fix(connectors): wrap fetch transport failures in the typed error class

.changeset/connectors-fetch-transport-errors.md

@@ -0,0 +1,8 @@
+---
+'@gemstack/connector-github': patch
+'@gemstack/connector-google-drive': patch
+---
+
+Wrap transport failures in the connector's typed error class.
+
+The clients only wrapped non-2xx responses in `GitHubError`/`GoogleDriveError`; a `fetch()` rejection (DNS failure, timeout, offline) escaped as a raw `TypeError`. Each `fetch` call site now rethrows transport failures as the connector's error type with `status: 0`, so all failures surface through one typed class.

packages/connector-github/src/client.ts

@@ -32,7 +32,7 @@ export async function gh<T = unknown>(
       'no GitHub token available — set GITHUB_TOKEN or provide one via the mount `credentials` option',
     )
   }
-  const res = await fetch(`${API}${path}`, {
+  const res = await ghFetch(`${API}${path}`, {
     method,
     headers: {
       Authorization: `Bearer ${token}`,
@@ -42,11 +42,20 @@ export async function gh<T = unknown>(
       ...(body !== undefined ? { 'Content-Type': 'application/json' } : {}),
     },
     ...(body !== undefined ? { body: JSON.stringify(body) } : {}),
-  })
+  }, `${method} ${path}`)
   if (!res.ok) {
     const detail = await res.text().catch(() => '')
     throw new GitHubError(res.status, `${method} ${path} -> ${res.status} ${res.statusText}${detail ? `: ${detail}` : ''}`)
   }
   if (res.status === 204) return undefined as T
   return (await res.json()) as T
 }
+
+/** `fetch`, but a transport failure (DNS, timeout, offline) is rethrown as a `GitHubError` (`status: 0`) instead of a raw `TypeError`. */
+async function ghFetch(url: string, init: RequestInit, label: string): Promise<Response> {
+  try {
+    return await fetch(url, init)
+  } catch (cause) {
+    throw new GitHubError(0, `${label} -> network error: ${cause instanceof Error ? cause.message : String(cause)}`)
+  }
+}

packages/connector-github/src/index.test.ts

@@ -4,7 +4,7 @@ import assert from 'node:assert/strict'
 import { McpTestClient } from '@gemstack/mcp/testing'
 import type { McpToolResult } from '@gemstack/mcp'
 import { mountConnectors } from '@gemstack/connectors'
-import github from './index.js'
+import github, { GitHubError } from './index.js'
 
 const realFetch = globalThis.fetch
 
@@ -119,3 +119,13 @@ test('a non-2xx response surfaces status and detail', async () => {
     /404/,
   )
 })
+
+test('a transport failure surfaces as a GitHubError with status 0', async () => {
+  globalThis.fetch = (async () => {
+    throw new TypeError('fetch failed')
+  }) as unknown as typeof fetch
+  await assert.rejects(
+    () => client().callTool('github_get-repo', { owner: 'o', repo: 'r' }),
+    (err: unknown) => err instanceof GitHubError && err.status === 0 && /network error/.test(err.message),
+  )
+})

packages/connector-google-drive/src/client.ts

@@ -36,15 +36,15 @@ export async function gd<T = unknown>(
   body?: unknown,
 ): Promise<T> {
   const token = bearer(ctx)
-  const res = await fetch(`${API}${path}`, {
+  const res = await gdFetch(`${API}${path}`, {
     method,
     headers: {
       Authorization: `Bearer ${token}`,
       Accept: 'application/json',
       ...(body !== undefined ? { 'Content-Type': 'application/json' } : {}),
     },
     ...(body !== undefined ? { body: JSON.stringify(body) } : {}),
-  })
+  }, `${method} ${path}`)
   if (!res.ok) {
     const detail = await res.text().catch(() => '')
     throw new GoogleDriveError(
@@ -59,10 +59,19 @@ export async function gd<T = unknown>(
 /** GET a file's raw bytes as text (for `alt=media` downloads and Docs exports). */
 export async function gdText(ctx: ConnectorContext, path: string): Promise<string> {
   const token = bearer(ctx)
-  const res = await fetch(`${API}${path}`, { method: 'GET', headers: { Authorization: `Bearer ${token}` } })
+  const res = await gdFetch(`${API}${path}`, { method: 'GET', headers: { Authorization: `Bearer ${token}` } }, `GET ${path}`)
   if (!res.ok) {
     const detail = await res.text().catch(() => '')
     throw new GoogleDriveError(res.status, `GET ${path} -> ${res.status} ${res.statusText}${detail ? `: ${detail}` : ''}`)
   }
   return await res.text()
 }
+
+/** `fetch`, but a transport failure (DNS, timeout, offline) is rethrown as a `GoogleDriveError` (`status: 0`) instead of a raw `TypeError`. */
+async function gdFetch(url: string, init: RequestInit, label: string): Promise<Response> {
+  try {
+    return await fetch(url, init)
+  } catch (cause) {
+    throw new GoogleDriveError(0, `${label} -> network error: ${cause instanceof Error ? cause.message : String(cause)}`)
+  }
+}

packages/connector-google-drive/src/index.test.ts

@@ -4,7 +4,7 @@ import assert from 'node:assert/strict'
 import { McpTestClient } from '@gemstack/mcp/testing'
 import type { McpToolResult } from '@gemstack/mcp'
 import { mountConnectors } from '@gemstack/connectors'
-import drive from './index.js'
+import drive, { GoogleDriveError } from './index.js'
 
 const realFetch = globalThis.fetch
 
@@ -185,3 +185,13 @@ test('a non-2xx response surfaces status and detail', async () => {
   mockFetch(() => ({ status: 404, body: 'File not found' }))
   await assert.rejects(() => client().callTool('google-drive_get-file', { fileId: 'nope' }), /404/)
 })
+
+test('a transport failure surfaces as a GoogleDriveError with status 0', async () => {
+  globalThis.fetch = (async () => {
+    throw new TypeError('fetch failed')
+  }) as unknown as typeof fetch
+  await assert.rejects(
+    () => client().callTool('google-drive_get-file', { fileId: 'x' }),
+    (err: unknown) => err instanceof GoogleDriveError && err.status === 0 && /network error/.test(err.message),
+  )
+})