diff --git a/.github/workflows/cuda.yml b/.github/workflows/cuda.yml
index 0a483b01e56c..1b1c10a7d556 100644
--- a/.github/workflows/cuda.yml
+++ b/.github/workflows/cuda.yml
@@ -43,9 +43,12 @@ jobs:
                 software-properties-common
             # set up nvidia-docker
             curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
-            sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" -y
+            sudo add-apt-repository -y \
+              "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
             curl -sL https://nvidia.github.io/nvidia-docker/gpgkey | sudo apt-key add -
-            curl -sL https://nvidia.github.io/nvidia-docker/$(. /etc/os-release;echo $ID$VERSION_ID)/nvidia-docker.list | sudo tee /etc/apt/sources.list.d/nvidia-docker.list
+            curl -sL \
+              https://nvidia.github.io/nvidia-docker/$(. /etc/os-release;echo $ID$VERSION_ID)/nvidia-docker.list \
+            | sudo tee /etc/apt/sources.list.d/nvidia-docker.list
             sudo apt-get update
             sudo apt-get install --no-install-recommends -y \
                 containerd.io \
@@ -58,6 +61,7 @@ jobs:
         run: |
           exit 0
   test:
+    # yamllint disable-line rule:line-length
     name: ${{ matrix.task }} ${{ matrix.cuda_version }} ${{ matrix.method }} (${{ matrix.linux_version }}, ${{ matrix.compiler }}, Python ${{ matrix.python_version }})
     runs-on: [self-hosted, linux]
     needs: [restart-docker]
diff --git a/.github/workflows/lock.yml b/.github/workflows/lock.yml
index 2286a82d62d1..41ed74f31ff4 100644
--- a/.github/workflows/lock.yml
+++ b/.github/workflows/lock.yml
@@ -34,12 +34,18 @@ jobs:
           remove-pr-labels: 'awaiting response,awaiting review,blocking,in progress'
           # what message should be posted prior to locking?
           issue-comment: >
-            This issue has been automatically locked since there has not been any recent activity since it was closed.
-            To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues
+            This issue has been automatically locked
+            since there has not been any recent activity since it was closed.
+
+            To start a new related discussion,
+            open a new issue at https://github.com/microsoft/LightGBM/issues
             including a reference to this.
           pr-comment: >
-            This pull request has been automatically locked since there has not been any recent activity since it was closed.
-            To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues
+            This pull request has been automatically locked
+            since there has not been any recent activity since it was closed.
+
+            To start a new related discussion,
+            open a new issue at https://github.com/microsoft/LightGBM/issues
             including a reference to this.
           # what should the locking status be?
           issue-lock-reason: 'resolved'
diff --git a/.github/workflows/no_response.yml b/.github/workflows/no_response.yml
index 1994f53d7bc7..4f07c8b40689 100644
--- a/.github/workflows/no_response.yml
+++ b/.github/workflows/no_response.yml
@@ -18,9 +18,14 @@ jobs:
       - uses: lee-dohm/no-response@v0.5.0
         with:
           closeComment: >
-              This issue has been automatically closed because it has been awaiting a response for too long.
-              When you have time to to work with the maintainers to resolve this issue, please post a new comment and it will be re-opened.
-              If the issue has been locked for editing by the time you return to it, please open a new issue and reference this one.
+              This issue has been automatically closed
+              because it has been awaiting a response for too long.
+
+              When you have time to to work with the maintainers to resolve this issue,
+              please post a new comment and it will be re-opened.
+              If the issue has been locked for editing by the time you return to it,
+              please open a new issue and reference this one.
+
               Thank you for taking the time to improve LightGBM!
           daysUntilClose: 30
           responseRequiredLabel: awaiting response
diff --git a/.github/workflows/optional_checks.yml b/.github/workflows/optional_checks.yml
index f794c38e770c..7c26d97bdeab 100644
--- a/.github/workflows/optional_checks.yml
+++ b/.github/workflows/optional_checks.yml
@@ -22,8 +22,11 @@ jobs:
             )
             for i in "${workflows[@]}"; do
                 workflow_name=${i%;*}
+                comment="The last reported status from workflow \"$workflow_name\" is failure."
