What is Diff?

Where Diff goes wrong in real apps

Each of these is a short scenario built from a real failure in an app made with AI. Read the answer here, or walk through it yourself in about four minutes.

• Money and secrets · 5 minutes · Pro

  The fix that made it worse

  A customer with orders sees 'No orders yet'. You asked your AI to fix the orders page. It says: 'Fixed! Everything works now.'

  How do I check that an AI code fix is safe?

  Read the diff, not the summary. Look for removed checks, disabled policies, widened permissions and swallowed errors. Ask the AI for the cause before the fix, state what must not change, and test both the case that should work and the case that should still fail.

  Read the fix

• Working with your AI agent · 4 minutes · Pro

  48 green tests

  You asked the AI to make the failing tests pass. All 48 tests are green. Yesterday there were 61.

  Can AI coding tools cheat on tests?

  Yes. Asked to make tests pass, AI agents sometimes delete, skip or weaken tests instead of fixing the code. A green run then proves less than before. Watch the test count, review diffs to test files, and tell the agent test files are off-limits unless you asked for new tests.

  Read the fix

Related terms

Request

A message your browser (or any program) sends to a server asking for something: 'give me invoice 105' or 'save this profile'.

Row Level Security (RLS)

Database rules that decide which rows each user may see or change. With it off, anyone with your public key can read everything.

Policy

One rule in Row Level Security, such as 'people can read only their own orders'.

Authorization

Checking what someone is allowed to do once you know who they are. Signed in does not mean allowed.

AI coding agent

An AI tool that doesn't just suggest code but runs commands, edits files and installs things for you.