Rewrites NIP-55 to start offering better error handling.

quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/core/Event.kt

@@ -20,6 +20,7 @@
  */
 package com.vitorpamplona.quartz.nip01Core.core
 
+import android.util.Log
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.nip01Core.jackson.EventManualSerializer
 import com.vitorpamplona.quartz.nip01Core.jackson.JsonMapper
@@ -58,6 +59,14 @@ open class Event(
     companion object {
         fun fromJson(json: String): Event = JsonMapper.fromJson(json)
 
+        fun fromJsonOrNull(json: String) =
+            try {
+                fromJson(json)
+            } catch (e: Exception) {
+                Log.e("Event", "Unable to parse event JSON: $json", e)
+                null
+            }
+
         fun build(
             kind: Int,
             content: String = "",

quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/jackson/JsonMapper.kt

@@ -35,9 +35,13 @@ import com.vitorpamplona.quartz.nip47WalletConnect.Request
 import com.vitorpamplona.quartz.nip47WalletConnect.RequestDeserializer
 import com.vitorpamplona.quartz.nip47WalletConnect.Response
 import com.vitorpamplona.quartz.nip47WalletConnect.ResponseDeserializer
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.Permission
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.PermissionDeserializer
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.PermissionSerializer
 import com.vitorpamplona.quartz.nip59Giftwrap.rumors.Rumor
 import com.vitorpamplona.quartz.nip59Giftwrap.rumors.RumorDeserializer
 import com.vitorpamplona.quartz.nip59Giftwrap.rumors.RumorSerializer
+import kotlin.jvm.java
 
 class JsonMapper {
     companion object Companion {
@@ -60,7 +64,9 @@ class JsonMapper {
                         .addSerializer(BunkerRequest::class.java, BunkerRequest.BunkerRequestSerializer())
                         .addDeserializer(BunkerRequest::class.java, BunkerRequest.BunkerRequestDeserializer())
                         .addSerializer(BunkerResponse::class.java, BunkerResponse.BunkerResponseSerializer())
-                        .addDeserializer(BunkerResponse::class.java, BunkerResponse.BunkerResponseDeserializer()),
+                        .addDeserializer(BunkerResponse::class.java, BunkerResponse.BunkerResponseDeserializer())
+                        .addDeserializer(Permission::class.java, PermissionDeserializer())
+                        .addSerializer(Permission::class.java, PermissionSerializer()),
                 )
 
         fun fromJson(json: String): Event = mapper.readValue(json, Event::class.java)

quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/signers/NostrSigner.kt

@@ -47,25 +47,25 @@ abstract class NostrSigner(
     )
 
     abstract fun nip04Encrypt(
-        decryptedContent: String,
+        plaintext: String,
         toPublicKey: HexKey,
         onReady: (String) -> Unit,
     )
 
     abstract fun nip04Decrypt(
-        encryptedContent: String,
+        ciphertext: String,
         fromPublicKey: HexKey,
         onReady: (String) -> Unit,
     )
 
     abstract fun nip44Encrypt(
-        decryptedContent: String,
+        plaintext: String,
         toPublicKey: HexKey,
         onReady: (String) -> Unit,
     )
 
     abstract fun nip44Decrypt(
-        encryptedContent: String,
+        ciphertext: String,
         fromPublicKey: HexKey,
         onReady: (String) -> Unit,
     )

quartz/src/main/java/com/vitorpamplona/quartz/nip01Core/signers/NostrSignerInternal.kt

@@ -45,35 +45,35 @@ class NostrSignerInternal(
     }
 
     override fun nip04Encrypt(
-        decryptedContent: String,
+        plaintext: String,
         toPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        signerSync.nip04Encrypt(decryptedContent, toPublicKey)?.let { onReady(it) }
+        signerSync.nip04Encrypt(plaintext, toPublicKey)?.let { onReady(it) }
     }
 
     override fun nip04Decrypt(
-        encryptedContent: String,
+        ciphertext: String,
         fromPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        signerSync.nip04Decrypt(encryptedContent, fromPublicKey)?.let { onReady(it) }
+        signerSync.nip04Decrypt(ciphertext, fromPublicKey)?.let { onReady(it) }
     }
 
     override fun nip44Encrypt(
-        decryptedContent: String,
+        plaintext: String,
         toPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        signerSync.nip44Encrypt(decryptedContent, toPublicKey)?.let { onReady(it) }
+        signerSync.nip44Encrypt(plaintext, toPublicKey)?.let { onReady(it) }
     }
 
     override fun nip44Decrypt(
-        encryptedContent: String,
+        ciphertext: String,
         fromPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        signerSync.nip44Decrypt(encryptedContent, fromPublicKey)?.let { onReady(it) }
+        signerSync.nip44Decrypt(ciphertext, fromPublicKey)?.let { onReady(it) }
     }
 