+                comment+=" Commit fixes and rerun the workflow."
                 trigger_phrase=${i#*;}
-                python "$GITHUB_WORKSPACE/.ci/get-workflow-status.py" "$trigger_phrase" \
-                || { echo "The last reported status from workflow \"$workflow_name\" is failure. Commit fixes and rerun the workflow."; \
-                exit 1; }
+                python \
+                    "$GITHUB_WORKSPACE/.ci/get-workflow-status.py" \
+                    "$trigger_phrase" \
+                || { echo "${comment}"; exit 1; }
             done
diff --git a/.github/workflows/r_package.yml b/.github/workflows/r_package.yml
index a168da086cfa..6780a3ba46f4 100644
--- a/.github/workflows/r_package.yml
+++ b/.github/workflows/r_package.yml
@@ -47,6 +47,7 @@ env:
 
 jobs:
   test:
+    # yamllint disable-line rule:line-length
     name: ${{ matrix.task }} (${{ matrix.os }}, ${{ matrix.compiler }}, R ${{ matrix.r_version }}, ${{ matrix.build_type }})
     runs-on: ${{ matrix.os }}
     container: ${{ matrix.container }}
@@ -244,7 +245,9 @@ jobs:
       - name: Install packages
         shell: bash
         run: |
-          RDscript${{ matrix.r_customization }} -e "install.packages(c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl', 'testthat'), repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())"
+          R_LIBS="c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl', 'testthat')"
+          RDscript${{ matrix.r_customization }} \
+            -e "install.packages(${R_LIBS}, repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())"
           sh build-cran-package.sh --r-executable=RD${{ matrix.r_customization }}
           RD${{ matrix.r_customization }} CMD INSTALL lightgbm_*.tar.gz || exit 1
       - name: Run tests with sanitizers
@@ -309,7 +312,9 @@ jobs:
       - name: Install packages and run tests
         shell: bash
         run: |
-          Rscript -e "install.packages(c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl'), repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())"
+          R_LIBS="c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl')"
+          Rscript \
+            -e "install.packages(${R_LIBS}, repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())"
           sh build-cran-package.sh
 
           # 'rchk' isn't run through 'R CMD check', use the approach documented at
diff --git a/.github/workflows/r_valgrind.yml b/.github/workflows/r_valgrind.yml
index 8593831eed56..961fe20942cb 100644
--- a/.github/workflows/r_valgrind.yml
+++ b/.github/workflows/r_valgrind.yml
@@ -33,17 +33,25 @@ jobs:
       - name: Send init status
         if: ${{ always() }}
         run: |
-          $GITHUB_WORKSPACE/.ci/set-commit-status.sh "${{ github.workflow }}" "pending" "${{ github.event.client_payload.pr_sha }}"
+          $GITHUB_WORKSPACE/.ci/set-commit-status.sh \
+            "${{ github.workflow }}" \
+            "pending" \
+            "${{ github.event.client_payload.pr_sha }}"
+          comment="Workflow **${{ github.workflow }}** has been triggered! 🚀\r\n"
+          comment+="${GITHUB_SERVER_URL}/microsoft/LightGBM/actions/runs/${GITHUB_RUN_ID}"
           $GITHUB_WORKSPACE/.ci/append-comment.sh \
             "${{ github.event.client_payload.comment_number }}" \
-            "Workflow **${{ github.workflow }}** has been triggered! 🚀\r\n${GITHUB_SERVER_URL}/microsoft/LightGBM/actions/runs/${GITHUB_RUN_ID}"
+            "${comment}"
       - name: Run tests with valgrind
         shell: bash
         run: ./.ci/test-r-package-valgrind.sh
       - name: Send final status
         if: ${{ always() }}
         run: |
-          $GITHUB_WORKSPACE/.ci/set-commit-status.sh "${{ github.workflow }}" "${{ job.status }}" "${{ github.event.client_payload.pr_sha }}"
+          $GITHUB_WORKSPACE/.ci/set-commit-status.sh \
+            "${{ github.workflow }}" \
+            "${{ job.status }}" \
+            "${{ github.event.client_payload.pr_sha }}"
           $GITHUB_WORKSPACE/.ci/append-comment.sh \
             "${{ github.event.client_payload.comment_number }}" \
             "Status: ${{ job.status }}."
