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mcp.ts
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| 2c2163e | 1 | /** |
| 2 | * Model Context Protocol HTTP transport. | |
| 3 | * | |
| 4 | * POST /mcp — JSON-RPC 2.0 requests; body is a single request | |
| 5 | * or an array (batch). Response shape mirrors. | |
| 6 | * GET /mcp — Lightweight discovery: returns server info + | |
| 7 | * protocol version + tool count. | |
| 8 | * | |
| 9 | * Auth: softAuth — `userId` in the McpContext is the cookie/PAT/OAuth | |
| 10 | * user when present, null otherwise. v1 tools are read-only and public- | |
| 11 | * only, so anonymous works; write tools (v2) will require requireAuth + | |
| 12 | * write-access on the target repo. | |
| 13 | * | |
| 14 | * Streamable-HTTP-mode is the recommended MCP transport for stateless | |
| 15 | * cloud servers. We don't emit server-sent notifications yet, so the | |
| 16 | * route is plain JSON in / JSON out. | |
| 17 | */ | |
| 18 | ||
| 19 | import { Hono } from "hono"; | |
| 8ed88f2 | 20 | import type { Context } from "hono"; |
| 2c2163e | 21 | import { softAuth } from "../middleware/auth"; |
| 22 | import type { AuthEnv } from "../middleware/auth"; | |
| 23 | import { | |
| 24 | routeMcpRequest, | |
| 25 | MCP_PROTOCOL_VERSION, | |
| 26 | MCP_SERVER_NAME, | |
| 27 | MCP_SERVER_VERSION, | |
| 28 | } from "../lib/mcp"; | |
| 3a15219 | 29 | import { defaultTools, mcpListResources, mcpReadResource } from "../lib/mcp-tools"; |
| 30 | ||
| 31 | // Resource provider: makes repos browsable in clients (Claude Desktop's | |
| 32 | // resource/attachment picker). ctx flows through so private repos only show | |
| 33 | // for their owner. | |
| 34 | const mcpResources = { | |
| 35 | list: (ctx: any) => mcpListResources(ctx), | |
| 36 | read: (uri: string, ctx: any) => mcpReadResource(uri, ctx), | |
| 37 | }; | |
| 0a6ebcd | 38 | import { config } from "../lib/config"; |
| 2c2163e | 39 | |
| 40 | const mcp = new Hono<AuthEnv>(); | |
| 41 | ||
| 42 | mcp.use("*", softAuth); | |
| 43 | ||
| 0a6ebcd | 44 | /** |
| 45 | * MCP authorization challenge (MCP auth spec + RFC 9728). | |
| 46 | * | |
| 47 | * When an anonymous client attempts to CALL a tool, respond 401 with a | |
| 48 | * `WWW-Authenticate: Bearer resource_metadata="…"` header pointing at our | |
| 49 | * protected-resource metadata. This is the signal a remote connector | |
| 50 | * (claude.ai, Cursor, Copilot, …) follows to start the OAuth flow — so adding | |
| 51 | * `<host>/mcp` as a connector and invoking a tool prompts sign-in, then works | |
| 52 | * end to end. | |
| 53 | * | |
| 54 | * The handshake (initialize / tools/list / ping / notifications) stays open so | |
| 55 | * any client can introspect the server unauthenticated — only `tools/call` | |
| 56 | * requires an identity. Session cookie / PAT (`glc_`) / OAuth bearer (`glct_`) | |
| 57 | * all satisfy it, so token clients (.mcp.json, CLI, VS Code extension) are | |
| 58 | * unaffected. GET /mcp discovery also stays open. | |
| 59 | */ | |
| b5a7bb3 | 60 | function authChallenge( |
| 8ed88f2 | 61 | c: Context<AuthEnv>, |
| b5a7bb3 | 62 | id: unknown, |
| 63 | opts?: { invalidToken?: boolean } | |
| 64 | ) { | |
| 0a6ebcd | 65 | const rm = `${config.appBaseUrl}/.well-known/oauth-protected-resource`; |
| b5a7bb3 | 66 | if (opts?.invalidToken) { |
| 67 | // RFC 6750 §3.1: `error="invalid_token"` tells the client its token is | |
| 68 | // expired/revoked, so it runs the refresh_token grant (or re-authorizes) | |
| 69 | // instead of replaying the dead token forever. The anonymous challenge | |
| 70 | // below deliberately omits `error=` — its absence means "no credentials | |
| 71 | // at all, start first-time auth". | |
| 72 | c.header( | |
| 73 | "WWW-Authenticate", | |
| 74 | `Bearer error="invalid_token", error_description="The access token is expired or invalid", resource_metadata="${rm}"` | |
| 75 | ); | |
| 76 | return c.json( | |
| 77 | { | |
| 78 | jsonrpc: "2.0", | |
| 79 | id: id ?? null, | |
| 80 | error: { | |
| 81 | code: -32001, | |
| 82 | message: "Invalid or expired access token — refresh or re-authorize", | |
| 83 | }, | |
| 84 | }, | |
| 85 | 401 | |
| 86 | ); | |
| 87 | } | |
| 0a6ebcd | 88 | c.header("WWW-Authenticate", `Bearer resource_metadata="${rm}"`); |
| 89 | return c.json( | |
| 90 | { | |
| 91 | jsonrpc: "2.0", | |
| 92 | id: id ?? null, | |
| 93 | error: { code: -32001, message: "Authentication required" }, | |
| 94 | }, | |
| 95 | 401 | |
| 96 | ); | |
| 97 | } | |
| 98 | ||
| b5a7bb3 | 99 | /** Extract the JSON-RPC id from a single (non-batch) envelope, else null. */ |
| 100 | function idOf(body: unknown): unknown { | |
