EPCI Core

Overview

EPCI (Explore → Plan → Code → Inspect) is a structured development methodology with validation at each phase.

The 4 Phases

Phase	Objective	Output
Explore	Understand needs and existing code	Functional brief
Plan	Design the solution	Implementation plan
Code	Implement with tests	Code + tests
Inspect	Validate and finalize	PR ready

Complexity Categories

Category	Files	LOC	Risk	Workflow
TINY	1	<50	None	/epci-quick
SMALL	2-3	<200	Low	/epci-quick
STANDARD	4-10	<1000	Medium	/epci
LARGE	10+	1000+	High	/epci
SPIKE	?	?	Unknown	/epci-spike

Feature Document

Central traceability document for each STANDARD/LARGE feature.

Structure

# Feature Document — [ID]

## §1 — Functional Brief
[Context, acceptance criteria, constraints]

## §2 — Implementation Plan
[Tasks, files, risks]

## §3 — Implementation
[Progress, tests, reviews]

## §4 — Finalization
[Commit, documentation, PR]

Location

docs/features/<feature-slug>.md

Breakpoints

Mandatory synchronization points:

Breakpoint	After	Pass Condition
BP1	Phase 1	Plan validated by @plan-validator
BP2	Phase 2	Code reviewed by @code-reviewer

Enriched Breakpoint Format (v3.1+)

Breakpoints display a decision dashboard with:

Section	Content	Source
Métriques	Complexity, files, time, risk	Scoring algorithm
Validations	Agent verdicts, skills loaded	Subagents
Preview	Next phase tasks (3-5)	Plan §2
Liens	Feature Document path	File system
Options	Interactive choices	Text instructions

See breakpoint-metrics skill for scoring algorithm and templates.

EPCI Subagents

Subagent	Role	Phase
@plan-validator	Validates technical plan	Phase 1 → BP1
@code-reviewer	Code quality review	Phase 2 → BP2
@security-auditor	OWASP security audit	Phase 2 (conditional)
@qa-reviewer	Test review	Phase 2 (conditional)
@doc-generator	Generates documentation	Phase 3

Routing

User brief
    │
    ▼
/epci-brief (evaluation)
    │
    ├─► TINY/SMALL ──► /epci-quick
    │
    ├─► STANDARD ────► /epci
    │
    ├─► LARGE ───────► /epci --large
    │
    └─► Uncertain ───► /epci-spike

EPCI Principles

1. Traceability — Everything is documented in the Feature Document
2. Validation — Each phase has an exit gate
3. Iteration — Phases can be revisited if needed
4. Adaptation — Workflow adapts to complexity
5. Automation — Subagents automate reviews