add prerelease workflow for open PR builds

.github/workflows/prerelease_open_pr_builds.yaml

@@ -0,0 +1,117 @@
+name: Prerelease Open PR Builds
+
+on:
+  workflow_dispatch:
+
+  workflow_run:
+    workflows:
+      - "Build OpenEarable v2 Firmware"
+    types:
+      - completed
+
+permissions:
+  contents: write
+  actions: read
+  pull-requests: read
+
+env:
+  TAG: pr-builds
+  BUILD_WORKFLOW_NAME: "Build OpenEarable v2 Firmware"
+
+jobs:
+  prerelease:
+    if: >
+      github.event_name != 'workflow_run' ||
+      (
+        github.event.workflow_run.conclusion == 'success' &&
+        github.event.workflow_run.event == 'pull_request'
+      )
+    runs-on: ubuntu-latest
+    steps:
+      - name: Ensure prerelease exists
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh release view "$TAG" --repo "${{ github.repository }}" >/dev/null 2>&1 || \
+          gh release create "$TAG" \
+            --repo "${{ github.repository }}" \
+            --prerelease \
+            --title "Open PR builds" \
+            --notes "Rolling prerelease containing build outputs from all open PRs."
+      - name: List open PRs
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh pr list --repo "${{ github.repository }}" --state open --json number,headRefOid,title --limit 200 > prs.json
+      - name: Download artifacts from each PR's latest successful build
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          set -euo pipefail
+          rm -rf collected && mkdir -p collected
+          jq -c '.[]' prs.json | while read -r pr; do
+            num=$(echo "$pr" | jq -r .number)
+            sha=$(echo "$pr" | jq -r .headRefOid)
+            title=$(echo "$pr" | jq -r .title)
+            safe_title=$(echo "$title" | sed 's/[^a-zA-Z0-9_-]/_/g' | cut -c1-50)
+            run_id=$(gh run list \
+              --repo "${{ github.repository }}" \
+              --workflow "$BUILD_WORKFLOW_NAME" \
+              --commit "$sha" \
+              --status success \
+              --limit 1 \
+              --json databaseId \
+              --jq '.[0].databaseId')
+            if [ -z "$run_id" ] || [ "$run_id" = "null" ]; then
+              echo "PR #$num: no successful run found"
+              continue
+            fi
+            out="collected/pr-$num"
+            rm -rf "$out" && mkdir -p "$out"
+            if ! gh run download "$run_id" --repo "${{ github.repository }}" -n "openearable_v2_firmware.elf" -D "$out/elf" 2>&1; then
+              echo "PR #$num: failed to download firmware.elf artifact (may be expired)"
+              rm -rf "$out"
+              continue
+            fi
+            if ! gh run download "$run_id" --repo "${{ github.repository }}" -n "openearable_v2_fota.zip" -D "$out/fota" 2>&1; then
+              echo "PR #$num: failed to download fota.zip artifact (may be expired)"
+              rm -rf "$out"
+              continue
+            fi
+            (cd "$out/fota" && zip -r "../openearable_v2_fota.zip" .)
+            mv "$out/elf/openearable_v2_firmware.elf" "$out/openearable_v2_firmware.elf"
+            rm -rf "$out/elf" "$out/fota"
+
+            echo "$safe_title" > "$out/title.txt"
+
+            echo "PR #$num ($title): artifacts downloaded and prepared successfully"
+          done
+      - name: Upload all PR assets to prerelease (overwrite)
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          set -euo pipefail
+          mkdir -p collected/upload
+          find collected -type f \( -name "*.elf" -o -name "*.zip" \) | while read -r f; do
+            pr=$(echo "$f" | sed -n 's#.*/pr-\([0-9]\+\)/.*#\1#p')
+            base=$(basename "$f")
+            title_file="collected/pr-$pr/title.txt"
+            if [ -f "$title_file" ]; then
+              safe_title=$(cat "$title_file")
+              asset="pr-${pr}-${safe_title}-${base}"
+            else
+              asset="pr-${pr}-${base}"
+            fi
+            cp "$f" "collected/upload/$asset"
+            gh release upload "$TAG" "collected/upload/$asset" --repo "${{ github.repository }}" --clobber
+          done
+          # delete assets of closed PRs
+          open_prs="$(jq -r '.[].number' prs.json || true)"
+          gh release view "$TAG" --repo "${{ github.repository }}" --json assets -q '.assets[].name' | while read -r asset; do
+            pr="$(echo "$asset" | sed -n 's/^pr-\([0-9]\+\)-.*$/\1/p')"
+            [ -n "$pr" ] || continue
+            if ! echo "$open_prs" | grep -qx "$pr"; then
+              echo "Deleting asset $asset (PR #$pr is closed/merged)"
+              gh release delete-asset "$TAG" "$asset" --repo "${{ github.repository }}" --yes
+            fi
+          done