| 101 | return !Array.isArray(body) && body && typeof body === "object" | |
| 102 | ? (body as { id?: unknown }).id ?? null | |
| 103 | : null; | |
| 104 | } | |
| 105 | ||
| 0a6ebcd | 106 | /** True when the JSON-RPC envelope (single or batch) invokes a tool. */ |
| 107 | function invokesTool(body: unknown): boolean { | |
| 108 | const isCall = (e: unknown): boolean => | |
| 109 | !!e && | |
| 110 | typeof e === "object" && | |
| 111 | (e as { method?: unknown }).method === "tools/call"; | |
| 112 | if (Array.isArray(body)) return body.some(isCall); | |
| 113 | return isCall(body); | |
| 114 | } | |
| 115 | ||
| 2c2163e | 116 | mcp.get("/mcp", (c) => { |
| b5a7bb3 | 117 | // A dead bearer on discovery gets the invalid_token signal too (plain JSON |
| 118 | // — this endpoint is not JSON-RPC). Anonymous discovery stays open. | |
| 119 | if (c.get("bearerInvalid")) { | |
| 120 | const rm = `${config.appBaseUrl}/.well-known/oauth-protected-resource`; | |
| 121 | c.header( | |
| 122 | "WWW-Authenticate", | |
| 123 | `Bearer error="invalid_token", error_description="The access token is expired or invalid", resource_metadata="${rm}"` | |
| 124 | ); | |
| 125 | return c.json( | |
| 126 | { error: "invalid_token", message: "Access token expired or invalid — refresh or re-authorize" }, | |
| 127 | 401 | |
| 128 | ); | |
| 129 | } | |
| 2c2163e | 130 | const tools = defaultTools(); |
| 131 | return c.json({ | |
| 132 | protocolVersion: MCP_PROTOCOL_VERSION, | |
| 133 | serverInfo: { name: MCP_SERVER_NAME, version: MCP_SERVER_VERSION }, | |
| 134 | transport: "http", | |
| 135 | toolCount: Object.keys(tools).length, | |
| 136 | docs: | |
| 137 | "POST /mcp with a JSON-RPC 2.0 envelope to call. See https://spec.modelcontextprotocol.io/", | |
| 138 | }); | |
| 139 | }); | |
| 140 | ||
| 141 | mcp.post("/mcp", async (c) => { | |
| 142 | const user = c.get("user") ?? null; | |
| 0feb720 | 143 | // Scope derivation mirrors the API-auth middleware: |
| 144 | // - OAuth bearer (glct_) → oauthScopes from middleware | |
| 145 | // - PAT (glc_) → oauthScopes from middleware | |
| 146 | // - Session cookie → full ["repo","user","admin"] | |
| 147 | // - Anonymous → [] | |
| 148 | const oauthScopes = c.get("oauthScopes"); | |
| 149 | let scopes: string[] = []; | |
| 150 | if (Array.isArray(oauthScopes)) { | |
| 151 | scopes = oauthScopes; | |
| 152 | } else if (user) { | |
| 153 | scopes = ["repo", "user", "admin"]; | |
| 154 | } | |
| 155 | const ctx = { userId: user?.id ?? null, scopes }; | |
| 2c2163e | 156 | const tools = defaultTools(); |
| 157 | ||
| 158 | let body: unknown; | |
| 159 | try { | |
| 160 | body = await c.req.json(); | |
| 161 | } catch { | |
| 162 | return c.json( | |
| 163 | { | |
| 164 | jsonrpc: "2.0", | |
| 165 | id: null, | |
| 166 | error: { code: -32700, message: "Parse error" }, | |
| 167 | }, | |
| 168 | 400 | |
| 169 | ); | |
| 170 | } | |
| 171 | ||
| b5a7bb3 | 172 | // A bearer token was presented but rejected (expired/revoked/unknown). |
| 173 | // Challenge EVERY method — including initialize — with invalid_token, so a | |
| 174 | // client reconnecting on a dead token fails loudly and refreshes or | |
| 175 | // re-authorizes, instead of getting a false-healthy handshake and then | |
| 176 | // looping on tools/call. Truly-anonymous handshake stays open below. | |
| 177 | if (c.get("bearerInvalid")) { | |
| 178 | return authChallenge(c, idOf(body), { invalidToken: true }); | |
| 179 | } | |
| 180 | ||
| 0a6ebcd | 181 | // Anonymous tool calls trigger the OAuth discovery challenge so connectors |
| 182 | // sign in. The handshake (initialize/tools-list/ping/notifications) is left | |
| 183 | // open above so clients can introspect without a token. | |
| 184 | if (!user && invokesTool(body)) { | |
| b5a7bb3 | 185 | return authChallenge(c, idOf(body)); |
| 0a6ebcd | 186 | } |
| 187 | ||
| 2c2163e | 188 | if (Array.isArray(body)) { |
| 189 | // Batched request — pass each through, drop nulls (notifications). | |
| 190 | const out = await Promise.all( | |
| 3a15219 | 191 | body.map((entry) => routeMcpRequest(entry, { ctx, tools, resources: mcpResources })) |
| 2c2163e | 192 | ); |
| 193 | const filtered = out.filter((r): r is NonNullable<typeof r> => r !== null); | |
| 194 | if (filtered.length === 0) return c.body(null, 204); | |
| 195 | return c.json(filtered); | |
| 196 | } | |
| 197 | ||
| 3a15219 | 198 | const result = await routeMcpRequest(body, { ctx, tools, resources: mcpResources }); |
| 2c2163e | 199 | if (result === null) { |
| 200 | // Notification — no response body, 204. | |
| 201 | return c.body(null, 204); | |
| 202 | } | |
| 203 | return c.json(result); | |
| 204 | }); | |
| 205 | ||
| 206 | export default mcp; |