     override fun decryptZapEvent(

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/ExternalSignerLauncher.kt

@@ -1,438 +0,0 @@
-/**
- * Copyright (c) 2025 Vitor Pamplona
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of
- * this software and associated documentation files (the "Software"), to deal in
- * the Software without restriction, including without limitation the rights to use,
- * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
- * Software, and to permit persons to whom the Software is furnished to do so,
- * subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
- * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
- * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
- * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-package com.vitorpamplona.quartz.nip55AndroidSigner
-
-import android.content.ContentResolver
-import android.content.Intent
-import android.util.Log
-import android.util.LruCache
-import androidx.core.net.toUri
-import com.fasterxml.jackson.annotation.JsonProperty
-import com.fasterxml.jackson.core.JsonParser
-import com.fasterxml.jackson.databind.DeserializationContext
-import com.fasterxml.jackson.databind.DeserializationFeature
-import com.fasterxml.jackson.databind.JsonNode
-import com.fasterxml.jackson.databind.ObjectMapper
-import com.fasterxml.jackson.databind.deser.std.StdDeserializer
-import com.fasterxml.jackson.databind.module.SimpleModule
-import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
-import com.fasterxml.jackson.module.kotlin.readValue
-import com.vitorpamplona.quartz.nip01Core.core.Event
-import com.vitorpamplona.quartz.nip01Core.core.HexKey
-import com.vitorpamplona.quartz.nip57Zaps.LnZapRequestEvent
-
-enum class SignerType {
-    SIGN_EVENT,
-    NIP04_ENCRYPT,
-    NIP04_DECRYPT,
-    NIP44_ENCRYPT,
-    NIP44_DECRYPT,
-    GET_PUBLIC_KEY,
-    DECRYPT_ZAP_EVENT,
-    DERIVE_KEY,
-}
-
-class Permission(
-    val type: String,
-    val kind: Int? = null,
-) {
-    fun toJson(): String = "{\"type\":\"${type}\",\"kind\":$kind}"
-}
-
-class Result(
-    @JsonProperty("package") val `package`: String?,
-    @JsonProperty("signature") val signature: String?,
-    @JsonProperty("result") val result: String?,
-    @JsonProperty("id") val id: String?,
-) {
-    companion object {
-        val mapper: ObjectMapper =
-            jacksonObjectMapper()
-                .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
-                .registerModule(
-                    SimpleModule().addDeserializer(Result::class.java, ResultDeserializer()),
-                )
-
-        private class ResultDeserializer : StdDeserializer<Result>(Result::class.java) {
-            override fun deserialize(
-                jp: JsonParser,
-                ctxt: DeserializationContext,
-            ): Result {
-                val jsonObject: JsonNode = jp.codec.readTree(jp)
-                return Result(
-                    jsonObject.get("package").asText().intern(),
-                    jsonObject.get("signature")?.asText()?.intern(),
-                    jsonObject.get("result")?.asText()?.intern(),
-                    jsonObject.get("id").asText().intern(),
-                )
-            }
-        }
-
-        fun fromJson(json: String): Result = mapper.readValue(json, Result::class.java)
-
-        /**
-         * Parses the json with a string of events to an Array of Event objects.
-         */
-        fun fromJsonArray(json: String): Array<Result> = mapper.readValue(json)
-    }
-}
-
-class ExternalSignerLauncher(
-    private val currentUserPubKeyHex: String,
-    val signerPackageName: String,
-) {
-    private val contentCache = LruCache<String, (String) -> Unit>(50)
-
-    private var signerAppLauncher: ((Intent) -> Unit)? = null
-    private var contentResolver: (() -> ContentResolver)? = null
-
-    /** Call this function when the launcher becomes available on activity, fragment or compose */
-    fun registerLauncher(
-        launcher: ((Intent) -> Unit),
-        contentResolver: (() -> ContentResolver),
-    ) {
-        this.signerAppLauncher = launcher
-        this.contentResolver = contentResolver
-    }
-
-    /** Call this function when the activity is destroyed or is about to be replaced. */
-    fun clearLauncherIf(launcher: ((Intent) -> Unit)) {
-        if (signerAppLauncher == launcher) {
-            this.signerAppLauncher = null
-            this.contentResolver = null
-        }
-    }
-
-    fun newResult(data: Intent) {
-        val results = data.getStringExtra("results")
-        if (results != null) {
-            val localResults: Array<Result> = Result.fromJsonArray(results)
-            localResults.forEach {
-                val signature = it.result ?: it.signature ?: ""
-                val packageName = it.`package`?.let { "-$it" } ?: ""
-                val id = it.id ?: ""
-                if (id.isNotBlank()) {
-                    val result = if (packageName.isNotBlank()) "$signature$packageName" else signature
-                    val contentCache = contentCache.get(id)
-                    contentCache?.invoke(result)
-                }
-            }
-        } else {
-            val signature = data.getStringExtra("result") ?: data.getStringExtra("signature") ?: ""
-            val packageName = data.getStringExtra("package")?.let { "-$it" } ?: ""
-            val id = data.getStringExtra("id") ?: ""
-            if (id.isNotBlank()) {
-                val result = if (packageName.isNotBlank()) "$signature$packageName" else signature
-                val contentCache = contentCache.get(id)
-                contentCache?.invoke(result)
-            }
-        }
-    }
-
-    fun openSignerApp(
-        data: String,
-        type: SignerType,
-        pubKey: HexKey,
-        id: String,
-        onReady: (String) -> Unit,
-    ) {
-        signerAppLauncher?.let {
-            openSignerApp(
-                data,
-                type,
-                it,
-                pubKey,
-                id,
-                onReady,
-            )
-        }
-    }
-
-    private fun defaultPermissions(): String {
-        val permissions =
-            listOf(
-                Permission(
-                    "sign_event",
-                    22242,
-                ),
-                Permission(
-                    "sign_event",
-                    31234,
-                ),
-                Permission(
-                    "nip04_encrypt",
-                ),
-                Permission(
-                    "nip04_decrypt",
-                ),
-                Permission(
-                    "nip44_encrypt",
-                ),
-                Permission(
-                    "nip44_decrypt",
-                ),
-                Permission(
-                    "decrypt_zap_event",
-                ),
-            )
-        val jsonArray = StringBuilder("[")
-        permissions.forEachIndexed { index, permission ->
-            jsonArray.append(permission.toJson())
-            if (index < permissions.size - 1) {
-                jsonArray.append(",")
-            }
-        }
-        jsonArray.append("]")
-
-        return jsonArray.toString()
-    }
-
-    private fun openSignerApp(
-        data: String,
-        type: SignerType,
-        intentLauncher: (Intent) -> Unit,
-        pubKey: HexKey,
-        id: String,
-        onReady: (String) -> Unit,
-    ) {
-        val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$data".toUri())
-        val signerType =
-            when (type) {
-                SignerType.SIGN_EVENT -> "sign_event"
-                SignerType.NIP04_ENCRYPT -> "nip04_encrypt"
-                SignerType.NIP04_DECRYPT -> "nip04_decrypt"
-                SignerType.NIP44_ENCRYPT -> "nip44_encrypt"
-                SignerType.NIP44_DECRYPT -> "nip44_decrypt"
-                SignerType.GET_PUBLIC_KEY -> "get_public_key"
-                SignerType.DECRYPT_ZAP_EVENT -> "decrypt_zap_event"
-                SignerType.DERIVE_KEY -> "derive_key"
-            }
-        intent.putExtra("type", signerType)
-        intent.putExtra("pubKey", pubKey)
-        intent.putExtra("id", id)
-        if (type !== SignerType.GET_PUBLIC_KEY) {
-            intent.putExtra("current_user", currentUserPubKeyHex)
-        } else {
-            intent.putExtra("permissions", defaultPermissions())
-        }
-        if (signerPackageName.isNotBlank()) {
-            intent.`package` = signerPackageName
-        }
-
-        intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_CLEAR_TOP)
-
-        contentCache.put(id, onReady)
-
-        intentLauncher(intent)
-    }
-
-    fun openSigner(
-        event: Event,
-        onReady: (String) -> Unit,
-    ) {
-        getDataFromResolver(
-            SignerType.SIGN_EVENT,
-            arrayOf(event.toJson(), event.pubKey),
-        ).fold(
-            onFailure = { },
-            onSuccess = {
-                if (it == null) {
-                    openSignerApp(
-                        event.toJson(),
-                        SignerType.SIGN_EVENT,
-                        "",
-                        event.id,
-                        onReady,
-                    )
-                } else {
-                    onReady(it)
-                }
-            },
-        )
-    }
-
-    private fun getDataFromResolver(
-        signerType: SignerType,
-        data: Array<out String>,
-    ): kotlin.Result<String?> = getDataFromResolver(signerType, data, contentResolver)
-
-    private fun getDataFromResolver(
-        signerType: SignerType,
-        data: Array<out String>,
-        contentResolver: (() -> ContentResolver)? = null,
-    ): kotlin.Result<String?> {
-        val localData =
-            if (signerType !== SignerType.GET_PUBLIC_KEY) {
-                arrayOf(*data, currentUserPubKeyHex)
-            } else {
-                data
-            }
-
-        try {
-            contentResolver
-                ?.let { it() }
-                ?.query(
-                    "content://$signerPackageName.$signerType".toUri(),
-                    localData,
-                    "1",
-                    null,
-                    null,
-                ).use {
-                    if (it == null) {
-                        return kotlin.Result.success(null)
-                    }
-                    if (it.moveToFirst()) {
-                        if (it.getColumnIndex("rejected") > -1) {
-                            Log.d("getDataFromResolver", "Permission denied")
-                            return kotlin.Result.failure(Exception("Permission denied"))
-                        }
-                        var index = it.getColumnIndex("result")
-                        if (index < 0) {
-                            index = it.getColumnIndex("signature")
-                        }
-                        if (index < 0) {
-                            Log.d("getDataFromResolver", "column 'signature' not found")
-                            return kotlin.Result.success(null)
-                        }
-                        return kotlin.Result.success(it.getString(index))
-                    }
-                }
-        } catch (e: Exception) {
-            Log.e("ExternalSignerLauncher", "Failed to query the Signer app in the background", e)
-            return kotlin.Result.success(null)
-        }
-
-        return kotlin.Result.success(null)
-    }
-
-    fun hashCodeFields(
-        str1: String,
-        onReady: (String) -> Unit,
-    ): Int {
-        var result = str1.hashCode()
-        result = 31 * result + onReady.hashCode()
-        return result
-    }
-
-    fun hashCodeFields(
-        str1: String,
-        str2: String,
-        onReady: (String) -> Unit,
-    ): Int {
-        var result = str1.hashCode()
-        result = 31 * result + str2.hashCode()
-        result = 31 * result + onReady.hashCode()
-        return result
-    }
-
-    fun decrypt(
-        encryptedContent: String,
-        pubKey: HexKey,
-        signerType: SignerType = SignerType.NIP04_DECRYPT,
-        onReady: (String) -> Unit,
-    ) {
-        getDataFromResolver(signerType, arrayOf(encryptedContent, pubKey)).fold(
-            onFailure = { },
-            onSuccess = {
-                if (it == null) {
-                    openSignerApp(
-                        encryptedContent,
-                        signerType,
-                        pubKey,
-                        hashCodeFields(encryptedContent, pubKey, onReady).toString(),
-                        onReady,
-                    )
-                } else {
-                    onReady(it)
-                }
-            },
-        )
-    }
-
-    fun encrypt(
-        decryptedContent: String,
-        pubKey: HexKey,
-        signerType: SignerType = SignerType.NIP04_ENCRYPT,
-        onReady: (String) -> Unit,
-    ) {
-        getDataFromResolver(signerType, arrayOf(decryptedContent, pubKey)).fold(
-            onFailure = { },
-            onSuccess = {
-                if (it == null) {
-                    openSignerApp(
-                        decryptedContent,
-                        signerType,
-                        pubKey,
-                        hashCodeFields(decryptedContent, pubKey, onReady).toString(),
-                        onReady,
-                    )
-                } else {
-                    onReady(it)
-                }
-            },
-        )
-    }
-
-    fun decryptZapEvent(
-        event: LnZapRequestEvent,
-        onReady: (String) -> Unit,
-    ) {
-        getDataFromResolver(SignerType.DECRYPT_ZAP_EVENT, arrayOf(event.toJson(), event.pubKey)).fold(
-            onFailure = { },
-            onSuccess = {
-                if (it == null) {
-                    openSignerApp(
-                        event.toJson(),
-                        SignerType.DECRYPT_ZAP_EVENT,
-                        event.pubKey,
-                        event.id,
-                        onReady,
-                    )
-                } else {
-                    onReady(it)
-                }
-            },
-        )
-    }
-
-    fun deriveKey(
-        nonce: HexKey,
-        signerType: SignerType = SignerType.DERIVE_KEY,
-        onReady: (String) -> Unit,
-    ) {
-        getDataFromResolver(signerType, arrayOf(nonce)).fold(
-            onFailure = { },
-            onSuccess = {
-                if (it == null) {
-                    openSignerApp(
-                        nonce,
-                        signerType,
-                        "",
-                        hashCodeFields(nonce, onReady).toString(),
-                        onReady,
-                    )
-                } else {
-                    onReady(it)
-                }
-            },
-        )
-    }
-}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/CommandType.kt

