13. What does impact analysis tell you, and when does it run?

Impact analysis follows the links in the knowledge graph from a specification to everything it touches: outcomes, components, services, database tables and code. For people, impact analysis writes a readable report with the reasons for each finding. For another agent, impact analysis returns structured data that lists the IDs of the affected items in each layer. When an agent owns the work, the agent reads the structured form and continues without waiting for a person. Impact analysis runs when the specification is written, again after the code is written, and again at the pull request, using the whole history of the change. One example is the saved-search alert feature, on an application of 1.6 million lines. The report found three things that would have been hard to find by hand. The report found that the database already had the column the feature needed, so no database change was required. The report flagged a likely and serious risk: without a new filter, weekly subscribers would also receive a daily email. The report also set the order of deployment across three repositories. A senior engineer would need three to five working days to produce a comparable analysis.

On the site: What It Does · Two Kinds of Output · When Impact Analysis Runs