Evaluate the seams between components. Clean interfaces make systems replaceable, testable, and understandable. Messy interfaces make everything fragile.

ultrathink

Rules

Every finding must identify a specific interface, contract, or boundary

"Tightly coupled" is not a finding. "The MUD command dispatch (§7.C) directly calls VizConfigContext setters, meaning command logic can't be tested without the React context — an interface boundary is missing" is a finding

Look for implicit contracts (assumptions that aren't documented) as hard as you look for explicit ones

If the design references existing code (reuse, refactor, replace), read that code before assessing interfaces. The existing code's contracts may answer questions the design doc leaves open. A finding that the code already resolves is not a finding.

Distinguish "not yet specified" (future phase placeholder) from "underspecified" (current phase gap). Phase 2+ placeholders in a phased design doc are expected, not findings.

Questions

Read referenced code first. If the design doc says "reuse X" or "replace Y," read those components' actual interfaces before reviewing. The code is ground truth for existing contracts.

Identify all interfaces/contracts in the design: APIs, context shapes, event protocols, file formats, command grammars

For each interface: is it minimal? Does either side depend on internal details of the other?

Could you swap one side of an interface without the other knowing? If not, why?

Where would a change ripple? If you modify component X, what else has to change?

Are there implicit contracts — things that must be true for the system to work but aren't documented as interfaces?

Are there missing interfaces — places where components interact without a defined contract?

Do interfaces have clear error contracts? What happens when one side sends unexpected input?

Output Format

Interface

Between

Issue

Severity

Recommendation

[name/description]

[Component A ↔ B]

[specific issue]

Critical / Important / Minor

[specific action]