Build Loop

Agentic Project Builder

Senior Software Developer skill for building SaaS / DaaS / AIaaS through a structured loop:

Prompt → Plan → Execute → Verify → Iterate

One external sub-skill is loaded when relevant:

• engineering:code-review — structured code review, loaded inline during Verify

Frontend design guidance and security review are fully embedded in this skill.

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Token Efficiency — Caveman Integration

Load references/caveman.md at session start and apply it for the full session. Full caveman rules, intensity levels, auto-clarity triggers, and persistence logic live there.

Default intensity: full. Switch mid-session with /caveman lite|full|ultra if needed.

Agentic-loop overrides (take precedence over base caveman rules):

• Phase headers [PLAN] [EXEC] [VERIFY] [ITERATE] → always kept verbatim
• Code files, CLI commands, schema → always full, never caveman-compressed
• User-facing questions and confirmations → short prose, not fragments
• Security warnings and irreversible actions → full prose (caveman auto-clarity rule applies)
• External sub-skill calls noted inline: [SUB: code-review]

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Loop Protocol

Phase 0 — PROMPT (Session Init)

Collect:

1. Goal — one sentence
2. Type — SaaS / DaaS / AIaaS (or hybrid)
3. Stack — from the Stack Menu below
4. Scope — MVP or full product?

Load the relevant project type reference(s) immediately:

• SaaS → references/saas-pattern.md
• DaaS → references/daas-pattern.md
• AIaaS → references/aiaas-pattern.md

Output confirmed Project Brief (caveman-compressed):

GOAL: [one-line]
TYPE: [SaaS|DaaS|AIaaS|hybrid]
STACK: [selected components]
SCOPE: [MVP|Full]
LOOP: 0

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Phase 1 — PLAN

The single next concrete step only — not the whole project.

Output (caveman-compressed):

[PLAN] Loop N
STEP: [verb + object, ≤10 words]
TASKS:
  1. [subtask]
  2. [subtask]
  3. [subtask]
DONE WHEN: [testable criterion]
STACK: [components this step]
UI? [YES|NO]
SECURITY? [YES|NO]

UI? YES → load frontend-design sub-skill in Execute. SECURITY? YES → run security checklist in Verify.

Security triggers automatically when the step touches: auth, user data, payments, API keys, file uploads, AI inference inputs/outputs, Docker configs, or CI secrets.

Keep tasks to 3–7 items. No rabbit holes.

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Phase 2 — EXECUTE

Carry out every planned task. Always produce full, runnable output — no stubs, no // TODO.

Outputs:

• Code files (full relative path as comment header)
• Config files (Dockerfiles, docker-compose, .env.example, CI YAML)
• Schema (SQL migrations, EF Core models)
• CLI commands (copy-pasteable with context)
• Folder scaffolding if starting fresh

Frontend Design (when UI? YES) — load references/frontend-design.md before writing any UI

Applies to: react-ts, blazor, flutter, winui. Follow the full process in that file:

• Ground the design in the subject's world before touching code
• Run the two-pass process: token system first (palette, type, layout, signature), then critique against the brief before building
• Avoid the three AI-generated defaults (cream+serif+terracotta, dark+acid-green, broadsheet hairlines) unless the brief explicitly calls for them
• Apply restraint: one bold signature element, everything else disciplined
• Write copy as design material — active voice, user-side language, consistent vocabulary across the flow
• Stack-specific: map the confirmed token system to ThemeData (Flutter) or ResourceDictionary (WinUI) — never ship the framework's default accent colour

Stack conventions:

• Flutter / WinUI → references/flutter-winui-pattern.md
• SaaS / DaaS / AIaaS → references/[type]-pattern.md

Playwright screenshots (when UI? YES and playwright is in the stack)

Follow references/testing-ci-pattern.md → Screenshots section: every new screen or component gets at least one explicit screenshot saved to test-results/screenshots/, and components built via frontend-design.md get a toHaveScreenshot baseline so future loops can't silently regress the confirmed design. Verify phase checks for this — see below.

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Phase 3 — VERIFY

Check every task against DONE WHEN. Always run the inline code-review checklist. Run the security checklist when SECURITY? YES (or auto-triggered — see Phase 1).

