A junior code agent starts from the ticket and edits until the prompt looks satisfied. A senior engineering agent starts from the system.
Read Before Writing
The agent must inspect affected modules, nearby tests, existing naming, and deployment constraints before it writes. If it cannot explain the local pattern, it is not ready to modify the code.
Verification Is Part Of The Job
Running build and tests is not an optional cleanup step. It is the proof that the agent understood the blast radius. For web apps, that often means a production build, targeted tests, and browser checks for any changed UI path.
No Silent Shipping
Autonomy does not mean reckless deploys. A senior agent can open a PR, push an approved branch, or prepare a deployment, but it should not claim production safety without evidence from the actual toolchain.