source-of-truth-preflight

source-of-truth-preflight is a skill for Codex from Kastalien-Research/thoughtbox. It costs 58 tokens per session (975 once invoked), scanned A, original, MIT.

A pre-implementation checklist for finding the existing model or source of truth before making substantial architectural or feature changes.

In plain words
What is it for?
Use it before changing domain models, lifecycle states, persistence, schemas, repositories, runtime providers, or other architectural boundaries.
Why use it?
It helps prevent duplicate concepts, conflicting state definitions, and plans based on the wrong part of a codebase.

Skill for Codex

Written for Codex: installed under .codex/.

Good fit Use it before changing domain models, lifecycle states, persistence, schemas, repositories, runtime providers, or other architectural boundaries.

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Install with agentmods
npx agentmods add skills/kastalien-research/thoughtbox/source-of-truth-preflight
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 Kastalien-Research/thoughtbox --skill source-of-truth-preflight
Clone the repo
git clone --depth 1 https://github.com/Kastalien-Research/thoughtbox

Made for: 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 source-of-truth-preflight

README.md
[![agentmods](https://agentmods.dev/badge/skills/kastalien-research/thoughtbox/source-of-truth-preflight/github.svg)](https://agentmods.dev/skills/kastalien-research/thoughtbox/source-of-truth-preflight)
Your own site
<a href="https://agentmods.dev/skills/kastalien-research/thoughtbox/source-of-truth-preflight"><img src="https://agentmods.dev/badge/skills/kastalien-research/thoughtbox/source-of-truth-preflight/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.

agentmods 80×15 button for source-of-truth-preflight

Your own site · 80×15
<a href="https://agentmods.dev/skills/kastalien-research/thoughtbox/source-of-truth-preflight"><img src="https://agentmods.dev/badge/skills/kastalien-research/thoughtbox/source-of-truth-preflight.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 975 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00058 $0.00975
Opus 5 $0.00029 $0.00487
Sonnet 5 $0.00012 $0.00195
Haiku 4.5 $0.00006 $0.00097

Measured 8d ago against content hash 3b1da52f473c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

source-of-truth-preflight 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 8d 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.

.codex/skills/source-of-truth-preflight/SKILL.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Source Of Truth Preflight

Run this skill before editing code for non-trivial feature work, especially when the task touches domain models, state machines, runtime providers, repository contracts, schema migrations, or existing subsystem boundaries.

This is a short gate, not a design ceremony. Produce the report before coding. If the report cannot identify the canonical model or enforcement points, pause instead of implementing.

Trigger Conditions

Use this skill when any of these are true:

  • adding or changing lifecycle states
  • compiling, parsing, importing, exporting, or graduating a domain object
  • adding a repository method, migration, runtime provider, broker, or handler
  • introducing a new type whose name overlaps an existing concept
  • seeing two or more files define similar domain terms
  • after two surprises during a task

Preflight Steps

1. Identify The Unit

State the requested unit in one sentence. Name explicit non-goals.

2. Inventory Existing Models

Search before designing. Prefer rg:

rg -n "export (interface|type|class|const) .*<Concept>|<Concept>Schema|type <Concept>|interface <Concept>" src apps .specs .adr docs
rg -n "from ['\"].*<concept>.*['\"]|<Concept>" src apps

Record:

  • canonical model candidates with file references
  • legacy or competing models with file references
  • runtime/schema/repository boundaries that already enforce the concept

3. Choose The Canonical Source Of Truth

Name the model the implementation will build on. If there are multiple live models, classify each as one of:

  • canonical: new work should build here
  • legacy-live: still used, but not the right extension point
  • adapter-only: used only to translate between systems
  • control-plane: metadata/registry state, not the domain object itself
  • test-fixture: fixture-only, not production semantics

If the choice is not obvious, pause and ask for a decision.

4. Illegal-State Pass

List the states that should be impossible. Check whether current types make them impossible.

Read the full file on GitHub · 158 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. 8d ago First seen · 158 lines · 58 tokens per session scan A 3b1da52f473c

Subscribe to this mod's changes

source-of-truth-preflight is a skill published in the GitHub repository Kastalien-Research/thoughtbox (64 stars, last pushed 1mo ago), licensed MIT. It adds 58 tokens to every session and 975 once invoked, about $0.0003 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 2026-09-03.