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1	---
2	title: "Your App as the Assistant"
3	summary: "Stuff I learnt about Android's Assist Service and how you can make your app replace Gemini"
4	date: 2026-08-23
5	---
6
7	Since I worked on out of the app voice notes as mentioned in [previous writing,](/writings/android-bt-sco-handshake) that feature is powered by replacing your google assistant with the app so that android opens your app instead of Gemini.
8
9	Time to yap about how to make your app advertise itself as an Assist app so you can replace Gemini with something else just cus you can(smirking at iOS users stuck with Siri lmao).
10
11	Android actually lets you do this without any rooting or signature permission or whatever. You declare some services, user picks your app in settings, done. The docs on it are pretty thin though and when you get it wrong nothing tells you, your app just isn't in the list and you sit there wondering.
12
13	To make your app to show up under the "Digital Assistant menu"(idk what other phones call it but I have only Samsung in my household), you will need 3 things:
14
15	1. a `VoiceInteractionService`
16	2. a `VoiceInteractionSessionService`
17	3. a `RecognitionService`
18
19	Two of those barely do anything but you still need all three, I tried skipping.
20
21	Lets go over them one by one.
22
23	### 1. VoiceInteractionService
24
25	This is the actual service which marks your app as a digital assistant app. It's what android looks for when it builds that settings list. You don't need to override any method here, the class body is empty.
26
27	### 2. VoiceInteractionSessionService
28
29	This is the service the android will invoke when a new Voice Interaction Session is created, which basically means the user did the assistant gesture. You need to override its `onNewSession` method and it must return an instance of `VoiceInteractionSession`.
30
31	What is `VoiceInteractionSession`?
32	It represents an active voice interaction session and gets `Context` as param and has an `onShow` method. The
33
34	If you want to create your own ui, you override `onCreateContentView` method as this method is before `onShow`. And if you don't want any ui at all (my case, phone is in the pocket) you can call
35
36	There's also `onHandleAssist` and `onHandleScreenshot` if you want the contents of the current screen or a screenshot of it, that's how the "what's on my screen" stuff works. You only get them if you ask for it in the xml config and the user can turn it off in settings anyway. I didn't need either so I skipped them.
37
38	### 3. RecognitionService
39
40	Its a speech recognizer if you are building an actual assistant app. It has `onStartListening`, `onCancel` and
41
42	You can't skip it even if you never transcribe anything because the voice interaction xml makes you name a recognition service, it's not optional. Leave it out and your app just doesn't appear in the assistant list, no error, no log, nothing.
43
44	# Setup
45
46	I will call my app `NotGoogleAssistant` with bundle id of `fyi.procrastinator.not.google.assistant`
47
48	1. Extend `VoiceInteractionSession`
49
50	```kotlin
51
52	package fyi.procrastinator.not.google.assistant
53
54	import android.content.Context
55	import android.os.Bundle
56	import android.service.voice.VoiceInteractionSession
57
58	class NotGoogleAssistantVoiceInteractionSession(context:Context
59	VoiceInteractionSession(context){
60	override fun onShow(args:
61	super.onShow(args, showFlags)
62
63	/**
64	* Whatever you want to do when the Voice Interaction Session starts, do it here.
65	* Like playing audio cue or something or idk rickroll the user.
66	* Or you can always extend `Activity` and start that activity
67	*/
68
69	hide()
70	}
71
72
73	}
74	```
75
76	Two things about this class that got me:
77
78	`hide()` kills the session, so anything you kicked off in `onShow` and expected to keep running is on borrowed time. My recording takes a while so I moved it into a foreground service instead of keeping it in here.
79
80	And `onShow` is on the main thread. Block it and the gesture feels broken and the user blames your app, fairly.
81
82	2. Create `VoiceInteractionSessionService`
83
84	```kotlin
85	package fyi.procrastinator.not.google.assistant
86
87	import android.os.Bundle
88	import android.service.voice.VoiceInteractionSession
89	import android.service.voice.VoiceInteractionSessionService
90
91	class NotGoogleAssistantVoiceInteractionSessionService : VoiceInteractionSessionService
92	override fun onNewSession(args:
93	NotGoogleAssistantVoiceInteractionSession(this)
94	}
95
96	```
97
98	3. Extend `VoiceInteractionService`
99
100	```kotlin
101	package fyi.procrastinator.not.google.assistant
102
103	import android.service.voice.VoiceInteractionService
104
105	class NotGoogleAssistantVoiceInteractionService : VoiceInteractionService
106
107	```
108
109	4. Create a stub `RecognitionService`
110	Since this app does not really need voice recognition, just need to receive audio - I will add a stub `RecognitionService`
111
112	```kotlin
113
114	package fyi.procrastinator.not.google.assistant
115
116	import android.content.Intent
117	import android.speech.RecognitionService
118	import android.speech.SpeechRecognizer
119
120	class NotGoogleAssistantRecognitionService : RecognitionService
121	override fun onStartListening(recognizerIntent:
122	listener?.error(SpeechRecognizer.ERROR_CLIENT)
123	}
124
125	override fun onCancel(listener:
126
127	override fun onStopListening(listener:
