feat: add the judgment-pack mcp server (offline, hand-rolled, zero new deps)#12
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Expose the offline validation core to Model Context Protocol clients over stdio, so an agent can validate documents as tool calls. The server speaks MCP's newline-delimited JSON-RPC 2.0 directly -- no SDK -- keeping the runtime's dependency set unchanged and its build on Go 1.21. internal/mcp handles the initialize handshake, tools/list, tools/call, and ping, and exposes four read-only tools that delegate to the existing engine and evaluate nothing: validate, test_conformance, get_schema, and describe_runtime. It holds no credential and opens no network connection -- an MCP client reaches exactly the same core the CLI reaches. Wired as a top-level "judgment-pack mcp" subcommand. Covered by a protocol round-trip test and a CLI-wiring test, and exercised end-to-end by a no-context agent that authored a valid document purely through the tools with no protocol violations. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Brian Jin <35789537+kikashy@users.noreply.github.com>
Mark ADR-0003 accepted and record the implementation decision: the server is hand-rolled rather than built on an MCP SDK, because both Go SDKs require a Go 1.25 toolchain and pull heavy dependencies (including oauth2) that conflict with this runtime's minimal, offline, Go 1.21 posture. An SDK belongs in a future commercial, authenticated service -- a separate layer per ADR-0002 and the repository boundary -- not in the public offline runtime. Add "judgment-pack mcp" to the README command list, and note in docs/agent-testing.md that the MCP surface now exists alongside the CLI loop. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Brian Jin <35789537+kikashy@users.noreply.github.com>
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Implements Phase 1 of ADR-0003: a Model Context Protocol server exposing the offline validator to any MCP client, so an agent can validate documents as tool calls.
What
internal/mcp— a hand-rolled MCP server over stdio (newline-delimited JSON-RPC 2.0): theinitializehandshake,tools/list,tools/call,ping, and error handling.validate,test_conformance,get_schema,describe_runtime.judgment-pack mcpsubcommand.Why hand-rolled (no SDK)
Both Go MCP SDKs (
modelcontextprotocol/go-sdk,mark3labs/mcp-go) require a Go 1.25 toolchain and pull heavy dependencies — includingoauth2, which a keyless offline server never uses. That conflicts with this runtime's minimal, offline, Go 1.21 posture. The MCP surface here is small (four read-only tools over stdio), so the server speaks the protocol directly and adds zero dependencies —go.mod/go.sumare unchanged and the build stays ongo 1.21. An SDK belongs in a future commercial, authenticated API/MCP service — a separate layer per ADR-0002 and the repository boundary. Recorded in ADR-0003 (now accepted).Keyless, offline, evaluates nothing — an MCP client reaches exactly the same core the CLI does.
Verification
judgment-pack mcponly through a strict MCP stdio client, authored a valid pack purely through the tools (valid on the firstvalidatecall). Zero protocol violations; correctisErrorsemantics (includingfalsefor invalid documents); all four tools behaved per schema;test_conformancereported 47/47 over MCP; diagnostics matched CLI quality (e.g.JPS-STRUCTURE-DECIMAL-OPERANDat the exact node, unresolved refs naming the id and the declared set).Docs: ADR-0003 marked accepted with the hand-roll rationale; the README and
docs/agent-testing.mdnote the command.No release.
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