<Title>
Summary
One paragraph describing the change.
Motivation
Why this is worth doing; the problem it solves.
Guide-level explanation
Optional. The design explained as if teaching it to another contributor.
Detailed design
The technical detail: data structures, algorithms, on-disk/runtime behavior, edge cases.
Evaluation
Optional. Evidence for the design: measurements, experiments, prototypes, and the reasoning behind parameter choices. Results that rule out an alternative belong here, referenced from Rationale and alternatives.
Drawbacks
Reasons this design might not be worth doing. Keep this section after promotion: it records what was accepted and why.
Rationale and alternatives
Why this design over others; what alternatives were considered.
Prior art
Optional. Comparable designs in other systems.
Unresolved questions
Open questions to settle during review. Drop this section when promoting to active,
folding settled answers into the design.
Future possibilities
Natural extensions, explicitly out of scope here.