fix: implement proper 2-step Android coverage workflow

Research showed we were missing the llvm-profdata merge step that
Android developers use. The correct workflow per Android documentation:

1. llvm-profdata merge: Convert profraw → profdata
2. llvm-cov export: Convert profdata → lcov

We were trying to use llvm-cov export directly on profraw files,
which causes "bad magic" errors because llvm-cov expects profdata.

The merge step is required even for single profraw files - it's not
just for combining multiple profiles, it's a necessary format conversion.

Using Swift toolchain's llvm-profdata and llvm-cov ensures version
compatibility since they match the clang that generated the profraw.

References:
- Android native coverage docs: https://android.googlesource.com/platform/build/soong/+/master/docs/native_code_coverage.md
- LLVM version matching: https://discourse.llvm.org/t/error-invalid-file-format-bad-magic-with-fprofile-instr-use/32852
- Profile format spec: https://leodido.dev/demystifying-profraw/

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: leogdion

.github/actions/swift-android-action/action.yml

@@ -599,8 +599,30 @@ runs:
           echo "  fi" >> ${SCRIPT_FILE}
           echo "done" >> ${SCRIPT_FILE}
 
-          echo "echo '==> NOTE: profraw files from Swift Android cannot be processed by llvm-cov'" >> ${SCRIPT_FILE}
-          echo "echo '==> Files saved to artifacts for investigation'" >> ${SCRIPT_FILE}
+          # Convert profraw to LCOV using Swift toolchain (2-step process per Android docs)
+          echo "echo '==> Converting profraw to LCOV format...'" >> ${SCRIPT_FILE}
+          echo "if [ -f '${COVERAGE_DIR}/default.profraw' ]; then" >> ${SCRIPT_FILE}
+          echo "  # Find the test binary" >> ${SCRIPT_FILE}
+          echo "  TEST_BINARY=\$(find \${SWIFT_SDK_TARGET}/debug -name '*.xctest' | head -n 1)" >> ${SCRIPT_FILE}
+          echo "  if [ -n \"\$TEST_BINARY\" ]; then" >> ${SCRIPT_FILE}
+          echo "    # Step 1: Merge profraw -> profdata (required even for single file)" >> ${SCRIPT_FILE}
+          echo "    SWIFT_PROFDATA=\"\${SWIFT_INSTALLATION}/bin/llvm-profdata\"" >> ${SCRIPT_FILE}
+          echo "    SWIFT_LLVM_COV=\"\${SWIFT_INSTALLATION}/bin/llvm-cov\"" >> ${SCRIPT_FILE}
+          echo "    if [ -f \"\$SWIFT_PROFDATA\" ] && [ -f \"\$SWIFT_LLVM_COV\" ]; then" >> ${SCRIPT_FILE}
+          echo "      echo \"Step 1: Merging profraw to profdata...\"" >> ${SCRIPT_FILE}
+          echo "      \"\$SWIFT_PROFDATA\" merge -sparse '${COVERAGE_DIR}/default.profraw' -o '${COVERAGE_DIR}/default.profdata' && {" >> ${SCRIPT_FILE}
+          echo "        echo \"Step 2: Exporting profdata to LCOV...\"" >> ${SCRIPT_FILE}
+          echo "        \"\$SWIFT_LLVM_COV\" export -format=lcov -instr-profile='${COVERAGE_DIR}/default.profdata' \"\$TEST_BINARY\" > '${COVERAGE_DIR}/coverage.lcov' && {" >> ${SCRIPT_FILE}
+          echo "          echo \"Successfully generated coverage.lcov\"" >> ${SCRIPT_FILE}
+          echo "        } || echo \"Warning: llvm-cov export failed\"" >> ${SCRIPT_FILE}
+          echo "      } || echo \"Warning: llvm-profdata merge failed\"" >> ${SCRIPT_FILE}
+          echo "    else" >> ${SCRIPT_FILE}
+          echo "      echo \"Warning: Swift LLVM tools not found\"" >> ${SCRIPT_FILE}
+          echo "    fi" >> ${SCRIPT_FILE}
+          echo "  else" >> ${SCRIPT_FILE}
+          echo "    echo \"Warning: Test binary not found\"" >> ${SCRIPT_FILE}
+          echo "  fi" >> ${SCRIPT_FILE}
+          echo "fi" >> ${SCRIPT_FILE}
 
           # List retrieved files for verification
           echo "echo '==> Coverage files retrieved:'" >> ${SCRIPT_FILE}

.github/workflows/MistKit.yml

@@ -173,10 +173,16 @@ jobs:
           collect-coverage: true
           coverage-output-dir: .build/coverage-android
 
-      # Note: Android coverage cannot be uploaded to Codecov due to Swift Android tooling limitations
-      # The profraw files cannot be processed by any available llvm-cov (host, NDK, or Swift toolchain)
-      # All attempts result in "bad magic" or "version mismatch" errors
-      # Keeping profraw files as artifacts for future investigation
+      - name: Upload coverage to Codecov
+        if: success() && hashFiles('coverage-android/coverage.lcov') != ''
+        uses: codecov/codecov-action@v4
+        with:
+          fail_ci_if_error: false
+          flags: android-api34-swift-nightly
+          verbose: true
+          token: ${{ secrets.CODECOV_TOKEN }}
+          files: coverage-android/coverage.lcov
+          # LCOV generated via llvm-profdata merge + llvm-cov export (Android native workflow)
 
       - name: Upload Android coverage files as artifact
         if: always()