digline-mcp

The MCP server for digline: it lets a coding agent read a digline result and measure a new one, and it does not let the agent promote a baseline.

Not because promotion is refused. Because there is no such tool.

The eight tools

promote is absent by construction, and so are migrate, view and report. A baseline is an approved reference, and promote writes into .digline/<tenant>/baselines/, which is committed — anything landing there arrives in somebody's diff and must arrive because they put it there. A refusal would be a conversation an agent could argue with; an absence is not.

The reasoning is ADR 0011, and the judgement layer it turns into surface is AGENTS.md.

Install and configure

uv pip install digline-mcp

One server serves one repository: the perimeter is the repo, and multi-project is N named servers rather than a registry.

{
  "mcpServers": {
    "digline-northwind": {
      "command": "digline-mcp",
      "args": ["--root", "/Users/you/src/northwind"]
    }
  }
}

--tenant and --env are accepted and verify; they never override. The suite decides, as it does everywhere else in digline.

What run costs, before it costs it

run takes a mandatory acknowledge_calls that must equal the suite's planned calls to the target. Called without it, the tool refuses and hands back the number:

run(suite="suite.py")
  → refused: this suite plans 100 calls to the target.
    20 cases × 5 samples = 100 calls to the target; each answer is judged
    3 times by llm_rubric.
    Call again with acknowledge_calls=100.

run(suite="suite.py", acknowledge_calls=100)   → executes

The first call is the probe. An agent cannot spend a hundred model calls without having stated the number — AGENTS.md §7 as a contract rather than as advice.

What never crosses

An MCP response goes into a model's context, and from there into transcripts and caches nobody controls. So the run tools return a verdict-only projection: the name, the identity, the status, the score, the threshold, the tolerance, the measured interval, and the metadata a suite disclosed.

Never the judge's reason — the judge quotes the output, so the reason is the output. Never the sentence explaining a suspension, never undisclosed metadata, never a case's inputs, and never a prompt or its digest unless the suite declares Disclosure(artifacts=True).