Add chatIdOrNull to duckchat api module and drop chatID string duplication

app/src/main/java/com/duckduckgo/app/browser/nativeinput/NativeInputManager.kt

@@ -41,6 +41,7 @@ import com.duckduckgo.common.ui.view.toPx
 import com.duckduckgo.di.scopes.FragmentScope
 import com.duckduckgo.duckchat.api.DuckAiFeatureState
 import com.duckduckgo.duckchat.api.DuckChat
+import com.duckduckgo.duckchat.api.toChatIdOrNull
 import com.duckduckgo.duckchat.impl.ui.nativeinput.views.NativeInputWidget
 import com.duckduckgo.navigation.api.GlobalActivityStarter
 import com.duckduckgo.subscriptions.api.SubscriptionScreens.SubscriptionPurchase
@@ -787,8 +788,7 @@ class RealNativeInputManager @Inject constructor(
     internal fun extractDuckAiChatId(rawUrl: String?): String? {
         if (rawUrl.isNullOrBlank()) return null
         val uri = runCatching { rawUrl.toUri() }.getOrNull() ?: return null
-        if (!duckChat.isDuckChatUrl(uri)) return null
-        return uri.getQueryParameter("chatID")?.takeIf { it.isNotBlank() }
+        return uri.toChatIdOrNull(duckChat)
     }
 
     companion object {

app/src/main/java/com/duckduckgo/app/fire/DuckAiTabsCleanupPlugin.kt

@@ -16,13 +16,13 @@
 
 package com.duckduckgo.app.fire
 
-import android.net.Uri
 import androidx.core.net.toUri
 import com.duckduckgo.app.tabs.model.TabRepository
 import com.duckduckgo.dataclearing.api.plugin.ClearableData
 import com.duckduckgo.dataclearing.api.plugin.DataClearingPlugin
 import com.duckduckgo.di.scopes.AppScope
 import com.duckduckgo.duckchat.api.DuckChat
+import com.duckduckgo.duckchat.api.toChatIdOrNull
 import com.squareup.anvil.annotations.ContributesMultibinding
 import logcat.logcat
 import javax.inject.Inject
@@ -61,19 +61,14 @@ class DuckAiTabsCleanupPlugin @Inject constructor(
      */
     private suspend fun closeTabsMatching(chatUrls: Set<String>) {
         if (chatUrls.isEmpty()) return
-        val targetChatIds = chatUrls.mapNotNullTo(mutableSetOf()) { it.toUri().chatIdOrNull() }
+        val targetChatIds = chatUrls.mapNotNullTo(mutableSetOf()) { it.toUri().toChatIdOrNull(duckChat) }
         if (targetChatIds.isEmpty()) return
         val ids = tabRepository.getTabs()
-            .filter { tab -> tab.url?.toUri()?.chatIdOrNull() in targetChatIds }
+            .filter { tab -> tab.url?.toUri()?.toChatIdOrNull(duckChat) in targetChatIds }
             .map { it.tabId }
         if (ids.isNotEmpty()) {
             logcat { "Closing ${ids.size} Duck.ai tab(s) matching the cleared subset" }
             tabRepository.deleteTabs(ids)
         }
     }
-
-    private fun Uri.chatIdOrNull(): String? {
-        if (!duckChat.isDuckChatUrl(this)) return null
-        return getQueryParameter("chatID")?.takeIf { it.isNotBlank() }
-    }
 }

duckchat/duckchat-api/src/main/java/com/duckduckgo/duckchat/api/UriExtension.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2026 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.duckduckgo.duckchat.api
+
+import android.net.Uri
+
+/**
+ * Returns the chatID from this [Uri] when it is a Duck.ai chat URL with a non-blank chatID;
+ * null otherwise (including for non-Duck.ai URLs).
+ */
+fun Uri.toChatIdOrNull(duckChat: DuckChat): String? {
+    if (!duckChat.isDuckChatUrl(this)) return null
+    return getQueryParameter("chatID")?.takeIf { it.isNotBlank() }
+}

