Missing component
- Search the system, archive, and deprecated entries.Documentation gaps are common; absence must be confirmed.
- Try extension before invention.Check whether an existing component can cover the job without breaking its contract.
- Build locally with semantic tokens when the gap is real.A local implementation is allowed; a hidden new standard is not.
- Leave the machine-readable gap marker.Record need, workaround, contribution-candidate, and date using the B&Co Gap Protocol.
- Graduate only with evidence.The Standard says repeated independent use or a gap that is actively slowing work can warrant a shared component.
Missing token
- Search the full token set and aliases.
- Check whether an existing semantic token already covers the intent.
- Flag the gap before using a value.
- Use the closest semantic token temporarily—never a raw production value.
- Report the gap so a formal token decision can be made.
Deviation is not silent customization.
If the product intentionally departs from the system, document the rationale, keep the implementation on semantic tokens, leave the deviation marker at the code, and identify whether the pattern should be reconsidered for shared use.
Product-local first; shared only when warranted.
Building Blocks should have a complete baseline, but product-specific jobs still belong in the product until there is evidence that the shared system should own them. Central completeness is not permission to absorb every one-off.