port: grp.SaveScreenShot via next-frame swapchain readback + JPEG

CPythonGraphic::SaveScreenShot queues a readback of the next presented
frame (ScreenShotHost -> VulkanWindow::request_frame); WriteScreenShot runs
the rest of 40250's function verbatim (X8R8G8B8 rows, SaveJPEG, EXIF tag).
jpeg_save is encoded with stb_image_write. SHGetSpecialFolderPath returns
$HOME/Documents (else cwd); CreateDirectory/_access/jpeg_save accept '\\'.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

audit/port-map/EterLib/JpegFile.cpp.json

@@ -0,0 +1,78 @@
+{
+  "reference": "EterLib/JpegFile.cpp",
+  "reference_sha256": "5e4417d5dfe77c4921e22b3196ca894a40034e41a19936fc49b509ad2c19b98a",
+  "priority": "P4",
+  "contracts": [],
+  "functions": {
+    "file_init_destination": {
+      "status": "N_A",
+      "note": "libjpeg stdio destination manager behind jpeg_save; stb_image_write writes through its own callback (see jpeg_save ADAPTED)."
+    },
+    "file_empty_output_buffer": {
+      "status": "N_A",
+      "note": "libjpeg stdio destination manager behind jpeg_save; stb_image_write writes through its own callback (see jpeg_save ADAPTED)."
+    },
+    "file_term_destination": {
+      "status": "N_A",
+      "note": "libjpeg stdio destination manager behind jpeg_save; stb_image_write writes through its own callback (see jpeg_save ADAPTED)."
+    },
+    "mem_init_destination": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_empty_output_buffer": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_term_destination": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "jpeg_save": {
+      "status": "ADAPTED",
+      "impl": [
+        "src/platform/EterLib/JpegFile.cpp:jpeg_save"
+      ],
+      "test": [
+        "tests/port/port_screenshot_test.cpp"
+      ],
+      "note": "40250 encodes with libjpeg-9a (stdio destination, JCS_RGB, jpeg_set_defaults + jpeg_set_quality(quality)); the port encodes the same top-down RGB rows at the same quality with stb_image_write into a baseline JFIF file. Invariant: returns 1 with a complete JPEG (SOI..EOI) at `filename`, 0 when the file cannot be opened. '\\\\' in the path is taken as a separator like the Win32 CRT fopen."
+    },
+    "jpeg_save_to_file": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "jpeg_save_to_mem": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_init_source": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_fill_input_buffer": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_skip_input_data": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_resync_to_restart": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "mem_term_source": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "jpeg_load_from_mem": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    },
+    "jpeg_load": {
+      "status": "N_A",
+      "note": "No caller in 40250 (LC_ALL=C grep -a over ClientVS22/source and the root .py: only CPythonGraphic::SaveJPEG calls jpeg_save); left undefined."
+    }
+  }
+}

audit/port-map/EterPythonLib/PythonGraphic.cpp.json

@@ -63,13 +63,32 @@
       "note": "Verbatim 40250. The recording device reports no D3DCAPS2_FULLSCREENGAMMA (windowed output, where D3D8 ignores the ramp as well), so it returns at the caps check; IDirect3DDevice8::SetGammaRamp added to the D3D8 shim."
     },
     "GenScreenShotTag": {
-      "status": "TODO"
+      "status": "PORTED",
+      "impl": [
+        "src/platform/EterPythonLib/PythonGraphic.cpp:GenScreenShotTag"
+      ],
+      "note": "Verbatim 40250; only reached when g_isScreenShotKey (false, never set)."
     },
     "CPythonGraphic::SaveJPEG": {
-      "status": "TODO"
+      "status": "PORTED",
+      "impl": [
+        "src/platform/EterPythonLib/PythonGraphic.cpp:CPythonGraphic::SaveJPEG"
+      ],
+      "test": [
+        "tests/port/port_screenshot_test.cpp"
+      ]
     },
     "CPythonGraphic::SaveScreenShot": {
-      "status": "TODO"
+      "status": "ADAPTED",
+      "impl": [
+        "src/platform/EterPythonLib/PythonGraphic.cpp:CPythonGraphic::SaveScreenShot",
+        "src/platform/EterPythonLib/PythonGraphic.cpp:ScreenShotHost::WriteScreenShot",
+        "src/host/live_client.cpp"
+      ],
+      "test": [
+        "tests/port/port_screenshot_test.cpp"
+      ],
+      "note": "40250 locks the D3D8 back buffer and writes the JPEG before returning. The script thread and the SDL host alternate, so the call queues a readback of the next presented frame (ScreenShotHost::SetRequest -> VulkanWindow::request_frame) and returns true; ScreenShotHost::WriteScreenShot runs the rest verbatim one frame later (X8R8G8B8 row loop, SaveJPEG, TraceError on failure, g_isScreenShotKey EXIF block). No host -> TraceError + false (40250's GetBackBuffer failure). Only the X8R8G8B8 branch exists: the swapchain is read back as BGRA. Checked on desktop: grp.SaveScreenShot() wrote ~/Documents/METIN2/<MMDD_hhmmss>.jpg with correct colours (SHGetSpecialFolderPath shim = $HOME/Documents, else cwd)."
     },
     "CPythonGraphic::PushState": {
       "status": "PORTED",