diff --git a/.github/workflows/static_analysis.yml b/.github/workflows/static_analysis.yml
index 3cf579f0707e..69b5b8df004d 100644
--- a/.github/workflows/static_analysis.yml
+++ b/.github/workflows/static_analysis.yml
@@ -63,10 +63,12 @@ jobs:
           submodules: true
       - name: Install packages
         shell: bash
+        # yamllint disable rule:line-length
         run: |
           Rscript -e "install.packages(c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl', 'roxygen2', 'testthat'), repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())"
           sh build-cran-package.sh || exit 1
           R CMD INSTALL --with-keep.source lightgbm_*.tar.gz || exit 1
+        # yamllint enable rule:line-length
       - name: Test documentation
         shell: bash --noprofile --norc {0}
         run: |
diff --git a/.github/workflows/triggering_comments.yml b/.github/workflows/triggering_comments.yml
index 1b5ea706fb91..452d487c42e5 100644
--- a/.github/workflows/triggering_comments.yml
+++ b/.github/workflows/triggering_comments.yml
@@ -6,7 +6,10 @@ on:
 
 jobs:
   triggering-tests:
-    if: github.event.issue.pull_request && contains('OWNER,MEMBER,COLLABORATOR', github.event.comment.author_association) && startsWith(github.event.comment.body, '/gha run')
+    if: |
+      github.event.issue.pull_request &&
+      contains('OWNER,MEMBER,COLLABORATOR', github.event.comment.author_association) &&
+      startsWith(github.event.comment.body, '/gha run')
     runs-on: ubuntu-latest
     env:
       SECRETS_WORKFLOW: ${{ secrets.WORKFLOW }}
diff --git a/.vsts-ci.yml b/.vsts-ci.yml
index 0d457a57cbef..6248dd66177f 100644
--- a/.vsts-ci.yml
+++ b/.vsts-ci.yml
@@ -137,7 +137,12 @@ jobs:
           filePath: $(Build.SourcesDirectory)/.ci/test.sh
           targetType: filePath
       - task: PublishBuildArtifacts@1
-        condition: and(succeeded(), in(variables['TASK'], 'regular', 'sdist', 'bdist', 'swig'), not(startsWith(variables['Build.SourceBranch'], 'refs/pull/')))
+        condition: >
+          and(
+          succeeded(),
+          in(variables['TASK'], 'regular', 'sdist', 'bdist', 'swig'),
+          not(startsWith(variables['Build.SourceBranch'], 'refs/pull/'))
+          )
         inputs:
           pathtoPublish: '$(Build.ArtifactStagingDirectory)'
           artifactName: PackageAssets
@@ -279,7 +284,12 @@ jobs:
             /bin/bash $BUILD_DIRECTORY/docker-script.sh
         displayName: 'Setup and run tests'
       - task: PublishBuildArtifacts@1
-        condition: and(succeeded(), in(variables['TASK'], 'bdist'), not(startsWith(variables['Build.SourceBranch'], 'refs/pull/')))
+        condition: >
+          and(
+          succeeded(),
+          in(variables['TASK'], 'bdist'),
+          not(startsWith(variables['Build.SourceBranch'], 'refs/pull/'))
+          )
         inputs:
           pathtoPublish: '$(Build.ArtifactStagingDirectory)'
           artifactName: PackageAssets
@@ -332,7 +342,12 @@ jobs:
           filePath: $(Build.SourcesDirectory)/.ci/test.sh
           targetType: filePath
       - task: PublishBuildArtifacts@1
-        condition: and(succeeded(), in(variables['TASK'], 'regular', 'bdist', 'swig'), not(startsWith(variables['Build.SourceBranch'], 'refs/pull/')))
+        condition: >
+          and(
+          succeeded(),
+          in(variables['TASK'], 'regular', 'bdist', 'swig'),
+          not(startsWith(variables['Build.SourceBranch'], 'refs/pull/'))
+          )
         inputs:
           pathtoPublish: '$(Build.ArtifactStagingDirectory)'
           artifactName: PackageAssets
@@ -377,7 +392,12 @@ jobs:
           cmd /c "powershell -ExecutionPolicy Bypass -File %BUILD_SOURCESDIRECTORY%/.ci/test-windows.ps1"
         displayName: Test
       - task: PublishBuildArtifacts@1
-        condition: and(succeeded(), in(variables['TASK'], 'regular', 'bdist', 'swig'), not(startsWith(variables['Build.SourceBranch'], 'refs/pull/')))
+        condition: >
+          and(
+          succeeded(),
+          in(variables['TASK'], 'regular', 'bdist', 'swig'),
+          not(startsWith(variables['Build.SourceBranch'], 'refs/pull/'))
+          )
         inputs:
           pathtoPublish: '$(Build.ArtifactStagingDirectory)'
           artifactName: PackageAssets
@@ -394,6 +414,7 @@ jobs:
       - script: |
           git clean -d -f -x
         displayName: 'Clean source directory'
+      # yamllint disable rule:line-length
       - script: |
           LGB_VER=$(head -n 1 VERSION.txt | sed "s/rc/-/g")
           R_LIB_PATH=~/Rlib
@@ -402,6 +423,7 @@ jobs:
           RDscript -e "install.packages(c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl'),  lib = '${R_LIB_PATH}', dependencies = c('Depends', 'Imports', 'LinkingTo'), repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())" || exit 1
           sh build-cran-package.sh --r-executable=RD || exit 1
           mv lightgbm_${LGB_VER}.tar.gz $(Build.ArtifactStagingDirectory)/lightgbm-${LGB_VER}-r-cran.tar.gz
+        # yamllint enable rule:line-length
         displayName: 'Build CRAN R-package'
       - task: PublishBuildArtifacts@1
         condition: succeeded()
diff --git a/.yamllint.yml b/.yamllint.yml
index aab153ab95c1..7bb0ae95ec74 100644
--- a/.yamllint.yml
+++ b/.yamllint.yml
@@ -4,7 +4,7 @@ extends: default
 rules:
   document-start: disable
   line-length:
-    max: 999  # temporarily increase allowed line length
+    max: 120
   truthy:
     # prevent treating GitHub Workflow "on" key as boolean value
     check-keys: false