External source reuse
Reuse maintained donor code when it is the shortest reliable route; do not turn reuse into ceremony.
Four routes
- Use upstream directly.
- Wrap an existing interface.
- Extract one bounded component or patch.
- Reimplement behavior when source reuse is unavailable or inappropriate.
ForkSense
When an external-code decision is consequential, inspect current source, issues, rejected proposals, live forks, maintenance, tests, license, and executable evidence. Do not rank candidates by popularity alone.