Creates new Source of Truth (SoT) files when existing templates don't fit your needs.

MITAuto-check passedDevelopment

Install Ghm Sot Builder

skills CLI
$ npx skills add mattgierhart/PRD-driven-context-engineering --skill ghm-sot-builder -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install mattgierhart/PRD-driven-context-engineering ghm-sot-builder --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/mattgierhart/PRD-driven-context-engineering.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/ghm-sot-builder .claude/skills/ghm-sot-builder && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
ghm-sot-builder
GitHub stars
180
Token cost
~2k tokens
SKILL.md length
883 words
Files
4 (incl. references, assets)
Skills in repo
45
Repo updated
First seen
Licence
MIT

At a glance

Creates new Source of Truth (SoT) files when existing templates don't fit your needs.

  • Works in 5 steps: Identify the Need → Design the Schema → Draft the Template → …
  • Requests to create a new SoT file
  • SKILL.md covers When to Use This Skill, Workflow Overview, Core Output Template and Step 1: Identify the Need, plus 8 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Ghm Sot Builder is an agent skill from mattgierhart/PRD-driven-context-engineering. Creates new Source of Truth (SoT) files when existing templates don't fit your needs. Triggers on requests to create a new SoT file, add a new artifact type, or when user says "I need to track [X] but there's no SoT for it", "create SoT", "new source of truth". Outputs a properly structured SoT..md file with ID prefix, frontmatter, and update protocol.

Its SKILL.md is about 2k tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files, including reference files and assets (for example `assets/sot-template.md`, `references/examples.md` and `references/sot-patterns.md`).

It sits in Development. The repository describes itself as: PRD-Led Context Engineering — Memory as Infrastructure. An ontology layer for product teams building products that solve real problems — with AI agents that remember. Gated PRD… The licence is MIT.

When your agent uses it

  • Requests to create a new SoT file
  • Add a new artifact type
  • User says I need to track [X] but theres no SoT for it
  • New source of truth

Example prompts

  • “I need to track [X] but there”
  • “create SoT”
  • “new source of truth”
  • “/ghm-sot-builder”

Requirements

  • Pre-approved tools (allowed-tools): Read, Write, Edit, Glob, Grep

Workflow steps

5 steps, taken from the step headings in SKILL.md.

  1. Identify the Need
  2. Design the Schema
  3. Draft the Template
  4. Validate Purity
  5. Register and Integrate

What it can do on your machine

Read from SKILL.md and the folder at commit 30ed1b0. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Write
    • Edit
    • Glob
    • Grep

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are markdown).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Ghm Sot Builder loads about 2k tokens when it runs, and up to ~5.8k if it reads all its reference files. Until then it costs about 93 tokens; SKILL.md has 883 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~93
When it runs · the whole SKILL.md, loaded when a task matches
~2k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~5.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from mattgierhart/PRD-driven-context-engineering at commit 30ed1b0, republished under its MIT licence (© mattgierhart). 883 words, ~2,035 tokens.

Download SKILL.mdSave it as .claude/skills/ghm-sot-builder/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.
name
ghm-sot-builder
description
Creates new Source of Truth (SoT) files when existing templates don't fit your needs. Triggers on requests to create a new SoT file, add a new artifact type, or when user says "I need to track [X] but there's no SoT for it", "create SoT", "new source of truth". Outputs a properly structured SoT.*.md file with ID prefix, frontmatter, and update protocol.
allowed-tools
Read, Write, Edit, Glob, Grep
context
fork

SoT Builder

Create new Source of Truth files that fit your product's unique needs while maintaining template purity.

When to Use This Skill

This skill is for rare occasions (3-4 times per product lifecycle) when:

  • You fork this repo and the existing SoT files don't cover your artifact types
  • Your product needs to track a concept that doesn't fit existing ID prefixes
  • You need to consolidate scattered documentation into a canonical SoT

Do NOT use when:

  • An existing SoT file covers your need (just add entries there)
  • You want to track temporary/session-specific data (use temp/ instead)
  • The artifact type is already covered by ghm-id-register

Workflow Overview

  1. Identify Need → Confirm no existing SoT fits
  2. Design Schema → Define ID prefix, categories, required fields
  3. Draft Template → Create pure structure (no methodology teaching)
  4. Validate Purity → Apply the litmus test
  5. Register & Integrate → Update SoT.README.md and ID system

Core Output Template

See assets/sot-template.md for the copy-paste starter template.

