feat: scaffold I2P as a parallel privacy transport to Tor

Foundational types for offering I2P alongside the existing internal Tor.
No wiring yet — HTTP managers, RoleBasedHttpClientBuilder, the Android
I2P service and the Privacy settings UI follow in later commits.

Quartz (relay URL classifier):
- Add isI2p() and classifyHidden() to RelayUrlNormalizer
- Add HiddenServiceKind { CLEARNET, LOCALHOST, ONION, I2P }
- Add NormalizedRelayUrl.isI2p() / classifyHidden() extensions
- Extend the scheme-default branch so .i2p hosts default to ws:// like .onion

Commons (transport-agnostic types):
- PrivacyTransport enum { DIRECT, TOR, I2P }
- TransportChoice (UI-facing per-feature picker, screen-coded for persistence)
- FeatureRole + FeatureTransportChoices: per-feature picks for clearnet traffic
- PrivacySettings aggregate { tor, i2p, features }
- PrivacyRouter.route(url, role, settings): hostname pin for hidden services,
  per-feature choice for clearnet, downgrades to DIRECT if backing transport is OFF

Commons (I2P settings model, mirrors tor/):
- I2pSettings, I2pType (OFF/INTERNAL/EXTERNAL), I2pRelaySettings
- I2pRelayEvaluation, I2pServiceStatus
- II2pManager, II2pSettingsPersistence (platform-agnostic interfaces)
- PrivacyRelayEvaluation composing TorRelayEvaluation + I2pRelayEvaluation

Tests:
- PrivacyRouterTest covers localhost bypass, onion pin, i2p pin, hostname-wins-over-picker,
  per-feature picks routing independently, downgrade-when-transport-OFF, .b32.i2p

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/i2p/I2pRelayEvaluation.kt

@@ -0,0 +1,48 @@
+/*
+ * 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.amethyst.commons.i2p
+
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.isI2p
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.isLocalHost
+
+class I2pRelayEvaluation(
+    val i2pSettings: I2pRelaySettings,
+    val trustedRelayList: Set<NormalizedRelayUrl>,
+    val dmRelayList: Set<NormalizedRelayUrl>,
+) {
+    fun useI2p(relay: NormalizedRelayUrl): Boolean =
+        if (i2pSettings.i2pType == I2pType.OFF) {
+            false
+        } else {
+            if (relay.isLocalHost()) {
+                false
+            } else if (relay.isI2p()) {
+                i2pSettings.i2pRelaysViaI2p
+            } else if (relay in dmRelayList) {
+                i2pSettings.dmRelaysViaI2p
+            } else if (relay in trustedRelayList) {
+                i2pSettings.trustedRelaysViaI2p
+            } else {
+                i2pSettings.newRelaysViaI2p
+            }
+        }
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/i2p/I2pRelaySettings.kt

@@ -0,0 +1,29 @@
+/*
+ * 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.amethyst.commons.i2p
+
+data class I2pRelaySettings(
+    val i2pType: I2pType = I2pType.OFF,
+    val i2pRelaysViaI2p: Boolean = true,
+    val dmRelaysViaI2p: Boolean = false,
+    val newRelaysViaI2p: Boolean = false,
+    val trustedRelaysViaI2p: Boolean = false,
+)

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/i2p/I2pServiceStatus.kt

@@ -0,0 +1,35 @@
+/*
+ * 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.amethyst.commons.i2p
+
+sealed class I2pServiceStatus {
+    data class Active(
+        val port: Int,
+    ) : I2pServiceStatus()
+
+    data object Off : I2pServiceStatus()
+
+    data object Connecting : I2pServiceStatus()
+
+    data class Error(
+        val message: String,
+    ) : I2pServiceStatus()
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/i2p/I2pSettings.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.amethyst.commons.i2p
+
+// Mirror of TorSettings. Per-relay-class booleans answer "should I2P handle this
+// kind of relay" — kept independent of TorSettings since the same questions can
+// be answered differently for each transport. Per-feature picks (images,
+// videos, etc.) live on PrivacySettings.features, not here.
+data class I2pSettings(
+    val i2pType: I2pType = I2pType.OFF,
+    val externalSocksPort: Int = 4447,
+    val i2pRelaysViaI2p: Boolean = true,
+    val dmRelaysViaI2p: Boolean = false,
+    val newRelaysViaI2p: Boolean = false,
+    val trustedRelaysViaI2p: Boolean = false,
+)
+
+enum class I2pType(
+    val screenCode: Int,
+) {
+    OFF(0),
+    INTERNAL(1),
+    EXTERNAL(2),
+}
+
+fun parseI2pType(code: Int?): I2pType =
+    when (code) {
+        I2pType.INTERNAL.screenCode -> I2pType.INTERNAL
+        I2pType.EXTERNAL.screenCode -> I2pType.EXTERNAL
+        else -> I2pType.OFF
+    }

