diff --git a/backend/apps/outputs/outputs.py b/backend/apps/outputs/outputs.py
index 31306b88..894363f1 100644
--- a/backend/apps/outputs/outputs.py
+++ b/backend/apps/outputs/outputs.py
@@ -230,7 +230,7 @@ def ensure_webapp_workspace_seeded_and_registered(
             from backend.apps.outputs.runtime import _find_free_port
             frontend_port = _find_free_port()
             seed_webapp_template_workspace(folder, frontend_port)
-            with open(os.path.join(folder, "SKILL.md"), "w") as f:
+            with open(os.path.join(folder, "SKILL.md"), "w", encoding="utf-8") as f:
                 f.write(load_app_builder_skill())
         existing = [o for o in _load_all() if o.workspace_id == workspace_id]
         if existing:
@@ -311,11 +311,11 @@ async def seed_workspace(body: WorkspaceSeedRequest):
             # SKILL.md still goes in workspace root; agent reads it for
             # context. Live content (user-editable via Skills page) is
             # injected into the system prompt regardless.
-            with open(os.path.join(folder, "SKILL.md"), "w") as f:
+            with open(os.path.join(folder, "SKILL.md"), "w", encoding="utf-8") as f:
                 f.write(load_app_builder_skill())
         meta = body.meta or {}
         if body.meta and not already_seeded:
-            with open(os.path.join(folder, "meta.json"), "w") as f:
+            with open(os.path.join(folder, "meta.json"), "w", encoding="utf-8") as f:
                 json.dump(body.meta, f, indent=2)
         # Create (or look up) the Output record so the app appears in
         # the Apps sidebar the moment the user kicks off generation.
@@ -360,12 +360,12 @@ async def seed_workspace(body: WorkspaceSeedRequest):
             if not full_path.startswith(os.path.normpath(folder)):
                 continue
             os.makedirs(os.path.dirname(full_path), exist_ok=True)
-            with open(full_path, "w") as f:
+            with open(full_path, "w", encoding="utf-8") as f:
                 f.write(content)
     else:
         for rel_path, content in VIEW_TEMPLATE_FILES.items():
             full_path = os.path.join(folder, rel_path)
-            with open(full_path, "w") as f:
+            with open(full_path, "w", encoding="utf-8") as f:
                 f.write(content)
 
     # Seed the workspace's SKILL.md with the LIVE skill content so an
@@ -374,11 +374,11 @@ async def seed_workspace(body: WorkspaceSeedRequest):
     # already-seeded workspaces (the system-prompt injection in
     # agent_manager reads live, so the agent always has the latest
     # rules regardless of this on-disk copy).
-    with open(os.path.join(folder, "SKILL.md"), "w") as f:
+    with open(os.path.join(folder, "SKILL.md"), "w", encoding="utf-8") as f:
         f.write(load_app_builder_skill())
 
     if body.meta:
-        with open(os.path.join(folder, "meta.json"), "w") as f:
+        with open(os.path.join(folder, "meta.json"), "w", encoding="utf-8") as f:
             json.dump(body.meta, f, indent=2)
 
     return {"path": os.path.abspath(folder), "template_mode": "flat"}
@@ -494,7 +494,7 @@ async def write_workspace_file(workspace_id: str, filepath: str, body: dict):
     if full_path != folder_norm and not full_path.startswith(folder_norm + os.sep):
         raise HTTPException(status_code=403, detail="Path traversal not allowed")
     os.makedirs(os.path.dirname(full_path), exist_ok=True)
-    with open(full_path, "w") as f:
+    with open(full_path, "w", encoding="utf-8") as f:
         f.write(body.get("content", ""))
     return {"ok": True}
 
diff --git a/backend/apps/outputs/view_builder_templates.py b/backend/apps/outputs/view_builder_templates.py
index 0db29bdb..3cc089f7 100644
--- a/backend/apps/outputs/view_builder_templates.py
+++ b/backend/apps/outputs/view_builder_templates.py
@@ -467,7 +467,7 @@ def _ensure_warm_python_venv() -> str | None:
                 logger.warning("warm-venv pip install failed: %s", r.stderr[-1500:])
                 return None
 
