Claude Code configuration works best when it is designed as a layered policy system: durable project guidance tells Claude how work should be done, settings select behavior at the right administrative scope, and permissions limit what the session may do. Start with the smallest stable instruction set and the least authority that supports the task; add reusable workflows and automation only after that baseline is sound.

Architecture Overview: Persistent Context Before Automation

Claude Code reads CLAUDE.md files as project memory. A repository-level file can capture conventions, architecture constraints, required checks, and safe working practices that should apply across sessions. Claude Code also supports rules for more targeted instructions.

Keep persistent context factual, concise, and reviewable. Record information a collaborator would need repeatedly: how to run tests, which directories are generated, required security checks, or conventions that affect edits. Do not place secrets, access tokens, customer data, or broad “always approve” directions in CLAUDE.md; these files influence future sessions and are commonly shared with the repository.

Settings Scopes and Precedence

Claude Code settings can be configured at user, project, local-project, managed, and command-line scopes. Project settings can travel with the repository, local project settings support machine-specific choices, and managed settings give an organization a way to enforce policy. For most conflicting scalar settings, the documented precedence is managed, command line, local, project, then user; array-valued settings may merge across scopes, and security-sensitive settings can have documented exceptions.

Choose scope by ownership, not convenience:

  • Put team-wide, reviewable defaults in project configuration.
  • Keep personal paths, local tooling, and non-portable preferences in local configuration that should not be shared.
  • Use managed settings for organization-wide safeguards that contributors must not be able to relax.

When multiple scopes can affect a value, verify precedence against the current documentation rather than assuming a more local file wins. A settings change can alter a tool's behavior across many sessions, so test it in a controlled repository before organization-wide rollout.

Permission Rules: Allow, Deny, and Ask

Claude Code permissions govern whether tools can run without prompting, are blocked, or require confirmation. Permission rules merge across the applicable settings scopes; allow, ask, and deny rules can all be configured, and a deny rule takes precedence where its rule matches.

Use deny rules to protect paths, commands, and resources that should never be reachable from a session. Use narrowly scoped allow rules only for repetitive, low-risk actions that have already been reviewed, and use configurable ask rules for operations that require confirmation. Leave unfamiliar, destructive, networked, or credential-bearing operations in an approval path.

Permissions are guardrails, not proof that an action is harmless. In particular, a deny rule for a file path does not constrain arbitrary subprocess access to that path unless a sandbox also enforces the filesystem boundary. A permitted shell command can still change production data, expose a secret through output, or cause cost. The underlying system must continue to enforce identity, authorization, and audit controls.

Permission Modes and Least Privilege

Claude Code offers permission modes that change how approvals are handled. In plan mode, Claude Code can read files and run read-only shell commands for exploration, while source edits remain blocked until approval; this behavior remains subject to the documented mode and version in use. Select a mode based on the environment and task risk, and consult the current mode documentation because available controls and behavior can evolve.

For a sensitive repository, begin in a planning or confirmation-oriented mode, review the proposed files and commands, and grant only the additional capability needed for the current task. In a low-risk disposable environment, a broader mode may improve throughput, but it should not become the default for source repositories, production credentials, or shared workstations.

Least privilege applies to more than shell commands. Restrict filesystem access, network destinations, environment variables, and connected services. Prefer short-lived, scoped credentials, and remove access from a session when the task no longer needs it.

A Practical Configuration Sequence

  1. Write repository guidance that is stable, specific, and safe to share.
  2. Put team behavior in project settings and personal machine behavior in local settings.
  3. Apply managed settings for controls that must hold across the organization.
  4. Add deny rules for prohibited operations before adding narrow allow rules for routine ones.
  5. Test with a non-sensitive repository and review logs or approval prompts before wider rollout.

This sequence prevents a useful convenience feature from becoming an undocumented privilege escalation.

Common Mistakes

Avoid using CLAUDE.md as a long-lived transcript or a secret store. Avoid copying permissive settings from a disposable sandbox into a shared repository. Also avoid assuming configuration and permissions are the same thing: settings choose behavior and policy locations, while permission decisions control specific tool access.

Skills and subagents can package specialized work, but they inherit the need for clear context and constrained authority. Event-triggered controls and non-interactive workflows need their own automation design.

Conclusion

Claude Code becomes more predictable when durable instructions, administrative scope, and tool authority are designed together. Keep context concise, assign settings to their rightful owner, make deny rules deliberate, and treat every additional permission as a reviewable risk decision.

Authoritative Sources