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/i2p/II2pManager.kt

@@ -0,0 +1,36 @@
+/*
+ * 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.amethyst.commons.i2p
+
+import kotlinx.coroutines.flow.StateFlow
+
+// Platform-agnostic interface for the I2P daemon lifecycle.
+// Android internal mode bundles net.i2p:router; external mode just opens a SOCKS
+// proxy to a user-run daemon. activePortOrNull surfaces whichever local SOCKS
+// port the HTTP manager should route I2P traffic through.
+interface II2pManager {
+    val status: StateFlow<I2pServiceStatus>
+    val activePortOrNull: StateFlow<Int?>
+
+    suspend fun dormant()
+
+    suspend fun active()
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/i2p/II2pSettingsPersistence.kt

@@ -0,0 +1,27 @@
+/*
+ * 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.amethyst.commons.i2p
+
+interface II2pSettingsPersistence {
+    fun load(): I2pSettings
+
+    fun save(settings: I2pSettings)
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/FeatureRole.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.amethyst.commons.privacy
+
+// What the network call is for. Used by PrivacyRouter to pick a transport for
+// clearnet traffic (hidden-service hostnames hard-pin and ignore the role).
+enum class FeatureRole {
+    IMAGE,
+    VIDEO,
+    URL_PREVIEW,
+    PROFILE_PIC,
+    NIP05,
+    MONEY,
+    UPLOAD,
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/FeatureTransportChoices.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.amethyst.commons.privacy
+
+data class FeatureTransportChoices(
+    val image: TransportChoice = TransportChoice.DIRECT,
+    val video: TransportChoice = TransportChoice.DIRECT,
+    val urlPreview: TransportChoice = TransportChoice.DIRECT,
+    val profilePic: TransportChoice = TransportChoice.DIRECT,
+    val nip05: TransportChoice = TransportChoice.DIRECT,
+    val money: TransportChoice = TransportChoice.DIRECT,
+    val upload: TransportChoice = TransportChoice.DIRECT,
+) {
+    fun choiceFor(role: FeatureRole): TransportChoice =
+        when (role) {
+            FeatureRole.IMAGE -> image
+            FeatureRole.VIDEO -> video
+            FeatureRole.URL_PREVIEW -> urlPreview
+            FeatureRole.PROFILE_PIC -> profilePic
+            FeatureRole.NIP05 -> nip05
+            FeatureRole.MONEY -> money
+            FeatureRole.UPLOAD -> upload
+        }
+
+    fun with(
+        role: FeatureRole,
+        choice: TransportChoice,
+    ): FeatureTransportChoices =
+        when (role) {
+            FeatureRole.IMAGE -> copy(image = choice)
+            FeatureRole.VIDEO -> copy(video = choice)
+            FeatureRole.URL_PREVIEW -> copy(urlPreview = choice)
+            FeatureRole.PROFILE_PIC -> copy(profilePic = choice)
+            FeatureRole.NIP05 -> copy(nip05 = choice)
+            FeatureRole.MONEY -> copy(money = choice)
+            FeatureRole.UPLOAD -> copy(upload = choice)
+        }
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/PrivacyRelayEvaluation.kt

