diff --git a/.buildkite/branch.json.py b/.buildkite/branch.json.py
index 4916a89cc..4f5a8ac95 100755
--- a/.buildkite/branch.json.py
+++ b/.buildkite/branch.json.py
@@ -30,6 +30,27 @@ def main():
                                                        ".buildkite/pipelines/format_and_validation.yml.sh"))
     config = buildConfig.Config()
     config.parse()
+
+    build_step_keys = []
+    test_step_keys = []
+    if config.build_linux and config.build_aarch64:
+        build_step_keys.append("build_test_linux-aarch64-RelWithDebInfo")
+        test_step_keys.append("test_linux-aarch64-RelWithDebInfo")
+    if config.build_linux and config.build_x86_64:
+        build_step_keys.append("build_test_linux-x86_64-RelWithDebInfo")
+        test_step_keys.append("test_linux-x86_64-RelWithDebInfo")
+    if config.build_macos and config.build_aarch64:
+        build_step_keys.append("build_test_macos-aarch64-RelWithDebInfo")
+        test_step_keys.append("test_macos-aarch64-RelWithDebInfo")
+    if config.build_windows and config.build_x86_64:
+        build_step_keys.append("build_test_Windows-x86_64-RelWithDebInfo")
+        test_step_keys.append("test_Windows-x86_64-RelWithDebInfo")
+
+    env = {
+        "ML_BUILD_STEP_KEYS": ",".join(build_step_keys),
+        "ML_TEST_STEP_KEYS": ",".join(test_step_keys),
+    }
+
     if config.build_windows:
         build_windows = pipeline_steps.generate_step_template("Windows", "build", "", config.build_x86_64)
         pipeline_steps.append(build_windows)
@@ -55,6 +76,7 @@ def main():
     pipeline_steps.append(pipeline_steps.generate_step("Upload daily releasable artifacts to GCS",
                                                        ".buildkite/pipelines/upload_dra_to_gcs.yml.sh"))
 
+    pipeline["env"] = env
     pipeline["steps"] = pipeline_steps
     print(json.dumps(pipeline, indent=2))
 
diff --git a/.buildkite/pipeline.json.py b/.buildkite/pipeline.json.py
index 1796a665b..73e54b3ea 100755
--- a/.buildkite/pipeline.json.py
+++ b/.buildkite/pipeline.json.py
@@ -23,11 +23,6 @@
     config as buildConfig,
 )
 
-# Ensure VERSION_QUALIFIER is always empty for PR builds
-env = {
-    "VERSION_QUALIFIER": ""
-}
-
 def main():
     pipeline = {}
     pipeline_steps = step.PipelineStep([])
@@ -39,6 +34,25 @@ def main():
                                                        ".buildkite/pipelines/format_and_validation.yml.sh"))
     config = buildConfig.Config()
     config.parse()
+
+    # Compute which build step keys will exist so that analytics steps
+    # can emit a correct depends_on list (not all platforms are built
+    # for every PR, depending on labels/comments).
+    build_step_keys = []
+    if config.build_linux and config.build_aarch64:
+        build_step_keys.append("build_test_linux-aarch64-RelWithDebInfo")
+    if config.build_linux and config.build_x86_64:
+        build_step_keys.append("build_test_linux-x86_64-RelWithDebInfo")
+    if config.build_macos and config.build_aarch64:
+        build_step_keys.append("build_test_macos-aarch64-RelWithDebInfo")
+    if config.build_windows and config.build_x86_64:
+        build_step_keys.append("build_test_Windows-x86_64-RelWithDebInfo")
+
+    env = {
+        "VERSION_QUALIFIER": "",
+        "ML_BUILD_STEP_KEYS": ",".join(build_step_keys),
+    }
+
     if config.build_windows:
         build_windows = pipeline_steps.generate_step_template("Windows", config.action, "", config.build_x86_64)
         pipeline_steps.append(build_windows)
diff --git a/.buildkite/pipelines/analyze_build_timings.yml.sh b/.buildkite/pipelines/analyze_build_timings.yml.sh
index 79bf79e2f..dac129751 100755
--- a/.buildkite/pipelines/analyze_build_timings.yml.sh
+++ b/.buildkite/pipelines/analyze_build_timings.yml.sh
@@ -8,17 +8,23 @@
 # compliance with the Elastic License 2.0 and the foregoing additional
 # limitation.
 
