diff --git a/.github/workflows/cleanup-stale-schemas.yml b/.github/workflows/cleanup-stale-schemas.yml
index bf8522866..899ffa58c 100644
--- a/.github/workflows/cleanup-stale-schemas.yml
+++ b/.github/workflows/cleanup-stale-schemas.yml
@@ -12,12 +12,19 @@ on:
         default: "24"
         description: Drop schemas older than this many hours
 
+permissions: {}
+
 env:
   TESTS_DIR: ${{ github.workspace }}/dbt-data-reliability/integration_tests
 
 jobs:
   cleanup:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    env:
+      WAREHOUSE: ${{ matrix.warehouse-type }}
+      MAX_AGE_HOURS: ${{ inputs.max-age-hours || '24' }}
     strategy:
       fail-fast: false
       matrix:
@@ -28,6 +35,14 @@ jobs:
           - databricks_catalog
           - athena
     steps:
+      - name: Validate max-age-hours input
+        # Fail-closed on non-integer input before it reaches dbt run-operation.
+        run: |
+          if ! [[ "$MAX_AGE_HOURS" =~ ^[0-9]+$ ]]; then
+            echo "::error::Invalid max-age-hours: '$MAX_AGE_HOURS' (must be a non-negative integer)"
+            exit 1
+          fi
+
       - name: Checkout dbt package
         uses: actions/checkout@v6
         with:
@@ -40,10 +55,9 @@ jobs:
           cache: "pip"
 
       - name: Install dbt
-        run: >
-          pip install
-          "dbt-core"
-          "dbt-${{ (matrix.warehouse-type == 'databricks_catalog' && 'databricks') || (matrix.warehouse-type == 'athena' && 'athena-community') || matrix.warehouse-type }}"
+        env:
+          DBT_ADAPTER_PKG: ${{ (matrix.warehouse-type == 'databricks_catalog' && 'databricks') || (matrix.warehouse-type == 'athena' && 'athena-community') || matrix.warehouse-type }}
+        run: pip install "dbt-core" "dbt-${DBT_ADAPTER_PKG}"
 
       - name: Write dbt profiles
         env:
@@ -61,13 +75,13 @@ jobs:
         run: dbt deps
 
       - name: Symlink local elementary package
-        run: ln -sfn ${{ github.workspace }}/dbt-data-reliability ${{ env.TESTS_DIR }}/dbt_project/dbt_packages/elementary
+        run: ln -sfn "${{ github.workspace }}/dbt-data-reliability" "${{ env.TESTS_DIR }}/dbt_project/dbt_packages/elementary"
 
       - name: Drop stale CI schemas
         working-directory: ${{ env.TESTS_DIR }}/dbt_project
         # Only dbt_ prefixed schemas are created in this repo's CI.
         # The elementary repo has its own workflow for py_ prefixed schemas.
-        run: >
-          dbt run-operation drop_stale_ci_schemas
-          --args '{prefixes: ["dbt_"], max_age_hours: ${{ inputs.max-age-hours || '24' }}}'
-          -t "${{ matrix.warehouse-type }}"
+        run: |
+          dbt run-operation drop_stale_ci_schemas \
+            --args '{prefixes: ["dbt_"], max_age_hours: '"$MAX_AGE_HOURS"'}' \
+            -t "$WAREHOUSE"
diff --git a/.github/workflows/test-all-warehouses-dbt-pre-releases.yml b/.github/workflows/test-all-warehouses-dbt-pre-releases.yml
index e1cad4283..d3e69d818 100644
--- a/.github/workflows/test-all-warehouses-dbt-pre-releases.yml
+++ b/.github/workflows/test-all-warehouses-dbt-pre-releases.yml
@@ -2,8 +2,12 @@ name: Test all warehouse platforms on dbt pre-releases
 on:
   workflow_dispatch:
 
+permissions: {}
+
 jobs:
   test:
+    permissions:
+      contents: read
     uses: ./.github/workflows/test-all-warehouses.yml
     secrets: inherit
     with:
diff --git a/.github/workflows/test-all-warehouses.yml b/.github/workflows/test-all-warehouses.yml
index 89b077b59..830438409 100644
--- a/.github/workflows/test-all-warehouses.yml
+++ b/.github/workflows/test-all-warehouses.yml
@@ -34,6 +34,8 @@ on:
         type: string
         required: false
 
