From 54e9a320c7670ab44934eb5a847abecd0fb832a1 Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Tue, 2 Jun 2026 16:28:33 +0300
Subject: [PATCH 01/10] introduce code coverage to the cpp sdk

---
 .github/actions/gcovr/action.yaml  | 58 +++++++++++++++++++++++
 .github/actions/gcovr/run_gcovr.sh | 49 +++++++++++++++++++
 .github/workflows/coverage.yml     | 75 ++++++++++++++++++++++++++++++
 CMakeLists.txt                     |  1 +
 CMakePresets.json                  | 15 ++++++
 cmake/ccache.cmake                 |  4 +-
 cmake/common.cmake                 |  2 +-
 cmake/coverage.cmake               | 19 ++++++++
 cmake/testing.cmake                |  1 +
 9 files changed, 222 insertions(+), 2 deletions(-)
 create mode 100644 .github/actions/gcovr/action.yaml
 create mode 100755 .github/actions/gcovr/run_gcovr.sh
 create mode 100644 .github/workflows/coverage.yml
 create mode 100644 cmake/coverage.cmake

diff --git a/.github/actions/gcovr/action.yaml b/.github/actions/gcovr/action.yaml
new file mode 100644
index 00000000000..b822bf9f1d8
--- /dev/null
+++ b/.github/actions/gcovr/action.yaml
@@ -0,0 +1,58 @@
+name: Gcovr
+description: Generate code coverage reports with gcovr and llvm-cov
+
+inputs:
+  build-directory:
+    description: Build directory containing coverage data (.gcda / .gcno)
+    required: false
+    default: build
+  source-root:
+    description: Source root for gcovr --root
+    required: false
+    default: ${{ github.workspace }}
+  gcov-executable:
+    description: gcov executable passed to gcovr (e.g. llvm-cov-16 gcov for Clang)
+    required: false
+    default: llvm-cov-16 gcov
+  gcovr-version:
+    description: gcovr PyPI version to install
+    required: false
+    default: "8.4"
+  output-directory:
+    description: Directory for generated coverage reports
+    required: false
+    default: build/coverage
+  fail-under-line:
+    description: Fail if line coverage is below this percent (0 disables the gate)
+    required: false
+    default: "0"
+
+runs:
+  using: composite
+  steps:
+    - name: Install gcovr
+      shell: bash
+      run: |
+        python3 -m pip install --user "gcovr==${{ inputs.gcovr-version }}"
+        echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+
+    - name: Verify llvm-cov
+      shell: bash
+      run: |
+        llvm_cov="${{ inputs.gcov-executable }}"
+        llvm_cov_bin="${llvm_cov%% *}"
+        if ! command -v "${llvm_cov_bin}" >/dev/null 2>&1; then
+          echo "::error::${llvm_cov_bin} not found; install LLVM or adjust gcov-executable"
+          exit 1
+        fi
+
+    - name: Generate coverage report
+      shell: bash
+      run: |
+        chmod +x "${{ github.action_path }}/run_gcovr.sh"
+        SOURCE_ROOT="${{ inputs.source-root }}" \
+        BUILD_DIR="${{ github.workspace }}/${{ inputs.build-directory }}" \
+        OUTPUT_DIR="${{ github.workspace }}/${{ inputs.output-directory }}" \
+        GCOV_EXECUTABLE="${{ inputs.gcov-executable }}" \
+        FAIL_UNDER_LINE="${{ inputs.fail-under-line }}" \
+        "${{ github.action_path }}/run_gcovr.sh"
diff --git a/.github/actions/gcovr/run_gcovr.sh b/.github/actions/gcovr/run_gcovr.sh
new file mode 100755
index 00000000000..94d3c418f43
--- /dev/null
+++ b/.github/actions/gcovr/run_gcovr.sh
@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+: "${SOURCE_ROOT:?SOURCE_ROOT is required}"
+: "${BUILD_DIR:?BUILD_DIR is required}"
+: "${OUTPUT_DIR:?OUTPUT_DIR is required}"
+: "${GCOV_EXECUTABLE:=llvm-cov-16 gcov}"
+
+mkdir -p "${OUTPUT_DIR}"
+
+gcovr_args=(
+  --root "${SOURCE_ROOT}"
+  --object-directory "${BUILD_DIR}"
+  --gcov-executable "${GCOV_EXECUTABLE}"
+  --print-summary
+  --json-summary "${OUTPUT_DIR}/summary.json"
+  --html --html-details
+  -o "${OUTPUT_DIR}/index.html"
+  --cobertura "${OUTPUT_DIR}/cobertura.xml"
+  --exclude '.*contrib/.*'
+  --exclude '.*tests/.*'
+  --exclude '.*/_deps/.*'
+  --filter 'src/'
+  --filter 'include/ydb-cpp-sdk/'
+  --filter 'plugins/'
+)
+
+if [[ -n "${FAIL_UNDER_LINE:-}" && "${FAIL_UNDER_LINE}" != "0" ]]; then
+  gcovr_args+=(--fail-under-line "${FAIL_UNDER_LINE}")
+fi
+
+gcovr "${gcovr_args[@]}"
+
+if [[ -n "${GITHUB_STEP_SUMMARY:-}" && -f "${OUTPUT_DIR}/summary.json" ]]; then
+  {
+    echo "## Code coverage"
+    echo ""
+    echo "| Metric | Covered | Total | Percent |"
+    echo "| --- | ---: | ---: | ---: |"
+    jq -r '
+      .line as $l
+      | .branch as $b
+      | .function as $f
+      | "| Line | \($l.covered) | \($l.num) | \($l.percent // 0)% |",
+        "| Branch | \($b.covered) | \($b.num) | \($b.percent // 0)% |",
+        "| Function | \($f.covered) | \($f.num) | \($f.percent // 0)% |"
+    ' "${OUTPUT_DIR}/summary.json"
+  } >> "${GITHUB_STEP_SUMMARY}"
+fi
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
new file mode 100644
index 00000000000..3dd28ad5c61
--- /dev/null
+++ b/.github/workflows/coverage.yml
@@ -0,0 +1,75 @@
+name: Coverage
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+    branches:
+      - main
+
+concurrency:
+  group: coverage-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  coverage:
+    runs-on: ubuntu-22.04
+    services:
+      ydb:
+        image: ydbplatform/local-ydb:24.4
+        ports:
+          - 2135:2135
+          - 2136:2136
+          - 8765:8765
+        volumes:
+          - /tmp/ydb_certs:/ydb_certs
+        env:
+          YDB_LOCAL_SURVIVE_RESTART: true
+          YDB_USE_IN_MEMORY_PDISKS: true
+          YDB_TABLE_ENABLE_PREPARED_DDL: true
+        options: '-h localhost'
+    steps:
+      - name: Checkout PR
+        uses: actions/checkout@v4
+        if: github.event.pull_request.head.sha != ''
+        with:
+          submodules: true
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - name: Checkout
+        uses: actions/checkout@v4
+        if: github.event.pull_request.head.sha == ''
+        with:
+          submodules: true
+
+      - name: Install dependencies
+        uses: ./.github/actions/prepare_vm
+
+      - name: Configure and build with coverage
+        shell: bash
+        run: |
+          mkdir -p build
+          rm -rf build/*
+          cmake --preset coverage-test-clang
+          cmake --build build -j"$(nproc)"
+
+      - name: Test
+        shell: bash
+        run: |
+          ctest -j2 --preset all --output-on-failure
+
+      - name: Generate coverage report
+        uses: ./.github/actions/gcovr
+        with:
+          build-directory: build
+          source-root: ${{ github.workspace }}
+          gcov-executable: llvm-cov-16 gcov
+
+      - name: Upload coverage reports
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-report
+          path: build/coverage/
+          retention-days: 14
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f4177996491..2cf1bc9e668 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,6 +43,7 @@ include(CMakePackageConfigHelpers)
 list(APPEND CMAKE_MODULE_PATH ${YDB_SDK_SOURCE_DIR}/cmake)
 
