ci: pin SOURCE_DATE_EPOCH, assert ISO uuid metadata, verify uploads

- Export SOURCE_DATE_EPOCH before mkarchiso so label, volume UUID,
  file mtimes and ext4 hash seed trace to one timestamp.
- Post-build step: assert blkid UUID of the ISO matches every
  /boot/<uuid>.uuid stem and archisosearchuuid= reference inside
  shipped boot configs, and that no %ARCHISO% placeholder remains.
- After upload: re-hash local ISOs, size-check API assets, download
  each back from the internal origin (bypasses traefik/Anubis) with
  percent-encoded filenames (iso_name contains a space), compare
  SHA-256. Definitive corruption (missing/size/sha mismatch) deletes
  the release; transport/API errors fail without deleting.

.gitea/workflows/build-iso.yaml

@@ -42,6 +42,14 @@ jobs:
       - name: Build Arch ISO
         run: |
           set -euo pipefail
+          # Pin one timestamp for the whole job: mkarchiso derives the ISO label,
+          # volume UUID, file mtimes, and ext4 hash seed from SOURCE_DATE_EPOCH.
+          # Exporting it explicitly makes every timestamp-derived value traceable
+          # (and lets later steps log the same value via $GITHUB_ENV).
+          SOURCE_DATE_EPOCH="$(date -u +%s)"
+          export SOURCE_DATE_EPOCH
+          echo "SOURCE_DATE_EPOCH=$SOURCE_DATE_EPOCH" >> "$GITHUB_ENV"
+          echo "Building with SOURCE_DATE_EPOCH=$SOURCE_DATE_EPOCH"
           # Clean up immediately even if this step is interrupted (cancel/exit):
           # unmount leftovers first, then remove the multi-GB work dir.
           trap 'umount -R "$PWD/work" 2>/dev/null || true; rm -rf "$PWD/work"' EXIT HUP INT TERM
@@ -51,6 +59,80 @@ jobs:
           mkdir -p "$PWD/out"
           mkarchiso -v -w "$PWD/work" -o "$PWD/out" -- "$PWD"
 
+      - name: Verify ISO search metadata
+        run: |
+          set -euo pipefail
+          shopt -s nullglob
+          isos=(out/*.iso)
+          if (( ${#isos[@]} != 1 )); then
+            echo "❌ Expected exactly 1 ISO in out/, found ${#isos[@]}" >&2
+            exit 1
+          fi
+          iso=${isos[0]}
+
+          # blkid exits non-zero when a field is missing; keep going so the
+          # explicit guard below can report a useful error.
+          vol_uuid=$(blkid -o value -s UUID "$iso" || true)
+          vol_label=$(blkid -o value -s LABEL "$iso" || true)
+          if [ -z "$vol_uuid" ]; then
+            echo "❌ blkid found no UUID for $iso — volume date chain broken?" >&2
+            exit 1
+          fi
+          echo "Volume UUID:  $vol_uuid"
+          echo "Volume label: ${vol_label:-<none>}"
+          echo "SOURCE_DATE_EPOCH: ${SOURCE_DATE_EPOCH:-<unset>}"
+
+          fail() {
+            echo "❌ $1" >&2
+            echo "   If you changed boot configs (efiboot/, syslinux/, grub/) on purpose," >&2
+            echo "   update this 'Verify ISO search metadata' step to match." >&2
+            exit 1
+          }
+
+          # 1) /boot/<uuid>.uuid (the archisosearchfilename fallback key) must
+          #    exist inside the ISO and its stem must equal the volume UUID.
+          uuid_refs=0
+          while IFS= read -r member; do
+            [ -z "$member" ] && continue
+            member=${member#/}
+            stem=$(basename "$member" .uuid)
+            if [ "$stem" != "$vol_uuid" ]; then
+              fail "$member: stem '$stem' != volume UUID '$vol_uuid'"
+            fi
+            echo "  ✅ $member matches volume UUID"
+            uuid_refs=$((uuid_refs + 1))
+          done < <(bsdtar -tf "$iso" | grep -E '(^|/)boot/[0-9A-Za-z-]+\.uuid$' || true)
+          if (( uuid_refs == 0 )); then
+            fail "no /boot/<uuid>.uuid file found inside the ISO"
+          fi
+
+          # 2) Every archisosearchuuid= in shipped boot configs must equal the
+          #    volume UUID; every %ARCHISO% placeholder must have been substituted.
+          search_refs=0
+          while IFS= read -r member; do
+            [ -z "$member" ] && continue
+            member=${member#/}
+            if ! content=$(bsdtar -xOf "$iso" "$member" 2>/dev/null); then
+              fail "could not extract $member from the ISO"
+            fi
+            if printf '%s\n' "$content" | grep -q '%ARCHISO'; then
+              fail "$member contains an unsubstituted %ARCHISO% placeholder"
+            fi
+            while IFS= read -r val; do
+              [ -z "$val" ] && continue
+              search_refs=$((search_refs + 1))
+              if [ "$val" != "$vol_uuid" ]; then
+                fail "$member: archisosearchuuid=$val != volume UUID '$vol_uuid'"
+              fi
+              echo "  ✅ $member: archisosearchuuid=$val matches volume UUID"
+            done < <(printf '%s\n' "$content" | grep -o 'archisosearchuuid=[^[:space:]]*' | cut -d= -f2- || true)
+          done < <(bsdtar -tf "$iso" | grep -E '(^|/)(loader/entries/.*\.conf|boot/.*\.(cfg|conf))$' || true)
+          if (( search_refs == 0 )); then
+            fail "no archisosearchuuid= references found in shipped boot configs (params removed without updating this check?)"
+          fi
+
+          echo "✅ ISO search metadata consistent: $uuid_refs uuid file(s), $search_refs search reference(s)"
+
       - name: Generate Unique Dynamic Tag
         id: tag
         env:
@@ -82,6 +164,7 @@ jobs:
           echo "release_name=Arch Linux ISO (${BASE_DATE} Rev ${REVISION})" >> "$GITHUB_OUTPUT"
 
