contract-builder

A tool for turning approved software plans into one written agreement for implementation. It combines the planned changes, requirements, design, tasks, and project rules into an execution contract.

In plain words
What is it for?
Use it when moving from planning to coding, especially in a spec-first workflow where requirements and task lists must guide the build.
Why use it?
It gives the person or coding agent building the software one shared reference for what must be done. It also prevents implementation from starting with missing, outdated, or inconsistent planning information.

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/magebyte-zero/spec-superflow/contract-builder
Any agent
npx skills add MageByte-Zero/spec-superflow --skill contract-builder
Clone the repo
git clone --depth 1 https://github.com/MageByte-Zero/spec-superflow

Made for: Claude Code, Codex.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,176 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 $0.00039 $0.01176
Opus 5 $0.00019 $0.00588
Sonnet 5 $0.00008 $0.00235
Haiku 4.5 $0.00004 $0.00118

Measured 2d ago against content hash 95d8b32d38b4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

contract-builder 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 2d 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.

skills/contract-builder/SKILL.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Contract Builder

Converts planning artifacts into a single execution handshake: execution-contract.md. Load the baseline with ssf runtime asset read templates/execution-contract.md.

Read before generating: .spec-superflow.yaml (especially dp_0_decisions), proposal.md, specs/, design.md, tasks.md, then load docs/artifact-contract.md with ssf runtime asset read docs/artifact-contract.md.

Artifact Language

Read artifact_language=<concrete-language> from dp_0_decisions. Generate execution-contract.md in the same language as that resolved value and the approved planning artifacts. Preserve required schema keywords and code identifiers verbatim; language consistency applies to explanatory prose and headings. If the concrete artifact language is missing or still auto, route back to workflow-start before writing the contract instead of guessing or silently defaulting to English.

Artifact Mapping

Source Extract
proposal.md## Why + ## What Changes Intent Lock (problem + scope)
proposal.md## Scope > ### Out of Scope Scope Fence
specs/ → each ### Requirement: Approved Requirements, Scenarios, Test Obligations
design.md## Decisions Architecture, Interface, Dependency Constraints
tasks.md → numbered task groups Execution Batches, Completion Definitions, Review Timing

Cross-Check: Requirement Coverage

Before finalizing:

  1. List every SHALL/MUST from specs/
  2. Verify each is reflected in Approved Behavior, has a test obligation, and appears in at least one batch
  3. Flag unmapped requirements in Escalation Rules
  4. Note cross-batch dependencies

Contract Structure

Must make obvious: approved behavior, out-of-scope, constraints, batches, test obligations, review gates, and conditions that force a rewind to planning. Prefer compression over repeating planning details.

Approval Model (DP-3)

After drafting: summarize handoff rules, identify ambiguity, flag unmapped requirements, ask user to approve explicitly. After approval:

ssf state set <change-dir> dp_3_result "approved: <summary>"
ssf state set <change-dir> dp_3_timestamp $(date -u +%Y-%m-%dT%H:%M:%SZ)

Read the full file on GitHub · 122 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. 2d ago First seen · 122 lines · 39 tokens per session scan A 95d8b32d38b4

Subscribe to this mod's changes

contract-builder is a skill published in the GitHub repository MageByte-Zero/spec-superflow (776 stars, last pushed 4d ago), licensed MIT. It adds 39 tokens to every session and 1,176 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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