spec

Original：🇺🇸 English

Translated

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.

2installs

Sourcejuliusbrussee/cavekit

Added on2026-04-20

NPX Install

npx skill4agent add juliusbrussee/cavekit spec

SKILL.md Content

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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:

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

NEW — idea → spec

Input: user idea.

Steps:

Extract goal (1 line, caveman). → §G.
List constraints user stated or implied. → §C.
List external surfaces user named. → §I.
Propose initial invariants. → §V (numbered V1…).
Break goal into ordered tasks. → §T pipe table, all status
```
.
```
, ids T1…
§B section with header row only (
```
id|date|cause|fix
```
).

Write to

SPEC.md

. Show user full file. Ask: "spec OK? suggest edits or invoke 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:

Parse bug description.
Find root cause (read relevant code).
Decide: would a new invariant catch recurrence? If yes → draft
```
V<next>
```
.
Append §B row:
```
B<next>|<date>|<cause>|V<N>
```
.
Append new invariant to §V.
If fix also changes behavior → add/update §T rows.
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.