Public Streamable HTTP MCP

Give coding agents a safe CI-validation tool.

The engine is open source: star DiffCI/core or watch Releases and Discussions for support and benchmark updates.

DiffCI's public MCP server plans change-aware validation, interprets observation reports, and checks GitHub Actions isolation without credentials or repository access.

https://diffci.com/mcp

Install DiffCI View Core source and local-plugin docs

Connect in one command

Codex

Codex CLI and app

codex mcp add diffci --url https://diffci.com/mcp
codex mcp list

This uses Codex's supported remote HTTP configuration. Official Codex MCP docs →

Claude Code

Add an HTTP server

claude mcp add --transport http diffci https://diffci.com/mcp

Claude Code setup and verification →

Cursor

MCP JSON

{
  "mcpServers": {
    "diffci": {
      "url": "https://diffci.com/mcp"
    }
  }
}

Cursor rules, MCP, and troubleshooting →

VS Code

MCP JSON

{
  "servers": {
    "diffci": {
      "type": "http",
      "url": "https://diffci.com/mcp"
    }
  }
}

Three read-only tools

diffci_validation_plan returns a safe local command for change-aware checks, observation, initialization, or workflow verification.
diffci_interpret_report validates and summarizes a diffci.observation.v1 report, including affected-test counts, fallbacks, and the conservative next action.
diffci_verify_workflow_text checks one GitHub Actions YAML document for a dedicated, non-blocking, read-only observer job and immutable references.

The server also exposes the diffci_validate_change prompt and agent-policy/setup resources.

Example tasks

Plan a read-only validation command for this repository change.
Interpret this diffci.observation.v1 report and explain every fallback.
Check whether this observer workflow can block or influence required CI.

The public endpoint returns plans and interpretations. It cannot inspect a local checkout because the server has no access to the caller's filesystem; use the local stdio server when a tool needs to read Git history, dependency files, or test configuration.

Know the trust boundary

The HTTPS endpoint is stateless. It requires no account, stores no session, receives no repository content unless you explicitly pass a report or workflow to a tool, and never executes a command.

For tools that inspect a checkout or run tests, use the local stdio server from the repository directory:

npx -p "@diffci.com/diffci@latest" diffci-mcp

The local server exposes diffci_verify, diffci_verify_changed, diffci_check, diffci_init, and diffci_verify_workflow. The verification tools return a structured receipt and block unless the exact commit range or working-tree snapshot passes. Required project CI remains authoritative.

Connection	Can read checkout	Can run repository tests	Use for
Public HTTPS	No	No	Plans, report interpretation, and submitted workflow-text checks
Local stdio	Yes, from configured working directory	Only when the selected tool and mode permit it	Real Git diff analysis, affected tests, initialization, and paired validation

Troubleshoot the connection

Symptom	Check	Resolution
Server is absent from the client	Transport must be Streamable HTTP and the URL must end in `/mcp`.	Re-add the server, restart client discovery, and list configured MCP servers.
Local tool cannot find a repository	The stdio process inherited the wrong working directory.	Set `cwd` to the Git repository root and retry.
`REFUSED` result	Comparison commits, Node, Git, or repository shape did not meet eligibility.	Preserve the reason and run the repository's normal validation.
Workflow check reports dependency findings	The observer may be required by another job or lack `continue-on-error`.	Restore isolation before treating the job as non-blocking.

For a client-independent policy, start with CI validation for AI coding agents. For execution behavior and full-run triggers, use the affected-tests safety guide.

Machine-readable discovery

The Server Card and AI Catalog formats are emerging discovery conventions; the official MCP Registry entry remains the canonical directory listing.