# LPC - LATENCY & PERFORMANCE CANON
version: v1.1
status: ACTIVE
parent: master_architecture_index.md
phase: 05
phase_name: Latency & Performance Canon
document_role: latency_budget_authority

## 1. OBJECTIVE
Define latency measurement, performance tracking, bounded execution and fallback rules across Devon.

This file owns:
- latency model
- hot path vs cold path distinction
- bounded execution expectations
- fallback behavior when latency budget is exceeded

## 2. CORE PRINCIPLE
Every operation must be measurable in time and traceable across the system.

Performance governance is not only measurement.
Performance governance also requires bounded path design.

## 3. LATENCY MODEL

### 3.1 Per Module
- each module must expose latency
- response time must be measurable

### 3.2 Per Stage
- input
- context resolve
- retrieval
- interpretation
- decision
- validation
- execution
- audit emit

Each stage must be timed independently.

### 3.3 End-to-End
- full request lifecycle must be tracked
- total latency must be observable

## 4. HOT PATH VS COLD PATH

### 4.1 Hot Path
Hot path is the production-critical path.

Rules:
- bounded number of stages
- minimal retrieval scope
- minimal transformation chain
- one main interpretation step by default
- deterministic decision must stay lightweight

### 4.2 Cold Path
Cold path is allowed for:
- deep analysis
- forensic reconstruction
- extended document exploration
- specialized graph exploration
- non-critical background reasoning

Cold path may be slower, but must remain auditable.

## 5. FALLBACK RULE
If latency budget is exceeded or threatened:
1. reduce retrieval scope
2. reduce chain depth
3. avoid optional reasoning branches
4. prefer minimal valid path
5. emit performance evidence

## 6. PERFORMANCE LAW
Architecture that adds stages without validated outcome adds noise.

Less code, less path, less latency.

## 7. TRACEABILITY
Every request must have:
- request ID
- stage timing
- total latency
- fallback indicator when triggered