 include(cmake/global_flags.cmake)
+include(cmake/coverage.cmake)
 include(cmake/global_vars.cmake)
 include(cmake/install.cmake)
 include(cmake/common.cmake)
diff --git a/CMakePresets.json b/CMakePresets.json
index e0a4f0ad0d2..508c9b83e3b 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -118,6 +118,21 @@
       "name": "debug-test-gcc",
       "inherits": ["debug-base", "gcc-toolchain", "test"],
       "displayName": "Default Debug Test Config (GCC)"
+    },
+    {
+      "name": "coverage-base",
+      "inherits": ["debug-base", "test"],
+      "hidden": true,
+      "cacheVariables": {
+        "YDB_SDK_COVERAGE": "ON",
+        "ARCADIA_ROOT": "${sourceDir}",
+        "ARCADIA_BUILD_ROOT": "."
+      }
+    },
+    {
+      "name": "coverage-test-clang",
+      "inherits": ["coverage-base", "clang-toolchain"],
+      "displayName": "Coverage Test Config (Clang)"
     }
   ],
   "buildPresets": [
diff --git a/cmake/ccache.cmake b/cmake/ccache.cmake
index ef68402c465..311a9b8f128 100644
--- a/cmake/ccache.cmake
+++ b/cmake/ccache.cmake
@@ -1,5 +1,7 @@
 find_program(CCACHE_PATH ccache)
-if (NOT CCACHE_PATH)
+if (YDB_SDK_COVERAGE)
+  message(STATUS "YDB_SDK_COVERAGE is ON: ccache compiler launchers disabled")
+elseif (NOT CCACHE_PATH)
   message(AUTHOR_WARNING
     "Ccache is not found, that will increase the re-compilation time; "
     "pass -DCCACHE_PATH=path/to/bin to specify the path to the `ccache` binary file."
diff --git a/cmake/common.cmake b/cmake/common.cmake
index fff0c92fcdf..b40eee34324 100644
--- a/cmake/common.cmake
+++ b/cmake/common.cmake
@@ -216,6 +216,7 @@ function(_ydb_sdk_add_library Tgt)
   target_compile_definitions(${Tgt} ${includeMode}
     YDB_SDK_OSS
   )
+  _ydb_sdk_apply_coverage(${Tgt})
   
 endfunction()
 
