yaze/docs/z3ed/IT-08-IMPLEMENTATION-GUIDE.md

IT-08: Enhanced Error Reporting Implementation Guide

Status: IT-08a Complete ✅ | IT-08b In Progress 🔄 | IT-08c Planned 📋
Date: October 2, 2025
Overall Progress: 33% Complete (1 of 3 phases)

---

Phase Overview

Phase	Task	Status	Time	Description
IT-08a	Screenshot RPC	✅ Complete	1.5h	SDL-based screenshot capture
IT-08b	Auto-Capture on Failure	🔄 Active	1-1.5h	Integrate with TestManager
IT-08c	Widget State Dumps	📋 Planned	30-45m	Capture UI context on failure
IT-08d	Error Envelope Standardization	📋 Planned	1-2h	Unified error format across services
IT-08e	CLI Error Improvements	📋 Planned	1h	Rich error output with artifacts

Total Estimated Time: 5-7 hours
Time Spent: 1.5 hours
Time Remaining: 3.5-5.5 hours

---

IT-08a: Screenshot RPC ✅ COMPLETE

Date Completed: October 2, 2025
Time: 1.5 hours

Implementation Summary

What Was Built

Implemented the Screenshot RPC in the ImGuiTestHarness service with the following capabilities:

1. SDL Renderer Integration: Accesses the ImGui SDL2 backend renderer through BackendRendererUserData
2. Framebuffer Capture: Uses SDL_RenderReadPixels to capture the full window contents (1536x864, 32-bit ARGB)
3. BMP File Output: Saves screenshots as BMP files using SDL's built-in SDL_SaveBMP function
4. Flexible Paths: Supports custom output paths or auto-generates timestamped filenames (/tmp/yaze_screenshot_<timestamp>.bmp)
5. Response Metadata: Returns file path, file size (bytes), and image dimensions

Technical Implementation

Location: /Users/scawful/Code/yaze/src/app/core/service/imgui_test_harness_service.cc

// Helper struct matching imgui_impl_sdlrenderer2.cpp backend data
struct ImGui_ImplSDLRenderer2_Data {
  SDL_Renderer* Renderer;
};

absl::Status ImGuiTestHarnessServiceImpl::Screenshot(
    const ScreenshotRequest* request, ScreenshotResponse* response) {
  // 1. Get SDL renderer from ImGui backend
  ImGuiIO& io = ImGui::GetIO();
  auto* backend_data = static_cast<ImGui_ImplSDLRenderer2_Data*>(io.BackendRendererUserData);
  
  if (!backend_data || !backend_data->Renderer) {
    response->set_success(false);
    response->set_message("SDL renderer not available");
    return absl::FailedPreconditionError("No SDL renderer available");
  }
  
  SDL_Renderer* renderer = backend_data->Renderer;
  
  // 2. Get renderer output size
  int width, height;
  SDL_GetRendererOutputSize(renderer, &width, &height);
  
  // 3. Create surface to hold screenshot
  SDL_Surface* surface = SDL_CreateRGBSurface(0, width, height, 32,
                                              0x00FF0000, 0x0000FF00,
                                              0x000000FF, 0xFF000000);
  
  // 4. Read pixels from renderer (ARGB8888 format)
  SDL_RenderReadPixels(renderer, nullptr, SDL_PIXELFORMAT_ARGB8888,
                      surface->pixels, surface->pitch);
  
  // 5. Determine output path (custom or auto-generated)
  std::string output_path = request->output_path();
  if (output_path.empty()) {
    output_path = absl::StrFormat("/tmp/yaze_screenshot_%lld.bmp",
                                  absl::ToUnixMillis(absl::Now()));
  }
  
  // 6. Save to BMP file
  SDL_SaveBMP(surface, output_path.c_str());
  
  // 7. Get file size and clean up
  std::ifstream file(output_path, std::ios::binary | std::ios::ate);
  int64_t file_size = file.tellg();
  
  SDL_FreeSurface(surface);
  
