Building a Music Streaming Site with AI‑Generated Code

The project began with a personal desire to collect and stream songs of a once‑popular singer whose tracks had been removed from mainstream platforms, prompting the decision to build a dedicated music website.

Because the author's 2014 Mac Pro could not run modern AI IDEs, they installed Codex CLI via the command line, effectively giving the legacy machine a new AI‑driven development engine.

Development started from an empty directory. The first step was to define the initial requirement—building a music playback site—and to establish a documentation framework that would automatically capture facts, AI‑completed narratives, and human‑validated decisions. The author created a hierarchy of markdown files such as README.md, AGENTS.md, and several folders under docs/ (e.g., 00-governance, 04-delivery, 06-context) to govern tasks, changes, and knowledge.

With the documentation system in place, the workflow became a loop: the author articulated a demand, Codex split it into tasks, placed them on a Kanban board, generated implementation plans, executed the code, and finally performed self‑validation. This cycle produced a total of 17 completed items, including a document governance plan (MUS‑000), technology stack and architecture (MUS‑002), CI checks (MUS‑003), MVP album playback design (MUS‑004), album page and browser player (MUS‑005), testing and release preparation (MUS‑006), persistent catalog data (MUS‑007), Cloudflare R2 audio hosting (MUS‑008), admin backend (MUS‑009), static asset CDN (MUS‑010), containerized deployment (MUS‑011), immutable URL scheme (MUS‑012), embedded‑Postgres tooling (MUS‑013), music library import and R2 sync (MUS‑014), favicon/SEO basics (MUS‑015), branding (MUS‑016), and global player with playback modes (MUS‑017).

One pending item (MUS‑001) concerns the pre‑launch licensing and source‑file strategy, which is blocked until the site moves to public operation. Additional blockers include the need to evaluate admin‑backend access before production deployment.

After completing the 17 tasks, the site evolved from a blank canvas into a small system capable of playing songs, managing albums, offering a global player with multiple modes, providing an admin interface, hosting audio on Cloudflare R2, serving static assets via CDN, and running in containers.

The author emphasizes that they wrote no code themselves; Codex CLI generated more than 6,000 lines of code based solely on natural‑language prompts.

Cost analysis shows a token expense of ¥7.59 after switching from the free Codex quota to the deepseek‑v4‑flash model, roughly two evenings of work time, free Cloudflare storage, a $11.86‑per‑year domain, and a $35.99‑per‑year 2 GB KVM VPS.

In reflection, the author contrasts the old mantra “Talk is cheap, show me the code” with the new reality “Talk is important, code is cheaper,” arguing that clear requirement articulation has become the scarce skill while code serves as a cheap lever.