Selected component engine (#1562)

<!-- This is an auto-generated description by cubic. -->

## Summary by cubic
Enable the Dyad Engine to prioritize a user-selected component by
flagging the file as focused and sending codebase files per request.
Keeps full context when the engine is on; falls back to path-scoped
context when it’s off.

- **New Features**
- Mark the selected component file as focused when the engine is
enabled.
- Send codebase files to the engine via dyadFiles, applied to
dyad_options unless disabled.
- Maintain full chatContext with engine; restrict to the selected file
path only when engine is off.

- **Refactors**
- Removed files from getModelClient and provider APIs; file transport
moved into request payload.
- Stream handlers now pass files to model calls and include
dyadDisableFiles/dyadFiles in the request.
  - Added focused flag to CodebaseFile.

<!-- End of auto-generated description by cubic. -->

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Sends codebase files per request to the Dyad Engine, focuses the
selected component when smart context is enabled, and refactors model
client/provider APIs to remove file parameters.
> 
> - **Engine integration**:
> - Send codebase files per request via `dyadFiles` in provider options;
propagate through `simpleStreamText` and `dyad-engine` options.
> - Add `isSmartContextEnabled` from `get_model_client` and gate context
behavior accordingly.
> - **Selected component focus**:
> - When smart context is on and a component is selected, mark its file
as `focused` in `CodebaseFile` and avoid broad smart context includes;
allow on-demand reads.
> - When smart context is off, restrict `chatContext` to the selected
file path.
> - **Refactors**:
> - Remove `files` parameter from `getModelClient` and Dyad provider;
move file transport into request body.
> - Update `llm_engine_provider` to read `dyadFiles` from request and
populate `dyad_options.files` unless `dyadDisableFiles`.
> - Extend `CodebaseFile` with optional `focused` flag; thread `files`
through `chat_stream_handlers` calls.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
022b26d0197ab5b5d4f5b589f45bc230de36e0e5. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

src/ipc/handlers/chat_stream_handlers.ts

@@ -25,7 +25,11 @@ import {
 import { getDyadAppPath } from "../../paths/paths";
 import { readSettings } from "../../main/settings";
 import type { ChatResponseEnd, ChatStreamParams } from "../ipc_types";
-import { extractCodebase, readFileWithCache } from "../../utils/codebase";
+import {
+  CodebaseFile,
+  extractCodebase,
+  readFileWithCache,
+} from "../../utils/codebase";
 import { processFullResponseActions } from "../processors/response_processor";
 import { streamTestResponse } from "./testing_chat_handlers";
 import { getTestResponse } from "./testing_chat_handlers";
@@ -437,21 +441,26 @@ ${componentSnippet}
         );
       } else {
         // Normal AI processing for non-test prompts
+        const { modelClient, isEngineEnabled, isSmartContextEnabled } =
+          await getModelClient(settings.selectedModel, settings);
 
         const appPath = getDyadAppPath(updatedChat.app.path);
-        const chatContext = req.selectedComponent
-          ? {
-              contextPaths: [
-                {
-                  globPath: req.selectedComponent.relativePath,
-                },
-              ],
-              smartContextAutoIncludes: [],
-            }
-          : validateChatContext(updatedChat.app.chatContext);
-
-        // Parse app mentions from the prompt
-        const mentionedAppNames = parseAppMentions(req.prompt);
+        // When we don't have smart context enabled, we
+        // only include the selected component's file for codebase context.
+        //
+        // If we have selected component and smart context is enabled,
+        // we handle this specially below.
+        const chatContext =
+          req.selectedComponent && !isSmartContextEnabled
+            ? {
+                contextPaths: [
+                  {
+                    globPath: req.selectedComponent.relativePath,
+                  },
+                ],
+                smartContextAutoIncludes: [],
+              }
+            : validateChatContext(updatedChat.app.chatContext);
 
         // Extract codebase for current app
         const { formattedOutput: codebaseInfo, files } = await extractCodebase({
@@ -459,6 +468,20 @@ ${componentSnippet}
           chatContext,
         });
 
+        // For smart context and selected component, we will mark the selected component's file as focused.
+        // This means that we don't do the regular smart context handling, but we'll allow fetching
+        // additional files through <dyad-read> as needed.
+        if (isSmartContextEnabled && req.selectedComponent) {
+          for (const file of files) {
+            if (file.path === req.selectedComponent.relativePath) {
+              file.focused = true;
+            }
+          }
+        }
+
+        // Parse app mentions from the prompt
+        const mentionedAppNames = parseAppMentions(req.prompt);
+
         // Extract codebases for mentioned apps
         const mentionedAppsCodebases = await extractMentionedAppsCodebases(
           mentionedAppNames,
@@ -489,11 +512,6 @@ ${componentSnippet}
           "estimated tokens",
           codebaseInfo.length / 4,
         );
-        const { modelClient, isEngineEnabled } = await getModelClient(
-          settings.selectedModel,
-          settings,
-          files,
-        );
 
         // Prepare message history for the AI
         const messageHistory = updatedChat.messages.map((message) => ({
@@ -709,9 +727,11 @@ This conversation includes one or more image attachments. When the user uploads
           tools,
           systemPromptOverride = systemPrompt,
           dyadDisableFiles = false,
+          files,
         }: {
           chatMessages: ModelMessage[];
           modelClient: ModelClient;
+          files: CodebaseFile[];
           tools?: ToolSet;
           systemPromptOverride?: string;
           dyadDisableFiles?: boolean;
@@ -729,6 +749,7 @@ This conversation includes one or more image attachments. When the user uploads
             "dyad-engine": {
               dyadRequestId,
               dyadDisableFiles,
+              dyadFiles: files,
               dyadMentionedApps: mentionedAppsCodebases.map(
                 ({ files, appName }) => ({
                   appName,
@@ -878,6 +899,7 @@ This conversation includes one or more image attachments. When the user uploads
               aiRules: await readAiRules(getDyadAppPath(updatedChat.app.path)),
               chatMode: "agent",
             }),
+            files: files,
             dyadDisableFiles: true,
           });
 
@@ -903,6 +925,7 @@ This conversation includes one or more image attachments. When the user uploads
         const { fullStream } = await simpleStreamText({
           chatMessages,
           modelClient,
+          files: files,
         });
 
         // Process the stream as before
@@ -939,6 +962,7 @@ This conversation includes one or more image attachments. When the user uploads
                   { role: "assistant", content: fullResponse },
                 ],
                 modelClient,
+                files: files,
               });
               for await (const part of contStream) {
                 // If the stream was aborted, exit early
@@ -1020,11 +1044,11 @@ ${problemReport.problems
                 const { modelClient } = await getModelClient(
                   settings.selectedModel,
                   settings,
-                  files,
                 );
 
                 const { fullStream } = await simpleStreamText({
                   modelClient,
+                  files: files,
                   chatMessages: [
                     ...chatMessages.map((msg, index) => {
                       if (