# Case Study: Adding Pagination With an Agent — Coding Agents & AI-Assisted Development

Source: https://www.geekswithgeeks.com/en/coding-agents/z-case

> Walk a realistic feature from task to merge.

## From request to merged PR

Task: add cursor pagination to `GET /orders` in a small web service. **Setup**: a clean checkout, a new branch `agent/orders-pagination`, tests green on the branch before starting, an `AGENTS.md` with test/lint commands and the rule "money is integer paise", and an agent running in a container with no production credentials. **Task text**: goal and reason, files to look at, constraints (response stays backward compatible; no new dependencies), how to verify (the unit-test command), scope (orders endpoint only). **Plan first**: the agent proposes steps and the cursor design (last-id cursor, default page size 20, max 100); the engineer approves, adding a requirement for the last-page case. **Implement**: the agent writes failing tests (page size, next cursor, last page, invalid cursor), the engineer reviews the tests, then it implements in two small commits, running tests each time. **Safeguards**: step cap and cost budget; the patch gate and secret scan pass; stuck-run detection never trips. **Review**: a 60-line diff and a summary; the engineer checks that no test was weakened, reads error handling for invalid cursors, and runs the service locally. **Merge**: CI passes, one human reviewer approves, the PR notes that an AI agent was used and how it was verified.

## Direct, bound, verify, review

Good results come from clear tasks, bounded runs, independent verification and human review.

![Four habits: specify, bound, verify, review.](assets/figures/coding-agents/section-8-map.svg) — Figure 8.1 — Specify, bound, verify and review.

## The workflow on one page

Each line maps to a section of this course.

```text
Setup      clean branch, green baseline, AGENTS.md, container without prod credentials      (Sec 1, 2, 3)
Task       goal + files + constraints + verify command + scope                                (Sec 4)
Plan       agent proposes, human approves (cursor design, last-page case)                      (Sec 4)
Implement  failing tests (reviewed) -> small commits -> tests each time                        (Sec 2, 4)
Safeguards step/cost caps, stuck-run detection, patch gate, secret scan, protected paths        (Sec 5)
Review     60-line diff, test changes scrutinised, local run, summary                          (Sec 5, 7)
Merge      CI green + one human approval + PR notes AI use and verification                   (Sec 2, 7)
```

## Capture lessons in the instruction file

Every mistake that cost you time is a candidate for a one-line rule in AGENTS.md.

**Quiz:** Why did the engineer approve the plan before the agent wrote code?

- [ ] Plans are required by CI
- [x] Fixing a plan is cheap; undoing wrong implementation is costly
- [ ] Agents cannot code without permission from a manager
- [ ] It makes the model faster

*Answer:* Fixing a plan is cheap; undoing wrong implementation is costly. Early correction prevents large wrong diffs.