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`mcp.ts`

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2c2163eClaude	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";
	20	import { softAuth } from "../middleware/auth";
	21	import type { AuthEnv } from "../middleware/auth";
	22	import {
	23	routeMcpRequest,
	24	MCP_PROTOCOL_VERSION,
	25	MCP_SERVER_NAME,
	26	MCP_SERVER_VERSION,
	27	} from "../lib/mcp";
	28	import { defaultTools } from "../lib/mcp-tools";
0a6ebcdccanty labs	29	import { config } from "../lib/config";
2c2163eClaude	30
	31	const mcp = new Hono<AuthEnv>();
	32
	33	mcp.use("*", softAuth);
	34
0a6ebcdccanty labs	35	/**
	36	* MCP authorization challenge (MCP auth spec + RFC 9728).
	37	*
	38	* When an anonymous client attempts to CALL a tool, respond 401 with a
	39	* `WWW-Authenticate: Bearer resource_metadata="…"` header pointing at our
	40	* protected-resource metadata. This is the signal a remote connector
	41	* (claude.ai, Cursor, Copilot, …) follows to start the OAuth flow — so adding
	42	* `<host>/mcp` as a connector and invoking a tool prompts sign-in, then works
	43	* end to end.
	44	*
	45	* The handshake (initialize / tools/list / ping / notifications) stays open so
	46	* any client can introspect the server unauthenticated — only `tools/call`
	47	* requires an identity. Session cookie / PAT (`glc_`) / OAuth bearer (`glct_`)
	48	* all satisfy it, so token clients (.mcp.json, CLI, VS Code extension) are
	49	* unaffected. GET /mcp discovery also stays open.
	50	*/
	51	function authChallenge(c: Parameters<Parameters<typeof mcp.post>[1]>[0], id: unknown) {
	52	const rm = `${config.appBaseUrl}/.well-known/oauth-protected-resource`;
	53	c.header("WWW-Authenticate", `Bearer resource_metadata="${rm}"`);
	54	return c.json(
	55	{
	56	jsonrpc: "2.0",
	57	id: id ?? null,
	58	error: { code: -32001, message: "Authentication required" },
	59	},
	60	401
	61	);
	62	}
	63
	64	/** True when the JSON-RPC envelope (single or batch) invokes a tool. */
	65	function invokesTool(body: unknown): boolean {
	66	const isCall = (e: unknown): boolean =>
	67	!!e &&
	68	typeof e === "object" &&
	69	(e as { method?: unknown }).method === "tools/call";
	70	if (Array.isArray(body)) return body.some(isCall);
	71	return isCall(body);
	72	}
	73
2c2163eClaude	74	mcp.get("/mcp", (c) => {
	75	const tools = defaultTools();
	76	return c.json({
	77	protocolVersion: MCP_PROTOCOL_VERSION,
	78	serverInfo: { name: MCP_SERVER_NAME, version: MCP_SERVER_VERSION },
	79	transport: "http",
	80	toolCount: Object.keys(tools).length,
	81	docs:
	82	"POST /mcp with a JSON-RPC 2.0 envelope to call. See https://spec.modelcontextprotocol.io/",
	83	});
	84	});
	85
	86	mcp.post("/mcp", async (c) => {
	87	const user = c.get("user") ?? null;
0feb720Claude	88	// Scope derivation mirrors the API-auth middleware:
	89	// - OAuth bearer (glct_) → oauthScopes from middleware
	90	// - PAT (glc_) → oauthScopes from middleware
	91	// - Session cookie → full ["repo","user","admin"]
	92	// - Anonymous → []
	93	const oauthScopes = c.get("oauthScopes");
	94	let scopes: string[] = [];
	95	if (Array.isArray(oauthScopes)) {
	96	scopes = oauthScopes;
	97	} else if (user) {
	98	scopes = ["repo", "user", "admin"];
	99	}
	100	const ctx = { userId: user?.id ?? null, scopes };
2c2163eClaude	101	const tools = defaultTools();
	102
	103	let body: unknown;
	104	try {
	105	body = await c.req.json();
	106	} catch {
	107	return c.json(
	108	{
	109	jsonrpc: "2.0",
	110	id: null,
	111	error: { code: -32700, message: "Parse error" },
	112	},
	113	400
	114	);
	115	}
	116
0a6ebcdccanty labs	117	// Anonymous tool calls trigger the OAuth discovery challenge so connectors
	118	// sign in. The handshake (initialize/tools-list/ping/notifications) is left
	119	// open above so clients can introspect without a token.
	120	if (!user && invokesTool(body)) {
	121	const id =
	122	!Array.isArray(body) && body && typeof body === "object"
	123	? (body as { id?: unknown }).id ?? null
	124	: null;
	125	return authChallenge(c, id);
	126	}
	127
2c2163eClaude	128	if (Array.isArray(body)) {
	129	// Batched request — pass each through, drop nulls (notifications).
	130	const out = await Promise.all(
	131	body.map((entry) => routeMcpRequest(entry, { ctx, tools }))
	132	);
	133	const filtered = out.filter((r): r is NonNullable<typeof r> => r !== null);
	134	if (filtered.length === 0) return c.body(null, 204);
	135	return c.json(filtered);
	136	}
	137
	138	const result = await routeMcpRequest(body, { ctx, tools });
	139	if (result === null) {
	140	// Notification — no response body, 204.
	141	return c.body(null, 204);
	142	}
	143	return c.json(result);
	144	});
	145
	146	export default mcp;