  // 8. Return success response
  response->set_success(true);
  response->set_message(absl::StrFormat("Screenshot saved to %s (%dx%d)",
                                        output_path, width, height));
  response->set_file_path(output_path);
  response->set_file_size_bytes(file_size);
  
  return absl::OkStatus();
}

Testing Results

Test Command:

grpcurl -plaintext \
  -import-path /Users/scawful/Code/yaze/src/app/core/proto \
  -proto imgui_test_harness.proto \
  -d '{"output_path": "/tmp/test_screenshot.bmp"}' \
  localhost:50052 yaze.test.ImGuiTestHarness/Screenshot

Response:

{
  "success": true,
  "message": "Screenshot saved to /tmp/test_screenshot.bmp (1536x864)",
  "filePath": "/tmp/test_screenshot.bmp",
  "fileSizeBytes": "5308538"
}

File Verification:

$ ls -lh /tmp/test_screenshot.bmp
-rw-r--r--  1 scawful  wheel   5.1M Oct  2 20:16 /tmp/test_screenshot.bmp

$ file /tmp/test_screenshot.bmp
/tmp/test_screenshot.bmp: PC bitmap, Windows 95/NT4 and newer format, 1536 x 864 x 32, cbSize 5308538, bits offset 122

✅ Result: Screenshot successfully captured, saved, and validated!

---

Design Decisions

Why BMP Format?

Chosen: SDL's built-in SDL_SaveBMP function
Rationale:

• ✅ Zero external dependencies (no need for libpng, stb_image_write, etc.)
• ✅ Guaranteed to work on all platforms where SDL works
• ✅ Simple, reliable, and fast
• ✅ Adequate for debugging/error reporting (file size not critical)
• ⚠️ Larger file sizes (5.3MB vs ~500KB for PNG), but acceptable for temporary debug files

Future Consideration: If disk space becomes an issue, can add PNG encoding using stb_image_write (single-header library, easy to integrate)

SDL Backend Integration

Challenge: How to access the SDL_Renderer from ImGui?
Solution:

• ImGui's BackendRendererUserData points to an ImGui_ImplSDLRenderer2_Data struct
• This struct contains the Renderer pointer as its first member
• Cast BackendRendererUserData to access the renderer safely

Why Not Store Renderer Globally?

• Multiple ImGui contexts could use different renderers
• Backend data pattern follows ImGui's architecture conventions
• More maintainable and future-proof

---

Integration with Test System

Current Usage (Manual RPC)

AI agents or CLI tools can manually capture screenshots:

# Capture screenshot after opening editor
z3ed agent test --prompt "Open Overworld Editor"
grpcurl ... yaze.test.ImGuiTestHarness/Screenshot

Next Step: Auto-Capture on Failure

The screenshot RPC is now ready to be integrated with TestManager to automatically capture context when tests fail:

Planned Implementation (IT-08 Phase 2):

// In TestManager::MarkHarnessTestCompleted()
if (test_result == IMGUI_TEST_STATUS_FAILED || 
    test_result == IMGUI_TEST_STATUS_TIMEOUT) {
  
  // Auto-capture screenshot
  ScreenshotRequest req;
  req.set_output_path(absl::StrFormat("/tmp/test_%s_failure.bmp", test_id));
  
  ScreenshotResponse resp;
  harness_service_->Screenshot(&req, &resp);
  
  test_history_[test_id].screenshot_path = resp.file_path();
  
  // Also capture widget state (IT-08 Phase 3)
  test_history_[test_id].widget_state = CaptureWidgetState();
}

---

---

IT-08b: Auto-Capture on Test Failure 🔄 IN PROGRESS

Goal: Automatically capture screenshots and context when tests fail
Time Estimate: 1-1.5 hours
Status: Ready to implement

Implementation Plan

Step 1: Modify TestManager (30 minutes)