ElementDefinitionRequired
YAML Frontmatterversion, purpose, id_prefix, authorityYes
Purpose BlockSingle paragraph explaining what this tracksYes
Navigation SectionCategory links for quick accessYes
Entry TemplateRepeatable structure for each IDYes
Cross-Reference IndexBidirectional links to other SoT filesYes
Update ProtocolWhen/how to add new entriesYes

Step 1: Identify the Need

Before creating a new SoT, verify:

Checklist
  • Searched existing SoT files for similar artifact types
  • Confirmed the concept is durable (survives multiple sessions)
  • Confirmed the concept needs unique IDs for cross-referencing
  • Confirmed this isn't better served by a subsection in an existing SoT
Questions to Answer
  1. What artifact type does this track?

    • Bad: "Notes" (too generic)
    • Good: "Partner Integration Contracts" (specific, durable)
  2. Why can't existing SoT files handle this?

    • Valid: "We need different fields than API contracts for partner integrations"
    • Invalid: "I just want a separate file" (preference, not need)
  3. What ID prefix will you use?

    • Must be unique across the system
    • 2-4 uppercase letters
    • Check SoT/SoT.UNIQUE_ID_SYSTEM.md for existing prefixes

Step 2: Design the Schema

Define the structure before writing:

ID Prefix Selection
Format: [PREFIX]-[XXX]
Examples: PIC-001, INT-042, MIG-003

Rules:

  • 2-4 uppercase letters
  • Descriptive but short
  • Unique across all SoT files
  • Check existing prefixes in SoT/SoT.UNIQUE_ID_SYSTEM.md
Category Ranges

Reserve ID ranges for logical groupings:

markdown
**Category A** (XXX-001 to XXX-099):
**Category B** (XXX-101 to XXX-199):
**Category C** (XXX-201 to XXX-299):
Required Fields per Entry

Define the minimum fields every entry needs:

FieldPurposeExample
IDUnique identifierPIC-001
TitleHuman-readable name"Stripe Payment Integration"
StatusCurrent stateActive / Deprecated / Planned
CreatedOrigin date2025-01-10
Last UpdatedLast modification2025-01-15
Related IDsCross-referencesBR-101, API-045
Optional Fields

Add domain-specific fields as needed, but keep them structural (not methodology):

  • Good: "Partner Contact" (data field)
  • Bad: "Best Practices for Partner Selection" (methodology teaching)

Step 3: Draft the Template

Use assets/sot-template.md as your starting point.

Structure Sections
  1. YAML Frontmatter - Metadata for the file
  2. Title & Purpose Block - What this SoT tracks
  3. Navigation by Category - Quick links to entries
  4. Entry Template - Repeatable structure (copy for each new entry)
  5. Deprecated Section - Where old entries go
  6. Cross-Reference Index - Bidirectional links
  7. Update Protocol - When/how to maintain
Template Purity Rules

KEEP in the template (self-documentation):

  • When to add new entries
  • Required fields checklist
  • Cross-reference integrity checks
  • File-specific maintenance procedures

MOVE to skill references (methodology teaching):

  • "Best practices" for this domain
  • "What makes a good entry"
  • Example workflows beyond format
  • Evaluation criteria
Show full SKILL.md (340 more words)Show less
Litmus Test

For each section, ask:

"Is this teaching me how to maintain the FILE STRUCTURE, or teaching me DOMAIN KNOWLEDGE about what makes good content?"

  • File structure maintenance → Keep in template
  • Domain knowledge → Move to skill references

Step 4: Validate Purity

Before finalizing, run this checklist:

Purity Checklist
  • No "how to analyze" or "how to evaluate" content
  • No "best practices" or "key learnings" sections
  • No cross-file workflows (multi-file coordination)
  • No "what makes a good entry" evaluation criteria
  • Examples show FORMAT only, not instructional CONTENT
  • Self-documentation is under 20% of total file size
Self-Documentation Checklist
  • Has "Update Protocol" section
  • Documents when to add new IDs
  • Includes cross-reference integrity checks
  • Specifies required fields for new entries
  • Self-documentation is file-specific (not generic)
Context Efficiency Checklist
  • Template can be read without loading other files
  • Methodology examples are in skill references, not template
  • General governance references SoT.README.md

Step 5: Register and Integrate

After creating the SoT file:

Update SoT.README.md

Add entry to the structure table:

markdown
| `SoT.{YOUR_FILE}.md` | {PREFIX}-### | {Purpose description} |
Update SoT.UNIQUE_ID_SYSTEM.md

