gmentci: add PR stack usage report via puncover

Add scripts and a CI workflow step that compare static stack usage
between a PR and its merge base. On each PR, the workflow rebuilds
with `CONFIG_STACK_USAGE=y`, runs puncover via `stack_threads.py`,
and posts a sticky comment with a per-thread table showing configured
size, max static depth, delta vs base, and remaining margin.

Thread entry points are discovered from `K_THREAD_DEFINE` in app
sources; Zephyr/NCS subsystem stacks are resolved via `rg` in the
west tree with a small fallback map. Work queues list configured
size only since puncover can't attribute depth per queue.

Signed-off-by: Simen S. Røstad <simen.rostad@nordicsemi.no>

Author: simensrostad

.github/workflows/build.yml

@@ -280,6 +280,28 @@ jobs:
           header: app-size-report
           path: ${{ github.workspace }}/size-comment.md
 
+      - name: Install puncover
+        if: github.event_name == 'pull_request'
+        run: pip install puncover --break-system-packages
+
+      - name: Generate PR stack margin comment for thingy91x image
+        if: github.event_name == 'pull_request'
+        env:
+          PR_APP_DIR: ${{ github.workspace }}/asset-tracker-template/app
+          STACK_COMMENT_PATH: ${{ github.workspace }}/stack-comment.md
+          CI_RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+        run: |
+          SDK_BIN=$(ls -d /opt/toolchains/zephyr-sdk-*/arm-zephyr-eabi/bin 2>/dev/null | head -1)
+          [ -n "$SDK_BIN" ] && export PATH="$SDK_BIN:$PATH"
+          bash asset-tracker-template/scripts/ci/pr-stack-usage.sh
+
+      - name: Post PR stack margin sticky comment for thingy91x image
+        if: github.event_name == 'pull_request'
+        uses: marocchino/sticky-pull-request-comment@0ea0beb66eb9baf113663a64ec522f60e49231c0 # v3.0.4
+        with:
+          header: stack-usage-report
+          path: ${{ github.workspace }}/stack-comment.md
+
       - name: Upload artifacts
         uses: actions/upload-artifact@v4
         with:

app/prj.conf

@@ -25,6 +25,7 @@ CONFIG_TFM_SPM_LOG_LEVEL_DEBUG=y
 CONFIG_MBEDTLS_PSA_STATIC_KEY_SLOTS=y
 
 # Heap and stacks
+CONFIG_STACK_USAGE=y
 CONFIG_MAIN_STACK_SIZE=2560
 # Extended AT host/monitor stack/heap sizes since some nrf_cloud credentials are longer than 1024 bytes.
 CONFIG_AT_MONITOR_HEAP_SIZE=2176

scripts/ci/pr-stack-usage.sh

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+# Generate a sticky-comment-ready markdown body with stack headroom % from the main CI build.
+#
+# Required env vars:
+#   STACK_COMMENT_PATH
+# Optional:
+#   PR_APP_DIR     (default: <repo>/app)
+#   CI_RUN_URL
+
+set -euo pipefail
+: "${STACK_COMMENT_PATH:?}"
+
+REPO_ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+WORKSPACE_DIR="$(cd "$REPO_ROOT/.." && pwd)"
+PR_APP_DIR="${PR_APP_DIR:-$REPO_ROOT/app}"
+BUILD_DIR="${PR_APP_DIR}/build"
+STACK_DIR="${STACK_DIR:-$(dirname "$STACK_COMMENT_PATH")/stack}"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+STACK_THREADS_PY="$SCRIPT_DIR/stack_threads.py"
+STACK_JSON="$STACK_DIR/stack.json"
+
+mkdir -p "$STACK_DIR" "$(dirname "$STACK_COMMENT_PATH")"
+
+write_failure_comment() {
+  echo "Stack margin report failed. See [CI run](${CI_RUN_URL:-}) for logs." >"$STACK_COMMENT_PATH"
+}
+
+ELF="$BUILD_DIR/app/zephyr/zephyr.elf"
+CONFIG="$BUILD_DIR/app/zephyr/.config"
+
+if [[ ! -f "$ELF" || ! -f "$CONFIG" ]]; then
+  echo "Missing build outputs under $BUILD_DIR" >&2
+  write_failure_comment
+  exit 0
+fi
+
+if ! python3 "$STACK_THREADS_PY" report \
+  "$ELF" "$BUILD_DIR/app" "$CONFIG" "$STACK_JSON" "$PR_APP_DIR" \
+  --west "$WORKSPACE_DIR"; then
+  write_failure_comment
+  exit 0
+fi
+
+if ! python3 "$STACK_THREADS_PY" format-comment \
+  "$STACK_JSON" \
+  "$PR_APP_DIR" \
+  --config "$CONFIG" \
+  --west "$WORKSPACE_DIR" \
+  --ci-url "${CI_RUN_URL:-}" \
+  >"$STACK_COMMENT_PATH"; then
+  write_failure_comment
+  exit 0
+fi