+permissions: {}
+
 jobs:
   # ── Local targets ─────────────────────────────────────────────────────
   # No secrets needed — run on pull_request (works for forks without approval).
@@ -42,6 +44,8 @@ jobs:
   # fully in-process adapters (duckdb).
   test-local:
     if: github.event_name != 'pull_request_target'
+    permissions:
+      contents: read
     strategy:
       fail-fast: false
       matrix:
@@ -88,35 +92,41 @@ jobs:
   # Determine if this is a fork PR and skip if wrong trigger is used
   check-fork-status:
     runs-on: ubuntu-latest
+    permissions: {}
     outputs:
       is_fork: ${{ steps.check.outputs.is_fork }}
       should_skip: ${{ steps.check.outputs.should_skip }}
     steps:
       - name: Check if PR is from fork
         id: check
+        env:
+          EVENT_NAME: ${{ github.event_name }}
+          PR_REPO: ${{ github.event.pull_request.head.repo.full_name }}
+          BASE_REPO: ${{ github.repository }}
         run: |
           IS_FORK="false"
           SHOULD_SKIP="false"
 
-          if [[ "${{ github.event_name }}" == "pull_request" || "${{ github.event_name }}" == "pull_request_target" ]]; then
-            if [[ "${{ github.event.pull_request.head.repo.full_name }}" != "${{ github.repository }}" ]]; then
+          if [[ "$EVENT_NAME" == "pull_request" || "$EVENT_NAME" == "pull_request_target" ]]; then
+            if [[ "$PR_REPO" != "$BASE_REPO" ]]; then
               IS_FORK="true"
             fi
 
             # Skip if: pull_request from fork (should use pull_request_target) OR pull_request_target from non-fork (should use pull_request)
-            if [[ "${{ github.event_name }}" == "pull_request" && "$IS_FORK" == "true" ]]; then
+            if [[ "$EVENT_NAME" == "pull_request" && "$IS_FORK" == "true" ]]; then
               SHOULD_SKIP="true"
-            elif [[ "${{ github.event_name }}" == "pull_request_target" && "$IS_FORK" == "false" ]]; then
+            elif [[ "$EVENT_NAME" == "pull_request_target" && "$IS_FORK" == "false" ]]; then
               SHOULD_SKIP="true"
             fi
           fi
 
-          echo "is_fork=$IS_FORK" >> $GITHUB_OUTPUT
-          echo "should_skip=$SHOULD_SKIP" >> $GITHUB_OUTPUT
+          echo "is_fork=$IS_FORK" >> "$GITHUB_OUTPUT"
+          echo "should_skip=$SHOULD_SKIP" >> "$GITHUB_OUTPUT"
 
   # Approval gate for fork PRs (only runs once for all platforms)
   approve-fork:
     runs-on: ubuntu-latest
+    permissions: {}
     needs: [check-fork-status]
     if: needs.check-fork-status.outputs.should_skip != 'true' && needs.check-fork-status.outputs.is_fork == 'true'
     environment: elementary_test_env
@@ -126,6 +136,8 @@ jobs:
 
   test-cloud:
     needs: [check-fork-status, approve-fork]
+    permissions:
+      contents: read
     if: |
       ! cancelled() &&
       needs.check-fork-status.result == 'success' &&
diff --git a/.github/workflows/test-warehouse.yml b/.github/workflows/test-warehouse.yml
index cab4a0511..2ddbc7123 100644
--- a/.github/workflows/test-warehouse.yml
+++ b/.github/workflows/test-warehouse.yml
@@ -51,6 +51,8 @@ on:
         default: "latest_official"
         required: false
 
+permissions: {}
+
 env:
   BRANCH_NAME: ${{ github.head_ref || github.ref_name }}
   TESTS_DIR: ${{ github.workspace }}/dbt-data-reliability/integration_tests
@@ -59,6 +61,11 @@ jobs:
   test:
     runs-on: ubuntu-latest
     timeout-minutes: 60
+    permissions:
+      contents: read
+    env:
+      WAREHOUSE: ${{ inputs.warehouse-type }}
+      DBT_VERSION: ${{ inputs.dbt-version }}
     concurrency:
       # Serialises runs for the same warehouse × dbt-version × branch.
       # The schema name is derived from a hash of this group (see "Write dbt profiles").
@@ -160,6 +167,8 @@ jobs:
 
