Explain the internal workflow of how Dependabot generates a pull request from detecting an outdated dependency?

From a scheduled trigger to an opened pull request, Dependabot runs through a defined sequence of steps, executed in an isolated environment per update job.

flowchart TD
    A[Scheduled trigger fires] --> B[Parse manifest/lock file for current dependency versions]
    B --> C[Query registry for latest available version matching config rules]
    C --> D{Newer version found, not excluded by ignore rules?}
    D -->|Yes| E[Resolve updated dependency tree in isolated environment]
    E --> F[Update manifest + lock file]
    F --> G[Generate commit + PR with changelog/release notes if available]
    G --> H[Apply reviewers/assignees/labels per config]

The dependency resolution step (E) is where Dependabot actually attempts to determine what the full, consistent set of resolved versions should look like after the bump — not just changing one number, but ensuring the whole dependency tree remains valid together, which is also where update attempts can fail silently if a fully resolvable combination can't be determined (discussed further elsewhere).