blue/.blue/docs/rfcs/0013-git-forge-integration.impl.md

RFC 0013: Git Forge Integration

Status	Implemented
Date	2026-01-25
Source Spike	Git Forge Integration for Blue MCP

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Problem

Blue's PR tools (blue_pr_create, blue_pr_verify, blue_pr_merge) shell out to gh CLI, which only works with GitHub. Users with Forgejo/Gitea remotes can't create PRs via Blue MCP - the commands fail silently or with cryptic errors.

This blocks the workflow for anyone not using GitHub.

Goals

1. Native REST API integration for GitHub and Forgejo/Gitea
2. Auto-detect forge type from git remotes
3. Unified interface - same Blue tools work regardless of forge
4. No external CLI dependencies (gh, tea, etc.)

Non-Goals

• GitLab support (different API, future RFC)
• Issue management (PRs only for now)
• Full forge feature parity (minimal surface for Blue's workflow)

Proposal

1. Forge Trait

pub trait Forge: Send + Sync {
    fn create_pr(&self, opts: CreatePrOpts) -> Result<PullRequest, ForgeError>;
    fn get_pr(&self, owner: &str, repo: &str, number: u64) -> Result<PullRequest, ForgeError>;
    fn merge_pr(&self, owner: &str, repo: &str, number: u64, strategy: MergeStrategy) -> Result<(), ForgeError>;
    fn pr_is_merged(&self, owner: &str, repo: &str, number: u64) -> Result<bool, ForgeError>;
}

pub struct CreatePrOpts {
    pub owner: String,
    pub repo: String,
    pub head: String,      // branch with changes
    pub base: String,      // target branch
    pub title: String,
    pub body: Option<String>,
    pub draft: bool,
}

pub enum MergeStrategy {
    Merge,
    Squash,
    Rebase,
}

2. Implementations

GitHubForge

• Endpoint: https://api.github.com/repos/{owner}/{repo}/pulls
• Auth: Authorization: Bearer {GITHUB_TOKEN}

ForgejoForge (works with Gitea too)

• Endpoint: https://{host}/api/v1/repos/{owner}/{repo}/pulls
• Auth: Authorization: token {FORGEJO_TOKEN}

3. Auto-Detection

Parse git remotes to detect forge type:

fn detect_forge(remote_url: &str) -> ForgeType {
    let url = parse_git_url(remote_url);

    match url.host {
        "github.com" => ForgeType::GitHub,
        "codeberg.org" => ForgeType::Forgejo,
        host if host.contains("gitea") => ForgeType::Forgejo,
        host if host.contains("forgejo") => ForgeType::Forgejo,
        _ => {
            // Probe /api/v1/version - Forgejo/Gitea respond, GitHub doesn't
            if probe_forgejo_api(&url.host) {
                ForgeType::Forgejo
            } else {
                ForgeType::GitHub // fallback
            }
        }
    }
}

Cache detected type in .blue/config.yaml:

forge:
  type: forgejo
  host: git.beyondtheuniverse.superviber.com
  owner: superviber
  repo: blue

4. Token Resolution

Environment variables with fallback chain:

Forge	Variables (in order)
GitHub	GITHUB_TOKEN, GH_TOKEN
Forgejo	FORGEJO_TOKEN, GITEA_TOKEN

5. Updated MCP Tools

blue_pr_create changes:

• Remove gh CLI dependency
• Use detected forge's REST API
• Return PR URL directly

Response includes forge info:

{
  "status": "success",
  "pr_url": "https://git.example.com/owner/repo/pulls/42",
  "pr_number": 42,
  "forge": "forgejo"
}

6. New Module Structure

crates/blue-core/src/
├── forge/
│   ├── mod.rs          # Forge trait, ForgeType, detection
│   ├── github.rs       # GitHub implementation
│   ├── forgejo.rs      # Forgejo/Gitea implementation
│   └── git_url.rs      # URL parsing utilities

Alternatives Considered

A. Keep shelling out to CLIs

Rejected: Requires users to install and configure gh/tea. Fragile, hard to get structured output.

B. Use existing MCP servers (forgejo-mcp, github-mcp)

Rejected: Adds external dependencies. forgejo-mcp doesn't support PR creation. Better to own the integration.

C. GitLab support in this RFC

Deferred: Different API patterns. Keep scope focused. Future RFC.

Implementation Plan

1. Add forge module to blue-core with trait and types
2. Implement ForgejoForge with REST client
3. Implement GitHubForge with REST client
4. Add auto-detection logic with caching
5. Update handle_pr_create to use forge
6. Update handle_pr_verify and handle_pr_merge
7. Remove gh CLI dependency

Test Plan

• ForgejoForge creates PR via REST API
• GitHubForge creates PR via REST API
• Auto-detection identifies github.com as GitHub
• Auto-detection identifies codeberg.org as Forgejo
• Auto-detection probes unknown hosts
• Token resolution finds FORGEJO_TOKEN
• Token resolution finds GITHUB_TOKEN
• blue_pr_create works with Forgejo remote
• blue_pr_create works with GitHub remote
• PR merge works with both forges

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"One interface, many forges. The abstraction serves the worker."

— Blue