File: src/app/core/test_manager.cc

Add screenshot capture in MarkHarnessTestCompleted():

void TestManager::MarkHarnessTestCompleted(const std::string& test_id,
                                           ImGuiTestStatus status) {
  auto& history_entry = test_history_[test_id];
  history_entry.status = status;
  history_entry.end_time = absl::Now();
  history_entry.execution_time_ms = absl::ToInt64Milliseconds(
      history_entry.end_time - history_entry.start_time);
  
  // Auto-capture screenshot on failure
  if (status == ImGuiTestStatus_Error || status == ImGuiTestStatus_Warning) {
    CaptureFailureContext(test_id);
  }
}

void TestManager::CaptureFailureContext(const std::string& test_id) {
  auto& history_entry = test_history_[test_id];
  
  // 1. Capture screenshot
  std::string screenshot_path = 
      absl::StrFormat("/tmp/yaze_test_%s_failure.bmp", test_id);
  
  if (harness_service_) {
    ScreenshotRequest req;
    req.set_output_path(screenshot_path);
    
    ScreenshotResponse resp;
    auto status = harness_service_->Screenshot(&req, &resp);
    
    if (status.ok()) {
      history_entry.screenshot_path = resp.file_path();
      history_entry.screenshot_size_bytes = resp.file_size_bytes();
    }
  }
  
  // 2. Capture widget state (IT-08c)
  // history_entry.widget_state = CaptureWidgetState();
  
  // 3. Capture execution context
  history_entry.failure_context = absl::StrFormat(
      "Frame: %d, Active Window: %s, Focused Widget: %s",
      ImGui::GetFrameCount(),
      ImGui::GetCurrentWindow() ? ImGui::GetCurrentWindow()->Name : "none",
      ImGui::GetActiveID());
}

Step 2: Update TestHistory Structure (15 minutes)

File: src/app/core/test_manager.h

Add failure context fields:

struct TestHistory {
  std::string test_id;
  std::string test_name;
  ImGuiTestStatus status;
  absl::Time start_time;
  absl::Time end_time;
  int64_t execution_time_ms;
  std::vector<std::string> logs;
  std::map<std::string, std::string> metrics;
  
  // IT-08b: Failure diagnostics
  std::string screenshot_path;
  int64_t screenshot_size_bytes = 0;
  std::string failure_context;
  std::string widget_state;  // IT-08c
};

Step 3: Update GetTestResults RPC (30 minutes)

File: src/app/core/service/imgui_test_harness_service.cc

Include screenshot path in results:

absl::Status ImGuiTestHarnessServiceImpl::GetTestResults(
    const GetTestResultsRequest* request,
    GetTestResultsResponse* response) {
  
  const auto& history = test_manager_->GetTestHistory(request->test_id());
  
  // ... existing result population ...
  
  // Add failure diagnostics
  if (!history.screenshot_path.empty()) {
    response->set_screenshot_path(history.screenshot_path);
    response->set_screenshot_size_bytes(history.screenshot_size_bytes);
  }
  
  if (!history.failure_context.empty()) {
    response->set_failure_context(history.failure_context);
  }
  
  return absl::OkStatus();
}

Step 4: Update Proto Schema (15 minutes)

File: src/app/core/proto/imgui_test_harness.proto

Add fields to GetTestResultsResponse:

message GetTestResultsResponse {
  string test_id = 1;
  TestStatus status = 2;
  int64 execution_time_ms = 3;
  repeated string logs = 4;
  map<string, string> metrics = 5;
  
  // IT-08b: Failure diagnostics
  string screenshot_path = 6;
  int64 screenshot_size_bytes = 7;
  string failure_context = 8;
  string widget_state = 9;  // IT-08c
}

Testing

# 1. Build with changes
cmake --build build-grpc-test --target yaze -j8

# 2. Start test harness
./build-grpc-test/bin/yaze.app/Contents/MacOS/yaze \
  --enable_test_harness --test_harness_port=50052 \
  --rom_file=assets/zelda3.sfc &

# 3. Trigger a failing test
grpcurl -plaintext \
  -import-path src/app/core/proto \
  -proto imgui_test_harness.proto \
  -d '{"target":"nonexistent_widget","type":"LEFT"}' \
  127.0.0.1:50052 yaze.test.ImGuiTestHarness/Click

# 4. Check for screenshot
ls -lh /tmp/yaze_test_*_failure.bmp

# 5. Query test results
grpcurl -plaintext \
  -import-path src/app/core/proto \
  -proto imgui_test_harness.proto \
  -d '{"test_id":"grpc_click_<timestamp>"}' \
  127.0.0.1:50052 yaze.test.ImGuiTestHarness/GetTestResults

# Expected: screenshot_path and failure_context populated

Success Criteria

• ✅ Screenshots auto-captured on test failure
• ✅ Screenshot path stored in test history
• ✅ GetTestResults returns screenshot metadata
• ✅ No performance impact on passing tests
• ✅ Screenshots cleaned up after test completion (optional)

---

IT-08c: Widget State Dumps 📋 PLANNED

Goal: Capture UI hierarchy and state on test failures
Time Estimate: 30-45 minutes
Status: Specification phase

Implementation Plan

Step 1: Create Widget State Capture Utility (30 minutes)

File: src/app/core/widget_state_capture.h (new file)

#ifndef YAZE_CORE_WIDGET_STATE_CAPTURE_H
#define YAZE_CORE_WIDGET_STATE_CAPTURE_H

#include <string>
#include "imgui/imgui.h"

namespace yaze {
namespace core {

struct WidgetState {
  std::string focused_window;
  std::string focused_widget;
  std::string hovered_widget;
  std::vector<std::string> visible_windows;
  std::vector<std::string> open_menus;
  std::string active_popup;
};

std::string CaptureWidgetState();
std::string SerializeWidgetStateToJson(const WidgetState& state);

}  // namespace core
}  // namespace yaze

#endif

File: src/app/core/widget_state_capture.cc (new file)

#include "src/app/core/widget_state_capture.h"
#include "absl/strings/str_format.h"
#include "nlohmann/json.hpp"

namespace yaze {
namespace core {

std::string CaptureWidgetState() {
  WidgetState state;
  
  // Capture focused window
  ImGuiWindow* current = ImGui::GetCurrentWindow();
  if (current) {
    state.focused_window = current->Name;
  }
  
  // Capture active widget
  ImGuiID active_id = ImGui::GetActiveID();
  if (active_id != 0) {
    state.focused_widget = absl::StrFormat("ID_%u", active_id);
  }
  
  // Capture hovered widget
  ImGuiID hovered_id = ImGui::GetHoveredID();
  if (hovered_id != 0) {
    state.hovered_widget = absl::StrFormat("ID_%u", hovered_id);
  }
  
  // Traverse window list
  ImGuiContext* ctx = ImGui::GetCurrentContext();
  for (ImGuiWindow* window : ctx->Windows) {
    if (window->Active && !window->Hidden) {
      state.visible_windows.push_back(window->Name);
    }
  }
  
  return SerializeWidgetStateToJson(state);
}

std::string SerializeWidgetStateToJson(const WidgetState& state) {
  nlohmann::json j;
  j["focused_window"] = state.focused_window;
  j["focused_widget"] = state.focused_widget;
  j["hovered_widget"] = state.hovered_widget;
  j["visible_windows"] = state.visible_windows;
  j["open_menus"] = state.open_menus;
  j["active_popup"] = state.active_popup;
  return j.dump(2);  // Pretty print with indent
}

}  // namespace core
}  // namespace yaze

Step 2: Integrate with TestManager (15 minutes)

Update CaptureFailureContext() in test_manager.cc:

void TestManager::CaptureFailureContext(const std::string& test_id) {
  auto& history_entry = test_history_[test_id];
  
  // 1. Screenshot (IT-08b)
  // ... existing code ...
  
  // 2. Widget state (IT-08c)
  history_entry.widget_state = core::CaptureWidgetState();
  
  // 3. Execution context
  // ... existing code ...
}

Output Example

{
  "focused_window": "Overworld Editor",
  "focused_widget": "ID_12345",
  "hovered_widget": "ID_67890",
  "visible_windows": [
    "Main Window",
    "Overworld Editor",
    "Palette Editor"
  ],
  "open_menus": [],
  "active_popup": ""
}

---

IT-08d: Error Envelope Standardization 📋 PLANNED

Goal: Unified error format across z3ed, TestManager, EditorManager
Time Estimate: 1-2 hours
Status: Design phase

Proposed Error Envelope

// Shared error structure
struct ErrorContext {
  absl::Status status;
  std::string component;  // "TestHarness", "EditorManager", "z3ed"
  std::string operation;  // "Click", "LoadROM", "RunTest"
  std::map<std::string, std::string> metadata;
  std::vector<std::string> artifact_paths;  // Screenshots, logs, etc.
  std::string actionable_hint;  // User-facing suggestion
};

Integration Points

1. TestManager: Wrap failures in ErrorContext
2. EditorManager: Use ErrorContext for all operations
3. z3ed CLI: Parse ErrorContext and format for display
4. ProposalDrawer: Display ErrorContext in GUI modal

---

IT-08e: CLI Error Improvements 📋 PLANNED

Goal: Rich error output in z3ed CLI
Time Estimate: 1 hour
Status: Design phase

Enhanced CLI Output

$ z3ed agent test --prompt "Open Overworld editor"

❌ Test Failed: grpc_click_1696357200
   Component: ImGuiTestHarness
   Operation: Click widget "Overworld"
   
   Error: Widget not found
   
   Artifacts:
   • Screenshot: /tmp/yaze_test_grpc_click_1696357200_failure.bmp
   • Widget State: /tmp/yaze_test_grpc_click_1696357200_state.json
   • Logs: /tmp/yaze_test_grpc_click_1696357200.log
   
   Context:
   • Visible Windows: Main Window, Debug
   • Focused Window: Main Window
   • Active Widget: None
   
   Suggestion:
   → Check if ROM is loaded (File → Open ROM)
   → Verify Overworld editor button is visible
   → Use 'z3ed agent gui discover' to list available widgets

---

Progress Tracking

Completed ✅

• IT-08a: Screenshot RPC (1.5 hours)

In Progress 🔄

• IT-08b: Auto-capture on failure (next priority)

Planned 📋

• IT-08c: Widget state dumps
• IT-08d: Error envelope standardization
• IT-08e: CLI error improvements

Time Investment

• Spent: 1.5 hours (IT-08a)
• Remaining: 3.5-5.5 hours (IT-08b/c/d/e)
• Total: 5-7 hours (as estimated)

---

Next Steps

Immediate (IT-08b - 1-1.5 hours):

1. Modify TestManager to capture screenshots on failure
2. Update TestHistory structure
3. Update GetTestResults RPC
4. Test with intentional failures

Short-term (IT-08c - 30-45 minutes):

1. Create widget state capture utility
2. Integrate with TestManager
3. Add to GetTestResults RPC

Medium-term (IT-08d/e - 2-3 hours):

1. Design unified error envelope
2. Implement across all services
3. Update CLI output formatting
4. Add ProposalDrawer error modal

---

References

• Implementation Plan: E6-z3ed-implementation-plan.md
• Test Harness Guide: IT-05-IMPLEMENTATION-GUIDE.md
• Source Files:
  • src/app/core/service/imgui_test_harness_service.cc
  • src/app/core/test_manager.{h,cc}
  • src/app/core/proto/imgui_test_harness.proto

---

Last Updated: October 2, 2025
Current Phase: IT-08b (Auto-capture on failure)
Overall Progress: 33% Complete (1 of 3 core phases)

---

Report Generated: October 2, 2025
Author: GitHub Copilot (AI Assistant)
Project: YAZE - Yet Another Zelda3 Editor
Component: z3ed CLI Tool - Test Automation Harness