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/DuckChatConstants.kt

@@ -18,7 +18,6 @@ package com.duckduckgo.duckchat.impl
 
 object DuckChatConstants {
     const val JS_MESSAGING_FEATURE_NAME = "aiChat"
-    const val CHAT_ID_PARAM = "chatID"
     const val DUCK_AI_FEATURE_PAGE = "duckai"
 
     object JsResponseKeys {

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/RealDuckChat.kt

@@ -833,7 +833,7 @@ class RealDuckChat @Inject constructor(
     }
 
     override fun buildChatUrl(chatId: String): String {
-        return appendParameters(mapOf(CHAT_ID_QUERY_NAME to chatId), getDuckChatLink())
+        return appendParameters(mapOf(CHAT_ID_QUERY_NAME to chatId) + nativeInputParameters(), getDuckChatLink())
     }
 
     override suspend fun setDefaultTogglePosition(position: DefaultTogglePosition) {

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/clearing/DuckChatDataClearingPlugin.kt

@@ -22,7 +22,7 @@ import com.duckduckgo.dataclearing.api.plugin.ClearableData
 import com.duckduckgo.dataclearing.api.plugin.DataClearingPlugin
 import com.duckduckgo.di.scopes.AppScope
 import com.duckduckgo.duckchat.api.DuckChat
-import com.duckduckgo.duckchat.impl.DuckChatConstants.CHAT_ID_PARAM
+import com.duckduckgo.duckchat.api.toChatIdOrNull
 import com.duckduckgo.duckchat.impl.repository.DuckChatFeatureRepository
 import com.duckduckgo.duckchat.impl.sync.DuckChatSyncRepository
 import com.duckduckgo.sync.api.engine.SyncEngine
@@ -75,7 +75,7 @@ class DuckChatDataClearingPlugin @Inject constructor(
         if (chatUrls.isEmpty()) return
         var anyDeleted = false
         chatUrls.forEach { chatUrl ->
-            val chatId = extractChatId(chatUrl) ?: return@forEach
+            val chatId = chatUrl.toUri().toChatIdOrNull(duckChat) ?: return@forEach
             if (duckChatDeleter.deleteChat(chatId)) {
                 duckChatSyncRepository.recordSingleChatDeletion(chatId)
                 anyDeleted = true
@@ -84,10 +84,4 @@ class DuckChatDataClearingPlugin @Inject constructor(
         // One sync trigger per user-visible delete action, not N.
         if (anyDeleted) syncEngine.triggerSync(SyncEngine.SyncTrigger.DATA_CHANGE)
     }
-
-    private fun extractChatId(url: String): String? {
-        val uri = url.toUri()
-        if (!duckChat.isDuckChatUrl(uri)) return null
-        return uri.getQueryParameter(CHAT_ID_PARAM)?.takeIf { it.isNotBlank() }
-    }
 }

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/contextual/DuckChatContextualViewModel.kt

@@ -24,7 +24,7 @@ import com.duckduckgo.anvil.annotations.ContributesViewModel
 import com.duckduckgo.common.utils.DispatcherProvider
 import com.duckduckgo.di.scopes.FragmentScope
 import com.duckduckgo.duckchat.api.DuckChat
-import com.duckduckgo.duckchat.impl.DuckChatConstants.CHAT_ID_PARAM
+import com.duckduckgo.duckchat.api.toChatIdOrNull
 import com.duckduckgo.duckchat.impl.DuckChatInternal
 import com.duckduckgo.duckchat.impl.feature.DuckChatFeature
 import com.duckduckgo.duckchat.impl.helper.DuckChatJSHelper
@@ -666,8 +666,10 @@ class DuckChatContextualViewModel @Inject constructor(
 
     private fun hasChatId(url: String?): Boolean = !extractChatId(url).isNullOrBlank()
 
-    private fun extractChatId(url: String?): String? =
-        url?.toUri()?.getQueryParameter(CHAT_ID_PARAM)?.takeIf { it.isNotBlank() }
+    private fun extractChatId(url: String?): String? {
+        val uri = url?.toUri() ?: return null
+        return uri.toChatIdOrNull(duckChat)
+    }
 
