spec

A library for recording architecture rules that must remain true, along with their status and verification. These rules describe future constraints, not merely how the code works today.

In plain words
What is it for?
Proposing, accepting, replacing, checking, and dividing long-lived architecture requirements in a project's specification directory.
Why use it?
It preserves important contracts across later changes and highlights violations that might otherwise go unnoticed because the software still runs.

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/musingfox/cc-plugins/spec
Any agent
npx skills add musingfox/cc-plugins --skill spec
Clone the repo
git clone --depth 1 https://github.com/musingfox/cc-plugins

Made for: Claude Code, Codex.

Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,542 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 $0.00081 $0.01542
Opus 5 $0.00041 $0.00771
Sonnet 5 $0.00016 $0.00308
Haiku 4.5 $0.00008 $0.00154

Measured yesterday against content hash 88fdfdec735f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec 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 yesterday.

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.

spec/skills/spec/SKILL.md · 147 lines

How it starts

The opening of the file, as written. The whole thing — 147 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Architecture Spec Library

A spec entry answers what must not change. An ADR answers why we chose this. Same directory convention, same status vocabulary, different lifespan: an ADR is history the moment it is accepted; a spec is load-bearing until it is superseded.

Do NOT use for: describing what the system currently looks like. That is the code's job, and a spec that restates it becomes a drift source the first time someone edits without updating the entry.

Directory

Scan docs/spec/. If it does not exist and the user wants an entry, ask where it should live. Override with SPEC_DIR.

What earns an entry

A rule belongs here only if its violation is silent. The entries already in this repo all close by naming that silence: a vendored copy drifts while both copies still run; rc=0 proves the process did not crash, not that the work is done; Edit turns a FAIL into a PASS and the deliverable still looks like the deliverable.

Anything that fails loudly needs no entry — the compiler catches it, or a test goes red. If you cannot write the sentence explaining why nobody would notice the violation, the rule probably does not belong in the library.

Entry format

One entry per file, named <id>.md. The id is kebab-case and shows up as the heading of every slice, so make it readable:

---
id: judge-seats-cannot-edit
status: accepted            # proposed | accepted | superseded
scope:                      # file globs, never module names
  - "pi-dispatch/agents/reviewer.md"
verify: check:<shell command that exits 0 when the spec holds>
related: [other-spec-id]    # entries this one bears on
source: null                # where it came from — milestone slug, or null
adr: null                   # link when superseded
---

source is the birth record. An entry has two birthplaces: a milestone settles and names an interface later flows must honour, or a flow finishes and main finds an invariant the run revealed. Either way, write down which — a rule whose origin nobody remembers is a rule nobody dares delete, and that is how a spec library silts up into a layer of untouchable sediment.

Read the full file on GitHub · 147 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. yesterday First seen · 147 lines · 81 tokens per session scan A 88fdfdec735f

Subscribe to this mod's changes

spec is a skill published in the GitHub repository musingfox/cc-plugins (2 stars, last pushed 2d ago), licensed MIT. It adds 81 tokens to every session and 1,542 once invoked, about $0.0004 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 2026-08-31.

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