Audio: per-game persisted format overrides + auto-learn

Persist audio overrides keyed by game image name (coop_audio_overrides.ini
next to the exe) so a known-bad game is auto-corrected on its next launch:
on attach to a guessed stream the host applies any saved override, and a
manual Override now saves too. A format the hook catches exactly at
IAudioClient::Initialize is auto-saved as that game's override (ground truth);
if it overwrites a differing stored value, a warning is logged. Host-originated
log lines now reach the Log window via IpcServer::host_log (color-coded).

Validated live (harness): a pre-seeded override for coop_tone is auto-applied
over the guess (state -> manual override, 48000/2/16). audio_overrides_test
covers persist/reload/case-insensitive lookup/differing-overwrite. Trim README.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/CMakeLists.txt

@@ -36,6 +36,15 @@ add_executable(rate_estimator_test rate_estimator_test.cpp)
 target_include_directories(rate_estimator_test PRIVATE ${CMAKE_SOURCE_DIR}/hook/src)
 add_test(NAME rate_estimator_test COMMAND rate_estimator_test)
 
+# Unit test for the per-game audio override store (persist/reload, case-insensitive
+# lookup, differing-overwrite detection). Reuses the shipping source. No device.
+add_executable(audio_overrides_test
+	audio_overrides_test.cpp
+	${CMAKE_SOURCE_DIR}/host/src/audio/audio_overrides.cpp)
+target_include_directories(audio_overrides_test PRIVATE ${CMAKE_SOURCE_DIR}/host/src)
+target_link_libraries(audio_overrides_test PRIVATE coop_common)
+add_test(NAME audio_overrides_test COMMAND audio_overrides_test)
+
 # Unit test for the host->game mouse coordinate mapping (letterbox inverse +
 # decorated-window client offset). Header-only, no device.
 add_executable(mkb_map_test mkb_map_test.cpp)
@@ -163,6 +172,7 @@ coop_output_subdir(tests
 	mkb_map_test
 	audio_mix_test
 	rate_estimator_test
+	audio_overrides_test
 	audio_loopback_test
 	audio_hook_test
 	srgb_format_test

tests/audio_overrides_test.cpp

@@ -0,0 +1,88 @@
+// Unit test for the per-game audio override store (save/load round-trip, case-insensitive
+// lookup by image name, and the differing-overwrite detection that drives the warning).
+#include <cstdint>
+#include <cstdio>
+#include <string>
+
+#include <windows.h>
+
+#include <mmreg.h>
+
+#include "audio/audio_overrides.hpp"
+
+using namespace coop;
+
+namespace
+{
+int g_failures = 0;
+void check(bool ok, const char* what)
+{
+	if (!ok)
+	{
+		std::printf("FAIL: %s\n", what);
+		++g_failures;
+	}
+	else
+	{
+		std::printf("  ok: %s\n", what);
+	}
+}
+
+std::wstring temp_path()
+{
+	wchar_t dir[MAX_PATH] = {};
+	GetTempPathW(MAX_PATH, dir);
+	return std::wstring(dir) + L"coop_overrides_test_" + std::to_wstring(GetCurrentProcessId()) + L".ini";
+}
+} // namespace
+
+int main()
+{
+	const std::wstring path = temp_path();
+	DeleteFileW(path.c_str());
+
+	const AudioFormatOverride brotato{44100, 2, 32, WAVE_FORMAT_IEEE_FLOAT};
+	const AudioFormatOverride snb{48000, 2, 16, WAVE_FORMAT_PCM};
+
+	{
+		AudioOverrideStore store(path);
+		store.load(); // missing file -> empty
+		AudioFormatOverride got;
+		check(!store.find(L"brotato.exe", got), "empty store: no entry");
+
+		bool differed = true;
+		store.set(L"C:\\games\\Brotato.exe", brotato, &differed); // full path -> basename key
+		check(!differed, "first set: not a differing overwrite");
+		store.set(L"snb.exe", snb, &differed);
+		check(!differed, "new game set: not a differing overwrite");
+
+		// Same value again -> not differing.
+		store.set(L"brotato.exe", brotato, &differed);
+		check(!differed, "identical re-set: not differing");
+
+		// Different value -> differing (drives the warning).
+		const AudioFormatOverride brotato2{48000, 2, 32, WAVE_FORMAT_IEEE_FLOAT};
+		store.set(L"brotato.exe", brotato2, &differed);
+		check(differed, "changed value: flagged as differing overwrite");
+	}
+
+	// Reload from disk in a fresh store: persistence + case-insensitive basename lookup.
+	{
+		AudioOverrideStore store(path);
+		store.load();
+		AudioFormatOverride got;
+		check(store.find(L"BROTATO.EXE", got), "reload: found case-insensitively");
+		check(got == AudioFormatOverride{48000, 2, 32, WAVE_FORMAT_IEEE_FLOAT}, "reload: latest value persisted");
+		check(store.find(L"D:\\steam\\snb.exe", got) && got == snb, "reload: found by full path basename");
+		check(!store.find(L"unknown.exe", got), "reload: unknown game absent");
+	}
+
+	DeleteFileW(path.c_str());
+	if (g_failures == 0)
+	{
+		std::printf("PASS audio_overrides_test\n");
+		return 0;
+	}
+	std::printf("FAILED audio_overrides_test (%d)\n", g_failures);
+	return 1;
+}