@@ -462,4 +463,3 @@ function(_ydb_sdk_validate_public_headers)
   )
   target_include_directories(validate_public_interface PUBLIC ${YDB_SDK_BINARY_DIR}/__validate_headers_dir/include)
 endfunction()
-
diff --git a/cmake/coverage.cmake b/cmake/coverage.cmake
new file mode 100644
index 00000000000..182b80d77ae
--- /dev/null
+++ b/cmake/coverage.cmake
@@ -0,0 +1,19 @@
+option(YDB_SDK_COVERAGE "Instrument SDK and tests for gcov/llvm-cov coverage" OFF)
+
+function(_ydb_sdk_apply_coverage target)
+  if (NOT YDB_SDK_COVERAGE)
+    return()
+  endif()
+  get_target_property(is_iface ${target} TYPE)
+  if (is_iface STREQUAL "INTERFACE_LIBRARY")
+    return()
+  endif()
+  target_compile_options(${target} PRIVATE
+    --coverage
+    -O0
+    -g
+    -fno-inline
+    -fprofile-abs-path
+  )
+  target_link_options(${target} PRIVATE --coverage)
+endfunction()
diff --git a/cmake/testing.cmake b/cmake/testing.cmake
index 641c855d8da..999e6a596d6 100644
--- a/cmake/testing.cmake
+++ b/cmake/testing.cmake
@@ -51,6 +51,7 @@ function(add_ydb_test)
   endif()
 
   add_executable(${YDB_TEST_NAME})
+  _ydb_sdk_apply_coverage(${YDB_TEST_NAME})
   target_include_directories(${YDB_TEST_NAME} PRIVATE ${YDB_TEST_INCLUDE_DIRS})
   target_link_libraries(${YDB_TEST_NAME} PRIVATE ${YDB_TEST_LINK_LIBRARIES})
   target_sources(${YDB_TEST_NAME} PRIVATE ${YDB_TEST_SOURCES})

From b87026e36a8a8f9e12afa4e51d0e9ad7e5b776c5 Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Tue, 2 Jun 2026 17:24:18 +0300
Subject: [PATCH 02/10] fix

---
 cmake/coverage.cmake | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/cmake/coverage.cmake b/cmake/coverage.cmake
index 182b80d77ae..33adc91e885 100644
--- a/cmake/coverage.cmake
+++ b/cmake/coverage.cmake
@@ -1,5 +1,9 @@
 option(YDB_SDK_COVERAGE "Instrument SDK and tests for gcov/llvm-cov coverage" OFF)
 
+if (YDB_SDK_COVERAGE)
+  add_link_options(--coverage)
+endif()
+
 function(_ydb_sdk_apply_coverage target)
   if (NOT YDB_SDK_COVERAGE)
     return()
@@ -8,12 +12,10 @@ function(_ydb_sdk_apply_coverage target)
   if (is_iface STREQUAL "INTERFACE_LIBRARY")
     return()
   endif()
-  target_compile_options(${target} PRIVATE
-    --coverage
-    -O0
-    -g
-    -fno-inline
-    -fprofile-abs-path
-  )
+  set(_coverage_compile_flags --coverage -O0 -g -fno-inline)
+  if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    list(APPEND _coverage_compile_flags -fprofile-abs-path)
+  endif()
+  target_compile_options(${target} PRIVATE ${_coverage_compile_flags})
   target_link_options(${target} PRIVATE --coverage)
 endfunction()

From 15ccdcd8bf91fded48df4b1e34ad3f15f8ef1392 Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Wed, 3 Jun 2026 15:04:38 +0300
Subject: [PATCH 03/10] fix timeout

---
 .github/workflows/coverage.yml |  2 +-
 CMakePresets.json              | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 3dd28ad5c61..1c1c48714f7 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -58,7 +58,7 @@ jobs:
       - name: Test
         shell: bash
         run: |
-          ctest -j2 --preset all --output-on-failure
+          ctest -j1 --preset coverage-all --output-on-failure
 
       - name: Generate coverage report
         uses: ./.github/actions/gcovr
diff --git a/CMakePresets.json b/CMakePresets.json
index 508c9b83e3b..d41ee7ce3e0 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -188,6 +188,24 @@
         "YDB_ENDPOINT": "localhost:2136",
         "YDB_DATABASE": "/local"
       }
+    },
+    {
+      "name": "coverage-all",
+      "inherits": "all",
+      "displayName": "Run All Tests (coverage CI)",
+      "execution": {
+        "timeout": 1800
+      },
+      "filter": {
+        "exclude": {
+          "name": "ManyMessages"
+        }
+      },
+      "environment": {
+        "YDB_ENDPOINT": "localhost:2136",
+        "YDB_DATABASE": "/local",
+        "YDB_VERSION": "24.4"
+      }
     }
   ]
 }

From 704d22724aa3bf1634c25bc9647719ef5c46217a Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Wed, 3 Jun 2026 16:00:00 +0300
Subject: [PATCH 04/10] add gh comment action

