Skip to content
Agentmart
Submit a tool

build

Plan-then-execute implementation against SPEC.md.

Skill by JuliusBrussee

IndexedMIT★ 1,157
Write a review

Install

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-build

Asks which of your tools to add it to (Claude Code, Codex, Cursor, VS Code, Windsurf, Gemini CLI, Claude Desktop) and shows the change first. See https://agentmart.dev/cli.

Get the weekly diff

The weekly diff: one email a week with new agent tools, notable updates and grade changes, plus security alerts for tools you follow. Double opt-in, one-click unsubscribe.

We use your email only for this newsletter. Privacy

About

Plan-then-execute implementation against SPEC.md. Native single-thread loop, no sub-agents. On test or build failure, auto-invokes the backprop skill before retrying — a failed verification always considers whether a new §V invariant would prevent recurrence. Triggers when the user asks to build, implement, execute the spec, or tackle a specific §T task (`build §T.3`, `build --next`, `implement next task`, `run the build`). Expects SPEC.md to exist; if not, defers to the spec skill.

Use cases: testing, productivity

No reviews yet. Installed it? Reviews come from verified installers only. How reviews work

Permissions

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

Tools
No tools found
Secrets
None asked for
Install scripts
None found

Network hosts it talks to 1

  • codeload.github.com · found in install command

Files it touches

  • ~/.claude/skills/build

What's inside

Skill name
build
Description
Plan-then-execute implementation against SPEC.md. Native single-thread loop, no sub-agents. On test or build failure, auto-invokes the backprop skill before retrying — a failed verification always considers whether a new §V invariant would prevent recurrence. Triggers when the user asks to build, implement, execute the spec, or tackle a specific §T task (`build §T.3`, `build --next`, `implement next task`, `run the build`). Expects SPEC.md to exist; if not, defers to the spec skill.
License
MIT
Instructions
71 lines in SKILL.md · view on GitHub

Files (1)

  • SKILL.md

SKILL.md (first lines)

# build — implement spec

Single-thread native plan→execute. You are main Claude. No swarm.

## LOAD

1. Read `SPEC.md`. If missing → tell user to invoke the spec skill first. Stop.
2. Read `FORMAT.md` once if not loaded.
3. Read §R if present — external facts the build must honor, ⊥ re-derive or contradict.
4. Parse invocation args:
   - `§T.n` → that task only
   - `--next` → lowest-numbered row with status `.` or `~`
   - `--all` or empty → every `.` row in §T order

High blast radius (shared module, auth, data, money, public §I)? Run `/review` first. Trivial & reversible? Skip planning ceremony, just do step EXECUTE.

## PLAN

Native plan mode — you delegate to it, you do not reinvent task breakdown. For chosen task(s):

1. Cite every §V invariant that applies. Plan must respect all.
2. Cite every §I interface touched. Plan must preserve shape.
3. List files to create / edit.
4. **Verification contract** — name the EXACT test(s) / acceptance criteria that
   prove each §V touched. Which test, not "add tests". "Do TDD" alone backfires;
   the spec says *what to check*. Each §V touched → a named test that fails first.
5. Name verification command (test, build, lint) — this is the external oracle. Green = done; ⊥ "looks done".

Show plan. Wait for user OK unless auto mode.

## EXECUTE

Per task in order:

1. Flip §T.n status cell `.` → `~`. Just write to SPEC.md.
2. Edit code per plan.
3. Run verification command.
4. **Pass** → flip `~` → `x`. Next task.
5. **Fail** → invoke backprop skill. Do NOT retry blindly.

## FAIL → BACKPROP

On test/build failure:

1. Read failure output.
2. Ask: is failure (a) my code bug, (b) spec wrong, or (c) unspecified edge case?
3. If (a) → fix code, re-run. No spec change.
4. If (b) or (c) → invoke spec skill with `bug: <cause>` first, let it update §V and §B, then resume build against updated spec.

Rule: never silently fix root-cause without considering backprop. §B is the memory that stops recurrence.

## WRITE POLICY

- Only flip §T status. No other SPEC.md edits from build.
- Other spec edits → invoke spec skill.
- Commit after each §T completes. Message: `T<n>: <goal line>` + §V cites.

## VERIFICATION

Task `x` only if:
- Verification command (the oracle) exits 0.
- Every §V touched has its named test from the verification contract, and it passes.
- No §V invariant regressed (run full test suite at end).

## NON-GOALS

- No sub-agents. No parallel workers. Main thread only.
- No progress dashboards. `cat SPEC.md | grep §T` is the dashboard.
- No speculative work beyond chosen task scope.

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

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