     // Owns the coupled (fullModeUrl, _chatId) invariant: _chatId is always extractChatId(fullModeUrl).
     private fun setSheetUrl(url: String) {

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/inputscreen/ui/viewmodel/InputScreenViewModel.kt

@@ -44,7 +44,6 @@ import com.duckduckgo.common.utils.DispatcherProvider
 import com.duckduckgo.common.utils.SingleLiveEvent
 import com.duckduckgo.common.utils.extensions.toBinaryString
 import com.duckduckgo.duckchat.api.DuckAiFeatureState
-import com.duckduckgo.duckchat.impl.DuckChatConstants.CHAT_ID_PARAM
 import com.duckduckgo.duckchat.impl.DuckChatInternal
 import com.duckduckgo.duckchat.impl.feature.DuckAiChatHistoryFeature
 import com.duckduckgo.duckchat.impl.feature.DuckChatFeature
@@ -863,12 +862,7 @@ class InputScreenViewModel @AssistedInject constructor(
         saveLastUsedTogglePosition()
         duckChatJSHelper.clearTabContextPromptEvent()
         viewModelScope.launch {
-            val url = duckChat.getDuckChatUrl("", false)
-                .toUri()
-                .buildUpon()
-                .appendQueryParameter(CHAT_ID_PARAM, chatId)
-                .build()
-                .toString()
+            val url = duckChat.buildChatUrl(chatId)
             command.value = Command.SubmitSearch(url)
 
             if (pinned) {

duckchat/duckchat-impl/src/main/java/com/duckduckgo/duckchat/impl/ui/NativeInputModeWidgetViewModel.kt

@@ -16,7 +16,6 @@
 
 package com.duckduckgo.duckchat.impl.ui
 
-import androidx.core.net.toUri
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.duckduckgo.anvil.annotations.ContributesViewModel
@@ -40,7 +39,6 @@ import com.duckduckgo.duckchat.api.nativeinput.NativeInputState
 import com.duckduckgo.duckchat.api.nativeinput.NativeInputStateProvider
 import com.duckduckgo.duckchat.api.nativeinput.NativeInputStatePublisher
 import com.duckduckgo.duckchat.impl.ChatState
-import com.duckduckgo.duckchat.impl.DuckChatConstants.CHAT_ID_PARAM
 import com.duckduckgo.duckchat.impl.DuckChatInternal
 import com.duckduckgo.duckchat.impl.feature.DuckAiChatHistoryFeature
 import com.duckduckgo.duckchat.impl.feature.maxUrlSuggestions
@@ -396,12 +394,7 @@ class NativeInputModeWidgetViewModel @Inject constructor(
     }
 
     fun buildChatSuggestionUrl(suggestion: ChatSuggestion): String =
-        duckChatInternal.getDuckChatUrl("", false)
-            .toUri()
-            .buildUpon()
-            .appendQueryParameter(CHAT_ID_PARAM, suggestion.chatId)
-            .build()
-            .toString()
+        duckChatInternal.buildChatUrl(suggestion.chatId)
 
     private fun getInputMode(
         isEnabled: Boolean,

duckchat/duckchat-impl/src/test/kotlin/com/duckduckgo/duckchat/impl/RealDuckChatTest.kt

@@ -1465,6 +1465,28 @@ class RealDuckChatTest {
         assertTrue(url == "https://duck.ai/chat?native-input=true&duckai=5")
     }
 
