What is Blast Radius?
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Blast radius is a measure of how far the impact of a code change propagates through a system — how many modules, services, endpoints, and data flows are affected if the change introduces a defect. A small, localized change has a small blast radius; a change to a shared utility has a large one.
Why does blast radius matter for engineering teams?
Not all PRs carry equal risk. A typo fix in a README has a blast radius of zero; a parameter change in a shared authentication middleware has a blast radius spanning every authenticated endpoint. Quantifying blast radius lets reviewers allocate attention proportionally — more scrutiny where the impact is wider.
How does Argus handle blast radius?
Argus does not compute a blast-radius score, and blast radius does not set review depth; file triage and the PR's change class do. For each PR, Argus walks the default-branch code graph up to two levels back from the changed files and adds up to 50 dependents to the reviewer model's prompt, with the source of up to 3 direct dependents that are not in the diff. The list is not posted on the PR, and it covers one repo: dependents in other repos are not traced. On Deep Review (off by default), a model also reads those direct dependents next to the diff and lists concrete breakage, and when it finds any, the judge is told to score findings in the changed files at 70 or higher.