Training and Certification Gate for a Volunteer CRM

We built the training module as part of the organization's web application: a piece of material, then a question, then an instant explanation. The test has a configurable pass threshold (the client set 80%) and an optional attempt limit. Passing issues a certificate on the spot, with a public verification page that works by number or QR code and needs no login. Without a certificate a volunteer neither sees nor takes tasks, and each of the 16 directions adds its own materials and test that open up tasks of that direction.

The hard part was making access unambiguous. In the Django backend, a single access gate answers "may this person work?" and returns a distinct reason for every refusal: training not passed, certificate revoked, direction not admitted, admission withdrawn. An automated test fails the build if any code reads certificates around that gate, so the rule cannot erode as the CRM grows.

Other decisions that keep the system honest:

• Correct answers are never sent to the browser.
• Certificate numbers carry a long random part, about 3.5·10¹³ combinations per country, so the public check page cannot be enumerated. It replaced a sequential counter.
• A double click used to create attempts above the limit and two certificates with different numbers. A per-volunteer row lock plus database uniqueness constraints closed that race.
• The threshold is stored in percent and the score counts only the questions actually shown, so editing a test neither softens the bar nor fails someone mid-attempt.
• A revoked certificate is marked with who, when and why instead of being deleted. Tasks already taken stay; a retake is closed.

The codebase is covered by about 3,100 backend tests and around 120 frontend test files, and admins sign in with mandatory two-factor authentication.