@@ -0,0 +1,46 @@
+/*
+ * 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.amethyst.commons.privacy
+
+import com.vitorpamplona.amethyst.commons.i2p.I2pRelayEvaluation
+import com.vitorpamplona.amethyst.commons.tor.TorRelayEvaluation
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.isI2p
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.isOnion
+
+// Per-relay transport pick. Onion always wins for Tor, I2P always wins for I2P
+// (matching PrivacyRouter's hostname pin). For non-hidden hosts, prefer I2P if
+// both transports want the relay — arbitrary tiebreak documented here so the
+// behavior is testable.
+class PrivacyRelayEvaluation(
+    private val tor: TorRelayEvaluation,
+    private val i2p: I2pRelayEvaluation,
+) {
+    fun transport(relay: NormalizedRelayUrl): PrivacyTransport {
+        if (relay.isOnion()) return if (tor.useTor(relay)) PrivacyTransport.TOR else PrivacyTransport.DIRECT
+        if (relay.isI2p()) return if (i2p.useI2p(relay)) PrivacyTransport.I2P else PrivacyTransport.DIRECT
+        return when {
+            i2p.useI2p(relay) -> PrivacyTransport.I2P
+            tor.useTor(relay) -> PrivacyTransport.TOR
+            else -> PrivacyTransport.DIRECT
+        }
+    }
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/PrivacyRouter.kt

@@ -0,0 +1,52 @@
+/*
+ * 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.amethyst.commons.privacy
+
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.HiddenServiceKind
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer
+
+// Decides which PrivacyTransport carries a request. Hidden-service hostnames
+// hard-pin (onion → Tor, i2p → I2P) regardless of the per-feature picker, since
+// no other transport can reach them. If the pinned or chosen transport is OFF,
+// downgrade to DIRECT — the caller decides whether to make the request anyway.
+object PrivacyRouter {
+    fun route(
+        url: String,
+        role: FeatureRole,
+        settings: PrivacySettings,
+    ): PrivacyTransport =
+        when (RelayUrlNormalizer.classifyHidden(url)) {
+            HiddenServiceKind.LOCALHOST -> PrivacyTransport.DIRECT
+            HiddenServiceKind.ONION -> if (settings.torAvailable) PrivacyTransport.TOR else PrivacyTransport.DIRECT
+            HiddenServiceKind.I2P -> if (settings.i2pAvailable) PrivacyTransport.I2P else PrivacyTransport.DIRECT
+            HiddenServiceKind.CLEARNET -> resolve(settings.features.choiceFor(role), settings)
+        }
+
+    private fun resolve(
+        choice: TransportChoice,
+        settings: PrivacySettings,
+    ): PrivacyTransport =
+        when (choice) {
+            TransportChoice.DIRECT -> PrivacyTransport.DIRECT
+            TransportChoice.TOR -> if (settings.torAvailable) PrivacyTransport.TOR else PrivacyTransport.DIRECT
+            TransportChoice.I2P -> if (settings.i2pAvailable) PrivacyTransport.I2P else PrivacyTransport.DIRECT
+        }
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/PrivacySettings.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.amethyst.commons.privacy
+
+import com.vitorpamplona.amethyst.commons.i2p.I2pSettings
+import com.vitorpamplona.amethyst.commons.i2p.I2pType
+import com.vitorpamplona.amethyst.commons.tor.TorSettings
+import com.vitorpamplona.amethyst.commons.tor.TorType
+
+// Aggregate of all privacy configuration. TorSettings and I2pSettings stay
+// independent (each owns its daemon-type + per-relay-class booleans, persisted
+// under its own pref-key namespace). FeatureTransportChoices is the single
+// source of truth for per-feature clearnet routing — UI presents one 3-way
+// picker per role rather than two parallel toggles.
+data class PrivacySettings(
+    val tor: TorSettings = TorSettings(),
+    val i2p: I2pSettings = I2pSettings(),
+    val features: FeatureTransportChoices = FeatureTransportChoices(),
+) {
+    val torAvailable: Boolean get() = tor.torType != TorType.OFF
+    val i2pAvailable: Boolean get() = i2p.i2pType != I2pType.OFF
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/PrivacyTransport.kt

