Claude Code Reverse Engineering — Architecture Visualization

System Overview

Architecture Layers

Claude Code CLI — TypeScript Strict · Bun · ESM-only

Terminal UI

React 19component tree

Ink (custom fork)96 files

Yoga WASMflexbox layout

Commander.jsCLI parser

346 .tsxcomponents

85+ hookscustom hooks

Core Engine

45+ ToolsbuildTool() factory

Query Enginestreaming executor

Concurrencysafe/unsafe flags

Recovery8-stage chain

Cost Trackerper-session USD

Extensions

MCP8 config types

Pluginsmarketplace + builtin

Skills17 bundled + custom

Hooks27 events

LSPcode intelligence

BridgeIDE comms

Services

API Client4 backends

Auth/OAuthPKCE + Keychain

AnalyticsDD + OTel

Settings5-layer merge

Migrations11 sync + 1 async

Security

7 Perm Modesdefault to bubble

23 Bash Checkscross-platform

Path Validator6-step pipeline

Auto-ModeYOLO classifier

Boot Sequence

Startup Pipeline

Phase 0

Side Effects

MDM, Keychain prefetch

Phase 1

main() entry

Basic initialization

Phase 2

preAction

init() → migrations

Phase 3

action()

setup → auth/perms

Phase 4

REPL render

Deferred prefetches

Core Engine

Tool Execution Flow

IN

User Input

prompt → QueryEngine

↓

AI

LLM API (streaming)

Anthropic / Bedrock / Vertex / Foundry

↓ tool_use block

FN

Tool Execution

Bash, FileEdit, Agent, MCP … 45+

↓

R

ToolResult

data, newMessages, contextModifier, mcpMeta

↺ next LLM turn

Documentation

8 Design Documents

01

Architecture Overview

5-phase startup, ESM-only module system, Bun bundler, 7-layer config, 89 feature flags, 110 global state fields

1,101 lines

startup config feature-flags

02

Core Engine

60+ field tool interface, buildTool() factory, concurrency safety flags, 8-stage recovery chain, per-session cost tracking

1,352 lines

tools streaming recovery

03

Permission & Security

7 permission modes, 4-step decision pipeline, 23 bash check IDs, 6-step path validation, YOLO auto-classifier

1,178 lines

permissions bash-security TOCTOU

04

Multi-Agent & Memory

3 swarm backends (fork/spawn/in-proc), 7 task types, file-based mailbox, 5-layer memory hierarchy, ETag-based sync

1,416 lines

agents memory teams

05

Extension Systems

6 extension points, MCP 8 transport types, 27 hook events, plugin marketplace, parallel loading, reconnection strategy

1,709 lines

MCP plugins hooks

06

UI Layer

Custom React reconciler (React 19), Ink fork (96 files), Yoga WASM layout, ANSI diff rendering, 346 .tsx components

1,784 lines

React Ink Yoga

07

Services & Infrastructure

4 API backends, OAuth PKCE with Keychain, Datadog + OTel analytics, 5-source settings merge, 11+1 migrations

1,845 lines

API OAuth analytics

08

Types, Schemas & API

Branded IDs, Zod schemas, ~100 field SettingsJson, DeepImmutable AppState, 60+ env vars, 89 feature flags, 44 DD events

2,194 lines

TypeScript Zod schemas

Security

Permission Decision Pipeline

0

Config deny rules

immediate deny

↓

1

Tool.checkPermissions()

allow / deny / ask / passthrough

↓

2

Permanent allow rules

skip prompt

↓

3

passthrough → ask conversion

↓

4

Post-processing

dontAsk • auto (YOLO) • headless

Multi-Agent

Agent & Memory Hierarchy

Agent Swarm Backends

Coordinator (orchestrator)

fork

shared context

spawn

independent

in-process

teammate

Memory Hierarchy (5 layers)

[1] Session Memory — in-context summaries

[2] Project Memory — .claude/memory/

[3] User Memory — ~/.claude/memory/

[4] Team Memory — server-synced shared

[5] External — MCP, LSP, git

Infrastructure

Deployment Options

Local Dev

Ollama/vLLM, Docker Stack, RTX 4090

$0–50/mo

AWS

ECS Fargate, Bedrock, Lambda, Cognito

$45–180/mo

Azure

Container Apps, Azure OpenAI, AD B2C

$50–190/mo

Supabase

Edge Functions, Realtime, PostgreSQL, Auth

$0–25/mo

Scale	Supabase + API	AWS Full	Hybrid (Local GPU)
Solo (1 dev)	$9–103/mo	$240–280/mo	$50/mo
Team (10 devs)	$46–116/dev	$65–110/dev	$35–60/dev
Enterprise (100 devs)	N/A	$45–111/dev	$25/dev

LLM token costs represent 60–95% of total spend at every scale.

Quality

8 Verification Passes

Pass 1

Type/value accuracy

16 corrections

Pass 2

Blocking implementation gaps

4 fixes

Pass 3

Line-by-line precision

7 corrections

Pass 4

Missing schemas/flows

3 fixes

Pass 5

Bridge, MDM, Keychain, Plugin additions

7 additions

Pass 6

Structural problem warnings

42 caveats

Pass 7

Convergence check

2 micro-fixes

Pass 8

CONVERGED — 24/24 spot-checks verified

0

Total: 39 corrections + 42 implementation caveats

Repository

File Structure

claude-code-reverse-engineering/ README.md docs/ 01-architecture-overview.md (1,101 lines) 02-core-engine.md (1,352 lines) 03-permission-security.md (1,178 lines) 04-multi-agent-memory.md (1,416 lines) 05-extension-systems.md (1,709 lines) 06-ui-layer.md (1,784 lines) 07-services-infrastructure.md (1,845 lines) 08-types-schemas-api.md (2,194 lines) infrastructure/ 01-local-development.md 02-aws-architecture.md 03-azure-architecture.md 04-supabase-backend.md 05-cost-analysis.md 06-architecture-diagram.md terraform/ (10 .tf files — production-ready IaC)

Claude Code Architecture