       - name: Install dbt-vertica
         if: inputs.warehouse-type == 'vertica' && inputs.dbt-version != 'fusion'
+        env:
+          DBT_CORE_PIN: ${{ (!startsWith(inputs.dbt-version, 'latest') && format('=={0}', inputs.dbt-version)) || '' }}
         run: |
           # dbt-vertica pins dbt-core~=1.8 which lacks native support for the
           # "arguments" test property used by the integration-test framework.
@@ -167,15 +176,17 @@ jobs:
           # dbt-core version separately (dbt-vertica works fine with newer
           # dbt-core versions).
           pip install dbt-vertica --no-deps
-          pip install vertica-python \
-            "dbt-core${{ (!startsWith(inputs.dbt-version, 'latest') && format('=={0}', inputs.dbt-version)) || '' }}"
+          pip install vertica-python "dbt-core${DBT_CORE_PIN}"
 
       - name: Install dbt
         if: ${{ inputs.dbt-version != 'fusion' && inputs.warehouse-type != 'vertica' }}
-        run:
-          pip install${{ (inputs.dbt-version == 'latest_pre' && ' --pre') || '' }}
-          "dbt-core${{ (!startsWith(inputs.dbt-version, 'latest') && format('=={0}', inputs.dbt-version)) || '' }}"
-          "dbt-${{ (inputs.warehouse-type == 'databricks_catalog' && 'databricks') || (inputs.warehouse-type == 'spark' && 'spark[PyHive]') || (inputs.warehouse-type == 'athena' && 'athena-community') || inputs.warehouse-type }}${{ (!startsWith(inputs.dbt-version, 'latest') && format('~={0}', inputs.dbt-version)) || '' }}"
+        env:
+          PIP_PRE_FLAG: ${{ (inputs.dbt-version == 'latest_pre' && '--pre') || '' }}
+          DBT_CORE_PIN: ${{ (!startsWith(inputs.dbt-version, 'latest') && format('=={0}', inputs.dbt-version)) || '' }}
+          DBT_ADAPTER_PKG: ${{ (inputs.warehouse-type == 'databricks_catalog' && 'databricks') || (inputs.warehouse-type == 'spark' && 'spark[PyHive]') || (inputs.warehouse-type == 'athena' && 'athena-community') || inputs.warehouse-type }}
+          DBT_ADAPTER_PIN: ${{ (!startsWith(inputs.dbt-version, 'latest') && format('~={0}', inputs.dbt-version)) || '' }}
+        run: |
+          pip install $PIP_PRE_FLAG "dbt-core${DBT_CORE_PIN}" "dbt-${DBT_ADAPTER_PKG}${DBT_ADAPTER_PIN}"
 
       - name: Install dbt-fusion
         if: inputs.dbt-version == 'fusion'
@@ -187,11 +198,17 @@ jobs:
           # For Vertica, dbt-vertica is already installed with --no-deps above;
           # using ".[vertica]" would re-resolve dbt-vertica's deps and downgrade
           # dbt-core to ~=1.8.  Install elementary without the adapter extra.
-          if [ "${{ inputs.warehouse-type }}" = "vertica" ]; then
-            pip install "./elementary"
-          else
-            pip install "./elementary[${{ (inputs.warehouse-type == 'databricks_catalog' && 'databricks') || inputs.warehouse-type }}]"
-          fi
+          case "$WAREHOUSE" in
+            vertica)
+              pip install "./elementary"
+              ;;
+            databricks_catalog)
+              pip install "./elementary[databricks]"
+              ;;
+            *)
+              pip install "./elementary[$WAREHOUSE]"
+              ;;
+          esac
 
