One-Shot Shop Challenge

Same specification, same technology, and this time the same original prompt as build #1. The idea was to check whether the increased 1M token context limit plus the 42 Claude Code releases since the first run (v2.1.39 to v2.1.81) produce a better result on their own, without any prompt engineering.

This also serves as a direct comparison to build #6 which used a very detailed prompt with instructions on HOW to build. Here, the agent gets no process instructions at all, only the specification of WHAT to build.

The result: 121 of 143 tests pass with an 88.8% weighted score, the highest across all builds. Zero SonarCloud bugs, all A-ratings, and 12.16 estimated Halstead bugs. The simple prompt with the upgraded context window outperformed the heavily engineered prompt from build #6.

Same specification, same technology, but this time with an advanced prompt combining several techniques: a thorough controller supporting the team lead, BDD and TDD, code reviews, and a dedicated QA teammate that actively tries to break the system. The prompt was designed to leverage the new 1M token context window.

The result speaks for itself: 119 of 143 E2E tests pass (83%), the highest since the original team mode run. However, this came at a steep price: about $285 in hypothetical API costs and almost 11 hours of runtime, with 176 active agents. The advanced prompt produced more robust code but consumed far more resources than any previous build.

Claude Code took a phased approach. The team lead read the full specification, broke it into 12 implementation phases with explicit dependencies, and then spawned specialized agents for each area: migrations, models, Livewire components, admin panel, seeders, and so on.

At peak, 31 agents were working simultaneously. The whole thing was done in just over an hour, producing 388 files across the full Laravel stack. Foundation first, then catalog, storefront, cart and checkout, payments, customer accounts, admin, search, analytics, and webhooks.

Same specification, same prompt structure, but this time Claude Code ran with sub-agents instead of team mode. No specialized agent instructions were prepared - the prompt simply told it to use sub-agents. Claude spawned 20 sub-agents total, 12 of which actively contributed code.

The build took about 2 hours and 13 minutes, producing 358 files. With an estimated API cost of $61.97, it sits between the team mode run ($73) and the Codex run ($8.79) in terms of cost.

Codex launched explorer agents to analyze the specification first, synthesized their findings into a phased roadmap, then delegated implementation to worker agents. The process took about 1 hour and 44 minutes with 16 sub-agents total.

On my first try, Codex actually finished after just a few minutes already with a surprisingly good but familiar result. That was suspicious. The shop looked exactly like the one Claude had built. Turns out, Codex found the other branch in the repo and switched to it instead of building from scratch. I had to start over with slightly adjusted instructions.

Same specification, same technology, but this time with a tuned prompt and strict quality constraints. The prompt included mandatory PHPStan compliance at max level, Deptrac architectural boundary checks, Pest test coverage, QA self-verification against every acceptance criterion, and a fresh agent review cycle where a new agent instance re-evaluated the entire codebase.

The idea was to see if explicit quality instructions produce measurably better code. The result: significantly fewer estimated bugs (12.4 vs 18.1), higher maintainability (89.7 vs 79.7), zero SonarCloud bugs, and 60% fewer code smells. The quality gate still failed on duplication (7.5%) and unreviewed security hotspots, but the core metrics improved across the board. The trade-off was runtime: the agent took about 3 hours, partly because it did not terminate on its own when done.

A few features were deferred: search was moved to a roadmap item instead of being fully implemented. The storefront uses a dark theme this time.

Same specification, same technology, but this time Codex received custom instructions with two additional quality tools: PHPStan (static analysis at max level) and Deptrac (architectural boundary checks). The idea was to see if giving Codex explicit quality constraints would produce measurably better code.

The result is mixed. On the positive side: zero SonarCloud bugs, zero vulnerabilities, and all A-ratings across reliability, security, and maintainability. On the other hand, the code smells tripled (153 vs 54) and estimated Halstead bugs jumped to 31.4 (vs 4.0 in v1). The quality focus seems to have shifted the agent towards more classes and more code, but with higher internal complexity in key controllers.

Only a single product was seeded, and the storefront UI is noticeably reduced compared to other builds. The quality-focused instructions appear to have consumed attention that would otherwise go to spec coverage and demo data. The admin panel, however, is functional with OAuth-based API authentication.