This glossary provides definitions for codebase-specific terms, jargon, and architectural concepts used within the Claude Code project. It is intended to help onboarding engineers navigate the system and understand the relationships between high-level concepts and their implementations.
An autonomous execution unit powered by a Large Language Model (LLM) that can use tools to accomplish tasks. Claude Code utilizes a hierarchical agent model where a main agent can spawn subagents for specialized tasks. Subagents can now spawn nested subagents up to a default depth of 3 CHANGELOG.md32
plugins/*/commands/ or triggered via the Agent tool.code-explorer, code-architect): README.md48-50 and .claude-plugin/marketplace.json62-71Ctrl+B CHANGELOG.md56A function or capability exposed to an Agent. Tools allow Claude to interact with the outside world (e.g., running bash commands, reading files, or interacting with GitHub).
allowed-tools frontmatter of agent/command definitions.auto mode, the classifier adjudicates dangerous commands (e.g., rm) instead of prompting CHANGELOG.md61An event listener that triggers logic at specific points in the agent's lifecycle.
SessionStart: Injects context or modifies behavior at the start of a session (used by output style plugins) .claude-plugin/marketplace.json51-60DirectoryAdded: Fires after /add-dir or SDK register_repo_root requests mid-session CHANGELOG.md11PreToolUse: Monitors or validates tool calls before execution (e.g., security-guidance plugin) .claude-plugin/marketplace.json139-148TeammateIdle: Fires when a subagent completes its task.A set of specialized instructions or domain-specific knowledge bundled within a plugin to guide agent behavior without necessarily being a standalone command.
SKILL.md files within plugin directories.frontend-design skill: plugins/frontend-design/skills/frontend-design/SKILL.md1-5claude-api skill: Now defaults to Claude Opus 5 CHANGELOG.md31This diagram shows how a user interaction triggers the Agent System to coordinate multiple specialized code entities, specifically focusing on the lifecycle from command to execution.
Sources: plugins/frontend-design/skills/frontend-design/SKILL.md1-40 CHANGELOG.md32 plugins/frontend-design/.claude-plugin/plugin.json1-9
This diagram bridges the conceptual "Issue Sweep" to the scripts and GitHub Actions that implement it.
Sources: .github/workflows/sweep.yml1-32 scripts/sweep.ts1-52 scripts/issue-lifecycle.ts3
| Term | Definition | Code Pointer |
|---|---|---|
| Compaction | Summarizing conversation history to fit context limits. Fork-session lineage is preserved after compaction CHANGELOG.md58 | CHANGELOG.md58 |
| MCP | Model Context Protocol. Standard for connecting AI to tools. Config errors are reported in stream-json CHANGELOG.md12 | CHANGELOG.md12-16 |
| Sandbox | Restricted environment for bash commands. sandbox.network.strictAllowlist denies non-allowlisted hosts CHANGELOG.md10 | CHANGELOG.md10 |
| Managed Settings | Fleet-wide policies. managed-settings.json supports environment variable resolution for MCP CHANGELOG.md27 | CHANGELOG.md27 |
| Worktree | Isolated git working tree for tasks. WorktreeCreate hook fires upon creation. | CHANGELOG.md25 |
| Gateway | Proxy (claude gateway) for upstream LLM providers (Vertex/Bedrock) with OIDC federation CHANGELOG.md60 | examples/gateway/gcp/README.md1-18 |
| Fast Mode | High-performance mode for specific models (Opus 5, Opus 4.8). Enabled via /fast CHANGELOG.md30 | CHANGELOG.md9 CHANGELOG.md30 |
| OIDC Federation | OpenID Connect federation used by the Gateway for authenticated access to cloud providers. | examples/gateway/gcp/gateway.yaml.example1-10 |
| Statsig | Feature flagging and telemetry service used for logging issue events and feature rollouts. | .devcontainer/init-firewall.sh71-72 |
Sources: CHANGELOG.md1-60 examples/gateway/gcp/README.md1-18 .devcontainer/init-firewall.sh71-72
The Gateway acts as an authenticated proxy between CLI users and upstream providers like Google Vertex AI or Amazon Bedrock.
setup.sh or Terraform in examples/gateway/.claude-opus-5 on Vertex) CHANGELOG.md9Direct VPC egress for private database connectivity in GCP examples/gateway/gcp/setup.sh8-9A secure execution layer for untrusted code or commands.
init-firewall.sh which uses iptables and ipset to enforce a default-deny policy with a strict allowlist of domains like api.anthropic.com and registry.npmjs.org .devcontainer/init-firewall.sh67-75NET_ADMIN and NET_RAW capabilities to manage these firewall rules .devcontainer/devcontainer.json12-15Standardized labels used by automation to manage the GitHub issue tracker.
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