feat: select screen area to record

AGENTS.md

@@ -1,10 +1,73 @@
-# Agent guide for Swift and SwiftUI
+# AGENT.md
 
-This repository contains an Xcode project written with Swift and SwiftUI. Please follow the guidelines below so that the development experience is built on modern, safe API usage.
+Behavioral guidelines to reduce common LLM coding mistakes. Merge with project-specific instructions as needed.
 
-## Role
+**Tradeoff:** These guidelines bias toward caution over speed. For trivial tasks, use judgment.
 
-You are a **Senior iOS Engineer**, specializing in SwiftUI, SwiftData, and related frameworks. Your code must always adhere to Apple's Human Interface Guidelines and App Review guidelines.
+## 1. Think Before Coding
+
+**Don't assume. Don't hide confusion. Surface tradeoffs.**
+
+Before implementing:
+
+- State your assumptions explicitly. If uncertain, ask.
+- If multiple interpretations exist, present them - don't pick silently.
+- If a simpler approach exists, say so. Push back when warranted.
+- If something is unclear, stop. Name what's confusing. Ask.
+
+## 2. Simplicity First
+
+**Minimum code that solves the problem. Nothing speculative.**
+
+- No features beyond what was asked.
+- No abstractions for single-use code.
+- No "flexibility" or "configurability" that wasn't requested.
+- No error handling for impossible scenarios.
+- If you write 200 lines and it could be 50, rewrite it.
+
+Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.
+
+## 3. Surgical Changes
+
+**Touch only what you must. Clean up only your own mess.**
+
+When editing existing code:
+
+- Don't "improve" adjacent code, comments, or formatting.
+- Don't refactor things that aren't broken.
+- Match existing style, even if you'd do it differently.
+- If you notice unrelated dead code, mention it - don't delete it.
+
+When your changes create orphans:
+
+- Remove imports/variables/functions that YOUR changes made unused.
+- Don't remove pre-existing dead code unless asked.
+
+The test: Every changed line should trace directly to the user's request.
+
+## 4. Goal-Driven Execution
+
+**Define success criteria. Loop until verified.**
+
+Transform tasks into verifiable goals:
+
+- "Add validation" → "Write tests for invalid inputs, then make them pass"
+- "Fix the bug" → "Write a test that reproduces it, then make it pass"
+- "Refactor X" → "Ensure tests pass before and after"
+
+For multi-step tasks, state a brief plan:
+
+```
+1. [Step] → verify: [check]
+2. [Step] → verify: [check]
+3. [Step] → verify: [check]
+```
+
+Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.
+
+---
+
+**These guidelines are working if:** fewer unnecessary changes in diffs, fewer rewrites due to overcomplication, and clarifying questions come before implementation rather than after mistakes.
 
 ## Core instructions
 

BetterCapture/Service/CaptureEngine.swift

@@ -95,7 +95,8 @@ final class CaptureEngine: NSObject {
     /// - Parameters:
     ///   - settings: The settings store containing capture configuration
     ///   - videoSize: The dimensions for the captured video
-    func startCapture(with settings: SettingsStore, videoSize: CGSize) async throws {
+    ///   - sourceRect: Optional rectangle for area selection (display points, top-left origin)
+    func startCapture(with settings: SettingsStore, videoSize: CGSize, sourceRect: CGRect? = nil) async throws {
         guard let filter = contentFilter else {
             throw CaptureError.noContentFilterSelected
         }
@@ -128,7 +129,7 @@ final class CaptureEngine: NSObject {
         let filteredContent = try await contentFilterService.applySettings(to: filter, settings: settings)
         logger.info("Content filter applied, creating stream...")
 