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Inline Code Review (every loop — engineering:code-review)

Apply the following checks to all code produced this loop:

• [ ] No N+1 queries or unbounded loops
• [ ] Null / empty / overflow edge cases handled
• [ ] Errors propagated — no silent swallows
• [ ] Type safety enforced end-to-end
• [ ] No hardcoded secrets or credentials anywhere in output
• [ ] If UI? YES + playwright in stack: new screens have an explicit screenshot, not just on-failure capture

Flag any failures as CODE-REVIEW: ISSUES and carry them forward to Iterate.

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Security Review (when SECURITY? YES)

Load references/security-review.md and follow its full process: severity scale, quick checklist, layer routing, and verify output format are all in that file. Load the relevant layer file(s) it points to for deeper per-layer checks.

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Verify Output (caveman-compressed):

[VERIFY] Loop N
DONE? [YES|NO|PARTIAL]
COMPLETED: [what was delivered]
CODE-REVIEW: [PASS | ISSUES: ]
SECURITY: [PASS | SKIPPED | CRITICAL:  | HIGH:  | WARN: ]
GAPS: [what is missing]
NEXT: [continue→loop N+1 | present→user | blocked→ask]

• DONE=YES + PASS → present to user, ask: continue or stop?
• DONE=NO/PARTIAL → Iterate
• SECURITY=CRITICAL → fix before iterating. Never ship a critical.

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Phase 4 — ITERATE

Feed gaps forward. Increment loop counter.

[ITERATE] → Loop N+1
CARRYING: [gaps + open code-review / security findings]

Restart at Phase 1.

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Stack Menu

Frontend

• react-ts — React + TypeScript (Vite, Tailwind, shadcn/ui) → references/frontend-design.md
• blazor — Blazor (.NET 8, MudBlazor or Radzen) → references/frontend-design.md
• flutter — Flutter / Dart (mobile + desktop) → references/frontend-design.md + references/flutter-winui-pattern.md
• winui — WinUI 3 (Windows App SDK, C#) → references/frontend-design.md + references/flutter-winui-pattern.md

Backend

• node — Node.js (Fastify, TypeScript, Zod)
• dotnet — C# .NET 8 (Minimal API or Controllers, Scalar docs)
• python — Python (FastAPI, Pydantic, async-first) → references/python-pattern.md

Database

• postgres — PostgreSQL (Docker-composed, Flyway or EF Core migrations)

AI / ML

• huggingface — HuggingFace Transformers (hosted or local)
• yolov8 — YOLOv8 (Ultralytics, Python REST wrapper)
• alpaca — Alpaca / LLaMA (fine-tuning, LoRA, llama.cpp)

Infrastructure

• docker — Docker (multi-stage builds, docker-compose)
• vercel — Vercel (Next.js or static React, preview deploys)

Integrations

• stripe — Stripe (webhook handler + subscription) → SECURITY? YES
• playwright — Playwright (e2e scaffold + matrix CI) → references/testing-ci-pattern.md
• github — GitHub Actions (CI/CD, branch protection)
• openapi — OpenAPI + Scalar (spec-first, auto docs)

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Reference Files

| File | Load when | |------|-----------| | references/saas-pattern.md | TYPE includes SaaS | | references/daas-pattern.md | TYPE includes DaaS | | references/aiaas-pattern.md | TYPE includes AIaaS | | references/flutter-winui-pattern.md | Stack includes flutter or winui | | references/testing-ci-pattern.md | Stack includes playwright, or any GitHub Actions CI step | | references/python-pattern.md | Stack includes python | | references/caveman.md | Session start — always load | | references/security-review.md | SECURITY? YES in any Verify phase | | references/frontend-design.md | UI? YES in any Plan phase | | references/backend-security.md | Security step touches backend / DB / Stripe / AI | | references/frontend-security.md | Security step touches any UI layer | | references/infra-security.md | Security step touches Docker / GitHub / Vercel |

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Loop Rules

1. One step at a time — never plan beyond the next concrete deliverable
2. Verify before iterating — no blind loops
3. UI triggers design — always read references/frontend-design.md before any visual layer
4. Always inline code-review — every Verify runs the review checklist
5. Never ship a CRITICAL — block iteration until resolved
6. Ask before context switch — confirm before resetting goal mid-loop
7. Caveman planning, full code — compressed phases, complete runnable output
8. Stack discipline — never introduce unlisted tools without asking
9. Loop cap — after 10 loops, surface a progress summary and ask user to confirm direction

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: lakreame
• Source: lakreame/build-loop
• License: MIT

Install and usage instructions live in the source repository linked above.