@@ -0,0 +1,27 @@
+/*
+ * 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.amethyst.commons.privacy
+
+enum class PrivacyTransport {
+    DIRECT,
+    TOR,
+    I2P,
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/privacy/TransportChoice.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.amethyst.commons.privacy
+
+// UI-facing per-feature choice. Kept separate from PrivacyTransport so a future
+// AUTO value can be added without churning the transport plumbing.
+enum class TransportChoice(
+    val screenCode: Int,
+) {
+    DIRECT(0),
+    TOR(1),
+    I2P(2),
+}
+
+fun parseTransportChoice(code: Int?): TransportChoice =
+    when (code) {
+        TransportChoice.TOR.screenCode -> TransportChoice.TOR
+        TransportChoice.I2P.screenCode -> TransportChoice.I2P
+        else -> TransportChoice.DIRECT
+    }
+
+fun TransportChoice.toTransport(): PrivacyTransport =
+    when (this) {
+        TransportChoice.DIRECT -> PrivacyTransport.DIRECT
+        TransportChoice.TOR -> PrivacyTransport.TOR
+        TransportChoice.I2P -> PrivacyTransport.I2P
+    }

commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/privacy/PrivacyRouterTest.kt

@@ -0,0 +1,120 @@
+/*
+ * 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.amethyst.commons.privacy
+
+import com.vitorpamplona.amethyst.commons.i2p.I2pSettings
+import com.vitorpamplona.amethyst.commons.i2p.I2pType
+import com.vitorpamplona.amethyst.commons.tor.TorSettings
+import com.vitorpamplona.amethyst.commons.tor.TorType
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class PrivacyRouterTest {
+    private val clearnet = "wss://relay.damus.io/"
+    private val onion = "wss://abc123.onion/"
+    private val i2p = "wss://abc.i2p/"
+    private val localhost = "ws://127.0.0.1:8080/"
+
+    private fun settings(
+        torOn: Boolean = false,
+        i2pOn: Boolean = false,
+        features: FeatureTransportChoices = FeatureTransportChoices(),
+    ) = PrivacySettings(
+        tor = TorSettings(torType = if (torOn) TorType.INTERNAL else TorType.OFF),
+        i2p = I2pSettings(i2pType = if (i2pOn) I2pType.INTERNAL else I2pType.OFF),
+        features = features,
+    )
+
+    @Test
+    fun localhost_alwaysDirect() {
+        assertEquals(PrivacyTransport.DIRECT, PrivacyRouter.route(localhost, FeatureRole.IMAGE, settings(torOn = true, i2pOn = true)))
+    }
+
+    @Test
+    fun onion_pinsToTor_whenAvailable() {
+        assertEquals(PrivacyTransport.TOR, PrivacyRouter.route(onion, FeatureRole.IMAGE, settings(torOn = true)))
+    }
+
+    @Test
+    fun onion_downgradesToDirect_whenTorOff() {
+        assertEquals(PrivacyTransport.DIRECT, PrivacyRouter.route(onion, FeatureRole.IMAGE, settings(torOn = false, i2pOn = true)))
+    }
+
+    @Test
+    fun i2p_pinsToI2p_whenAvailable() {
+        assertEquals(PrivacyTransport.I2P, PrivacyRouter.route(i2p, FeatureRole.IMAGE, settings(i2pOn = true)))
+    }
+
+    @Test
+    fun i2p_downgradesToDirect_whenI2pOff() {
+        assertEquals(PrivacyTransport.DIRECT, PrivacyRouter.route(i2p, FeatureRole.IMAGE, settings(torOn = true, i2pOn = false)))
+    }
+
+    @Test
+    fun i2p_ignoresFeatureChoice() {
+        // Per-feature picker is irrelevant for hidden-service hosts.
+        val features = FeatureTransportChoices(image = TransportChoice.TOR)
+        assertEquals(PrivacyTransport.I2P, PrivacyRouter.route(i2p, FeatureRole.IMAGE, settings(torOn = true, i2pOn = true, features = features)))
+    }
+
+    @Test
+    fun clearnet_followsFeatureChoice_tor() {
+        val features = FeatureTransportChoices(image = TransportChoice.TOR)
+        assertEquals(PrivacyTransport.TOR, PrivacyRouter.route(clearnet, FeatureRole.IMAGE, settings(torOn = true, features = features)))
+    }
+
+    @Test
+    fun clearnet_followsFeatureChoice_i2p() {
+        val features = FeatureTransportChoices(video = TransportChoice.I2P)
+        assertEquals(PrivacyTransport.I2P, PrivacyRouter.route(clearnet, FeatureRole.VIDEO, settings(i2pOn = true, features = features)))
+    }
+
+    @Test
+    fun clearnet_choiceWithoutBackingTransport_downgradesToDirect() {
+        val features = FeatureTransportChoices(image = TransportChoice.TOR)
+        assertEquals(PrivacyTransport.DIRECT, PrivacyRouter.route(clearnet, FeatureRole.IMAGE, settings(torOn = false, features = features)))
+    }
+
+    @Test
+    fun clearnet_defaultChoice_isDirect() {
+        assertEquals(PrivacyTransport.DIRECT, PrivacyRouter.route(clearnet, FeatureRole.NIP05, settings(torOn = true, i2pOn = true)))
+    }
+
+    @Test
+    fun perFeatureRouting_routesIndependently() {
+        val features =
+            FeatureTransportChoices(
+                image = TransportChoice.TOR,
+                video = TransportChoice.I2P,
+                urlPreview = TransportChoice.DIRECT,
+            )
+        val s = settings(torOn = true, i2pOn = true, features = features)
+        assertEquals(PrivacyTransport.TOR, PrivacyRouter.route(clearnet, FeatureRole.IMAGE, s))
+        assertEquals(PrivacyTransport.I2P, PrivacyRouter.route(clearnet, FeatureRole.VIDEO, s))
+        assertEquals(PrivacyTransport.DIRECT, PrivacyRouter.route(clearnet, FeatureRole.URL_PREVIEW, s))
+    }
+
+    @Test
+    fun b32_i2p_address_pinsToI2p() {
+        val b32 = "wss://abcdefghijklmnopqrstuvwxyz234567.b32.i2p/"
+        assertEquals(PrivacyTransport.I2P, PrivacyRouter.route(b32, FeatureRole.IMAGE, settings(i2pOn = true)))
+    }
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/normalizer/HiddenServiceKind.kt

