Day 2Level 1 — Core Mental Models
Constraints First: Scale, Budget, Latency, Team
Learn: 45 minMap: 30 minDesign: 60 min
Core Concepts (5)
- 1.Constraints are the design space — requirements are just wishes until constrained
- 2.Every NFR must have a number: QPS, p99 latency, storage growth, budget/month
- 3.Team topology (Conway's Law) is a hard constraint, not a soft preference
- 4.Data residency, compliance, connectivity — non-negotiables that shape everything
- 5.Write constraints down first. They are the guardrails for every later decision.
Map to Your Experience
Take the system from Day 1. For each of the 5 decisions, what constraints were present? Were they explicit? If not, what implicit constraints shaped the outcome?
Design Brief: Constraint Specification for Your System
Requirements
- •Quantify every NFR with numbers
- •Include team topology and Conway implications
- •List compliance and data residency constraints
- •Document existing technical estate dependencies
Constraints
- •Use real numbers from your system or realistic estimates
- •No 'low latency' — say 'p99 < 200ms at 10k QPS'
Must Cover
quantified-nfrsteam-topologycompliance-residencyexisting-estate
Trade-off Axis
constraint completeness vs design velocity
Referenced Patterns
Competencies Advanced
requirements constraints → L2economics evolution → L2
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