Document C4 Components and Generate Diagrams

This skill produces C4 model Component-level documentation - the zoomed-in view showing the logical components living inside a single container and how they relate. Its template captures, per component: a name, short description, type (application/service/library/etc.), and primary technology; a detailed purpose statement; a software-features list; links to the individual code-level files that make up the component (c4-code-file-*.md); interfaces exposed (protocol - REST/GraphQL/gRPC/events - plus named operations with parameters and return types); and dependencies, split into other components used and external systems integrated with. It renders relationships as a Mermaid C4Component diagram scoped to a Container_Boundary, showing components, a component-level database if present, and relationships (Rel) both between components and out to external containers/systems - following c4model.com's component-diagram principles: zoom into a single container, focus on logical components and their responsibilities, show component interfaces, show inter-component interaction, and include external dependencies. A master component index template aggregates multiple components into a system overview with links to each component's individual documentation file and a combined relationship diagram. Example interactions include synthesizing a set of c4-code-*.md files into logical components, defining component boundaries for a specific subsystem (e.g. auth/authz), and grouping database-access code into components with documented relationships.

Use this skill when documenting the component-level view of a system's C4 model - defining logical component boundaries within a single container, their interfaces, and their relationships - typically by synthesizing multiple lower-level code documentation files. It is not for documenting individual code elements (that's the companion C4-Code level), mapping components to deployment units (that's the C4-Container level), or producing a high-level whole-system diagram (that's the C4-Context level) - each of those is a distinct, named level in the same documentation system.

Input is a container's constituent code files or an existing informal description of its logical structure. Output is per-component documentation (features, interfaces, dependencies) plus a Mermaid C4Component diagram and a master component index linking all documented components together.

Produces Mermaid C4Component diagrams per the C4 model (c4model.com), linking to companion C4-Code (individual code elements), C4-Container (deployment mapping), and C4-Context (system-level) documentation levels.

C4Component
    title Component Diagram for [Container Name]

    Container_Boundary(container, "Container Name") {
        Component(component1, "Component 1", "Type", "Description")
        Component(component2, "Component 2", "Type", "Description")
    }
    Rel(component1, component2, "Uses")

Architects and engineers documenting a system's C4 model who need to define logical component boundaries, interfaces, and relationships within a single container, consistently formatted and linked to code- and container-level documentation.