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spec

Create, amend, or backprop bugs into SPEC.md at repo root.

Skill by JuliusBrussee

IndexedMIT★ 1,157
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Works with Claude Code, Claude apps, Codex, Cursor, Gemini CLI, GitHub Copilot, VS Code, OpenCode, Goose, Windsurf. Read the repository before you give any tool access to your data.

npx agentmarket install skill/juliusbrussee-spec

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About

Create, amend, or backprop bugs into SPEC.md at repo root. Sole mutator of the project spec. Triggers when the user asks to write a spec, start a new spec, distill a spec from existing code, add invariants, amend sections (§G, §C, §I, §V, §T, §B), or record a bug via backprop. Common phrasings: "write the spec for...", "new spec", "bug: ...", "amend §V.3", "distill spec from code", "spec this idea". Reads and follows FORMAT.md for the caveman encoding rules and pipe-table shape of §T and §B.

Use cases: writing

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Permissions

What this skill can do and what it asks for, from its SKILL.md. Checked Oct 25, 2026.

Tools
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Secrets
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Install scripts
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Network hosts it talks to 1

  • codeload.github.com · found in install command

Files it touches

  • ~/.claude/skills/spec

What's inside

Skill name
spec
Description
Create, amend, or backprop bugs into SPEC.md at repo root. Sole mutator of the project spec. Triggers when the user asks to write a spec, start a new spec, distill a spec from existing code, add invariants, amend sections (§G, §C, §I, §V, §T, §B), or record a bug via backprop. Common phrasings: "write the spec for...", "new spec", "bug: ...", "amend §V.3", "distill spec from code", "spec this idea". Reads and follows FORMAT.md for the caveman encoding rules and pipe-table shape of §T and §B.
License
MIT
Instructions
84 lines in SKILL.md · view on GitHub

Files (1)

  • SKILL.md

SKILL.md (first lines)

# spec — spec mutator

Read `FORMAT.md` at repo root if not already loaded. Caveman skill applies to all writes here.

## DISPATCH

Inspect user request and project state:

1. No `SPEC.md` at repo root AND args describe idea → **NEW**
2. No `SPEC.md` AND `from-code` in args → **DISTILL**
3. `SPEC.md` exists AND args start `bug:` → **BACKPROP**
4. `SPEC.md` exists AND args start `amend` → **AMEND**
5. `SPEC.md` exists, no args → ask user which mode

## INPUTS — spec is the sole mutator

The other verbs produce material; spec writes it. Ingest their handoff blocks
into the right section, show a diff, write on OK:

- **grill** → sharpened §G + §C
- **research** → §R rows (add the §R section if absent)
- **review** → drafted §V lines + the risk verdict
- **deepen** → §I/§V/§T amendments

⊥ rewrite a section the handoff did not name. Sectioned ownership (see FORMAT.md).

## NEW — idea → spec

Input: user idea. If it arrived fuzzy, prefer running **grill** first.

Steps:
1. Extract goal (1 line, caveman). → §G.
2. List constraints user stated or implied. → §C.
3. List external surfaces user named. → §I.
4. §R only if **research** ran — else omit the section (right-size).
5. Propose initial invariants. → §V (numbered V1…).
6. Break goal into ordered tasks. → §T pipe table, all status `.`, ids T1…
7. §B section with header row only (`id|date|cause|fix`).

Write to `SPEC.md`. Show user full file. Ask: "spec OK? `/review` if high-blast-radius, else `/build`."

## DISTILL — code → spec

Walk repo. Produce §G (infer from README/package.json/main entry), §C (infer from stack), §I (enumerate public APIs/CLIs/configs), §V (derive from tests and assertions), §T (one task per known TODO or missing test), §B (empty).

Caveman everywhere. Flag uncertain items with `?` in text so user can confirm.

## BACKPROP — bug → §B + §V

Input: `bug: <description>`.

Steps:
1. Parse bug description.
2. Find root cause (read relevant code).
3. Decide: would a new invariant catch recurrence? If yes → draft `V<next>`.
4. Append §B row: `B<next>|<date>|<cause>|V<N>`.
5. Append new invariant to §V.
6. If fix also changes behavior → add/update §T rows.
7. Show diff. Apply only on user OK.

Rule: every bug gets a §B entry. Invariant optional but preferred.

## AMEND — targeted edit

Input: `amend §V.3` or `amend §T` etc.

Read that section. Show current. Ask user what changes. Write. Show diff.

Never silently rewrite sections user did not name.

## OUTPUT RULES

- Caveman format per `FORMAT.md`.
- Preserve identifiers, paths, code verbatim.
- Numbering monotonic — never reuse §V.N or §B.N.
- §T row `cites` column ! list §V/§I deps: `T5|.|impl auth mw|V2,I.api`.

## NON-GOALS

- No sub-agents. Main thread writes.
- No dashboards, no logs, no state files beyond SPEC.md itself.
- No auto-build after spec. User invokes build explicitly.

From JuliusBrussee/cavekit, MIT.

Signals

Stars
1,157
Forks
89
Open issues
12
Last commit (this folder)
Jun 18, 2026 (4 months ago)
Last release
Apr 18, 2026 (6 months ago)

From GitHub (fetched Oct 24, 2026).

Details

License
MIT
First seen
Oct 24, 2026
Last checked
Oct 24, 2026

More from JuliusBrussee

Cite this page

spec skill. Agent Mart. https://agentmart.dev/skills/juliusbrussee-spec (last updated 2026-10-24)