@storybook/instrumenter

The @storybook/instrumenter package provides function call interception and step-through debugging for Storybook interactions. In practice, it's primarily an internal Storybook dependency that instruments your component interactions for the test runner and addon-interactions. The API revolves around wrapping function calls to capture execution flow, which works reliably for its narrow purpose.

From a security perspective, the instrumentation layer introduces runtime overhead and potentially exposes function call metadata that might contain sensitive data. There's minimal documentation around what gets captured, how to sanitize instrumented data, or how to prevent sensitive information from leaking through error stack traces. The library doesn't provide clear input validation helpers or guidance on securing instrumented code paths.

The dependency chain is moderate but includes typical Storybook ecosystem packages. Error handling can be verbose and occasionally exposes internal implementation details. While it follows secure-by-default principles for what it does, the lack of security-focused documentation and the potential for inadvertent information disclosure through instrumentation metadata are concerns for security-sensitive applications.

The @storybook/instrumenter package provides a runtime instrumentation layer primarily for interaction testing and play functions in Storybook. In practice, it wraps browser APIs and framework methods to capture interactions for replay and debugging. Day-to-day, you rarely interact with it directly—it's a transitive dependency pulled in when using @storybook/test or addon-interactions.

From a security perspective, the package has minimal attack surface since it's development-only tooling. However, it instruments global browser APIs at runtime which creates potential for unexpected behavior if accidentally bundled in production. The error messages are generally helpful for debugging instrumentation failures, but don't expose sensitive data. The main concern is the Storybook ecosystem's rapid release cycle—staying current with security patches means frequent dependency updates across the entire @storybook/* namespace.

The package follows secure-by-default principles for its limited scope, with no network calls or data persistence. Input validation is present for instrumented function calls, though edge cases with custom browser API polyfills can cause issues.

@storybook/instrumenter is primarily an internal Storybook package for wrapping and intercepting function calls in stories, particularly for the interactions addon. In production-adjacent environments (visual regression testing, interaction testing), you'll encounter it indirectly through play functions.

The instrumentation layer itself is lightweight with minimal runtime overhead, but observability is severely limited. There's no built-in logging of instrumentation state, no hooks for monitoring wrapped function performance, and debugging instrumented calls requires digging through Storybook's internal state. Error handling is basic—when instrumented functions throw, stack traces can be confusing due to wrapper layers. There's no configurable retry behavior or timeout management at this level.

Breaking changes between major Storybook versions have historically affected the instrumenter API surface, though most developers interact with it indirectly. Resource management is straightforward as it doesn't hold connections or pools, but the lack of configuration options means you're stuck with default behavior. Documentation assumes you're extending Storybook internals rather than direct integration, making it challenging for custom tooling.