       - name: Create Release and Upload ISO
+        id: release
         env:
           GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
           # Use internal Gitea URL to bypass traefik proxy timeout on large uploads
@@ -141,6 +224,8 @@ jobs:
           # Build the release body with SHA-256 checksums
           printf -v body 'Arch Linux live ISO %s\n\nChecksums (SHA-256):\n' "$RELEASE_NAME"
           for i in "${!isos[@]}"; do
+            # Release body: markdown backticks are literal (printf format below)
+            # shellcheck disable=SC2016
             printf -v line -- '- `%s`: sha256 `%s`\n' "$(basename "${isos[$i]}")" "${sha256sums[$i]}"
             body+="$line"
           done
@@ -160,6 +245,7 @@ jobs:
             echo "❌ Release response contained no id" >&2
             exit 1
           fi
+          echo "release_id=${RELEASE_ID}" >> "$GITHUB_OUTPUT"
           echo "  ✅ Created release $TAG_NAME (ID: $RELEASE_ID)"
 
           # Upload each ISO as a release asset, up to 3 attempts per file
@@ -224,6 +310,124 @@ jobs:
           echo "✅ All ISOs uploaded to release $TAG_NAME"
           exit 0
 
+      - name: Verify uploaded ISO checksums
+        if: success()
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          # Internal origin bypasses traefik (and its Anubis bot wall) — the
+          # same host the upload step already uses.
+          GITEA_API: http://192.168.1.168:3000/api/v1
+          GITEA_ORIGIN: http://192.168.1.168:3000
+          REPOSITORY: ${{ github.repository }}
+          TAG_NAME: ${{ steps.tag.outputs.tag_name }}
+          RELEASE_ID: ${{ steps.release.outputs.release_id }}
+        run: |
+          set -euo pipefail
+          shopt -s nullglob
+          tmpdir=$(mktemp -d)
+          trap 'rm -rf "$tmpdir"' EXIT
+
+          for var in GITEA_TOKEN TAG_NAME RELEASE_ID; do
+            if [ -z "${!var:-}" ]; then
+              echo "❌ $var is empty" >&2
+              exit 1
+            fi
+          done
+          case "$RELEASE_ID" in
+            ''|*[!0-9]*) echo "❌ RELEASE_ID is not numeric: $RELEASE_ID" >&2; exit 1 ;;
+          esac
+
+          # fail_verify <reason...>: job fails but the release is kept — used
+          # for transport/API errors where the upload itself may be fine.
+          fail_verify() {
+            echo "❌ $1" >&2
+            echo "   Release $TAG_NAME (ID $RELEASE_ID) left in place (not proven corrupt)." >&2
+            exit 1
+          }
+
+          # abort_release <reason...>: the asset is provably wrong — delete the
+          # release so a corrupt asset can never be published, then fail.
+          abort_release() {
+            echo "❌ $1" >&2
+            echo "Deleting release $TAG_NAME (ID $RELEASE_ID) so the bad upload cannot be used..." >&2
+            if ! curl -sf -X DELETE -H "Authorization: token $GITEA_TOKEN" \
+                "$GITEA_API/repos/$REPOSITORY/releases/$RELEASE_ID" -o /dev/null; then
+              echo "⚠️ Could not delete release $RELEASE_ID — delete it manually!" >&2
+            fi
+            exit 1
+          }
+
+          isos=(out/*.iso)
+          if (( ${#isos[@]} == 0 )); then
+            echo "❌ No ISO in out/ to verify" >&2
+            exit 1
