, original, MIT.

A practice of defining the goal, boundaries, expected results, and verification plan before making significant code changes.

In plain words
What is it for?
Use it for features, projects, APIs, migrations, and other changes that affect multiple files, teams, systems, or users.
Why use it?
It prevents code from silently encoding guesses about unclear requirements or out-of-scope behavior.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it for features, projects, APIs, migrations, and other changes that affect multiple files, teams, systems, or users.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/plazmodium/odin-workflow/spec-driven-development
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.

Any agent
npx skills add Plazmodium/odin-workflow --skill spec-driven-development
Clone the repo
git clone --depth 1 https://github.com/Plazmodium/odin-workflow

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for spec-driven-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/plazmodium/odin-workflow/spec-driven-development.svg)](https://agentmods.dev/skills/plazmodium/odin-workflow/spec-driven-development)
Your own site
<a href="https://agentmods.dev/skills/plazmodium/odin-workflow/spec-driven-development"><img src="https://agentmods.dev/badge/skills/plazmodium/odin-workflow/spec-driven-development.svg" alt="Measured on agentmods" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 336 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00020 $0.00336
Opus 5 $0.00010 $0.00168
Sonnet 5 $0.00004 $0.00067
Haiku 4.5 $0.00002 $0.00034

Measured 6d ago against content hash a7e0e9e0cc58, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

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 6d 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/workflow/spec-driven-development/SKILL.md · 44 lines

What it actually says

spec-driven-development

When To Use

  • Starting a feature, project, API, migration, or significant behavior change.
  • The work crosses files, teams, trust boundaries, or user-visible behavior.
  • The user asks for a spec, PRD, or design before implementation.

Workflow

  1. State the goal and why it matters.
  2. Define in-scope and out-of-scope work.
  3. Capture assumptions and unresolved questions.
  4. Write acceptance criteria as observable outcomes.
  5. Describe user-visible behavior and failure behavior.
  6. Identify affected files, APIs, data, dependencies, and trust boundaries.
  7. Define the verification plan before coding.
  8. Stop if acceptance criteria or boundaries are materially unclear.

Anti-Rationalization

Excuse Rebuttal
"This task is too simple for a spec." Acceptance criteria can be five lines. Zero lines is the problem.
"The code will clarify the requirements." Code written before requirements tends to encode guesses.
"The user already knows what they want." The agent must know what is being optimized and what is excluded.

Verification

  • Spec includes goal, scope, non-goals, assumptions, acceptance criteria, and verification.
  • Ambiguities that affect implementation are resolved or explicitly deferred.
  • The verification plan can produce concrete evidence.

Exit Criteria

  • A reviewer can tell what success means without reading the implementation.
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. 6d ago First seen · 44 lines · 20 tokens per session scan A a7e0e9e0cc58

Subscribe to this mod's changes

spec-driven-development is a skill published in the GitHub repository Plazmodium/odin-workflow (0 stars, last pushed 3mo ago), licensed MIT. It adds 20 tokens to every session and 336 once invoked, about $0.0001 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 2026-09-01.

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