diff --git a/.gitea/workflows/preview.yml b/.gitea/workflows/preview.yml
index bf4ad7b..3a060ee 100644
--- a/.gitea/workflows/preview.yml
+++ b/.gitea/workflows/preview.yml
@@ -21,6 +21,34 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 1
+      - name: Apply additive Workspace migration to dev preview
+        if: gitea.ref == 'refs/heads/dev'
+        run: |
+          set -Eeuo pipefail
+          root=/opt/prompt-preview
+          test -f "$root/ready"
+          exec 8>/var/lock/prompt-preview-sync.lock
+          flock -w 30 8
+          id=$(docker ps -q --filter label=com.docker.compose.project=prompt-preview --filter label=com.docker.compose.service=postgres)
+          [[ "$id" =~ ^[a-f0-9]{12}$ ]]
+          sql=apps/waterfall-wiki/db/018_workspaces.sql
+          previous=$(cat "$root/fingerprint")
+          scratch=$(mktemp -d)
+          trap 'rm -rf "$scratch"' EXIT
+          mkdir -p "$scratch/apps/waterfall-wiki/db" "$scratch/packages/brand"
+          cp pnpm-workspace.yaml "$scratch/"
+          cp apps/waterfall-wiki/{pnpm-lock.yaml,next.config.ts,tsconfig.json,postcss.config.mjs,package.json} "$scratch/apps/waterfall-wiki/"
+          cp packages/brand/package.json "$scratch/packages/brand/"
+          cp apps/waterfall-wiki/db/*.sql "$scratch/apps/waterfall-wiki/db/"
+          rm "$scratch/$sql"
+          candidate=$(node scripts/preview/fingerprint.mjs "$PWD")
+          if [[ "$candidate" == "$previous" ]]; then exit 0; fi
+          test "$(node scripts/preview/fingerprint.mjs "$scratch")" = "$previous"
+          applied=$(docker exec "$id" psql -XAt -v ON_ERROR_STOP=1 -U prompt -d prompt -c "SELECT 1 FROM schema_migrations WHERE version='018_workspaces'")
+          if [[ "$applied" != 1 ]]; then
+            docker exec -i "$id" psql -X -v ON_ERROR_STOP=1 -U prompt -d prompt < "$sql"
+          fi
+          printf '%s\n' "$candidate" > "$root/fingerprint"
       - name: Initialize once, otherwise synchronize files only
         env:
           SOURCE_SHA: ${{ gitea.sha }}