128	}
129	```
130
131	Time to do the spicy android manifest stuff now.
132
133	```xml
134
135	<service
136	android:name="
137	android:exported="
138	android:permission="
139	<meta-data
140	android:name="
141	android:resource="
142	<intent-filter>
143	<action android:name
144	</intent-filter>
145	</service>
146	<service
147	android:name="
148	android:exported="
149	android:permission="
150	<service
151	android:name="
152	android:exported="
153	android:permission="
154	<intent-filter>
155	<action android:name
156	</intent-filter>
157	<meta-data
158	android:name="
159	android:resource="
160	</service>
161	```
162
163	All three need `android:exported="true"` because it's the system process binding to them, not you. The `android:permission` lines mean only something holding
164
165	Also the session service has no intent filter and that's correct, it gets reached through the xml config below and not through an action. I added one the first time because it looked wrong without one. It does nothing.
166
167	The resource xml:
168
169	1. `voice_interaction_service.xml`
170
171	```xml
172	<?xml version="1.0" encoding
173	<voice-interaction-service xmlns:android
174	android:sessionService="
175	android:recognitionService="
176	android:supportsAssist="
177	android:supportsLaunchVoiceAssistFromKeyguard=
178	```
179
180	Careful with those two class names, they're fully qualified strings so the compiler doesn't check them and neither does lint. If you typo one the build still succeeds and your app just doesn't show up in settings. I typed `NotGoogleAssitant` instead of `NotGoogleAssistant` and spent way too long on it before I noticed.
181
182	`supportsAssist="true"` is what makes you eligible to be the assistant instead of just some voice interaction thing, without it you won't show up in the picker.
183
184	`supportsLaunchVoiceAssistFromKeyguard="true"` lets the gesture work while the phone is locked, which I needed since the whole point was phone stays in pocket. Worth knowing it does not mean the phone is unlocked, so anything in there is running on the lock screen and file access can still be blocked until first unlock.
185
186	2. `recognition_service.xml`
187
188	```xml
189	<?xml version="1.0" encoding
190	<recognition-service xmlns:android
191	```
192
193	Empty tag, it just needs to exist so the meta-data has something to point at.
194
195	## Actually turning it on
196
197	Installing the app doesn't make you the assistant, the user has to pick you. On Samsung it's Settings > Apps > Default apps > Digital assistant app. On stock android it's Settings > Apps > Assistant & voice input. Other OEMs put it somewhere else obviously.
198
199	Instead of writing a 5 step guide in onboarding you can just send them there:
200
201	```kotlin
202	fun openAssistantSettings(context: Context
203	val intent = Intent(Settings.ACTION_VOICE_INPUT_SETTINGS)
204	.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
205	runCatching { context.startActivity(intent) }
206	.onFailure {
207	// some OEMs don't have this screen, fall back to the top level
208	context.startActivity(
209	Intent(Settings.ACTION_SETTINGS).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
210	)
211	}
212	}
213	```
214
215	Keep the `runCatching`, there's always some device where that screen doesn't exist.
216
217	And to check if you're currently the one selected, useful for showing a "set me as your assistant" prompt without annoying people who already did:
218
219	```kotlin
220	fun isDefaultAssistant(context: Context
221	val current = Settings.Secure.getString(context.contentResolver, "voice_interaction_service"
222	return current?.startsWith(context.packageName) == true
223	}
224	```
225
226	That key isn't public API, it's just a settings string that's been stable forever. Use it for ui, don't gate real logic on it. If it comes back null just show the prompt.
227
228	## Stuff that wasted my time
229
230	App not in the list at all. Almost always a typo'd class name in `voice_interaction_service.xml`. Otherwise a missing `
231
232	App in the list but selecting it does nothing. Session service isn't resolvable, or it's missing `BIND_VOICE_INTERACTION` so the system refuses to bind to it.