mcpField
S
spec

spec

github.com/juliusbrusseeDevelopment1.2k2.7k installsUpdated 11w ago
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About spec

spec is a skill for creating and maintaining a project’s SPEC.md from ideas, code, or handoffs from related skills. It supports targeted edits and bug backpropagation, and presents changes for approval before writing.

Key features

  1. 01Create specs from ideas
  2. 02Derive specs from existing code
  3. 03Ingest skill handoffs by section
  4. 04Amend named spec sections
  5. 05Record bugs and update invariants

Use cases

  1. 01Turn a project idea into a task spec
  2. 02Document a codebase as a spec
  3. 03Incorporate review or research findings
  4. 04Update a spec after a bug

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/juliusbrussee/cavekit --skill spec

After installing, type/specin Claude Code to confirm it loaded.

Details

From the project README

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.

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