@@ -0,0 +1,50 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api
+
+enum class CommandType(
+    val code: String,
+) {
+    SIGN_EVENT("sign_event"),
+    NIP04_ENCRYPT("nip04_encrypt"),
+    NIP04_DECRYPT("nip04_decrypt"),
+    NIP44_ENCRYPT("nip44_encrypt"),
+    NIP44_DECRYPT("nip44_decrypt"),
+    GET_PUBLIC_KEY("get_public_key"),
+    DECRYPT_ZAP_EVENT("decrypt_zap_event"),
+    DERIVE_KEY("derive_key"),
+    ;
+
+    companion object Companion {
+        fun parse(code: String): CommandType? =
+            when (code) {
+                SIGN_EVENT.code -> SIGN_EVENT
+                NIP04_ENCRYPT.code -> NIP04_ENCRYPT
+                NIP04_DECRYPT.code -> NIP04_DECRYPT
+                NIP44_ENCRYPT.code -> NIP44_ENCRYPT
+                NIP44_DECRYPT.code -> NIP44_DECRYPT
+                GET_PUBLIC_KEY.code -> GET_PUBLIC_KEY
+                DECRYPT_ZAP_EVENT.code -> DECRYPT_ZAP_EVENT
+                DERIVE_KEY.code -> DERIVE_KEY
+                else -> null
+            }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/SignerResult.kt

@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api
+
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
+
+interface RequestAddressed
+
+sealed class SignerResult<T : IResult> {
+    class Successful<T : IResult>(
+        val result: T,
+    ) : SignerResult<T>(),
+        RequestAddressed
+
+    class Rejected<T : IResult> :
+        SignerResult<T>(),
+        RequestAddressed
+
+    class ReceivedButCouldNotPerform<T : IResult>(
+        message: String? = null,
+    ) : SignerResult<T>(),
+        RequestAddressed
+
+    class ReceivedButCouldNotParseEventFromResult<T : IResult>(
+        val eventJson: String,
+    ) : SignerResult<T>(),
+        RequestAddressed
+
+    class ReceivedButCouldNotVerifyResultingEvent<T : IResult>(
+        val invalidEvent: Event,
+    ) : SignerResult<T>(),
+        RequestAddressed
+
+    class ErrorExceptionCallingContentResolver<T : IResult>(
+        val e: Exception? = null,
+    ) : SignerResult<T>()
+
+    class RequiresManualApproval<T : IResult> : SignerResult<T>()
+}
+
+interface IResult
+
+data class PubKeyResult(
+    val pubkey: HexKey,
+    val packageName: String,
+) : IResult
+
+data class SignResult(
+    val event: Event,
+) : IResult
+
+data class EncryptionResult(
+    val ciphertext: String,
+) : IResult
+
+data class DecryptionResult(
+    val plaintext: String,
+) : IResult
+
+data class ZapEventDecryptionResult(
+    val privateEvent: LnZapPrivateEvent,
+) : IResult
+
+data class DerivationResult(
+    val newPrivKey: HexKey,
+) : IResult

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/DecryptZapQuery.kt

@@ -0,0 +1,66 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.verify
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.ZapEventDecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
+import kotlin.text.isNullOrBlank
+
+class DecryptZapQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    fun query(event: Event): SignerResult<ZapEventDecryptionResult> =
+        contentResolver.query(
+            "content://$packageName.${CommandType.DECRYPT_ZAP_EVENT}".toUri(),
+            arrayOf(event.toJson(), event.pubKey, loggedInUser),
+        ) { cursor ->
+            val decryptedEventAsJson = cursor.getStringByName("result")
+            if (!decryptedEventAsJson.isNullOrBlank()) {
+                if (decryptedEventAsJson.startsWith("{")) {
+                    val event = Event.fromJsonOrNull(decryptedEventAsJson) as? LnZapPrivateEvent
+                    if (event != null) {
+                        if (event.verify()) {
+                            SignerResult.Successful(ZapEventDecryptionResult(event))
+                        } else {
+                            SignerResult.ReceivedButCouldNotVerifyResultingEvent(event)
+                        }
+                    } else {
+                        SignerResult.ReceivedButCouldNotParseEventFromResult(decryptedEventAsJson)
+                    }
+                } else {
+                    SignerResult.ReceivedButCouldNotPerform(decryptedEventAsJson)
+                }
+            } else {
+                SignerResult.ReceivedButCouldNotPerform(decryptedEventAsJson)
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/DeriveKeyQuery.kt

