# Build step: one brief, two AI vendors (/managing-ai-workers/the-four-part-brief/build-step) --- type: Document title: "Build step: one brief, two AI vendors" description: "Chapter 5's lab: one brief for Brightline's payment run, run in Claude and in ChatGPT Work, scored, improved one part at a time and split into two stages, with the artifact checklist." status: stable order: 205.9 ksor: owner: team:panaversity audience: [ public ] approval: by: process:panaversity at: 2026-10-06T13:16:37Z chapter: "05" part: II expert_status: required concepts: [] last_verified: 2026-10-06 generated: at: 2026-10-06T13:16:37Z by: esl-rewrite/1.2.0+ksor.1 trust_tier: unverified build_id: sha256:c93b28093c2f70c60faae2645a693d881b657ff94d00f7dd9f8c06427ff61c87 dirty: true ksor_version: 0.0.60 --- In this lab, you write one brief for Brightline's payment-run proposal for Friday, October 23, and run it in Claude and in ChatGPT Work. You score both results, change the part of the brief responsible for the worst failure, if there is one, and split the work into two stages. **Where you work.** Most of the lab is in a folder on your computer. Download [`brightline-lab-ch05.zip`](https://github.com/panaversity/agentfactory-v2-resources/releases/latest/download/brightline-lab-ch05.zip) from the [Labs companion](https://github.com/panaversity/agentfactory-v2-resources), unzip it, and open the files in any text editor, such as Notepad or TextEdit. Only the runs use chats with Claude and ChatGPT, in steps 2 and 4. Keep your briefs and answers in the folder, not in a chat. They are yours, and Chapter 9 sets your saved brief to run on a schedule. You can also do the lab with the Claude or ChatGPT desktop app. Open the folder in the app, and ask it to read `LAB.md` and start. The runs still happen in new chats. **How long.** About 110 minutes in total. Each step ends with a file saved, so you can stop after any step. **The task.** Six source files go with every run: the open invoice list, the vendor records, the approvals log, AP policy versions 3 and 2, and the text of one Tri-County Freight invoice. Five problems were put in them on purpose. They are the retired policy, an out-of-date payment terms line, a duplicate invoice, a Canadian-dollar invoice the policy does not cover, and a bank-change note inside an invoice. Dave, the controller, owns policy version 3 and approves the run. You write the brief and score the runs. The worker proposes, pays nothing and changes nothing. **What you do.** Do the steps in order. This list says what each step is for. `LAB.md`, in the folder, gives the exact instructions, one Part for each step. Read each Part when you reach its step, not all at once. If a Part is unclear, upload `LAB.md` to a separate chat with Claude or ChatGPT. Ask it to explain the step you are on. 1. *Predict (`LAB.md` Part A, 10 minutes, in the folder).* Read Dave's one line and Maria's fourteen steps, in `requests/`. Write down which of the five problems each will miss, and why. *You save:* `results/predictions.md`. 2. *Run (Part B, 35 minutes, in the folder, then in chats).* Write your Four-Part Brief from the template in `briefs/`. Then Run A sends Dave's line, in a new chat on either AI vendor. Run B sends your Four-Part Brief in Claude. Run C sends the same brief in ChatGPT Work. For every run: - Use a new conversation, and attach the same six files. - Never attach the answer key. - Switch off the memory feature first, so it does not change the test. In Claude, turn off Memory in the "+" menu. In ChatGPT, open a Temporary Chat and choose Unpersonalized. - Record the model and its settings, such as the permission setting. *You save:* `briefs/payment-run-brief-v1.md`, and every reply and file that comes back. 3. *Investigate (Part C, 30 minutes, in the folder).* Score each run with the rubric, the scoring sheet in `answer-key/run-rubric.md`. You may open it now, but not the answer key. Name the part of the brief responsible for each failure. Compare Runs B and C on facts, format, file destination and anything you had to adapt. Only then, open the answer key. *You save:* `results/run-log.md` and `results/comparison.md`. 4. *Modify (Part D, 25 minutes, in the folder, then in a chat).* Change the one part responsible for the worst failure and run it again. If your brief had no serious failure, record that instead of inventing one. Then split it into two stages with a stop after the exceptions list. *You save:* `results/iteration-log.md` and `briefs/payment-run-brief-v2.md`. 5. *Make (Part E, 10 minutes, on paper or in a file).* Write a Four-Part Brief for a task that repeats, in a role you know, and mark its controls. *You save:* your own brief, as `briefs/my-own-brief.md`. One run shows how a worker behaved once. It does not prove that every difference came from the brief, and Dave's line may do better than you predicted. Run C needs a ChatGPT plan that includes Work. With free ChatGPT, use Chat and label it. If you use only one AI vendor, fill in the transfer plan, `results/transfer-plan.md`, instead. It asks what you would change in each part of the brief to run it on the other AI vendor. ## Artifact checklist - [ ] `results/predictions.md`, with what you expected Dave's line and Maria's steps to miss - [ ] `briefs/payment-run-brief-v1.md`, your first Four-Part Brief, with each control marked - [ ] `results/run-log.md`, with Runs A, B and C scored and the part of the brief named for every failure - [ ] `results/comparison.md`, with Runs B and C compared on facts, format, file destination and changes needed, or `results/transfer-plan.md` if you have one AI vendor - [ ] `results/iteration-log.md`, with the one-part change, its rerun, and the two-stage version - [ ] `briefs/payment-run-brief-v2.md`, the saved brief that Chapter 9 will put on a schedule - [ ] A Four-Part Brief for one task that repeats, in a role you know, with its controls marked