What this stage settles
This is the production stage. Everything the agent needs was decided in Spec and fenced in Rules, so the only question here is whether it is implemented and whether it holds together.
Spec Kit calls this phase *implement*, and its discipline is the useful part: the agent executes the plan. A build that starts inventing strategy is not moving faster - it is redoing the first two stages badly, in code, where the mistake is most expensive to find.
When the agent hits a question the spec does not answer, the answer is not a guess. It goes back to the stage that owns it.
Steps
Guide
Follow the build flow, in this order
Each step assumes the one before it. Out of order, the agent rebuilds work it already did:
- Start from a template - an approved repository or existing structure, so the foundation is not re-created from scratch.
- Load the inputs - the preparation pack is read before anything is implemented.
- Apply the reusable parts - header, footer, colours, metadata, consent, tracking and QA come from the Skills, not from fresh guesses.
- Build the pages - routes, layouts, sections, copy blocks, media and responsive behaviour.
- Add the integrations - forms, embeds, APIs, CRM handoffs and widgets that the scope actually named.
- Add the tracking - events and consent-aware scripts from the measurement plan.
- Run the local checks - build, lint, links, metadata, accessibility and mobile, before anyone reviews it.
- Write the delivery notes - what changed, what was checked, what still needs a human.
Close the gaps between the parts
Skills produce good parts and no part owns the seams. The header and footer disagree about navigation, a language switcher works on one route and not the next, two components use the same element id. This is the pass that finds them.
Send strategy questions back, do not answer them in code
If the agent needs a decision that the spec does not contain - a legal line, a brand value, an integration destination, a page that was never scoped - that is a Spec or Rules question. Answering it in the build buries the decision in a commit nobody reviews as a decision.
Be Aware
The agent starts making strategic decisions during the build.
Send unclear strategy, content, legal, brand, or integration questions back to the input stage instead of guessing in code.
The parts are all correct and the site still feels stitched together.
Run the glue pass. Gaps live between responsibilities, so no single Skill will find them.
Checks are run after the review instead of before it.
A review that spends its time on broken links never reaches the questions only a person can answer.
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