@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DerivationResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class DeriveKeyQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    val uri = "content://$packageName.${CommandType.DERIVE_KEY}".toUri()
+
+    fun query(nonce: HexKey): SignerResult<DerivationResult> =
+        contentResolver.query(
+            uri,
+            arrayOf(nonce, loggedInUser),
+        ) { cursor ->
+            val newPrivateKey = cursor.getStringByName("result")
+            if (!newPrivateKey.isNullOrBlank()) {
+                SignerResult.Successful(DerivationResult(newPrivateKey))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/LoginQuery.kt

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.PubKeyResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class LoginQuery(
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    companion object {
+        val LOGIN = arrayOf("login")
+    }
+
+    val uri = "content://$packageName.${CommandType.GET_PUBLIC_KEY}".toUri()
+
+    fun query(): SignerResult<PubKeyResult> =
+        contentResolver.query(
+            uri,
+            LOGIN,
+        ) { cursor ->
+            val pubkeyHex = cursor.getStringByName("result")
+            if (!pubkeyHex.isNullOrBlank()) {
+                SignerResult.Successful(PubKeyResult(pubkeyHex, packageName))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/Nip04DecryptQuery.kt

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class Nip04DecryptQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    val uri = "content://$packageName.${CommandType.NIP04_DECRYPT}".toUri()
+
+    fun query(
+        ciphertext: String,
+        fromPubKey: HexKey,
+    ): SignerResult<DecryptionResult> =
+        contentResolver.query(
+            uri,
+            arrayOf(ciphertext, fromPubKey, loggedInUser),
+        ) { cursor ->
+            val plaintext = cursor.getStringByName("result")
+            if (!plaintext.isNullOrBlank()) {
+                SignerResult.Successful(DecryptionResult(plaintext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/Nip04EncryptQuery.kt

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class Nip04EncryptQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    val uri = "content://$packageName.${CommandType.NIP04_ENCRYPT}".toUri()
+
+    fun query(
+        plaintext: String,
+        toPubKey: HexKey,
+    ): SignerResult<EncryptionResult> =
+        contentResolver.query(
+            uri,
+            arrayOf(plaintext, toPubKey, loggedInUser),
+        ) { cursor ->
+            val ciphertext = cursor.getStringByName("result")
+            if (!ciphertext.isNullOrBlank()) {
+                SignerResult.Successful(EncryptionResult(ciphertext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/Nip44DecryptQuery.kt

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class Nip44DecryptQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    val uri = "content://$packageName.${CommandType.NIP44_DECRYPT}".toUri()
+
+    fun query(
+        ciphertext: String,
+        fromPubKey: HexKey,
+    ): SignerResult<DecryptionResult> =
+        contentResolver.query(
+            uri,
+            arrayOf(ciphertext, fromPubKey, loggedInUser),
+        ) { cursor ->
+            val plaintext = cursor.getStringByName("result")
+            if (!plaintext.isNullOrBlank()) {
+                SignerResult.Successful(DecryptionResult(plaintext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/Nip44EncryptQuery.kt

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class Nip44EncryptQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    val uri = "content://$packageName.${CommandType.NIP44_ENCRYPT}".toUri()
+
+    fun query(
+        plaintext: String,
+        toPubKey: HexKey,
+    ): SignerResult<EncryptionResult> =
+        contentResolver.query(
+            uri,
+            arrayOf(plaintext, toPubKey, loggedInUser),
+        ) { cursor ->
+            val ciphertext = cursor.getStringByName("result")
+            if (!ciphertext.isNullOrBlank()) {
+                SignerResult.Successful(EncryptionResult(ciphertext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/queries/SignQuery.kt

@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries
+
+import android.content.ContentResolver
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.EventFactory
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.verify
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.getStringByName
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils.query
+
+class SignQuery(
+    val loggedInUser: HexKey,
+    val packageName: String,
+    val contentResolver: ContentResolver,
+) {
+    val uri = "content://$packageName.${CommandType.SIGN_EVENT}".toUri()
+
+    fun query(unsignedEvent: Event): SignerResult<SignResult> =
+        contentResolver.query(
+            uri,
+            arrayOf(unsignedEvent.toJson(), unsignedEvent.pubKey, loggedInUser),
+        ) { cursor ->
+            val eventJson = cursor.getStringByName("event")
+            if (!eventJson.isNullOrBlank()) {
+                if (eventJson.startsWith("{")) {
+                    val event = Event.fromJsonOrNull(eventJson)
+                    if (event != null) {
+                        if (event.verify()) {
+                            SignerResult.Successful(SignResult(event))
+                        } else {
+                            SignerResult.ReceivedButCouldNotVerifyResultingEvent(event)
+                        }
+                    } else {
+                        SignerResult.ReceivedButCouldNotParseEventFromResult(eventJson)
+                    }
+                } else {
+                    SignerResult.ReceivedButCouldNotParseEventFromResult(eventJson)
+                }
+            } else {
+                val signature = cursor.getStringByName("result")
+                if (!signature.isNullOrBlank()) {
+                    val event =
+                        EventFactory.create(
+                            id = unsignedEvent.id,
+                            pubKey = unsignedEvent.pubKey,
+                            createdAt = unsignedEvent.createdAt,
+                            kind = unsignedEvent.kind,
+                            tags = unsignedEvent.tags,
+                            content = unsignedEvent.content,
+                            sig = signature,
+                        )
+                    if (event.verify()) {
+                        SignerResult.Successful(SignResult(event))
+                    } else {
+                        SignerResult.ReceivedButCouldNotVerifyResultingEvent(event)
+                    }
+                } else {
+                    SignerResult.ReceivedButCouldNotPerform()
+                }
+            }
+        }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/utils/ContentResolverExt.kt

@@ -0,0 +1,56 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils
+
+import android.content.ContentResolver
+import android.database.Cursor
+import android.net.Uri
+import android.util.Log
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.IResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+fun <T : IResult> ContentResolver.query(
+    uri: Uri,
+    projection: Array<out String>,
+    map: (cursor: Cursor) -> SignerResult<T>,
+): SignerResult<T> =
+    try {
+        query(
+            uri,
+            projection,
+            null,
+            null,
+            null,
+        ).use {
+            if (it != null && it.moveToFirst()) {
+                if (it.getColumnIndex("rejected") > -1) {
+                    SignerResult.Rejected()
+                } else {
+                    map(it)
+                }
+            } else {
+                SignerResult.RequiresManualApproval()
+            }
+        }
+    } catch (e: Exception) {
+        Log.e("ExternalSignerLauncher", "Failed to query the Signer app in the background", e)
+        SignerResult.ErrorExceptionCallingContentResolver(e)
+    }

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/background/utils/CursorExt.kt

