Glossary
Key terms and concepts used throughout this documentation.
A
Agent — A sub-process spawned via the Agent tool to handle tasks autonomously. Each agent has its own conversation context and filtered tool set. See Sub-Agents & Coordination.
AppState — The central state store (Zustand-like) that holds all application state: messages, tasks, permissions, UI state. See State & Sessions.
Auto-memory — The system that automatically stores useful information learned during conversations for future reference. See Prompt, Memory & Context.
B
buildTool() — Factory function that creates a Tool from a partial definition, filling in safe defaults for methods like rendering and permissions. See Tool Architecture.
Bun — JavaScript runtime and bundler used to build Claude Code. The build uses Bun's feature() API for compile-time dead code elimination. See Build Guide.
C
CLAUDE.md — Configuration files that provide persistent context to Claude. Loaded from multiple layers (enterprise, global, project, local). See Prompt, Memory & Context.
Compaction — The process of summarizing conversation history when it exceeds the context window. See Prompt, Memory & Context.
Coordinator — A special agent mode that decomposes tasks and delegates to worker agents. Gated behind the COORDINATOR_MODE feature flag. See Sub-Agents & Coordination.
D
Dead code elimination — Build-time removal of code branches gated by feature() calls set to false. Reduces bundle size by excluding internal features. See Feature Flags.
E
end_turn — The API stop reason indicating the model has finished responding and is not requesting any tool executions.
F
Feature flag — A compile-time or runtime toggle that enables/disables functionality. 90+ flags are defined in build.ts. See Feature Flags.
G
GrowthBook — Feature flag and A/B testing service used for runtime flag evaluation. See Analytics & Telemetry.
H
Hook — A lifecycle extension point that runs shell commands before/after tool executions, agent loop turns, and session events. Can veto tool calls and modify inputs. See Hooks.
I
Ink — A React renderer for terminal applications. Claude Code uses Ink 6 to render its interactive UI. See Components & Rendering.
L
LocalCommand — A slash command type that executes immediately without involving the AI model. Used for config, navigation, and utility commands. See Command System.
M
MACRO — Compile-time constants injected during build (e.g., MACRO.VERSION, MACRO.BUILD_TIME). Similar to C preprocessor macros.
MCP — Model Context Protocol. An open standard for connecting AI models to external tools and data sources. See MCP Integration.
P
Permission mode — The current security mode (default, acceptEdits, auto, bypassPermissions, etc.) that determines how tool use approvals are handled. See Permission Model.
Plugin — A full CLI extension that can add commands, tools, and hooks. More powerful than skills. See Plugins & Skills.
PromptCommand — A slash command type that injects content into the conversation for the AI model to process. Skills become PromptCommands. See Command System.
Q
Query Engine — The core logic that drives each turn of the agent loop. Its responsibilities are covered across Prompt, Memory & Context (assembly, memory, compaction) and API Client (streaming & retries).
R
REPL — Read-Eval-Print Loop. The main interactive screen where users converse with Claude. See Input & Rendering.
S
Skill — A lightweight extension — a markdown file with YAML frontmatter that injects prompt content when invoked as a slash command. See Plugins & Skills.
Source map — The cli.js.map file in the npm package that contains all original TypeScript source files, enabling the source recovery this analysis is based on.
StreamingToolExecutor — The engine that manages parallel and sequential tool execution during streaming API responses. See Tool Execution.
Swarm — A mode where multiple in-process agents collaborate via a mailbox system. Related to coordinator mode. See Sub-Agents & Coordination.
T
Task — A background unit of work (shell command, agent, workflow) that runs independently and reports completion via notifications. See Task Management.
Tool — A structured capability that the AI model can invoke. Tools have schemas, permissions, execution logic, and rendering. See Tool Architecture.
tool_use — An API response block type indicating the model wants to invoke a tool with specific arguments.
tool_result — An API request block type containing the output of a tool execution, sent back to the model.
W
Worktree — A git worktree used for agent isolation. Sub-agents can work in isolated copies of the repo without affecting the main working directory. See Sub-Agents & Coordination.
Y
Yoga — A cross-platform flexbox layout engine (from Meta) used by Ink for terminal UI layout. See Components & Rendering.
Z
Zod — A TypeScript schema validation library used for tool input validation. Every tool's inputSchema is a Zod schema. See Tool Architecture.
Zustand — A minimal state management library. Claude Code uses a Zustand-like pattern (not Zustand itself) for its AppState store. See State & Sessions.