diff --git a/src/commands/services.ts b/src/commands/services.ts
index e5bdf03..9717b7f 100644
--- a/src/commands/services.ts
+++ b/src/commands/services.ts
@@ -62,7 +62,7 @@ export function resolveComputeServiceId(services: Array<{ id: string; type: stri
 
 // ---- commands ----
 
-export type ServicesAddOpts = { branch?: string; public?: boolean; image?: string; port?: string; region?: string; alwaysOn?: boolean; volume?: string }
+export type ServicesAddOpts = { branch?: string; public?: boolean; image?: string; port?: string; region?: string; alwaysOn?: boolean; volume?: string; json?: boolean }
 
 // Map service-add options to the platform POST body. Pure, so it's unit-tested without a network
 // mock (mirrors deployRequestBody in deploy.ts). Validation (which options are valid for which
@@ -93,6 +93,7 @@ export async function servicesAdd(type: string, name: string, opts: ServicesAddO
   const branch = opts.branch ?? p.branch
   const res = await api.rawRequest('POST', `/projects/${p.projectId}/services`, servicesAddRequestBody(type, name, branch, opts))
   if (handleApproval(res)) return
+  if (opts.json) return printJson(res.body.service)
   const svc = res.body.service
   const access = svc.type === 'storage' ? `  [${svc.public ? 'public' : 'private'}]` : ''
   const img = svc.image ? `  running ${svc.image}${svc.port ? `:${svc.port}` : ''}` : ''
diff --git a/src/index.ts b/src/index.ts
index b2bcfc7..54f1201 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -127,8 +127,9 @@ svc.command('add [type] [name]').description('Provision a service on demand (ass
   .option('--port <n>', 'compute only: port the image listens on (default 8080)')
   .option('--always-on', 'compute only: create as always-on — never scales to zero (all plans; billing is actual usage either way)')
   .option('--volume <gi>', 'compute only: attach a persistent /data volume of this many whole Gi (also attachable later: `insta compute volume <name> --size <gi>`; any plan may attach at the default 1; larger sizes are paid and plan-capped). Volume services keep 1 machine and stop (cold wake) instead of suspend when idle')
+  .option('--json')
   .action(guard(async (type, name, o) => {
-    const a = await resolveServiceArgs(type, name, serviceArgsDeps())
+    const a = await resolveServiceArgs(type, name, serviceArgsDeps(o.json))
     return services.servicesAdd(a.type, a.name, o)
   }))
 svc.command('list').option('--json').option('--branch <branch>', 'branch (default: current)')
diff --git a/src/resolve-service.ts b/src/resolve-service.ts
index 90bdda2..61f2ffc 100644
--- a/src/resolve-service.ts
+++ b/src/resolve-service.ts
@@ -80,10 +80,11 @@ export async function promptServiceName(kind: ServiceKind): Promise<string> {
 }
 
 /** Prompts on a real terminal only — an agent's stdin is not one, and must never block. */
-export function serviceArgsDeps(): ServiceArgsDeps {
+export function serviceArgsDeps(json?: boolean): ServiceArgsDeps {
   return {
     selectType: promptServiceType,
     askName: promptServiceName,
-    tty: !!process.stdin.isTTY && !!process.stdout.isTTY,
+    // --json asked for parseable output, so a caller that happens to own a TTY still gets the error.
+    tty: !json && !!process.stdin.isTTY && !!process.stdout.isTTY,
   }
 }
diff --git a/test/resolve-service.test.ts b/test/resolve-service.test.ts
index f7cc02f..a4f17e1 100644
--- a/test/resolve-service.test.ts
+++ b/test/resolve-service.test.ts
@@ -8,6 +8,7 @@ import {
   SERVICE_KINDS,
   missingArgsMessage,
   resolveServiceArgs,
+  serviceArgsDeps,
   serviceKindLines,
   type ServiceArgsDeps,
 } from '../src/resolve-service.js'
@@ -60,6 +61,19 @@ test('unknown type: passed through for assertType to report, prompts untouched',
   expect(r).toEqual({ type: 'mysql', name: '' })
 })
 
+// --json promises parseable stdout; a prompt would corrupt it and hang an agent that owns a TTY.
+test('--json opts out of the prompts even on a terminal', () => {
+  const io = [process.stdin, process.stdout] as Array<{ isTTY?: boolean }>
+  const saved = io.map((s) => s.isTTY)
+  for (const s of io) s.isTTY = true
+  try {
+    expect(serviceArgsDeps().tty).toBe(true)
+    expect(serviceArgsDeps(true).tty).toBe(false)
+  } finally {
+    io.forEach((s, i) => { s.isTTY = saved[i] })
+  }
+})
+
 test('kind lines stay one per type and mention what each is', () => {
   const lines = serviceKindLines()
   expect(lines).toHaveLength(SERVICE_TYPES.length)