feat(amazonq): clicking on changed file in Q chat opens up file diff in editor (#5675)

* clicking q chat diff opens diff view in editor

* feedback

* detekt

Author: samgst-amazon

plugins/amazonq/shared/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonq/lsp/AmazonQLanguageClient.kt

@@ -11,6 +11,8 @@ import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.ChatU
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.GET_SERIALIZED_CHAT_REQUEST_METHOD
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.GetSerializedChatParams
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.GetSerializedChatResult
+import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OPEN_FILE_DIFF
+import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OpenFileDiffParams
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OpenTabParams
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OpenTabResult
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.SHOW_SAVE_FILE_DIALOG_REQUEST_METHOD
@@ -38,4 +40,7 @@ interface AmazonQLanguageClient : LanguageClient {
 
     @JsonNotification(CHAT_SEND_UPDATE)
     fun sendChatUpdate(params: ChatUpdateParams): CompletableFuture<Unit>
+
+    @JsonNotification(OPEN_FILE_DIFF)
+    fun openFileDiff(params: OpenFileDiffParams): CompletableFuture<Unit>
 }

plugins/amazonq/shared/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonq/lsp/AmazonQLanguageClientImpl.kt

@@ -4,6 +4,9 @@
 package software.aws.toolkits.jetbrains.services.amazonq.lsp
 
 import com.google.gson.Gson
+import com.intellij.diff.DiffContentFactory
+import com.intellij.diff.DiffManager
+import com.intellij.diff.requests.SimpleDiffRequest
 import com.intellij.notification.NotificationType
 import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.fileChooser.FileChooserFactory
@@ -34,6 +37,7 @@ import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.ChatU
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.GET_SERIALIZED_CHAT_REQUEST_METHOD
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.GetSerializedChatParams
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.GetSerializedChatResult
+import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OpenFileDiffParams
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OpenTabParams
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.OpenTabResult
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat.ShowSaveFileDialogParams
@@ -42,6 +46,9 @@ import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.credential
 import software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.credentials.SsoProfileData
 import software.aws.toolkits.jetbrains.services.codewhisperer.customization.CodeWhispererModelConfigurator
 import software.aws.toolkits.jetbrains.settings.CodeWhispererSettings
+import software.aws.toolkits.resources.message
+import java.io.File
+import java.nio.file.Paths
 import java.util.UUID
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.TimeUnit
@@ -262,6 +269,45 @@ class AmazonQLanguageClientImpl(private val project: Project) : AmazonQLanguageC
         return CompletableFuture.completedFuture(Unit)
     }
 
+    override fun openFileDiff(params: OpenFileDiffParams): CompletableFuture<Unit> =
+        CompletableFuture.supplyAsync(
+            {
+                try {
+                    val contentFactory = DiffContentFactory.getInstance()
+                    val fileName = Paths.get(params.originalFileUri).fileName.toString()
+
+                    val originalContent = params.originalFileContent ?: run {
+                        val file = File(params.originalFileUri)
+                        if (file.exists()) file.readText() else ""
+                    }
+                    val (leftContent, rightContent) = when {
+                        params.isDeleted -> {
+                            // For deleted files, show original on left, empty on right
+                            contentFactory.create(originalContent) to
+                                contentFactory.createEmpty()
+                        }
+                        else -> {
+                            // For new or modified files
+                            val newContent = params.fileContent.orEmpty()
+                            contentFactory.create(originalContent) to
+                                contentFactory.create(newContent)
+                        }
+                    }
+                    val diffRequest = SimpleDiffRequest(
+                        "$fileName ${message("aws.q.lsp.client.diff_message")}",
+                        leftContent,
+                        rightContent,
+                        "Original",
+                        if (params.isDeleted) "Deleted" else "Modified"
+                    )
+                    DiffManager.getInstance().showDiff(project, diffRequest)
+                } catch (e: Exception) {
+                    LOG.warn { "Failed to open file diff: ${e.message}" }
+                }
+            },
+            ApplicationManager.getApplication()::invokeLater
+        )
+
     companion object {
         private val LOG = getLogger<AmazonQLanguageClientImpl>()
     }

plugins/amazonq/shared/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonq/lsp/model/aws/chat/FlareChatCommands.kt

@@ -31,4 +31,5 @@ const val CHAT_SEND_UPDATE = "aws/chat/sendChatUpdate"
 const val CHAT_CREATE_PROMPT = "aws/chat/createPrompt"
 const val SHOW_SAVE_FILE_DIALOG_REQUEST_METHOD = "aws/showSaveFileDialog"
 const val GET_SERIALIZED_CHAT_REQUEST_METHOD = "aws/chat/getSerializedChat"
+const val OPEN_FILE_DIFF = "aws/openFileDiff"
 const val STOP_CHAT_RESPONSE = "stopChatResponse"

plugins/amazonq/shared/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonq/lsp/model/aws/chat/OpenFileDiffParams.kt

@@ -0,0 +1,11 @@
+// Copyright 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package software.aws.toolkits.jetbrains.services.amazonq.lsp.model.aws.chat
+
+data class OpenFileDiffParams(
+    val originalFileUri: String,
+    val originalFileContent: String? = null,
+    val isDeleted: Boolean,
+    val fileContent: String? = null,
+)

plugins/core/resources/resources/software/aws/toolkits/resources/MessagesBundle.properties

@@ -253,6 +253,7 @@ aws.onboarding.getstarted.panel.login_with_iam=<a>Use Professional License</a>
 aws.onboarding.getstarted.panel.share_feedback=<a>Share Feedback</a>
 aws.onboarding.getstarted.panel.signup_iam_text=Sign up for free
 aws.onboarding.getstarted.panel.title=Authenticate with AWS Toolkit
+aws.q.lsp.client.diff_message=(Generated by Amazon Q)
 aws.q.migration.action.install.text=Install
 aws.q.migration.action.manage_plugins.text=Manage plugins
 aws.q.migration.action.read_more.text=Read more