@@ -0,0 +1,28 @@
+/*
+ * 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.nip01Core.relay.normalizer
+
+enum class HiddenServiceKind {
+    CLEARNET,
+    LOCALHOST,
+    ONION,
+    I2P,
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/normalizer/NormalizedRelayUrl.kt

@@ -46,4 +46,8 @@ fun NormalizedRelayUrl.toHttp() =
 
 fun NormalizedRelayUrl.isOnion() = url.contains(".onion/")
 
+fun NormalizedRelayUrl.isI2p() = RelayUrlNormalizer.isI2p(this.url)
+
 fun NormalizedRelayUrl.isLocalHost() = RelayUrlNormalizer.isLocalHost(this.url)
+
+fun NormalizedRelayUrl.classifyHidden(): HiddenServiceKind = RelayUrlNormalizer.classifyHidden(this.url)

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/relay/normalizer/RelayUrlNormalizer.kt

@@ -48,6 +48,16 @@ class RelayUrlNormalizer {
 
         fun isOnion(url: String) = url.endsWith(".onion") || url.contains(".onion/")
 
+        fun isI2p(url: String) = url.endsWith(".i2p") || url.contains(".i2p/")
+
+        fun classifyHidden(url: String): HiddenServiceKind =
+            when {
+                isLocalHost(url) -> HiddenServiceKind.LOCALHOST
+                isOnion(url) -> HiddenServiceKind.ONION
+                isI2p(url) -> HiddenServiceKind.I2P
+                else -> HiddenServiceKind.CLEARNET
+            }
+
         fun isRelaySchemePrefix(url: String) = url.length > 6 && url[0] == 'w' && url[1] == 's'
 
         fun isRelaySchemePrefixSecure(url: String) = url[2] == 's' && url[3] == ':' && url[4] == '/' && url[5] == '/' && url[6] != '/'
@@ -149,7 +159,7 @@ class RelayUrlNormalizer {
                 return null
             }
 
-            return if (isOnion(trimmed) || isLocalHost(trimmed)) {
+            return if (isOnion(trimmed) || isI2p(trimmed) || isLocalHost(trimmed)) {
                 "ws://$trimmed"
             } else {
                 "wss://$trimmed"