-        let streamConfig = createStreamConfiguration(from: settings, contentSize: videoSize)
+        let streamConfig = createStreamConfiguration(from: settings, contentSize: videoSize, sourceRect: sourceRect)
 
         stream = SCStream(filter: filteredContent, configuration: streamConfig, delegate: self)
 
@@ -182,13 +183,23 @@ final class CaptureEngine: NSObject {
     // MARK: - Configuration
 
     /// Creates an SCStreamConfiguration from user settings
-    private func createStreamConfiguration(from settings: SettingsStore, contentSize: CGSize) -> SCStreamConfiguration {
+    /// - Parameters:
+    ///   - settings: The settings store containing capture configuration
+    ///   - contentSize: The output dimensions for the captured video
+    ///   - sourceRect: Optional rectangle for area selection (display points, top-left origin)
+    private func createStreamConfiguration(from settings: SettingsStore, contentSize: CGSize, sourceRect: CGRect? = nil) -> SCStreamConfiguration {
         let config = SCStreamConfiguration()
 
         // Set output dimensions - required for proper capture
         config.width = Int(contentSize.width)
         config.height = Int(contentSize.height)
 
+        // Set source rect for area selection (only works with display captures)
+        if let sourceRect {
+            config.sourceRect = sourceRect
+            logger.info("Source rect set: \(sourceRect.origin.x),\(sourceRect.origin.y) \(sourceRect.width)x\(sourceRect.height)")
+        }
+
         // Frame rate - native uses display sync (1/120 timescale)
         if settings.frameRate == .native {
             config.minimumFrameInterval = CMTime(value: 1, timescale: 120)

BetterCapture/Service/PreviewService.swift

@@ -29,6 +29,7 @@ final class PreviewService: NSObject {
 
     private var stream: SCStream?
     private var currentFilter: SCContentFilter?
+    private var currentSourceRect: CGRect?
     private let previewQueue = DispatchQueue(label: "com.bettercapture.previewQueue", qos: .userInteractive)
 
     private let logger = Logger(
@@ -43,20 +44,30 @@ final class PreviewService: NSObject {
     // MARK: - Public Methods
 
     /// Updates the content filter and captures a static thumbnail
-    /// - Parameter filter: The content filter to use
-    func setContentFilter(_ filter: SCContentFilter) async {
+    /// - Parameters:
+    ///   - filter: The content filter to use
+    ///   - sourceRect: Optional rectangle for area selection (display points, top-left origin)
+    func setContentFilter(_ filter: SCContentFilter, sourceRect: CGRect? = nil) async {
         currentFilter = filter
-        await captureStaticThumbnail(for: filter)
+        currentSourceRect = sourceRect
+        await captureStaticThumbnail(for: filter, sourceRect: sourceRect)
     }
 
     /// Captures a single static frame as a thumbnail (no continuous streaming)
-    private func captureStaticThumbnail(for filter: SCContentFilter) async {
+    /// - Parameters:
+    ///   - filter: The content filter to capture
+    ///   - sourceRect: Optional rectangle for area selection (display points, top-left origin)
+    private func captureStaticThumbnail(for filter: SCContentFilter, sourceRect: CGRect? = nil) async {
         let config = SCStreamConfiguration()
         config.width = previewWidth
         config.height = previewHeight
         config.pixelFormat = kCVPixelFormatType_32BGRA
         config.showsCursor = true
 
+        if let sourceRect {
+            config.sourceRect = sourceRect
+        }
+
         do {
             let image = try await SCScreenshotManager.captureImage(
                 contentFilter: filter,
@@ -98,28 +109,6 @@ final class PreviewService: NSObject {
         await stopStream()
     }
 
-    /// Starts or updates the preview stream for the given content filter
-    /// - Parameter filter: The content filter to capture
-    func captureSnapshot(for filter: SCContentFilter) async {
-        currentFilter = filter
-
-        // If already streaming, update the filter
-        if let stream, isCapturing {
-            do {
-                try await stream.updateContentFilter(filter)
-                logger.info("Updated preview stream filter")
-            } catch {
-                logger.error("Failed to update preview filter: \(error.localizedDescription)")
-                await stopStream()
-                await startStream(with: filter)
-            }
-            return
-        }
-
-        // Otherwise start a new stream
-        await startStream(with: filter)
-    }
-
     /// Starts the preview stream
     private func startStream(with filter: SCContentFilter) async {
         guard !isCapturing else { return }
@@ -198,6 +187,11 @@ final class PreviewService: NSObject {
         // Show cursor in preview
         config.showsCursor = true
 
+        // Apply source rect for area selection
+        if let sourceRect = currentSourceRect {
+            config.sourceRect = sourceRect
+        }
+
         return config
     }