---
 .github/actions/gcovr/action.yaml        |  21 +++++
 .github/actions/gcovr/post_pr_comment.sh | 100 +++++++++++++++++++++++
 .github/workflows/coverage.yml           |   4 +
 3 files changed, 125 insertions(+)
 create mode 100755 .github/actions/gcovr/post_pr_comment.sh

diff --git a/.github/actions/gcovr/action.yaml b/.github/actions/gcovr/action.yaml
index b822bf9f1d8..a128d35d2bc 100644
--- a/.github/actions/gcovr/action.yaml
+++ b/.github/actions/gcovr/action.yaml
@@ -26,6 +26,14 @@ inputs:
     description: Fail if line coverage is below this percent (0 disables the gate)
     required: false
     default: "0"
+  post-pr-comment:
+    description: Post or update a sticky coverage summary on the pull request
+    required: false
+    default: "true"
+  github-token:
+    description: Token for posting PR comments
+    required: false
+    default: ${{ github.token }}
 
 runs:
   using: composite
@@ -56,3 +64,16 @@ runs:
         GCOV_EXECUTABLE="${{ inputs.gcov-executable }}" \
         FAIL_UNDER_LINE="${{ inputs.fail-under-line }}" \
         "${{ github.action_path }}/run_gcovr.sh"
+
+    - name: Post coverage PR comment
+      if: inputs.post-pr-comment == 'true'
+      shell: bash
+      env:
+        GH_TOKEN: ${{ inputs.github-token }}
+        PR_NUMBER: ${{ github.event.pull_request.number }}
+        OUTPUT_DIR: ${{ github.workspace }}/${{ inputs.output-directory }}
+        GITHUB_REPOSITORY: ${{ github.repository }}
+        GITHUB_RUN_ID: ${{ github.run_id }}
+      run: |
+        chmod +x "${{ github.action_path }}/post_pr_comment.sh"
+        "${{ github.action_path }}/post_pr_comment.sh"
diff --git a/.github/actions/gcovr/post_pr_comment.sh b/.github/actions/gcovr/post_pr_comment.sh
new file mode 100755
index 00000000000..031a64632e5
--- /dev/null
+++ b/.github/actions/gcovr/post_pr_comment.sh
@@ -0,0 +1,100 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+: "${OUTPUT_DIR:?OUTPUT_DIR is required}"
+: "${GITHUB_REPOSITORY:?GITHUB_REPOSITORY is required}"
+: "${GITHUB_RUN_ID:?GITHUB_RUN_ID is required}"
+
+MARKER='<!-- ydb-cpp-sdk-coverage -->'
+SUMMARY_JSON="${OUTPUT_DIR}/summary.json"
+
+if [[ -z "${PR_NUMBER:-}" ]]; then
+  echo "PR_NUMBER is not set; skipping coverage PR comment"
+  exit 0
+fi
+
+if [[ ! -f "${SUMMARY_JSON}" ]]; then
+  echo "::warning::${SUMMARY_JSON} not found; skipping coverage PR comment"
+  exit 0
+fi
+
+if ! command -v gh >/dev/null 2>&1; then
+  echo "::error::gh CLI is required to post PR comments"
+  exit 1
+fi
+
+BODY="$(MARKER="${MARKER}" SUMMARY_JSON="${SUMMARY_JSON}" GITHUB_REPOSITORY="${GITHUB_REPOSITORY}" GITHUB_RUN_ID="${GITHUB_RUN_ID}" python3 <<'PY'
+import json
+import os
+from pathlib import Path
+
+marker = os.environ["MARKER"]
+summary = json.loads(Path(os.environ["SUMMARY_JSON"]).read_text())
+repo = os.environ["GITHUB_REPOSITORY"]
+run_id = os.environ["GITHUB_RUN_ID"]
+
+line = summary["line"]
+branch = summary["branch"]
+func = summary["function"]
+
+def bar(percent: float) -> str:
+    filled = max(0, min(10, int(round(percent / 10))))
+    return "█" * filled + "░" * (10 - filled)
+
+files = [
+    f for f in summary.get("files", [])
+    if f.get("line_total", 0) >= 20
+]
+files.sort(key=lambda f: f.get("line_percent") or 0)
+lowest = files[:8]
+
+run_url = f"https://github.com/{repo}/actions/runs/{run_id}"
+lines = [
+    marker,
+    "## Code coverage",
+    "",
+    f"Workflow run: [Coverage job #{run_id}]({run_url}) · download the **coverage-report** artifact for the HTML report.",
+    "",
+    "| Metric | Coverage | Covered / total |",
+    "| --- | --- | --- |",
+    f"| Line | **{line['percent']:.1f}%** {bar(line['percent'])} | {line['covered']} / {line['num']} |",
+    f"| Branch | **{branch['percent']:.1f}%** {bar(branch['percent'])} | {branch['covered']} / {branch['num']} |",
+    f"| Function | **{func['percent']:.1f}%** {bar(func['percent'])} | {func['covered']} / {func['num']} |",
+    "",
+    "Scope: `src/`, `include/ydb-cpp-sdk/`, `plugins/` (contrib, tests, and `_deps` excluded).",
+]
+
+if lowest:
+    lines.extend([
+        "",
+        "<details>",
+        "<summary>Lowest line coverage (≥ 20 lines)</summary>",
+        "",
+        "| File | Line % | Covered / total |",
+        "| --- | ---: | --- |",
+    ])
+    for f in lowest:
+        pct = f.get("line_percent") or 0
+        lines.append(
+            f"| `{f['filename']}` | {pct:.1f}% | {f['line_covered']} / {f['line_total']} |"
+        )
+    lines.extend(["", "</details>"])
+
+print("\n".join(lines))
+PY
+)"
+
+COMMENT_ID="$(gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
+  --paginate \
+  --jq ".[] | select(.body | contains(\"${MARKER}\")) | .id" \
+  | head -n1)"
+
+if [[ -n "${COMMENT_ID}" ]]; then
+  gh api -X PATCH "repos/${GITHUB_REPOSITORY}/issues/comments/${COMMENT_ID}" \
+    -f body="${BODY}" >/dev/null
+  echo "Updated coverage comment ${COMMENT_ID} on PR #${PR_NUMBER}"
+else
+  gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
+    -f body="${BODY}" >/dev/null
+  echo "Posted coverage comment on PR #${PR_NUMBER}"
+fi
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 1c1c48714f7..c7bcea5640d 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -16,6 +16,9 @@ concurrency:
 jobs:
   coverage:
     runs-on: ubuntu-22.04
+    permissions:
+      contents: read
+      pull-requests: write
     services:
       ydb:
         image: ydbplatform/local-ydb:24.4
@@ -66,6 +69,7 @@ jobs:
           build-directory: build
           source-root: ${{ github.workspace }}
           gcov-executable: llvm-cov-16 gcov
+          post-pr-comment: ${{ github.event_name == 'pull_request' }}
 