Add new prefix to Section 1.2 Standard Prefixes:

markdown
| **{PREFIX}** | {Meaning} | `SoT.{YOUR_FILE}.md` |
Create Index Tables

Add empty index table in Part 2 of SoT.UNIQUE_ID_SYSTEM.md:

markdown
#### {Your Type} ({PREFIX}-XXX)

| ID | Title | Status | Used By |
|----|-------|--------|---------|
| {PREFIX}-001 | {Title} | Active | {IDs} |

Quality Gates

Pass Checklist
  • ID prefix is unique across all SoT files
  • Template follows purity standard
  • Update protocol included
  • Cross-reference index structure defined
  • SoT.README.md updated
  • SoT.UNIQUE_ID_SYSTEM.md updated
Testability Check
  • Can create a new entry using only the template instructions
  • Cross-references can be validated programmatically
  • Entries can be found by ID search

Anti-Patterns

PatternExampleFix
Methodology in template"Best practices for partner selection"Move to skill references
Duplicate prefixUsing BR- for a new fileChoose unique prefix
Too generic"Notes.md"Be specific: "Partner_Integrations.md"
No update protocolTemplate with no maintenance sectionAdd "Update Protocol" section
Orphan SoTNot registered in SoT.README.mdAlways register new files

Bundled Resources

  • references/sot-patterns.md — Common patterns across existing SoT files
  • references/examples.md — Before/after examples of SoT creation
  • assets/sot-template.md — Copy-paste starter template

Handoff

After creating a new SoT:

  1. SoT file exists at SoT/SoT.{NAME}.md
  2. SoT.README.md lists the new file
  3. SoT.UNIQUE_ID_SYSTEM.md has the new prefix
  4. Ready to use ghm-id-register for adding entries

© mattgierhart, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (references, assets) in .claude/skills/ghm-sot-builder of mattgierhart/PRD-driven-context-engineering.

  • SKILL.md
  • assets/sot-template.md
  • references/examples.md
  • references/sot-patterns.md

Open the folder on GitHubat commit 30ed1b0

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Categories

Questions about Ghm Sot Builder

What does Ghm Sot Builder do?

Creates new Source of Truth (SoT) files when existing templates don't fit your needs. Ghm Sot Builder is an agent skill from mattgierhart/PRD-driven-context-engineering. Creates new Source of Truth (SoT) files when existing templates don't fit your needs.

When should I use Ghm Sot Builder?

Ghm Sot Builder fits situations like: requests to create a new SoT file; add a new artifact type; user says I need to track [X] but theres no SoT for it; new source of truth.

How do I install Ghm Sot Builder in Claude Code?

Run `npx skills add mattgierhart/PRD-driven-context-engineering --skill ghm-sot-builder -a claude-code`. Or copy the skill folder (.claude/skills/ghm-sot-builder in mattgierhart/PRD-driven-context-engineering) into .claude/skills/ghm-sot-builder in your project. Claude Code loads it when a task matches its description.

How do I install Ghm Sot Builder in Codex?

Run `npx skills add mattgierhart/PRD-driven-context-engineering --skill ghm-sot-builder -a codex`. Or copy the skill folder (.claude/skills/ghm-sot-builder in mattgierhart/PRD-driven-context-engineering) into .agents/skills/ghm-sot-builder in your project. Codex loads it when a task matches its description.

Can I use Ghm Sot Builder in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add mattgierhart/PRD-driven-context-engineering --skill ghm-sot-builder -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ghm-sot-builder, .gemini/skills/ghm-sot-builder, .github/skills/ghm-sot-builder and .opencode/skills/ghm-sot-builder in your project.

What does Ghm Sot Builder need to run?

SKILL.md names no scripts, command-line tools or credentials: Ghm Sot Builder is instructions for the agent only. Its frontmatter pre-approves these tools: Read, Write, Edit, Glob, Grep.

Does Ghm Sot Builder access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Ghm Sot Builder safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Ghm Sot Builder use?

Ghm Sot Builder is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Ghm Sot Builder use?

About 2k tokens (SKILL.md is roughly 8.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 3.8k tokens, read only when the agent opens those files.

What are the alternatives to Ghm Sot Builder?

Skills that share tags, products or a category with Ghm Sot Builder: Vercel Composition Patterns (supabase/supabase, 111k stars), Finishing a Development Branch (obra/superpowers, 297k stars), Typescript Advanced Types (rolling-scopes/rsschool-app, 10k stars) and PR Babysitter (openinterpreter/openinterpreter, 69k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Ghm Sot Builder?

mattgierhart (a GitHub user) maintains it in mattgierhart/PRD-driven-context-engineering, which has 180 GitHub stars. The repository holds 45 skills in this directory. The repository was last updated on August 31, 2026.

Source: mattgierhart/PRD-driven-context-engineering on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.