Github Rag

Language: English | Japanese

GitHub issue, pull request, release, and documentation search for MCP clients on Cloudflare Workers.

github-rag-mcp is designed as a shared working memory over GitHub. It does not try to remember every conversation. Instead, it helps agents recover the current project state from durable artifacts that humans can also inspect: issues, pull requests, docs, and releases.

It is the search-oriented counterpart to github-webhook-mcp. Together they provide both:

• push-based awareness of what just happened
• hybrid retrieval (dense + sparse) of the state that matters for the next step

Memory Model

The project treats GitHub as a visible state store for AI work.

• Do not aim for complete memory.
• Do not add unnecessary material.
• Do not omit information required for the next correct action.
• Preserve state in human-readable, reviewable artifacts.
• Recover context by search instead of replaying full chat history.

For a fuller explanation, see:

• docs/1-memory-philosophy.md
• docs/1-memory-philosophy.ja.md

Architecture

GitHub webhooks + GitHub API
            |
            v
     Cloudflare Worker
     + MCP HTTP surface
     + webhook receiver
     + cron poller (fallback)
     + embedding pipeline
     + hybrid retrieval (dense + sparse + RRF fusion + cross-encoder rerank)
            |
            +--> Vectorize (dense semantic index)
            +--> D1 FTS5 (BM25 sparse index)
            +--> Durable Object / SQLite (structured state store)
            +--> Workers AI BGE-M3 (embeddings)
            +--> Workers AI bge-reranker-base (cross-encoder rerank)

• The MCP surface exposes hybrid retrieval and context tools to AI clients.
• The webhook receiver updates memory in near real time when GitHub changes.
• The cron poller repairs missed updates and supports backfill.
• Vectorize stores semantic embeddings for the dense side of retrieval.
• D1 FTS5 stores the BM25 sparse index for exact-term and identifier queries.
• The cross-encoder reranker re-scores fused candidates as the 3rd tier (toggleable per query).
• Durable Object keeps structured state for fast lookups and activity views.

Why GitHub

GitHub already contains the artifacts that matter for software work:

• issues for requirements and open decisions
• pull requests for implementation history and review state
• documentation for stabilized understanding
• releases for shipped checkpoints

Using those artifacts as memory makes handoff and auditing easier than keeping state inside a private chat transcript.

Installation

See:

• docs/installation.md
• docs/installation.ja.md

Requirements

See:

• docs/0-requirements.md
• docs/0-requirements.ja.md

MCP Tools

This MCP server exposes a single consolidated tool. All retrieval modes — semantic search, time-ordered activity scan, and inline doc content fetch — are reached through search via its parameter set. Earlier builds split these across get_issue_context, get_doc_content, and list_recent_activity; those tools have been removed and their use cases now fold into the parameters below.

search

Unified search across GitHub issues, pull requests, releases, repository documentation, GitHub Wiki pages, commit diffs, and comment / review surfaces (top-level comments on issues and PRs, PR review bodies, and PR inline review comments).

Three modes are selected by the combination of query and sort:

1. Hybrid semantic search (default) — dense BGE-M3 over Vectorize + sparse BM25 over D1 FTS5, fused via Reciprocal Rank Fusion (RRF, k=60), then re-scored with the @cf/baai/bge-reranker-base cross-encoder. Pass a natural-language query.
2. Time-ordered activity scan — omit or leave query empty and set sort to "updated_desc" or "created_desc". Optionally narrow with since / until to list recent activity across every type. This subsumes the previous list_recent_activity tool.
3. Doc / wiki content fetch — set include_content: true. For result rows whose type is "doc", the raw file content is fetched from the GitHub contents API; for type: "wiki_doc" rows, the raw markup is fetched from raw.githubusercontent.com/wiki/. Both are inlined as a content field. Capped at the first few rows of each type to bound API fan-out. This subsumes the previous get_doc_content tool.

Structured filters (repo, state, labels, milestone, assignee, type) apply in every mode.

Bot-authored comments (sender.login ending in [bot]) and comments shorter than 10 characters (trimmed) are filtered out at ingest time so noise such as LGTM, +1, or CI chatter does not dilute the retrieval surface.

Parameters

Name	Type	Description
query	string (optional)	Natural-language query. Omit or empty = scan mode.
repo	string	Filter by repository (owner/repo).
state	"open" | "closed" | "all"	Filter by state (default all).
labels	string[]	Filter by label names (AND).
milestone	string	Filter by milestone title.
assignee	string	Filter by assignee login.
type	see below	Filter by type (default all).
top_k	number	Max results (default 10, max 50).
fusion	"rrf" | "dense_only" | "sparse_only"	Fusion strategy (default rrf). Ignored in scan mode.
rerank	boolean	Cross-encoder rerank (default true). Ignored in scan mode.
sort	"relevance" | "updated_desc" | "created_desc"	Result ordering. Default relevance with a query, updated_desc without. Time sorts override ranker score.
since	ISO 8601 string	Keep only results with updated_at >= since.
until	ISO 8601 string	Keep only results with updated_at < until.
include_content	boolean	Inline raw content on top doc results (default false).

type values

Value	Surface
"issue"	GitHub issues (title + body).
"pull_request"	Pull request descriptions (title + body).
"release"	Release notes (name + body).
"doc"	Markdown documentation files.
"diff"	Per-file commit diffs (commit message + file path + patch).
"issue_comment"	Top-level comments on issues and PRs.
"pr_review"	PR review bodies (APPROVED / CHANGES_REQUESTED / COMMENTED).
"pr_review_comment"	PR inline review comments (per-line diff comments).
"all"	Union of every type above (default).

Examples

Semantic search for a specific topic:

{
  "query": "rerank latency budget",
  "repo": "Liplus-Project/github-rag-mcp",
  "top_k": 5
}

Time-ordered activity scan across the last 24 hours:

{
  "sort": "updated_desc",
  "since": "2026-04-22T00:00:00Z",
  "top_k": 20
}

Semantic search with inline doc content on the top doc hits:

{
  "query": "memory philosophy",
  "type": "doc",
  "include_content": true,
  "top_k": 3
}

Search past PR review judgments about a specific topic:

{
  "query": "rerank threshold tuning",
  "type": "pr_review",
  "top_k": 5
}

Repository Structure

src/
  index.ts
  mcp.ts
  oauth.ts
  webhook.ts
  pipeline.ts
  github-ip.ts
  poller.ts
  store.ts
  types.ts
docs/
  0-requirements.md
  0-requirements.ja.md
  1-memory-philosophy.md
  1-memory-philosophy.ja.md
  installation.md
  installation.ja.md
mcp-server/
wrangler.toml

Related

• Liplus-Project/github-webhook-mcp
• Liplus-Project/liplus-language