       - name: Write dbt profiles
         env:
@@ -205,7 +222,7 @@ jobs:
           # Budget (PostgreSQL 63-char limit):
           #   dbt_(4) + timestamp(13) + _(1) + branch(≤18) + _(1) + hash(8) = 45
           #   + _elementary(11) + _gw7(4) = 60
-          CONCURRENCY_GROUP="tests_${{ inputs.warehouse-type }}_dbt_${{ inputs.dbt-version }}_${BRANCH_NAME}"
+          CONCURRENCY_GROUP="tests_${WAREHOUSE}_dbt_${DBT_VERSION}_${BRANCH_NAME}"
           SHORT_HASH=$(echo -n "$CONCURRENCY_GROUP" | sha256sum | head -c 8)
           SAFE_BRANCH=$(echo "${BRANCH_NAME}" | awk '{print tolower($0)}' | sed "s/[^a-z0-9]/_/g; s/__*/_/g" | head -c 18)
           DATE_STAMP=$(date -u +%y%m%d_%H%M%S)
@@ -221,8 +238,9 @@ jobs:
       - name: Install dependencies
         working-directory: ${{ env.TESTS_DIR }}
         run: |
-          ${{ (inputs.dbt-version == 'fusion' && '~/.local/bin/dbt') || 'dbt' }} deps --project-dir dbt_project
-          ln -sfn ${{ github.workspace }}/dbt-data-reliability dbt_project/dbt_packages/elementary
+          if [ "$DBT_VERSION" = "fusion" ]; then DBT_BIN="$HOME/.local/bin/dbt"; else DBT_BIN="dbt"; fi
+          "$DBT_BIN" deps --project-dir dbt_project
+          ln -sfn "${{ github.workspace }}/dbt-data-reliability" dbt_project/dbt_packages/elementary
           pip install -r requirements.txt
 
       - name: Start Vertica
@@ -240,15 +258,24 @@ jobs:
       - name: Check DWH connection
         working-directory: ${{ env.TESTS_DIR }}
         run: |
-          ${{ (inputs.dbt-version == 'fusion' && '~/.local/bin/dbt') || 'dbt' }} debug -t "${{ inputs.warehouse-type }}"
+          if [ "$DBT_VERSION" = "fusion" ]; then DBT_BIN="$HOME/.local/bin/dbt"; else DBT_BIN="dbt"; fi
+          "$DBT_BIN" debug -t "$WAREHOUSE"
 
       - name: Test
         working-directory: "${{ env.TESTS_DIR }}/tests"
-        run: py.test -n${{ (inputs.warehouse-type == 'spark' && '4') || '8' }} -vvv --target "${{ inputs.warehouse-type }}" --junit-xml=test-results.xml --html=detailed_report_${{ inputs.warehouse-type }}_dbt_${{ inputs.dbt-version }}.html --self-contained-html --clear-on-end ${{ (inputs.dbt-version == 'fusion' && '--runner-method fusion') || '' }}
+        env:
+          PYTEST_PARALLEL: ${{ (inputs.warehouse-type == 'spark' && '4') || '8' }}
+          FUSION_RUNNER_FLAG: ${{ (inputs.dbt-version == 'fusion' && '--runner-method fusion') || '' }}
+        run: |
+          py.test -n"$PYTEST_PARALLEL" -vvv --target "$WAREHOUSE" \
+            --junit-xml=test-results.xml \
+            --html="detailed_report_${WAREHOUSE}_dbt_${DBT_VERSION}.html" \
+            --self-contained-html --clear-on-end $FUSION_RUNNER_FLAG
 
       - name: Upload test results
         if: always()
-        uses: pmeier/pytest-results-action@v0.8.0
+        # pmeier/pytest-results-action v0.8.0, checked 2026-04-26.
+        uses: pmeier/pytest-results-action@0841ca7226ab155943837380769373a5dd14d7ed
         with:
           path: ${{ env.TESTS_DIR }}/tests/test-results.xml
           summary: true
@@ -269,6 +296,7 @@ jobs:
         working-directory: ${{ env.TESTS_DIR }}
         continue-on-error: true
         run: |
-          ${{ (inputs.dbt-version == 'fusion' && '~/.local/bin/dbt') || 'dbt' }} run-operation elementary_tests.drop_test_schemas \
+          if [ "$DBT_VERSION" = "fusion" ]; then DBT_BIN="$HOME/.local/bin/dbt"; else DBT_BIN="dbt"; fi
+          "$DBT_BIN" run-operation elementary_tests.drop_test_schemas \
             --project-dir dbt_project \
-            -t "${{ inputs.warehouse-type }}"
+            -t "$WAREHOUSE"