       - name: Upload coverage reports
         uses: actions/upload-artifact@v4

From c9d12d1721c451075a8b1e278bbebc80b677374c Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Wed, 3 Jun 2026 16:11:41 +0300
Subject: [PATCH 05/10] run the whole test suite

---
 CMakePresets.json | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/CMakePresets.json b/CMakePresets.json
index d41ee7ce3e0..a1bc9ad68de 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -195,16 +195,6 @@
       "displayName": "Run All Tests (coverage CI)",
       "execution": {
         "timeout": 1800
-      },
-      "filter": {
-        "exclude": {
-          "name": "ManyMessages"
-        }
-      },
-      "environment": {
-        "YDB_ENDPOINT": "localhost:2136",
-        "YDB_DATABASE": "/local",
-        "YDB_VERSION": "24.4"
       }
     }
   ]

From 17281d8d2fe774d44d98e6015098fe62a2639d80 Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Wed, 3 Jun 2026 18:43:31 +0300
Subject: [PATCH 06/10] fix build issues

---
 .github/workflows/coverage.yml |  4 ++--
 CMakePresets.json              | 23 ++++++++++++++++-------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index c7bcea5640d..24bbb2deed1 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -55,7 +55,7 @@ jobs:
         run: |
           mkdir -p build
           rm -rf build/*
-          cmake --preset coverage-test-clang
+          cmake --preset coverage-test-gcc
           cmake --build build -j"$(nproc)"
 
       - name: Test
@@ -68,7 +68,7 @@ jobs:
         with:
           build-directory: build
           source-root: ${{ github.workspace }}
-          gcov-executable: llvm-cov-16 gcov
+          gcov-executable: gcov-13
           post-pr-comment: ${{ github.event_name == 'pull_request' }}
 
       - name: Upload coverage reports
diff --git a/CMakePresets.json b/CMakePresets.json
index a1bc9ad68de..750174e9159 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -121,18 +121,16 @@
     },
     {
       "name": "coverage-base",
-      "inherits": ["debug-base", "test"],
+      "inherits": ["release-base", "test"],
       "hidden": true,
       "cacheVariables": {
-        "YDB_SDK_COVERAGE": "ON",
-        "ARCADIA_ROOT": "${sourceDir}",
-        "ARCADIA_BUILD_ROOT": "."
+        "YDB_SDK_COVERAGE": "ON"
       }
     },
     {
-      "name": "coverage-test-clang",
-      "inherits": ["coverage-base", "clang-toolchain"],
-      "displayName": "Coverage Test Config (Clang)"
+      "name": "coverage-test-gcc",
+      "inherits": ["coverage-base", "gcc-toolchain"],
+      "displayName": "Coverage Test Config (GCC)"
     }
   ],
   "buildPresets": [
@@ -193,8 +191,19 @@
       "name": "coverage-all",
       "inherits": "all",
       "displayName": "Run All Tests (coverage CI)",
+      "configurePreset": "coverage-test-gcc",
       "execution": {
         "timeout": 1800
+      },
+      "filter": {
+        "exclude": {
+          "name": "(ManyMessages|DiscoveryHang|DescribeHang)"
+        }
+      },
+      "environment": {
+        "YDB_ENDPOINT": "localhost:2136",
+        "YDB_DATABASE": "/local",
+        "YDB_VERSION": "24.4"
       }
     }
   ]

