An AI coding agent can write the page. Production work starts when it can also understand the repository, respect existing decisions, run the right checks, and show you what changed.
This section examines agents as working environments, not as leaderboard entries. The useful questions are concrete: Which files provide project context? What can the agent execute? How are permissions handled? Does the workflow fit a static Astro site? Where does human review still matter?
Start with the operating model
Different agents can produce similar code while using different instruction systems. Codex reads AGENTS.md through a documented hierarchy. Claude Code uses CLAUDE.md and can import a shared instruction file. Cursor adds project rules. OpenCode can combine repository rules with a choice of model provider.
Those details matter more than brand preference once a project has real constraints. A polished website depends on decisions that should survive the current chat: routes, design tokens, content sources, accessibility rules, performance budgets, deployment commands, and actions that require approval.
The field guides below separate documented product behavior from our operating judgment. Use the comparison library when the decision is between tools, the AGENTS.md field guide when the problem is repository context, and the technical guides when you are ready to implement.
What every agent still needs
The agent is one layer in the system. It does not replace an approved brief, a coherent design system, or deterministic release checks. Prompts can suggest standards. Tests and build commands enforce the parts that software can verify.
That distinction is central to Brief & Ship: instructions explain the work, repository architecture narrows the solution space, and CI checks the result. The agent remains useful precisely because it is not asked to reinvent those three layers on every run.