-cat <<EOL
+cat <<'EOL'
 steps:
   - label: "Analyse build timings :chart_with_upwards_trend:"
     key: "analyze_build_timings"
     command:
         - "python3 .buildkite/scripts/steps/analyze_build_timings.py"
-    depends_on:
-        - "test_linux-aarch64-RelWithDebInfo"
-        - "test_linux-x86_64-RelWithDebInfo"
-        - "test_macos-aarch64-RelWithDebInfo"
-        - "test_Windows-x86_64-RelWithDebInfo"
+EOL
+
+if [ -n "${ML_TEST_STEP_KEYS:-}" ]; then
+    echo '    depends_on:'
+    IFS=',' read -ra STEP_KEYS <<< "$ML_TEST_STEP_KEYS"
+    for key in "${STEP_KEYS[@]}"; do
+        echo "        - \"${key}\""
+    done
+fi
+
+cat <<'EOL'
     allow_dependency_failure: true
     soft_fail: true
     agents:
diff --git a/.buildkite/pipelines/check_build_regression.yml.sh b/.buildkite/pipelines/check_build_regression.yml.sh
index f800666ff..f84c2f119 100755
--- a/.buildkite/pipelines/check_build_regression.yml.sh
+++ b/.buildkite/pipelines/check_build_regression.yml.sh
@@ -8,17 +8,27 @@
 # compliance with the Elastic License 2.0 and the foregoing additional
 # limitation.
 
-cat <<EOL
+cat <<'EOL'
 steps:
   - label: "Check build timing regressions :chart_with_downwards_trend:"
     key: "check_build_regression"
     command:
         - "python3 dev-tools/check_build_regression.py --annotate"
-    depends_on:
-        - "build_test_linux-aarch64-RelWithDebInfo"
-        - "build_test_linux-x86_64-RelWithDebInfo"
-        - "build_test_macos-aarch64-RelWithDebInfo"
-        - "build_test_Windows-x86_64-RelWithDebInfo"
+EOL
+
+# Emit depends_on dynamically — ML_BUILD_STEP_KEYS is a comma-separated
+# list of step keys set by the pipeline generator.  Only keys that
+# actually exist in this build are included, avoiding Buildkite errors
+# when a platform is not built.
+if [ -n "${ML_BUILD_STEP_KEYS:-}" ]; then
+    echo '    depends_on:'
+    IFS=',' read -ra STEP_KEYS <<< "$ML_BUILD_STEP_KEYS"
+    for key in "${STEP_KEYS[@]}"; do
+        echo "        - \"${key}\""
+    done
+fi
+
+cat <<'EOL'
     allow_dependency_failure: true
     soft_fail: true
     agents:
diff --git a/.buildkite/pipelines/ingest_build_timings.yml.sh b/.buildkite/pipelines/ingest_build_timings.yml.sh
index 92f314ea4..93026d638 100755
--- a/.buildkite/pipelines/ingest_build_timings.yml.sh
+++ b/.buildkite/pipelines/ingest_build_timings.yml.sh
@@ -8,18 +8,24 @@
 # compliance with the Elastic License 2.0 and the foregoing additional
 # limitation.
 
-cat <<EOL
+cat <<'EOL'
 steps:
   - label: "Ingest build timings :elasticsearch:"
     key: "ingest_build_timings"
     command:
         - "pip3 install --quiet requests 2>/dev/null || true"
-        - "python3 dev-tools/ingest_build_timings.py --pipeline \$BUILDKITE_PIPELINE_SLUG --build \$BUILDKITE_BUILD_NUMBER"
-    depends_on:
-        - "build_test_linux-aarch64-RelWithDebInfo"
-        - "build_test_linux-x86_64-RelWithDebInfo"
-        - "build_test_macos-aarch64-RelWithDebInfo"
-        - "build_test_Windows-x86_64-RelWithDebInfo"
+        - "python3 dev-tools/ingest_build_timings.py --pipeline $BUILDKITE_PIPELINE_SLUG --build $BUILDKITE_BUILD_NUMBER"
+EOL
+
+if [ -n "${ML_BUILD_STEP_KEYS:-}" ]; then
+    echo '    depends_on:'
+    IFS=',' read -ra STEP_KEYS <<< "$ML_BUILD_STEP_KEYS"
+    for key in "${STEP_KEYS[@]}"; do
+        echo "        - \"${key}\""
+    done
+fi
+
+cat <<'EOL'
     allow_dependency_failure: true
     soft_fail: true
     agents: