Claude Code reverse-engineering wiki

This wiki reverse-engineers @anthropic-ai/claude-code to explain how Claude Code works, with source-anchored implementation notes. The primary readable artifact for this analysis is:

claude-code-pkg/src/entrypoints/cli.js

The wiki is organized around reverse-engineered internals questions: how the Bun standalone runtime starts, routes command-line modes, shapes model context, exposes tools, persists sessions, supports remote control, runs agents, and exposes operational/debug/native surfaces.

Because cli.renamed.js is a renamed view of a bundled/minified artifact, symbol names are unstable across builds. Source anchors are intended for searching the analyzed bundle, not as public API names. Implementation pages use Semantic alias as the first source-anchor table column, followed by the anchor string or symbol grep target and a one-line meaning.

Semantic alias and minified anchor mapping

This home page is a navigation index, not a direct cli.renamed.js implementation analysis. Concrete topic pages map stable semantic aliases to version-specific minified anchors.

Semantic alias	Minified anchor	Scope
Wiki home	N/A — navigation page	Orients readers to the canonical sections and reading paths.
Section indexes	N/A — see linked section README pages	Curated reader routes through source-anchored implementation pages.
Topic implementation pages	See page-level source anchor tables	Bundle-specific anchors live in focused implementation documents.

Internals wiki map

flowchart TD
  Home[Wiki home] --> Start[00 Start here]
  Home --> Runtime[01 Runtime lifecycle]
  Home --> Loop[02 Context and model loop]
  Home --> Tools[03 Tools, integrations, and security]
  Home --> Sessions[04 Sessions, persistence, and remote]
  Home --> Hosted[05 Hosted agent ops]
  Home --> Agents[06 Agents and automation]
  Home --> Atlas[99 Research atlas]

  Start --> Runtime
  Runtime --> Loop
  Loop --> Tools
  Runtime --> Sessions
  Sessions --> Hosted
  Loop --> Agents
  Atlas --> Start

  click Home "./" "Open wiki home"
  click Start "./00-start-here/" "Open Start here"
  click Runtime "./01-runtime-lifecycle/" "Open Runtime lifecycle"
  click Loop "./02-context-model-loop/" "Open Context and model loop"
  click Tools "./03-tools-integrations-security/" "Open Tools, integrations, and security"
  click Sessions "./04-sessions-persistence-remote/" "Open Sessions, persistence, and remote"
  click Hosted "./05-hosted-agent-ops/" "Open Hosted agent ops"
  click Agents "./06-agents-automation/" "Open Agents and automation"
  click Atlas "./99-research-atlas/" "Open Research atlas"

Canonical sections

Section	Purpose
Start here	Minimal orientation: what the bundle is, how to read anchors, and the first path through the runtime.
Runtime lifecycle	Package/Bun bootstrap, CLI flags, root command routing, headless/interactive modes, and subcommands.
Context and model loop	Prompt/context sources, memory/settings, model/provider/auth selection, and headless stream-JSON turns.
Tools, integrations, and security	Built-in tools, permissions, MCP, plugins, hooks, settings policy, IDE/Chrome/file integrations.
Sessions, persistence, and remote	Local JSONL transcripts, resume/continue/fork/rewind, remote sessions, teleport, and Remote Control.
Hosted agent ops	Debug logs, telemetry/traffic policy, doctor/update, hosted review signals, and native image/audio modules.
Agents and automation	Custom/background agents, task/subagent tools, lifecycle hooks, slash commands, and auto-mode.
Research atlas	Artifact maps, bytecode caveats, decoded chunk audits, and promotion rules for future source reads.

Goal	Read this path
Get oriented quickly	Start here → Glossary and aliases → Main feature map → System architecture → CLI main paths
Answer protocol and boundary questions	System architecture → Runtime communication protocols → Remote control and teleport
Understand one complete local run	CLI main paths → Prompt, context, and memory → Prompt assembly scenarios → Prompt template catalog
Understand context budgets and model billing	Context, memory, compaction, checkpoints, and rewind → Model selection, calls, usage, quota, and billing → Headless streaming and resilience
Understand scriptable/headless mode	Commands and flags → Headless streaming and resilience → Context and model loop architecture
Use canonical reference tables	Command-line reference → Tool inventory and schemas → Hooks and events reference → Settings schema reference → Environment variables reference
Understand durable sessions and remote control	Sessions, persistence, and remote → Session resume and transcripts → Remote control and teleport → Session API, events, and storage
Review trust boundaries	Tools, integrations, and security → Tool runtime, events, and integration flows → Built-in tools and permissions → Sandbox and isolation → MCP, plugins, and hooks
Understand voice/audio dictation	Hosted agent ops → Media native modules → Audio capture and voice mode
Study agents and automation	Agents and automation → Agents, tasks, and subagents → Agent runtime, scheduling, and completion → Slash commands and automation

Cross-cutting implementation matrix

Concern	Primary internals section	Supporting sections
Runtime mode selection	Runtime lifecycle	Command-line reference, Start here, Sessions, persistence, and remote
Communication protocols	Runtime communication protocols	MCP, plugins, and hooks, Remote control and teleport, Agents and automation
Context engineering	Context and model loop	Context, memory, compaction, checkpoints, and rewind, Agents and automation, Tools, integrations, and security
Model usage, quota, and billing	Model selection, calls, usage, quota, and billing	Models, providers, and auth, Headless streaming and resilience
Tool execution	Tool inventory and schemas	Built-in tools and permissions, Tool runtime, events, and integration flows, Agents and automation
Session/event lifecycle	Session API, events, and storage	Data models and frame schemas, Hooks and events reference, Hosted agent ops
Remote/hosted operation	Sessions, persistence, and remote	Hosted agent ops, Agents and automation
Permissions and policy	Tools, integrations, and security	Context and model loop, Hosted agent ops
Settings, hooks, and environment references	Settings schema reference	Hooks and events reference, Environment variables reference, Settings, policy, and integrations
Sandbox and isolation	Sandbox and isolation	Built-in tools and permissions, Settings, policy, and integrations
Voice/audio dictation	Audio capture and voice mode	Media native modules, Prompt, context, and memory
Subagents and automation	Agent runtime, scheduling, and completion	Agents and automation, Tools, integrations, and security, Sessions, persistence, and remote
Artifact/decode triage	Research atlas	Decoded-classified decompilation audit, Artifact map and bytecode notes

Mechanism-level deep dives

Mechanism	Start here
Semantic aliases, minified anchors, and terminology	Glossary and aliases
System module boundaries and data/control flow	System architecture
Runtime protocol families across modules, agents, bridges, and remote servers	Runtime communication protocols
Command-line flags, subcommands, and aliases	Command-line reference
Per-module architecture deep dives	Runtime lifecycle architecture, Context and model loop architecture, Tool runtime and security architecture, Session and remote-control architecture, Operations and native-support architecture, Agent and automation architecture
Headless stream/control event loop	Headless streaming and resilience
Prompt/template extraction catalog	Prompt template catalog
Major prompt assembly scenarios	Prompt assembly scenarios
Context compaction, memory selection, checkpoints, and rewind	Context, memory, compaction, checkpoints, and rewind
Dynamic model selection, provider calls, usage, quota, and billing	Model selection, calls, usage, quota, and billing
Tool runtime, events, shell execution, SDK/LSP/Web, context exclusion, settings, and persistence	Tool runtime, events, and integration flows
Tool names, schema owners, and tool-family reference	Tool inventory and schemas
Tool authorization and execution boundary	Built-in tools and permissions
Hook names, lifecycle events, and stream/control frames	Hooks and events reference
Known settings roots, keys, and policy groups	Settings schema reference
Command sandbox design and platform isolation	Sandbox and isolation
MCP runtime connection and elicitation	MCP, plugins, and hooks
Resume/continue/fork state restoration	Session resume and transcripts
Session API, event, storage, and remote-control reference	Session API, events, and storage
Session data models, transcript records, and frame schemas	Data models and frame schemas
Diagnostics and debug logs	Diagnostics and debug logs
Telemetry and tracing	Telemetry and tracing
Feature gates	Feature gates reference
Updater and doctor	Updater and doctor
Environment variable reference	Environment variables reference
Task/subagent runtime behavior	Agents, tasks, and subagents
Agent task scheduling, completion, and cron	Agent runtime, scheduling, and completion
Voice capture, transcription stream, and prompt injection	Audio capture and voice mode

Source policy

Treat claude-code-pkg/src/entrypoints/cli.js as the primary readable artifact for reverse-engineering claims.
Use approximate line numbers plus byte offsets because the file is bundled and many logical modules sit on very long lines.
Preserve exact strings, flags, environment variables, and symbols in source-anchor tables.
Do not treat .jsc bytecode dumps as recoverable JavaScript source.
Keep broad synthesis pages, implementation pages, and reference pages distinct; promote confirmed findings into the focused section page that owns the behavior.

Important caveat

These pages are reverse-engineering notes over a bundled/minified production artifact, not recovered clean source. Semantic names in prose and diagrams are explanatory aliases. Generated/minified symbols are retained only when useful as search anchors for the analyzed bundle.

Created and maintained by Yingting Huang.