Add quickstart variant that launches with predefined credentials.

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsFragment.kt

@@ -65,6 +65,7 @@ import org.thoughtcrime.securesms.megaphone.Megaphones
 import org.thoughtcrime.securesms.payments.DataExportUtil
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
+import org.thoughtcrime.securesms.registration.data.QuickstartCredentialExporter
 import org.thoughtcrime.securesms.storage.StorageSyncHelper
 import org.thoughtcrime.securesms.util.ConversationUtil
 import org.thoughtcrime.securesms.util.adapter.mapping.MappingAdapter
@@ -164,6 +165,16 @@ class InternalSettingsFragment : DSLSettingsFragment(R.string.preferences__inter
         }
       )
 
+      if (BuildConfig.DEBUG) {
+        clickPref(
+          title = DSLSettingsText.from("Export quickstart credentials"),
+          summary = DSLSettingsText.from("Export registration credentials to a JSON file for quickstart builds."),
+          onClick = {
+            exportQuickstartCredentials()
+          }
+        )
+      }
+
       clickPref(
         title = DSLSettingsText.from("Unregister"),
         summary = DSLSettingsText.from("This will unregister your account without deleting it."),
@@ -1144,6 +1155,21 @@ class InternalSettingsFragment : DSLSettingsFragment(R.string.preferences__inter
     }
   }
 
+  private fun exportQuickstartCredentials() {
+    MaterialAlertDialogBuilder(requireContext())
+      .setTitle("Export quickstart credentials?")
+      .setMessage("This will export your account's private keys and credentials to an unencrypted file on disk. This is very dangerous! Only use it with test accounts.")
+      .setPositiveButton("Export") { _, _ ->
+        SimpleTask.run({
+          QuickstartCredentialExporter.export(requireContext())
+        }) { file ->
+          Toast.makeText(requireContext(), "Exported to ${file.absolutePath}", Toast.LENGTH_LONG).show()
+        }
+      }
+      .setNegativeButton(android.R.string.cancel, null)
+      .show()
+  }
+
   private fun promptUserForSentTimestamp() {
     val input = EditText(requireContext()).apply {
       inputType = android.text.InputType.TYPE_CLASS_NUMBER

app/src/main/java/org/thoughtcrime/securesms/registration/data/QuickstartCredentialExporter.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.registration.data
+
+import android.content.Context
+import android.util.Base64
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.signal.core.util.logging.Log
+import org.thoughtcrime.securesms.dependencies.AppDependencies
+import org.thoughtcrime.securesms.keyvalue.SignalStore
+import org.thoughtcrime.securesms.recipients.Recipient
+import java.io.File
+
+/**
+ * Exports current account registration credentials to a JSON file
+ * that can be used with quickstart builds.
+ */
+object QuickstartCredentialExporter {
+
+  private val TAG = Log.tag(QuickstartCredentialExporter::class.java)
+
+  private val json = Json { prettyPrint = true }
+
+  fun export(context: Context): File {
+    val aci = SignalStore.account.requireAci()
+    val pni = SignalStore.account.requirePni()
+    val e164 = SignalStore.account.requireE164()
+    val servicePassword = SignalStore.account.servicePassword ?: error("No service password")
+
+    val aciIdentityKeyPair = SignalStore.account.aciIdentityKey
+    val pniIdentityKeyPair = SignalStore.account.pniIdentityKey
+
+    val aciSignedPreKey = AppDependencies.protocolStore.aci().loadSignedPreKey(SignalStore.account.aciPreKeys.activeSignedPreKeyId)
+    val aciLastResortKyberPreKey = AppDependencies.protocolStore.aci().loadKyberPreKey(SignalStore.account.aciPreKeys.lastResortKyberPreKeyId)
+    val pniSignedPreKey = AppDependencies.protocolStore.pni().loadSignedPreKey(SignalStore.account.pniPreKeys.activeSignedPreKeyId)
+    val pniLastResortKyberPreKey = AppDependencies.protocolStore.pni().loadKyberPreKey(SignalStore.account.pniPreKeys.lastResortKyberPreKeyId)
+
+    val self = Recipient.self()
+    val profileKey = self.profileKey ?: error("No profile key")
+    val profileName = self.profileName
+
+    val credentials = QuickstartCredentials(
+      aci = aci.toString(),
+      pni = pni.toString(),
+      e164 = e164,
+      servicePassword = servicePassword,
+      aciIdentityKeyPair = Base64.encodeToString(aciIdentityKeyPair.serialize(), Base64.NO_WRAP),
+      pniIdentityKeyPair = Base64.encodeToString(pniIdentityKeyPair.serialize(), Base64.NO_WRAP),
+      aciSignedPreKey = Base64.encodeToString(aciSignedPreKey.serialize(), Base64.NO_WRAP),
+      aciLastResortKyberPreKey = Base64.encodeToString(aciLastResortKyberPreKey.serialize(), Base64.NO_WRAP),
+      pniSignedPreKey = Base64.encodeToString(pniSignedPreKey.serialize(), Base64.NO_WRAP),
+      pniLastResortKyberPreKey = Base64.encodeToString(pniLastResortKyberPreKey.serialize(), Base64.NO_WRAP),
+      profileKey = Base64.encodeToString(profileKey, Base64.NO_WRAP),
+      registrationId = SignalStore.account.registrationId,
+      pniRegistrationId = SignalStore.account.pniRegistrationId,
+      profileGivenName = profileName.givenName,
+      profileFamilyName = profileName.familyName
+    )
+
+    val outputDir = context.getExternalFilesDir(null) ?: error("No external files directory")
+    val outputFile = File(outputDir, "quickstart-credentials.json")
+    outputFile.writeText(json.encodeToString(credentials))
+
+    Log.i(TAG, "Exported quickstart credentials to ${outputFile.absolutePath}")
+    return outputFile
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/registration/data/QuickstartCredentials.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.registration.data
+
+import kotlinx.serialization.Serializable
+
+/**
+ * JSON-serializable bundle of registration credentials for quickstart builds.
+ * All byte arrays are base64-encoded strings.
+ */
+@Serializable
+data class QuickstartCredentials(
+  val version: Int = 1,
+  val aci: String,
+  val pni: String,
+  val e164: String,
+  val servicePassword: String,
+  val aciIdentityKeyPair: String,
+  val pniIdentityKeyPair: String,
+  val aciSignedPreKey: String,
+  val aciLastResortKyberPreKey: String,
+  val pniSignedPreKey: String,
+  val pniLastResortKyberPreKey: String,
+  val profileKey: String,
+  val registrationId: Int,
+  val pniRegistrationId: Int,
+  val profileGivenName: String,
+  val profileFamilyName: String
+)