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 mattgierhart/PRD-driven-context-engineering --skill ghm-sot-buildergit clone --depth 1 https://github.com/mattgierhart/PRD-driven-context-engineeringWrote 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/mattgierhart/prd-driven-context-engineering/ghm-sot-builder)<a href="https://agentmods.dev/skills/mattgierhart/prd-driven-context-engineering/ghm-sot-builder"><img src="https://agentmods.dev/badge/skills/mattgierhart/prd-driven-context-engineering/ghm-sot-builder/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/mattgierhart/prd-driven-context-engineering/ghm-sot-builder"><img src="https://agentmods.dev/badge/skills/mattgierhart/prd-driven-context-engineering/ghm-sot-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 193 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 | $0.00094 | $0.02031 |
| Opus 5 | $0.00047 | $0.01015 |
| Sonnet 5 | $0.00019 | $0.00406 |
| Haiku 4.5 | $0.00009 | $0.00203 |
Grade A, and why
ghm-sot-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 9d 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 — 257 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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
- Identify Need → Confirm no existing SoT fits
- Design Schema → Define ID prefix, categories, required fields
- Draft Template → Create pure structure (no methodology teaching)
- Validate Purity → Apply the litmus test
- Register & Integrate → Update SoT.README.md and ID system
Core Output Template
See assets/sot-template.md for the copy-paste starter template.
| Element | Definition | Required |
|---|---|---|
| YAML Frontmatter | version, purpose, id_prefix, authority | Yes |
| Purpose Block | Single paragraph explaining what this tracks | Yes |
| Navigation Section | Category links for quick access | Yes |
| Entry Template | Repeatable structure for each ID | Yes |
| Cross-Reference Index | Bidirectional links to other SoT files | Yes |
| Update Protocol | When/how to add new entries | Yes |
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
- What artifact type does this track?
- Bad: "Notes" (too generic)
- Good: "Partner Integration Contracts" (specific, durable)
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 9d ago First seen · 257 lines · 94 tokens per session scan A b51ef6cdfd89
ghm-sot-builder is a skill published in the GitHub repository mattgierhart/PRD-driven-context-engineering (182 stars, last pushed 8d ago), licensed MIT. It adds 94 tokens to every session and 2,031 once invoked, about $0.0005 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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Manages context window optimization, session state persistence, and token budget allocation for multi-agent workflows. Use for token budget management, context limits, or session handoff across agents.