Dependency Graph

This page shows how skelegent’s crates depend on each other. The fundamental rule is that dependencies flow downward: higher layers depend on lower layers, never the reverse.

Note: The ASCII diagram below reflects the core dependency relationships but is incomplete — skg-effects-core, skg-effects-local, skg-turn-kit, skg-auth, and skg-crypto are not shown. See the crate list in layers.md for the complete and authoritative crate inventory.

ASCII dependency graph

                        skelegent (umbrella)
                 feature-gated re-exports of all layers
                              │
         ┌────────────────────┼────────────────────────┐
         │                    │                        │
         ▼                    ▼                        ▼
  skg-context-engine  skg-op-single-shot     skg-orch-local
  (Layer 1)          (Layer 1)                 (Layer 2)
    │  │                 │                       │  │
    │  │                 │                       │  └──► skg-orch-kit (L2)
    │  │                 │                       │         │
    │  └─────────────────┼───────────────────────┘        │
    │                    │                                │
    │                    ▼                                │
    │                 skg-turn ◄───────────────────────┘
    │                 (Layer 1)
    │                    ▲  ▲  ▲
    │        ┌───────────┘  │  └───────────┐
    │        │              │              │
    │  skg-provider-  skg-provider-  skg-provider-
    │  anthropic         openai            ollama
    │  (Layer 1)         (Layer 1)         (Layer 1)
    │
    ▼
  skg-tool              skg-mcp
  (Layer 1)                (Layer 1)
    │                        │
    │                        │
    └────────┬───────────────┘
             │
             ▼
           layer0
         (Layer 0)
             ▲
             │
    ┌────────┼──────────┬──────────────┐
    │        │          │              │
skg-   skg-    skg-       skg-
state-    state-     env-local     secret-*
memory    fs         (Layer 4)     skg-auth-*
(Layer 3) (Layer 3)                skg-crypto-*
                                   (Layer 4)

Key relationships

Layer 0: The foundation

layer0 has no workspace dependencies. It depends only on:

• serde (serialization for protocol messages)
• async-trait (object-safe async traits)
• thiserror (ergonomic error types)
• rust_decimal (precise cost tracking)
• serde_json (for Value in metadata and state)

Every other crate in the workspace depends on layer0, directly or transitively.

Layer 1: Operator ecosystem

The operator ecosystem has several internal dependencies:

• skg-turn provides the Provider trait and shared types. All three provider crates depend on it.
• skg-tool provides ToolDyn and ToolRegistry. It depends only on layer0.
• skg-mcp depends on skg-tool (it creates tools from MCP servers).
• skg-context-engine depends on skg-turn (for Provider), skg-tool (for ToolRegistry), and layer0 (for middleware traits).
• skg-op-single-shot depends on skg-turn and layer0.

Layer 2: Orchestration

• skg-orch-local depends on layer0 and skg-orch-kit. It holds Arc<dyn Operator> references.
• skg-orch-kit provides shared utilities for orchestrator implementations.

Layer 3: State

• skg-state-memory and skg-state-fs depend only on layer0 (and tokio for async I/O). They are completely independent of each other and of all other layers.

Layer 4: Environment and credentials

• skg-env-local depends on layer0. It holds an Arc<dyn Operator>.
• The secret backends (skg-secret-*), auth backends (skg-auth-*), and crypto backends (skg-crypto-*) depend on skg-secret/skg-auth/skg-crypto respectively, and transitively on layer0.

Layer 5: Cross-cutting

• skg-hook-security depends on layer0 (for middleware traits). It provides RedactionMiddleware and ExfilGuardMiddleware.

The umbrella

• skelegent depends on everything, all behind optional = true with feature flags. It re-exports but adds no logic.

External dependencies by layer

Crates not shown in the ASCII diagram

The following crates were added after the diagram was drawn and are not yet reflected in the ASCII art above: