Spec a job report form that survives no signal

Your field-service web app runs on technicians' phones in basements, lifts and rural sites with patchy signal. A junior used an agent to build the "submit job report" form, and it works perfectly in the office. In the field, technicians are losing reports. The agent will make a second attempt from your spec.

Write the spec you would hand the agent.

What you know:

• the app is a React single-page app, installed to the home screen as a progressive web app
• a report has text fields, a checklist, a signature and up to 10 photos, and takes 10 to 20 minutes to fill in
• POST /api/reports returns 201, and you can change the server
• technicians carry both Android phones and iPhones

Then, in a few sentences: what did the first attempt fundamentally not account for?