+    @Test
+    fun `when native input disabled and build chat url then url contains chatID without native input param`() = runTest {
+        whenever(mockDuckChatFeatureRepository.isNativeInputFieldUserSettingEnabled()).thenReturn(false)
+        testee.onPrivacyConfigDownloaded()
+        coroutineRule.testScope.advanceUntilIdle()
+
+        val url = testee.buildChatUrl(chatId = "abc-123")
+
+        assertTrue(url == "https://duck.ai/chat?chatID=abc-123&duckai=5")
+    }
+
+    @Test
+    fun `when native input enabled and build chat url then url contains both chatID and native input param`() = runTest {
+        whenever(mockDuckChatFeatureRepository.isNativeInputFieldUserSettingEnabled()).thenReturn(true)
+        testee.onPrivacyConfigDownloaded()
+        coroutineRule.testScope.advanceUntilIdle()
+
+        val url = testee.buildChatUrl(chatId = "abc-123")
+
+        assertTrue(url == "https://duck.ai/chat?chatID=abc-123&native-input=true&duckai=5")
+    }
+
     @Test
     fun `when url can be handled by webview return true`() {
         assertTrue(testee.canHandleOnAiWebView("https://duck.ai/somepath"))

duckchat/duckchat-impl/src/test/kotlin/com/duckduckgo/duckchat/impl/clearing/DuckChatDataClearingPluginTest.kt

@@ -203,7 +203,6 @@ class DuckChatDataClearingPluginTest {
 
     @Test
     fun `DuckChats Selected deletes each chat in the set and records per-chat sync deletions`() = runTest {
-        whenever(duckChat.isDuckChatUrl(any())).thenReturn(true)
         whenever(duckChat.isDuckChatUrl(eq(Uri.parse("https://duck.ai?chatID=alpha")))).thenReturn(true)
         whenever(duckChat.isDuckChatUrl(eq(Uri.parse("https://duck.ai?chatID=beta")))).thenReturn(true)
         whenever(duckChatDeleter.deleteChat("alpha")).thenReturn(true)

duckchat/duckchat-impl/src/test/kotlin/com/duckduckgo/duckchat/impl/contextual/DuckChatContextualViewModelTest.kt

@@ -1577,7 +1577,8 @@ class DuckChatContextualViewModelTest {
             sidebar: Boolean,
         ): String = nextUrl
 
-        override fun isDuckChatUrl(uri: android.net.Uri): Boolean = false
+        override fun isDuckChatUrl(uri: android.net.Uri): Boolean =
+            uri.host == "duck.ai" || uri.host == "duckduckgo.com"
         override suspend fun wasOpenedBefore(): Boolean = false
         override fun showNewAddressBarOptionChoiceScreen(
             context: android.content.Context,

duckchat/duckchat-impl/src/test/kotlin/com/duckduckgo/duckchat/impl/ui/NativeInputModeWidgetViewModelTest.kt

@@ -409,8 +409,9 @@ class NativeInputModeWidgetViewModelTest {
     }
 
     @Test
-    fun whenBuildChatSuggestionUrlThenAppendsChatIdParam() {
-        whenever(duckChatInternal.getDuckChatUrl("", false)).thenReturn("https://duckduckgo.com/?q=DuckDuckGo+AI+Chat&ia=chat&duckai=5")
+    fun whenBuildChatSuggestionUrlThenDelegatesToDuckChat() {
+        whenever(duckChatInternal.buildChatUrl("abc-123"))
+            .thenReturn("https://duckduckgo.com/?ia=chat&duckai=5&chatID=abc-123")
         val suggestion = ChatSuggestion(
             chatId = "abc-123",
             title = "Title",

duckchat/duckchat-impl/src/test/kotlin/com/duckduckgo/duckchat/impl/ui/inputscreen/InputScreenViewModelTest.kt

@@ -122,6 +122,7 @@ class InputScreenViewModelTest {
             )
             whenever(duckChat.wasOpenedBefore()).thenReturn(false)
             whenever(duckChat.getDuckChatUrl(any(), any(), any())).thenReturn(duckChatURL)
+            whenever(duckChat.buildChatUrl(any())).thenAnswer { "$duckChatURL&chatID=${it.arguments[0]}" }
             whenever(duckChat.observeChatSuggestionsUserSettingEnabled()).thenReturn(flowOf(true))
             whenever(chatSuggestionsReader.fetchSuggestions(any())).thenReturn(emptyList())
             whenever(inputScreenConfigResolver.useTopBar()).thenReturn(true)