019 CLI Mcp Parity

Status: Proposed

Date: 2026-07-17

Context:

ComplyPack exposes compliance operations through two transport layers: a CLI (cmd/complypack/cli/) and an MCP server (internal/mcp/). Both are thin wiring over domain packages in internal/.

Issue #85 proposed removing the MCP server entirely and replacing it with CLI commands, arguing that the underlying data is static (cached OCI artifacts) and does not benefit from a session-based protocol. After discussion, issue #87 reframed the goal: keep both transports but ensure the CLI can do everything the MCP server can, where it makes sense.

The current gap:

Four MCP tools have no CLI equivalent. Two have only partial coverage because their functionality is embedded inside the pack command’s pre-pack validation pipeline rather than exposed as standalone commands.

Additionally, some domain logic currently lives in the MCP transport layer (extractFromResolvedPolicy and resolveFromCatalog in internal/mcp/tool_assessment.go) rather than in domain packages, which prevents the CLI from reusing it.

Decision:

Both the CLI and the MCP server are maintained as thin transport layers over shared domain functions. New capabilities SHOULD be exposed through both transports where it makes sense:

• CLI provides deterministic, scriptable access for automation and CI/CD.
• MCP provides conversational, LLM-assisted workflows.

This is a SHOULD-level guideline, not a hard requirement. Some capabilities are naturally transport-specific (e.g., complypack init is interactive and has no MCP equivalent; MCP resources serve discovery data that a CLI user would not need). Developers use common sense to decide when parity applies.

To enable parity, shared infrastructure must be extracted from the MCP layer into domain packages:

1. Domain logic (extractFromResolvedPolicy, resolveFromCatalog) moves to internal/requirement/.
2. The artifact loading pipeline (config parsing, source fetching, policy resolution) is extracted into a reusable function so both transports can load artifacts without duplicating the setup sequence.
3. Schema loading is extracted from internal/mcp/ into internal/schema/ so both pack and new CLI commands share the same path.

Consequences:

• Six new CLI commands will be added to close the parity gap: requirements, delta, triage, applicability, validate, and test.
• Domain logic must not live in either transport layer. Adding a new capability means writing the domain function first, then wiring from both CLI and MCP.
• Both transports support flexible configuration: --config for file-based setup and --source/--schema flags for ad-hoc usage (matching ADR 013).
• CLI commands default to human-readable output with --output json for machine consumption. MCP tools continue to return JSON.