@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.background.utils
+
+import android.database.Cursor
+
+fun Cursor.getStringByName(name: String): String? {
+    val index = getColumnIndex(name)
+    return if (index >= 0) {
+        val result = getString(index)
+        result.ifBlank { null }
+    } else {
+        null
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/IntentRequestDatabase.kt

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground
+
+import android.content.Intent
+import androidx.collection.LruCache
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.utils.RandomInstance
+
+class IntentRequestDatabase {
+    private val awaitingRequests = LruCache<String, NewResultProcessor>(2000)
+    private var appLauncher: ((Intent) -> Unit)? = null
+
+    /** Call this function when the launcher becomes available on activity, fragment or compose */
+    fun registerForegroundLauncher(launcher: ((Intent) -> Unit)) {
+        this.appLauncher = launcher
+    }
+
+    /** Call this function when the activity is destroyed or is about to be replaced. */
+    fun unregisterForegroundLauncher(launcher: ((Intent) -> Unit)) {
+        if (this.appLauncher == launcher) {
+            this.appLauncher = null
+        }
+    }
+
+    fun newResponse(data: Intent) {
+        val callId = data.getStringExtra("id")
+        if (callId != null) {
+            awaitingRequests[callId]?.process(data)
+            awaitingRequests.remove(callId)
+        }
+    }
+
+    fun launch(
+        requestIntent: Intent,
+        responseProcessor: NewResultProcessor,
+    ) {
+        appLauncher?.let {
+            val callId = RandomInstance.randomChars(32)
+            awaitingRequests.put(callId, responseProcessor)
+
+            requestIntent.putExtra("id", callId)
+            requestIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_CLEAR_TOP)
+            it.invoke(requestIntent)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/NewResultProcessor.kt

@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground
+
+import android.content.Intent
+
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+interface NewResultProcessor {
+    fun process(intent: Intent)
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/DecryptZapRequest.kt

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip57Zaps.LnZapRequestEvent
+
+class DecryptZapRequest {
+    companion object {
+        fun assemble(
+            event: LnZapRequestEvent,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:${event.toJson()}".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.NIP44_DECRYPT.code)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/DeriveKeyRequest.kt

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class DeriveKeyRequest {
+    companion object {
+        fun assemble(
+            nonce: HexKey,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$nonce".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.DERIVE_KEY.code)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/LoginRequest.kt

@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.jackson.JsonMapper
+import com.vitorpamplona.quartz.nip42RelayAuth.RelayAuthEvent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.Permission
+
+class LoginRequest {
+    companion object {
+        val DefaultPermissions =
+            listOf(
+                Permission(CommandType.SIGN_EVENT, RelayAuthEvent.KIND),
+                Permission(CommandType.NIP04_ENCRYPT),
+                Permission(CommandType.NIP04_DECRYPT),
+                Permission(CommandType.NIP44_DECRYPT),
+                Permission(CommandType.NIP44_DECRYPT),
+                Permission(CommandType.DECRYPT_ZAP_EVENT),
+            )
+
+        fun assemble(permissions: List<Permission> = DefaultPermissions): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:".toUri())
+            intent.putExtra("type", CommandType.GET_PUBLIC_KEY.code)
+            intent.putExtra("permissions", JsonMapper.mapper.writeValueAsString(permissions))
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/Nip04DecryptRequest.kt

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class Nip04DecryptRequest {
+    companion object {
+        fun assemble(
+            ciphertext: String,
+            fromPubKey: HexKey,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$ciphertext".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.NIP04_DECRYPT.code)
+            intent.putExtra("pubKey", fromPubKey)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/Nip04EncryptRequest.kt

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class Nip04EncryptRequest {
+    companion object {
+        fun assemble(
+            plaintext: String,
+            toPubKey: HexKey,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$plaintext".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.NIP04_ENCRYPT.code)
+            intent.putExtra("pubKey", toPubKey)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/Nip44DecryptRequest.kt

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class Nip44DecryptRequest {
+    companion object {
+        fun assemble(
+            ciphertext: String,
+            fromPubKey: HexKey,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$ciphertext".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.NIP44_DECRYPT.code)
+            intent.putExtra("pubKey", fromPubKey)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/Nip44EncryptRequest.kt

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class Nip44EncryptRequest {
+    companion object {
+        fun assemble(
+            plaintext: String,
+            toPubKey: HexKey,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:$plaintext".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.NIP44_ENCRYPT.code)
+            intent.putExtra("pubKey", toPubKey)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/requests/SignRequest.kt

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests
+
+import android.content.Intent
+import androidx.core.net.toUri
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class SignRequest {
+    companion object {
+        fun assemble(
+            event: Event,
+            loggedInUser: HexKey,
+            packageName: String,
+        ): Intent {
+            val intent = Intent(Intent.ACTION_VIEW, "nostrsigner:${event.toJson()}".toUri())
+            intent.`package` = packageName
+            intent.putExtra("type", CommandType.SIGN_EVENT.code)
+            intent.putExtra("current_user", loggedInUser)
+            return intent
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/DecryptZapResponse.kt

@@ -0,0 +1,55 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.ZapEventDecryptionResult
+import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
+
+class DecryptZapResponse {
+    companion object {
+        fun assemble(event: LnZapPrivateEvent): Intent {
+            val intent = Intent()
+            intent.putExtra("result", event.toJson())
+            return intent
+        }
+
+        fun parse(intent: Intent): SignerResult<ZapEventDecryptionResult> {
+            val eventJson = intent.getStringExtra("result")
+            return if (!eventJson.isNullOrBlank()) {
+                if (eventJson.startsWith("{")) {
+                    val event = Event.fromJsonOrNull(eventJson) as? LnZapPrivateEvent
+                    if (event != null) {
+                        SignerResult.Successful(ZapEventDecryptionResult(event))
+                    } else {
+                        SignerResult.ReceivedButCouldNotParseEventFromResult(eventJson)
+                    }
+                } else {
+                    SignerResult.ReceivedButCouldNotPerform()
+                }
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/DeriveKeyResponse.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DerivationResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class DeriveKeyResponse {
+    companion object {
+        fun parse(intent: Intent): SignerResult<DerivationResult> {
+            val newPrivateKey = intent.getStringExtra("result")
+            return if (newPrivateKey != null) {
+                SignerResult.Successful(DerivationResult(newPrivateKey))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/LoginResponse.kt

@@ -0,0 +1,45 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.PubKeyResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class LoginResponse {
+    companion object {
+        fun parse(intent: Intent): SignerResult<PubKeyResult> {
+            val pubkey = intent.getStringExtra("result")
+            val packageName = intent.getStringExtra("package")
+
+            return if (pubkey != null && packageName != null) {
+                SignerResult.Successful(
+                    PubKeyResult(
+                        pubkey = pubkey,
+                        packageName = packageName,
+                    ),
+                )
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/Nip04DecryptResponse.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class Nip04DecryptResponse {
+    companion object {
+        fun parse(intent: Intent): SignerResult<DecryptionResult> {
+            val ciphertext = intent.getStringExtra("result")
+            return if (ciphertext != null) {
+                SignerResult.Successful(DecryptionResult(ciphertext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/Nip04EncryptResponse.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class Nip04EncryptResponse {
+    companion object {
+        fun parse(intent: Intent): SignerResult<EncryptionResult> {
+            val ciphertext = intent.getStringExtra("result")
+            return if (ciphertext != null) {
+                SignerResult.Successful(EncryptionResult(ciphertext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/Nip44DecryptResponse.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class Nip44DecryptResponse {
+    companion object {
+        fun parse(intent: Intent): SignerResult<DecryptionResult> {
+            val ciphertext = intent.getStringExtra("result")
+            return if (ciphertext != null) {
+                SignerResult.Successful(DecryptionResult(ciphertext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/Nip44EncryptResponse.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class Nip44EncryptResponse {
+    companion object {
+        fun parse(intent: Intent): SignerResult<EncryptionResult> {
+            val ciphertext = intent.getStringExtra("result")
+            return if (ciphertext != null) {
+                SignerResult.Successful(EncryptionResult(ciphertext))
+            } else {
+                SignerResult.ReceivedButCouldNotPerform()
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/intents/responses/SignResponse.kt

@@ -0,0 +1,76 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses
+
+import android.content.Intent
+import com.vitorpamplona.quartz.EventFactory
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.verify
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+
+class SignResponse {
+    companion object {
+        fun parse(
+            intent: Intent,
+            unsignedEvent: Event,
+        ): SignerResult<SignResult> {
+            val eventJson = intent.getStringExtra("event")
+            return if (eventJson != null) {
+                if (eventJson.startsWith("{")) {
+                    val event = Event.fromJsonOrNull(eventJson)
+                    if (event != null) {
+                        if (event.verify()) {
+                            SignerResult.Successful(SignResult(event))
+                        } else {
+                            SignerResult.ReceivedButCouldNotVerifyResultingEvent(event)
+                        }
+                    } else {
+                        SignerResult.ReceivedButCouldNotParseEventFromResult(eventJson)
+                    }
+                } else {
+                    SignerResult.ReceivedButCouldNotPerform(eventJson)
+                }
+            } else {
+                val signature = intent.getStringExtra("result")
+                if (signature != null && signature.length == 128) {
+                    val event =
+                        EventFactory.create(
+                            id = unsignedEvent.id,
+                            pubKey = unsignedEvent.pubKey,
+                            createdAt = unsignedEvent.createdAt,
+                            kind = unsignedEvent.kind,
+                            tags = unsignedEvent.tags,
+                            content = unsignedEvent.content,
+                            sig = signature,
+                        )
+                    if (event.verify()) {
+                        SignerResult.Successful(SignResult(event))
+                    } else {
+                        SignerResult.ReceivedButCouldNotVerifyResultingEvent(event)
+                    }
+                } else {
+                    SignerResult.ReceivedButCouldNotPerform(signature)
+                }
+            }
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/DecryptZapResultProcessor.kt

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.ZapEventDecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.DecryptZapResponse
+import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
+
+class DecryptZapResultProcessor(
+    val onReady: (LnZapPrivateEvent) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = DecryptZapResponse.parse(intent)
+
+        if (foregroundResult is SignerResult.Successful<ZapEventDecryptionResult>) {
+            onReady(foregroundResult.result.privateEvent)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/DeriveKeyResultProcessor.kt

@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DerivationResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.DeriveKeyResponse
+
+class DeriveKeyResultProcessor(
+    val onReady: (String) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = DeriveKeyResponse.parse(intent)
+
+        if (foregroundResult is SignerResult.Successful<DerivationResult>) {
+            onReady(foregroundResult.result.newPrivKey)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/LoginResultProcessor.kt

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.PubKeyResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.LoginResponse
+
+class LoginResultProcessor(
+    val onReady: (HexKey, String) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = LoginResponse.parse(intent)
+
+        if (foregroundResult is SignerResult.Successful<PubKeyResult>) {
+            onReady(foregroundResult.result.pubkey, foregroundResult.result.packageName)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/Nip04DecryptResultProcessor.kt

@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.Nip04DecryptResponse
+
+class Nip04DecryptResultProcessor(
+    val onReady: (String) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = Nip04DecryptResponse.parse(intent)
+
+        if (foregroundResult is SignerResult.Successful<DecryptionResult>) {
+            onReady(foregroundResult.result.plaintext)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/Nip04EncryptResultProcessor.kt

@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.Nip04EncryptResponse
+
+class Nip04EncryptResultProcessor(
+    val onReady: (String) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = Nip04EncryptResponse.parse(intent)
+
+        if (foregroundResult is SignerResult.Successful<EncryptionResult>) {
+            onReady(foregroundResult.result.ciphertext)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/Nip44DecryptResultProcessor.kt

@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.Nip44DecryptResponse
+
+class Nip44DecryptResultProcessor(
+    val onReady: (String) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = Nip44DecryptResponse.parse(intent)
+
+        if (foregroundResult is SignerResult.Successful<DecryptionResult>) {
+            onReady(foregroundResult.result.plaintext)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/Nip44EncryptResultProcessor.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.Nip44EncryptResponse
+
+class Nip44EncryptResultProcessor(
+    val onReady: (String) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = Nip44EncryptResponse.parse(intent)
+        if (foregroundResult is SignerResult.Successful<EncryptionResult>) {
+            onReady(foregroundResult.result.ciphertext)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/foreground/processors/SignResultProcessor.kt

@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.NewResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.SignResponse
+
+class SignResultProcessor(
+    val unsignedEvent: Event,
+    val onReady: (Event) -> Unit,
+) : NewResultProcessor {
+    override fun process(intent: Intent) {
+        val foregroundResult = SignResponse.parse(intent, unsignedEvent)
+
+        if (foregroundResult is SignerResult.Successful<SignResult>) {
+            onReady(foregroundResult.result.event)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/permission/Permission.kt

@@ -0,0 +1,37 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.permission
+
+import com.vitorpamplona.quartz.nip01Core.jackson.JsonMapper
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class Permission(
+    val type: CommandType?,
+    val kind: Int? = null,
+) {
+    fun toJson(): String = JsonMapper.mapper.writeValueAsString(this)
+
+    companion object {
+        fun fromJson(json: String): Permission = JsonMapper.mapper.readValue(json, Permission::class.java)
+
+        fun fromJsonArray(json: String): Array<Permission> = JsonMapper.mapper.readValue(json, Array<Permission>::class.java)
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/permission/PermissionDeserializer.kt

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.permission
+
+import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.JsonNode
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
+
+class PermissionDeserializer : StdDeserializer<Permission>(Permission::class.java) {
+    override fun deserialize(
+        jp: JsonParser,
+        ctxt: DeserializationContext,
+    ): Permission {
+        val jsonObject: JsonNode = jp.codec.readTree(jp)
+        return Permission(
+            type = CommandType.parse(jsonObject.get("type").asText()),
+            kind = jsonObject.get("kind")?.asInt(),
+        )
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/api/permission/PermissionSerializer.kt

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.api.permission
+
+import com.fasterxml.jackson.core.JsonGenerator
+import com.fasterxml.jackson.databind.SerializerProvider
+import com.fasterxml.jackson.databind.ser.std.StdSerializer
+
+class PermissionSerializer : StdSerializer<Permission>(Permission::class.java) {
+    override fun serialize(
+        permission: Permission,
+        gen: JsonGenerator,
+        provider: SerializerProvider,
+    ) {
+        gen.writeStartObject()
+        permission.type.let { gen.writeStringField("type", it?.code) }
+        if (permission.kind != null) {
+            gen.writeNumberField("kind", permission.kind)
+        } else {
+            gen.writeNullField("kind")
+        }
+        gen.writeEndObject()
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/client/ExternalSignerLogin.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.client
+
+import android.content.Intent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.PubKeyResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.LoginRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.responses.LoginResponse
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.Permission
+
+object ExternalSignerLogin {
+    fun createIntent(permissions: List<Permission> = LoginRequest.DefaultPermissions): Intent {
+        val intent = LoginRequest.assemble(permissions)
+        intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_CLEAR_TOP)
+        return intent
+    }
+
+    fun parseResult(data: Intent): SignerResult<PubKeyResult> = LoginResponse.parse(data)
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/client/IActivityLauncher.kt

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.client
+
+import android.content.Intent
+
+interface IActivityLauncher {
+    fun registerForegroundLauncher(launcher: ((Intent) -> Unit))
+
+    fun unregisterForegroundLauncher(launcher: ((Intent) -> Unit))
+
+    fun newResponse(data: Intent)
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/client/IsExternalSignerInstalled.kt

@@ -0,0 +1,37 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.client
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.content.Intent
+import androidx.core.net.toUri
+
+@SuppressLint("QueryPermissionsNeeded")
+fun isExternalSignerInstalled(context: Context): Boolean =
+    context.packageManager
+        .queryIntentActivities(
+            Intent().apply {
+                action = Intent.ACTION_VIEW
+                data = "nostrsigner:".toUri()
+            },
+            0,
+        ).isNotEmpty()

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/client/NostrSignerExternal.kt

@@ -18,23 +18,42 @@
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-package com.vitorpamplona.quartz.nip55AndroidSigner
+package com.vitorpamplona.quartz.nip55AndroidSigner.client
 
-import android.util.Log
-import com.vitorpamplona.quartz.EventFactory
+import android.content.ContentResolver
+import android.content.Intent
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.crypto.EventHasher
 import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
+import com.vitorpamplona.quartz.nip55AndroidSigner.client.handlers.BackgroundRequestHandler
+import com.vitorpamplona.quartz.nip55AndroidSigner.client.handlers.ForegroundRequestHandler
 import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
 import com.vitorpamplona.quartz.nip57Zaps.LnZapRequestEvent
 
 class NostrSignerExternal(
     pubKey: HexKey,
-    val launcher: ExternalSignerLauncher,
-) : NostrSigner(pubKey) {
+    packageName: String,
+    contentResolver: ContentResolver,
+) : NostrSigner(pubKey),
+    IActivityLauncher {
     override fun isWriteable(): Boolean = true
 
+    val backgroundQuery = BackgroundRequestHandler(pubKey, packageName, contentResolver)
+    val foregroundQuery = ForegroundRequestHandler(pubKey, packageName)
+
+    override fun registerForegroundLauncher(launcher: ((Intent) -> Unit)) {
+        this.foregroundQuery.launcher.registerForegroundLauncher(launcher)
+    }
+
+    override fun unregisterForegroundLauncher(launcher: ((Intent) -> Unit)) {
+        this.foregroundQuery.launcher.unregisterForegroundLauncher(launcher)
+    }
+
+    override fun newResponse(data: Intent) {
+        this.foregroundQuery.launcher.newResponse(data)
+    }
+
     override fun <T : Event> sign(
         createdAt: Long,
         kind: Int,
@@ -42,7 +61,7 @@ class NostrSignerExternal(
         content: String,
         onReady: (T) -> Unit,
     ) {
-        val event =
+        val unsignedEvent =
             Event(
                 id = EventHasher.hashId(pubKey, createdAt, kind, tags, content),
                 pubKey = pubKey,
@@ -53,109 +72,70 @@ class NostrSignerExternal(
                 sig = "",
             )
 
-        launcher.openSigner(event) { signature ->
-            if (signature.startsWith("{")) {
-                val localEvent = Event.fromJson(signature)
-                (
-                    EventFactory.create(
-                        localEvent.id,
-                        localEvent.pubKey,
-                        localEvent.createdAt,
-                        localEvent.kind,
-                        localEvent.tags,
-                        localEvent.content,
-                        localEvent.sig,
-                    ) as? T?
-                )?.let { onReady(it) }
-            } else {
-                (
-                    EventFactory.create(
-                        event.id,
-                        event.pubKey,
-                        event.createdAt,
-                        event.kind,
-                        event.tags,
-                        event.content,
-                        signature.split("-")[0],
-                    ) as? T?
-                )?.let { onReady(it) }
-            }
+        val newOnReady: (Event) -> Unit = { result ->
+            (result as? T)?.let(onReady)
+        }
+
+        if (!backgroundQuery.sign(unsignedEvent, newOnReady)) {
+            foregroundQuery.sign(unsignedEvent, newOnReady)
         }
     }
 
     override fun nip04Encrypt(
-        decryptedContent: String,
+        plaintext: String,
         toPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        launcher.encrypt(
-            decryptedContent,
-            toPublicKey,
-            SignerType.NIP04_ENCRYPT,
-            onReady,
-        )
+        if (!backgroundQuery.nip04Encrypt(plaintext, toPublicKey, onReady)) {
+            foregroundQuery.nip04Encrypt(plaintext, toPublicKey, onReady)
+        }
     }
 
     override fun nip04Decrypt(
-        encryptedContent: String,
+        ciphertext: String,
         fromPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        launcher.decrypt(
-            encryptedContent,
-            fromPublicKey,
-            SignerType.NIP04_DECRYPT,
-            onReady,
-        )
+        if (!backgroundQuery.nip04Decrypt(ciphertext, fromPublicKey, onReady)) {
+            foregroundQuery.nip04Decrypt(ciphertext, fromPublicKey, onReady)
+        }
     }
 
     override fun nip44Encrypt(
-        decryptedContent: String,
+        plaintext: String,
         toPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        launcher.encrypt(
-            decryptedContent,
-            toPublicKey,
-            SignerType.NIP44_ENCRYPT,
-            onReady,
-        )
+        if (!backgroundQuery.nip44Encrypt(plaintext, toPublicKey, onReady)) {
+            foregroundQuery.nip44Encrypt(plaintext, toPublicKey, onReady)
+        }
     }
 
     override fun nip44Decrypt(
-        encryptedContent: String,
+        ciphertext: String,
         fromPublicKey: HexKey,
         onReady: (String) -> Unit,
     ) {
-        launcher.decrypt(
-            encryptedContent,
-            fromPublicKey,
-            SignerType.NIP44_DECRYPT,
-            onReady,
-        )
+        if (!backgroundQuery.nip44Decrypt(ciphertext, fromPublicKey, onReady)) {
+            foregroundQuery.nip44Decrypt(ciphertext, fromPublicKey, onReady)
+        }
     }
 
     override fun deriveKey(
         nonce: HexKey,
         onReady: (HexKey) -> Unit,
     ) {
-        launcher.deriveKey(
-            nonce,
-            SignerType.DERIVE_KEY,
-            onReady,
-        )
+        if (!backgroundQuery.deriveKey(nonce, onReady)) {
+            foregroundQuery.deriveKey(nonce, onReady)
+        }
     }
 
     override fun decryptZapEvent(
         event: LnZapRequestEvent,
         onReady: (LnZapPrivateEvent) -> Unit,
     ) {
-        launcher.decryptZapEvent(event) { jsonEvent ->
-            try {
-                (Event.fromJson(jsonEvent) as? LnZapPrivateEvent)?.let { onReady(it) }
-            } catch (e: Exception) {
-                Log.e("NostrExternalSigner", "Unable to parse returned decrypted Zap: $jsonEvent")
-            }
+        if (!backgroundQuery.decryptZapEvent(event, onReady)) {
+            foregroundQuery.decryptZapEvent(event, onReady)
         }
     }
 }