+          fi
+
+          # Recompute local checksums
+          declare -A local_sha local_size
+          for iso in "${isos[@]}"; do
+            fname=$(basename "$iso")
+            local_sha["$fname"]=$(sha256sum "$iso" | awk '{print $1}')
+            local_size["$fname"]=$(stat -c %s "$iso")
+            if [ -z "${local_sha[$fname]}" ]; then
+              echo "❌ Failed to compute SHA-256 for '$iso'" >&2
+              exit 1
+            fi
+          done
+
+          # List the release's assets as uploaded (API error = transient, no delete)
+          if ! curl -sf -H "Authorization: token $GITEA_TOKEN" \
+              "$GITEA_API/repos/$REPOSITORY/releases/$RELEASE_ID/assets" \
+              -o "$tmpdir/assets.json"; then
+            fail_verify "Failed to list assets of release $RELEASE_ID (API/transport error)"
+          fi
+
+          for iso in "${isos[@]}"; do
+            fname=$(basename "$iso")
+            api_size=$(jq -er --arg name "$fname" \
+              '.[] | select(.name == $name) | .size' "$tmpdir/assets.json" 2>/dev/null) \
+              || abort_release "Asset '$fname' missing from release $RELEASE_ID"
+            if [ "$api_size" != "${local_size[$fname]}" ]; then
+              abort_release "Asset '$fname' size mismatch: server=$api_size local=${local_size[$fname]}"
+            fi
+
+            # Download from the internal origin (traefik/Anubis bypassed).
+            # iso_name contains a space ("Alvin archlinux"), so the filename
+            # must be percent-encoded or curl rejects the URL outright.
+            enc_fname=$(jq -rn --arg v "$fname" '$v|@uri')
+            url="$GITEA_ORIGIN/$REPOSITORY/releases/download/$TAG_NAME/$enc_fname"
+            downloaded=0
+            for attempt in 1 2 3; do
+              # Try header auth, then ?token=, then anonymous (public repo).
+              if curl -sfL --max-time 600 -H "Authorization: token $GITEA_TOKEN" \
+                  "$url" -o "$tmpdir/$fname"; then
+                downloaded=1
+              elif curl -sfL --max-time 600 "$url?token=$GITEA_TOKEN" \
+                  -o "$tmpdir/$fname"; then
+                downloaded=1
+              elif curl -sfL --max-time 600 "$url" -o "$tmpdir/$fname"; then
+                downloaded=1
+              fi
+              [ "$downloaded" -eq 1 ] && break
+              echo "  ⚠️ Download of $fname failed (attempt $attempt/3)" >&2
+              [ "$attempt" -lt 3 ] && sleep $(( attempt * 10 ))
+            done
+            if [ "$downloaded" -ne 1 ]; then
+              fail_verify "Could not download asset '$fname' back from release $RELEASE_ID (auth/transport error, not proven corrupt)"
+            fi
+
+            actual=$(sha256sum "$tmpdir/$fname" | awk '{print $1}')
+            expected=${local_sha[$fname]}
+            if [ "$actual" != "$expected" ]; then
+              abort_release "SHA-256 mismatch for '$fname': server=$actual local=$expected"
+            fi
+            echo "  ✅ $fname: size and SHA-256 match"
+            rm -f "$tmpdir/$fname"
+          done
+
+          echo "✅ All uploaded assets verified against local ISO checksums"
+          exit 0
+
       - name: Keep only latest 2 releases
         if: success()
         env: