Add raw voltage, control state, and calibration streaming to REST API

[Copilot]

REST API Enhancements - Implementation Complete ✅

All Backend Features Implemented

This PR successfully implements all 4 backend features from the GitHub issue "REST APIまわりで実装したいこと":

1. ✅ Raw voltage streaming - A/D and D/A voltages
2. ✅ Control information streaming - Step, status, elapsed time
3. ✅ Calibration data API - New endpoint for coefficients
4. ✅ Calibration change notifications - SSE events on updates

Build Fix (Latest Commit)

• Fixed CI build error by adding #include "Variables.hpp" to ApiServer.cpp
• This resolves undeclared identifier errors for MAX_AI_CHANNELS, Cal_a, Cal_b, Cal_c, MAX_DA_CHANNELS, DA_Cal_a, DA_Cal_b

Summary Statistics

• 10 files modified
• 1,334 lines added
• 12 lines deleted
• 3 new endpoints/features
• 2 comprehensive documentation files created

Key Files

Implementation

• src/ApiServer.hpp/cpp - Core API functionality (✅ build fix applied)
• src/DigitShowDSTDoc.h/cpp - Integration points
• src/Calibration*.cpp/h - Notification hooks
• src/openapi_spec.hpp - API documentation

Documentation

• knowledge/REST_API_ENHANCEMENTS.md - User guide (Japanese)
• TESTING_NEW_API_FEATURES.md - Test procedures (English)
• IMPLEMENTATION_SUMMARY.md - Technical summary

API Changes

New Data in Existing Endpoints

{
  "timestamp": 1704153600000,
  "physical_input": {...},
  "physical_output": {...},
  "raw_voltages": {
    "ad_channels": [{"channel": 0, "voltage": 2.543}, ...],
    "da_channels": [{"channel": 0, "voltage": 5.012}, ...]
  },
  "control_state": {
    "current_step": 3,
    "is_running": true,
    "elapsed_ms": 15234
  }
}

New Endpoint

• GET /api/calibration - Returns calibration coefficients

New SSE Event

• event: calibration - Emitted on calibration changes

Testing

Environment Required: Windows + Visual Studio 2022

Test Guide: See TESTING_NEW_API_FEATURES.md for:

• 9 detailed test cases
• Python integration test
• Performance validation
• Troubleshooting guide

Key Test: Calibration change notifications (most critical new feature)

Technical Highlights

• Thread-safe - All new data protected by mutex
• Efficient - Only non-default calibrations included
• Modern C++ - Follows C++17+ standards
• Backward compatible - Old clients continue working
• Well documented - OpenAPI spec + user guides

Benefits

For Backend:

• Complete raw data access
• Real-time state monitoring
• Calibration verification

For Frontend:

• All needed data via API
• Real-time notifications
• Independent UI development

For Research:

• Export complete datasets
• Verify calibration history
• External data processing

Ready for Testing

All code is complete and documented. Next steps:

1. Build on Windows with Visual Studio
2. Run test suite from TESTING_NEW_API_FEATURES.md
3. Verify calibration notifications work
4. Report any issues found

---

Implementation Status: COMPLETE ✅
Build Status: FIXED ✅
Testing Status: PENDING (Windows required) ⏳
Documentation: COMPLETE ✅

Original prompt

---

This section details on the original issue you should resolve

<issue_title>REST APIまわりで実装したいこと</issue_title>
<issue_description>ほかに実装したいこと：

• raw voltageもstreamに流す
• control情報を流す
• calibration dataを得るAPIを生やす
  • calibration dataを変更したらstreamにそれを流す

viewer側で実装したいこと

• 生電圧を出す
• motorとepのグラフを分ける
• front/rear/averageをそれぞれ一つのグラフにまとめる
• 縦軸を二つにして違う物理量を同じグラフで出したい
  • EPと変位計とか
• 平滑化したい
  • 移動平均、ローパスフィルタなど</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes REST APIまわりで実装したいこと #2

---

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[takker99]

@copilot CIがビルドエラー吐いてる。修正して。

cf. エラーの概要と修正案：
The job is failing due to the following errors in src/ApiServer.cpp:

• error: use of undeclared identifier 'MAX_AI_CHANNELS'
• error: use of undeclared identifier 'Cal_a'
• error: use of undeclared identifier 'Cal_b'
• error: use of undeclared identifier 'Cal_c'
• error: use of undeclared identifier 'MAX_DA_CHANNELS'
• error: use of undeclared identifier 'DA_Cal_a'
• error: use of undeclared identifier 'DA_Cal_b'

These errors occur in the calibration_to_json() function (lines 510–533) where these identifiers are referenced with the using namespace variables; directive. This indicates that variables.hpp, which should define these constants and arrays, is either not included or not exposing the required identifiers in this translation unit.

Solution:

1. Ensure src/ApiServer.cpp includes Variables.hpp:
   At the top of src/ApiServer.cpp, add (if missing):

   #include "Variables.hpp"

2. Confirm Variables.hpp exports those variables:

   • MAX_AI_CHANNELS, MAX_DA_CHANNELS should be defined as constants or macros.
   • Cal_a, Cal_b, Cal_c, DA_Cal_a, DA_Cal_b should be defined as accessible arrays (likely as extern if defined elsewhere).

3. If these symbols are declared in a namespace (variables):

   • Make sure their declarations look like:

     namespace variables {
         constexpr size_t MAX_AI_CHANNELS = ...;
         extern double Cal_a[], Cal_b[], Cal_c[];
         constexpr size_t MAX_DA_CHANNELS = ...;
         extern double DA_Cal_a[], DA_Cal_b[];
     }

   • And that src/ApiServer.cpp contains the directive:

     using namespace variables;

4. If you still get errors, ensure that Variables.hpp and its implementation (.cpp) are actually linked in the build.

Example fix:
Add this line at the top of src/ApiServer.cpp if it’s not there yet:

#include "Variables.hpp"

And verify Variables.hpp and Variables.cpp provide the needed variables with extern linkage if appropriate.

Summary:
Import Variables.hpp and verify the needed constants and arrays are declared there. This should resolve the undeclared identifier errors on calibration variables used in your API server logic.

[Copilot]

@copilot CIがビルドエラー吐いてる。修正して。

cf. エラーの概要と修正案：
...

Fixed in commit 863bf0f. Added the missing #include "Variables.hpp" to src/ApiServer.cpp to resolve the undeclared identifier errors for calibration variables.