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/client/handlers/BackgroundRequestHandler.kt

@@ -0,0 +1,163 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.client.handlers
+
+import android.content.ContentResolver
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.DerivationResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.EncryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.PubKeyResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.RequestAddressed
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.ZapEventDecryptionResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.DecryptZapQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.DeriveKeyQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.LoginQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.Nip04DecryptQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.Nip04EncryptQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.Nip44DecryptQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.Nip44EncryptQuery
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.background.queries.SignQuery
+import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
+import com.vitorpamplona.quartz.nip57Zaps.LnZapRequestEvent
+
+class BackgroundRequestHandler(
+    loggedInUser: HexKey,
+    packageName: String,
+    contentResolver: ContentResolver,
+) {
+    val login = LoginQuery(packageName, contentResolver)
+    val sign = SignQuery(loggedInUser, packageName, contentResolver)
+    val nip04Encrypt = Nip04EncryptQuery(loggedInUser, packageName, contentResolver)
+    val nip04Decrypt = Nip04DecryptQuery(loggedInUser, packageName, contentResolver)
+    val nip44Encrypt = Nip44EncryptQuery(loggedInUser, packageName, contentResolver)
+    val nip44Decrypt = Nip44DecryptQuery(loggedInUser, packageName, contentResolver)
+    val decryptZap = DecryptZapQuery(loggedInUser, packageName, contentResolver)
+    val deriveKey = DeriveKeyQuery(loggedInUser, packageName, contentResolver)
+
+    fun login(onReady: (HexKey) -> Unit): Boolean {
+        val backgroundResult = login.query()
+
+        if (backgroundResult is SignerResult.Successful<PubKeyResult>) {
+            onReady(backgroundResult.result.pubkey)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun sign(
+        unsignedEvent: Event,
+        onReady: (Event) -> Unit,
+    ): Boolean {
+        val backgroundResult = sign.query(unsignedEvent)
+
+        if (backgroundResult is SignerResult.Successful<SignResult>) {
+            onReady(backgroundResult.result.event)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun nip04Encrypt(
+        plaintext: String,
+        toPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ): Boolean {
+        val backgroundResult = nip04Encrypt.query(plaintext, toPubKey)
+
+        if (backgroundResult is SignerResult.Successful<EncryptionResult>) {
+            onReady(backgroundResult.result.ciphertext)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun nip04Decrypt(
+        ciphertext: String,
+        fromPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ): Boolean {
+        val backgroundResult = nip04Decrypt.query(ciphertext, fromPubKey)
+
+        if (backgroundResult is SignerResult.Successful<DecryptionResult>) {
+            onReady(backgroundResult.result.plaintext)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun nip44Encrypt(
+        plaintext: String,
+        toPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ): Boolean {
+        val backgroundResult = nip44Encrypt.query(plaintext, toPubKey)
+
+        if (backgroundResult is SignerResult.Successful<EncryptionResult>) {
+            onReady(backgroundResult.result.ciphertext)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun nip44Decrypt(
+        ciphertext: String,
+        fromPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ): Boolean {
+        val backgroundResult = nip44Decrypt.query(ciphertext, fromPubKey)
+
+        if (backgroundResult is SignerResult.Successful<DecryptionResult>) {
+            onReady(backgroundResult.result.plaintext)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun decryptZapEvent(
+        event: LnZapRequestEvent,
+        onReady: (LnZapPrivateEvent) -> Unit,
+    ): Boolean {
+        val backgroundResult = decryptZap.query(event)
+
+        if (backgroundResult is SignerResult.Successful<ZapEventDecryptionResult>) {
+            onReady(backgroundResult.result.privateEvent)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+
+    fun deriveKey(
+        nonce: HexKey,
+        onReady: (HexKey) -> Unit,
+    ): Boolean {
+        val backgroundResult = deriveKey.query(nonce)
+
+        if (backgroundResult is SignerResult.Successful<DerivationResult>) {
+            onReady(backgroundResult.result.newPrivKey)
+        }
+
+        return backgroundResult is RequestAddressed
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/nip55AndroidSigner/client/handlers/ForegroundRequestHandler.kt

@@ -0,0 +1,108 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nip55AndroidSigner.client.handlers
+
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.IntentRequestDatabase
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.DecryptZapRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.DeriveKeyRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.Nip04DecryptRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.Nip04EncryptRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.Nip44DecryptRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.Nip44EncryptRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.intents.requests.SignRequest
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.DecryptZapResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.DeriveKeyResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.Nip04DecryptResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.Nip04EncryptResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.Nip44DecryptResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.Nip44EncryptResultProcessor
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.foreground.processors.SignResultProcessor
+import com.vitorpamplona.quartz.nip57Zaps.LnZapPrivateEvent
+import com.vitorpamplona.quartz.nip57Zaps.LnZapRequestEvent
+
+class ForegroundRequestHandler(
+    val loggedInUser: HexKey,
+    val packageName: String,
+) {
+    val launcher = IntentRequestDatabase()
+
+    fun sign(
+        unsignedEvent: Event,
+        onReady: (Event) -> Unit,
+    ) = launcher.launch(
+        SignRequest.assemble(unsignedEvent, loggedInUser, packageName),
+        SignResultProcessor(unsignedEvent, onReady),
+    )
+
+    fun nip04Encrypt(
+        plaintext: String,
+        toPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ) = launcher.launch(
+        Nip04EncryptRequest.assemble(plaintext, toPubKey, loggedInUser, packageName),
+        Nip04EncryptResultProcessor(onReady),
+    )
+
+    fun nip04Decrypt(
+        ciphertext: String,
+        fromPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ) = launcher.launch(
+        Nip04DecryptRequest.assemble(ciphertext, fromPubKey, loggedInUser, packageName),
+        Nip04DecryptResultProcessor(onReady),
+    )
+
+    fun nip44Encrypt(
+        plaintext: String,
+        toPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ) = launcher.launch(
+        Nip44EncryptRequest.assemble(plaintext, toPubKey, loggedInUser, packageName),
+        Nip44EncryptResultProcessor(onReady),
+    )
+
+    fun nip44Decrypt(
+        ciphertext: String,
+        fromPubKey: HexKey,
+        onReady: (String) -> Unit,
+    ) = launcher.launch(
+        Nip44DecryptRequest.assemble(ciphertext, fromPubKey, loggedInUser, packageName),
+        Nip44DecryptResultProcessor(onReady),
+    )
+
+    fun decryptZapEvent(
+        event: LnZapRequestEvent,
+        onReady: (LnZapPrivateEvent) -> Unit,
+    ) = launcher.launch(
+        DecryptZapRequest.assemble(event, loggedInUser, packageName),
+        DecryptZapResultProcessor(onReady),
+    )
+
+    fun deriveKey(
+        nonce: HexKey,
+        onReady: (HexKey) -> Unit,
+    ) = launcher.launch(
+        DeriveKeyRequest.assemble(nonce, loggedInUser, packageName),
+        DeriveKeyResultProcessor(onReady),
+    )
+}