From 30e1f06a2721e437507cc55d8edffd873ebe390f Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Thu, 4 Jun 2026 09:37:50 +0300
Subject: [PATCH 07/10] fix relpath abspath issue

---
 cmake/coverage.cmake | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cmake/coverage.cmake b/cmake/coverage.cmake
index 33adc91e885..d21180b7d3e 100644
--- a/cmake/coverage.cmake
+++ b/cmake/coverage.cmake
@@ -12,10 +12,10 @@ function(_ydb_sdk_apply_coverage target)
   if (is_iface STREQUAL "INTERFACE_LIBRARY")
     return()
   endif()
+  # Do not use -fprofile-abs-path: it expands __FILE__/__LOCATION__ to absolute paths
+  # and breaks util/system/src_location_ut and src_root_ut (and similar assertions).
+  # gcovr --root maps profile data to the source tree without it.
   set(_coverage_compile_flags --coverage -O0 -g -fno-inline)
-  if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-    list(APPEND _coverage_compile_flags -fprofile-abs-path)
-  endif()
   target_compile_options(${target} PRIVATE ${_coverage_compile_flags})
   target_link_options(${target} PRIVATE --coverage)
 endfunction()

From b24bbfbb85fed2f5d21d6c58554af450523fb15a Mon Sep 17 00:00:00 2001
From: Artem Ermoshkin <shfdis@yandex-team.ru>
Date: Thu, 4 Jun 2026 11:06:32 +0300
Subject: [PATCH 08/10] fix relpath 2.0

---
 CMakePresets.json | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/CMakePresets.json b/CMakePresets.json
index 750174e9159..2061ba6b78f 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -124,7 +124,9 @@
       "inherits": ["release-base", "test"],
       "hidden": true,
       "cacheVariables": {
-        "YDB_SDK_COVERAGE": "ON"
+        "YDB_SDK_COVERAGE": "ON",
+        "ARCADIA_ROOT": "${sourceDir}",
+        "ARCADIA_BUILD_ROOT": "${sourceDir}/build"
       }
     },
     {

From 816dde0d0edcdfd3cf345a15c8eae25d512550ff Mon Sep 17 00:00:00 2001
From: Shfdis <shfdis@yandex-team.ru>
Date: Fri, 19 Jun 2026 12:43:33 +0300
Subject: [PATCH 09/10] add proper codecov label to the repo

---
 .github/actions/gcovr/post_pr_comment.sh | 15 ++++++++++++---
 .github/actions/gcovr/run_gcovr.sh       | 16 +++++++++++++---
 .github/workflows/coverage.yml           | 12 ++++++++++++
 README.md                                |  2 ++
 4 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/.github/actions/gcovr/post_pr_comment.sh b/.github/actions/gcovr/post_pr_comment.sh
index 031a64632e5..7c5212fa51c 100755
--- a/.github/actions/gcovr/post_pr_comment.sh
+++ b/.github/actions/gcovr/post_pr_comment.sh
@@ -33,9 +33,18 @@ summary = json.loads(Path(os.environ["SUMMARY_JSON"]).read_text())
 repo = os.environ["GITHUB_REPOSITORY"]
 run_id = os.environ["GITHUB_RUN_ID"]
 
-line = summary["line"]
-branch = summary["branch"]
-func = summary["function"]
+def metric(name: str) -> dict:
+    if name in summary:
+        return summary[name]
+    return {
+        "covered": summary[f"{name}_covered"],
+        "num": summary[f"{name}_total"],
+        "percent": summary.get(f"{name}_percent") or 0,
+    }
+
+line = metric("line")
+branch = metric("branch")
+func = metric("function")
 
 def bar(percent: float) -> str:
     filled = max(0, min(10, int(round(percent / 10))))
diff --git a/.github/actions/gcovr/run_gcovr.sh b/.github/actions/gcovr/run_gcovr.sh
index 94d3c418f43..18bc940cb4c 100755
--- a/.github/actions/gcovr/run_gcovr.sh
+++ b/.github/actions/gcovr/run_gcovr.sh
@@ -38,9 +38,19 @@ if [[ -n "${GITHUB_STEP_SUMMARY:-}" && -f "${OUTPUT_DIR}/summary.json" ]]; then
     echo "| Metric | Covered | Total | Percent |"
     echo "| --- | ---: | ---: | ---: |"
     jq -r '
-      .line as $l
-      | .branch as $b
-      | .function as $f
+      def metric($name):
+        if has($name) then
+          .[$name]
+        else
+          {
+            covered: .[$name + "_covered"],
+            num: .[$name + "_total"],
+            percent: .[$name + "_percent"]
+          }
+        end;
+      metric("line") as $l
+      | metric("branch") as $b
+      | metric("function") as $f
       | "| Line | \($l.covered) | \($l.num) | \($l.percent // 0)% |",
         "| Branch | \($b.covered) | \($b.num) | \($b.percent // 0)% |",
         "| Function | \($f.covered) | \($f.num) | \($f.percent // 0)% |"
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 24bbb2deed1..20ad15c24c0 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -18,6 +18,7 @@ jobs:
     runs-on: ubuntu-22.04
     permissions:
       contents: read
+      id-token: write
       pull-requests: write
     services:
       ydb:
@@ -71,6 +72,17 @@ jobs:
           gcov-executable: gcov-13
           post-pr-comment: ${{ github.event_name == 'pull_request' }}
 
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          use_oidc: true
+          files: build/coverage/cobertura.xml
+          disable_search: true
+          flags: sdk
+          name: ydb-cpp-sdk
+          fail_ci_if_error: true
+          verbose: true
+
       - name: Upload coverage reports
         uses: actions/upload-artifact@v4
         with:
diff --git a/README.md b/README.md
index a1d15c65aba..affad1c8443 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # YDB C++ SDK: driver for [YDB](https://github.com/ydb-platform/ydb)
 
+[![Codecov](https://codecov.io/gh/ydb-platform/ydb-cpp-sdk/branch/main/graph/badge.svg)](https://app.codecov.io/gh/ydb-platform/ydb-cpp-sdk)
+
 ## Building YDB C++ SDK from sources
 
 ### Prerequisites

From 24ec5b3199170bff830db5edaf8973d089ae509d Mon Sep 17 00:00:00 2001
From: Shfdis <shfdis@yandex-team.ru>
Date: Fri, 19 Jun 2026 12:48:28 +0300
Subject: [PATCH 10/10] simplify the action

---
 .github/actions/gcovr/action.yaml        |  21 -----
 .github/actions/gcovr/post_pr_comment.sh | 109 -----------------------
 .github/actions/gcovr/run_gcovr.sh       |  27 ------
 .github/workflows/coverage.yml           |   2 -
 4 files changed, 159 deletions(-)
 delete mode 100755 .github/actions/gcovr/post_pr_comment.sh

diff --git a/.github/actions/gcovr/action.yaml b/.github/actions/gcovr/action.yaml
index a128d35d2bc..b822bf9f1d8 100644
--- a/.github/actions/gcovr/action.yaml
+++ b/.github/actions/gcovr/action.yaml
@@ -26,14 +26,6 @@ inputs:
     description: Fail if line coverage is below this percent (0 disables the gate)
     required: false
     default: "0"
-  post-pr-comment:
-    description: Post or update a sticky coverage summary on the pull request
-    required: false
-    default: "true"
-  github-token:
-    description: Token for posting PR comments
-    required: false
-    default: ${{ github.token }}
 
 runs:
   using: composite
@@ -64,16 +56,3 @@ runs:
         GCOV_EXECUTABLE="${{ inputs.gcov-executable }}" \
         FAIL_UNDER_LINE="${{ inputs.fail-under-line }}" \
         "${{ github.action_path }}/run_gcovr.sh"
-
-    - name: Post coverage PR comment
-      if: inputs.post-pr-comment == 'true'
-      shell: bash
-      env:
-        GH_TOKEN: ${{ inputs.github-token }}
-        PR_NUMBER: ${{ github.event.pull_request.number }}
-        OUTPUT_DIR: ${{ github.workspace }}/${{ inputs.output-directory }}
-        GITHUB_REPOSITORY: ${{ github.repository }}
-        GITHUB_RUN_ID: ${{ github.run_id }}
-      run: |
-        chmod +x "${{ github.action_path }}/post_pr_comment.sh"
-        "${{ github.action_path }}/post_pr_comment.sh"
diff --git a/.github/actions/gcovr/post_pr_comment.sh b/.github/actions/gcovr/post_pr_comment.sh
deleted file mode 100755
index 7c5212fa51c..00000000000
--- a/.github/actions/gcovr/post_pr_comment.sh
+++ /dev/null
@@ -1,109 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-: "${OUTPUT_DIR:?OUTPUT_DIR is required}"
-: "${GITHUB_REPOSITORY:?GITHUB_REPOSITORY is required}"
-: "${GITHUB_RUN_ID:?GITHUB_RUN_ID is required}"
-
-MARKER='<!-- ydb-cpp-sdk-coverage -->'
-SUMMARY_JSON="${OUTPUT_DIR}/summary.json"
-
-if [[ -z "${PR_NUMBER:-}" ]]; then
-  echo "PR_NUMBER is not set; skipping coverage PR comment"
-  exit 0
-fi
-
-if [[ ! -f "${SUMMARY_JSON}" ]]; then
-  echo "::warning::${SUMMARY_JSON} not found; skipping coverage PR comment"
-  exit 0
-fi
-
-if ! command -v gh >/dev/null 2>&1; then
-  echo "::error::gh CLI is required to post PR comments"
-  exit 1
-fi
-
-BODY="$(MARKER="${MARKER}" SUMMARY_JSON="${SUMMARY_JSON}" GITHUB_REPOSITORY="${GITHUB_REPOSITORY}" GITHUB_RUN_ID="${GITHUB_RUN_ID}" python3 <<'PY'
-import json
-import os
-from pathlib import Path
-
-marker = os.environ["MARKER"]
-summary = json.loads(Path(os.environ["SUMMARY_JSON"]).read_text())
-repo = os.environ["GITHUB_REPOSITORY"]
-run_id = os.environ["GITHUB_RUN_ID"]
-
-def metric(name: str) -> dict:
-    if name in summary:
-        return summary[name]
-    return {
-        "covered": summary[f"{name}_covered"],
-        "num": summary[f"{name}_total"],
-        "percent": summary.get(f"{name}_percent") or 0,
-    }
-
-line = metric("line")
-branch = metric("branch")
-func = metric("function")
-
-def bar(percent: float) -> str:
-    filled = max(0, min(10, int(round(percent / 10))))
-    return "█" * filled + "░" * (10 - filled)
-
-files = [
-    f for f in summary.get("files", [])
-    if f.get("line_total", 0) >= 20
-]
-files.sort(key=lambda f: f.get("line_percent") or 0)
-lowest = files[:8]
-
-run_url = f"https://github.com/{repo}/actions/runs/{run_id}"
-lines = [
-    marker,
-    "## Code coverage",
-    "",
-    f"Workflow run: [Coverage job #{run_id}]({run_url}) · download the **coverage-report** artifact for the HTML report.",
-    "",
-    "| Metric | Coverage | Covered / total |",
-    "| --- | --- | --- |",
-    f"| Line | **{line['percent']:.1f}%** {bar(line['percent'])} | {line['covered']} / {line['num']} |",
-    f"| Branch | **{branch['percent']:.1f}%** {bar(branch['percent'])} | {branch['covered']} / {branch['num']} |",
-    f"| Function | **{func['percent']:.1f}%** {bar(func['percent'])} | {func['covered']} / {func['num']} |",
-    "",
-    "Scope: `src/`, `include/ydb-cpp-sdk/`, `plugins/` (contrib, tests, and `_deps` excluded).",
-]
-
-if lowest:
-    lines.extend([
-        "",
-        "<details>",
-        "<summary>Lowest line coverage (≥ 20 lines)</summary>",
-        "",
-        "| File | Line % | Covered / total |",
-        "| --- | ---: | --- |",
-    ])
-    for f in lowest:
-        pct = f.get("line_percent") or 0
-        lines.append(
-            f"| `{f['filename']}` | {pct:.1f}% | {f['line_covered']} / {f['line_total']} |"
-        )
-    lines.extend(["", "</details>"])
-
-print("\n".join(lines))
-PY
-)"
-
-COMMENT_ID="$(gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
-  --paginate \
-  --jq ".[] | select(.body | contains(\"${MARKER}\")) | .id" \
-  | head -n1)"
-
-if [[ -n "${COMMENT_ID}" ]]; then
-  gh api -X PATCH "repos/${GITHUB_REPOSITORY}/issues/comments/${COMMENT_ID}" \
-    -f body="${BODY}" >/dev/null
-  echo "Updated coverage comment ${COMMENT_ID} on PR #${PR_NUMBER}"
-else
-  gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
-    -f body="${BODY}" >/dev/null
-  echo "Posted coverage comment on PR #${PR_NUMBER}"
-fi
diff --git a/.github/actions/gcovr/run_gcovr.sh b/.github/actions/gcovr/run_gcovr.sh
index 18bc940cb4c..c89a81e8878 100755
--- a/.github/actions/gcovr/run_gcovr.sh
+++ b/.github/actions/gcovr/run_gcovr.sh
@@ -30,30 +30,3 @@ if [[ -n "${FAIL_UNDER_LINE:-}" && "${FAIL_UNDER_LINE}" != "0" ]]; then
 fi
 
 gcovr "${gcovr_args[@]}"
-
-if [[ -n "${GITHUB_STEP_SUMMARY:-}" && -f "${OUTPUT_DIR}/summary.json" ]]; then
-  {
-    echo "## Code coverage"
-    echo ""
-    echo "| Metric | Covered | Total | Percent |"
-    echo "| --- | ---: | ---: | ---: |"
-    jq -r '
-      def metric($name):
-        if has($name) then
-          .[$name]
-        else
-          {
-            covered: .[$name + "_covered"],
-            num: .[$name + "_total"],
-            percent: .[$name + "_percent"]
-          }
-        end;
-      metric("line") as $l
-      | metric("branch") as $b
-      | metric("function") as $f
-      | "| Line | \($l.covered) | \($l.num) | \($l.percent // 0)% |",
-        "| Branch | \($b.covered) | \($b.num) | \($b.percent // 0)% |",
-        "| Function | \($f.covered) | \($f.num) | \($f.percent // 0)% |"
-    ' "${OUTPUT_DIR}/summary.json"
-  } >> "${GITHUB_STEP_SUMMARY}"
-fi
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 20ad15c24c0..97cc17eca74 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -19,7 +19,6 @@ jobs:
     permissions:
       contents: read
       id-token: write
-      pull-requests: write
     services:
       ydb:
         image: ydbplatform/local-ydb:24.4
@@ -70,7 +69,6 @@ jobs:
           build-directory: build
           source-root: ${{ github.workspace }}
           gcov-executable: gcov-13
-          post-pr-comment: ${{ github.event_name == 'pull_request' }}
 
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v5