-            with open(sentinel, "w") as fh:
+            with open(sentinel, "w", encoding="utf-8") as fh:
                 fh.write("ok\n")
             logger.info("webapp-template: warm backend venv ready at %s", venv_dir)
             return venv_dir
@@ -568,6 +568,16 @@ def seed_webapp_template_workspace(workspace_dir: str, frontend_port: int) -> No
     src_example = os.path.join(WEBAPP_TEMPLATE_DIR, ".env.example")
     if os.path.exists(src_example):
         shutil.copyfile(src_example, env_path)
+    else:
+        # .env.example can be absent from a packaged build whose copy step
+        # stripped dotfiles (the Windows build's recursive '.env.*' exclude did
+        # exactly this). Write the default directly so the workspace always has
+        # a .env with BACKEND_PORT=NONE; without it run.sh sees no BACKEND_PORT,
+        # takes the backend branch, and dies on a backend that isn't there,
+        # leaving the app stuck on the splash. Mac was unaffected because its
+        # build anchors the exclude and ships .env.example.
+        with open(env_path, "w", encoding="utf-8") as f:
+            f.write("BACKEND_PORT=NONE\nFRONTEND_PORT=4949\n")
 
     _patch_env_port(env_path, "FRONTEND_PORT", str(frontend_port))
     _patch_env_port(env_example_path, "FRONTEND_PORT", str(frontend_port))
diff --git a/backend/apps/outputs/webapp_template/run.sh b/backend/apps/outputs/webapp_template/run.sh
index cd182530..40ed3fbd 100755
--- a/backend/apps/outputs/webapp_template/run.sh
+++ b/backend/apps/outputs/webapp_template/run.sh
@@ -39,8 +39,14 @@ cleanup() {
 }
 trap cleanup EXIT
 
-if [[ "${BACKEND_PORT}" == "NONE" ]]; then
-    echo "BACKEND_PORT=NONE — running frontend only (no backend)."
+if [[ "${BACKEND_PORT}" == "NONE" || -z "${BACKEND_PORT}" || ! -f "$ROOT_DIR/backend/run.sh" ]]; then
+    # Frontend-only is the safe default: BACKEND_PORT=NONE (frontend-only app),
+    # OR unset/empty (e.g. .env missing — never start a backend that isn't
+    # configured), OR there is genuinely no backend/run.sh to run. Without the
+    # last two guards an unset BACKEND_PORT fell through to the backend branch
+    # and `bash backend/run.sh` died with "No such file or directory", tearing
+    # the whole app down before the frontend could show.
+    echo "Running frontend only (no backend configured)."
     echo ""
 
     bash "$ROOT_DIR/frontend/run.sh" 2>&1 | awk '{printf "\033[32m[frontend]\033[0m %s\n", $0; fflush()}' &
diff --git a/scripts/build-app-win.ps1 b/scripts/build-app-win.ps1
index 3273040d..ce27c4ea 100644
--- a/scripts/build-app-win.ps1
+++ b/scripts/build-app-win.ps1
@@ -329,6 +329,20 @@ function Copy-Excluded($Source, $Dest, $Exclude) {
 Copy-Excluded `
     (Join-Path $ProjectRoot 'backend') (Join-Path $Staging 'backend') `
     @{ Dirs = @('__pycache__','.venv','data','uv-bin','tests'); Files = @('*.pyc','.env','.env.*') }
+# The '.env.*' exclude above is recursive, so it also strips the vendored
+# webapp_template/.env.example that seed_workspace copies into each new app's
+# .env (BACKEND_PORT=NONE). The mac build anchors its exclude to avoid this;
+# here we restore the one file. Without it, Windows-built apps seed with no
+# .env, run.sh takes the backend branch, and the app dies on a missing backend.
+# (seed_workspace also now writes a default .env when this is absent, but
+# shipping it keeps the template snapshot complete and matches mac.)
+$EnvExampleSrc = Join-Path $ProjectRoot 'backend\apps\outputs\webapp_template\.env.example'
+$EnvExampleDst = Join-Path $Staging 'backend\apps\outputs\webapp_template\.env.example'
+if (Test-Path $EnvExampleSrc) {
+    New-Item -ItemType Directory -Force -Path (Split-Path $EnvExampleDst -Parent) | Out-Null
+    Copy-Item -Force $EnvExampleSrc $EnvExampleDst
+    Write-Host "Restored webapp_template/.env.example (stripped by the .env.* exclude)"
+}
 # data: backend/config/paths.py points DATA_ROOT at %APPDATA%/OpenSwarm/data in
 # packaged mode and no code seeds from the bundle, so the entire shipped
 # backend/data/ tree was dead weight (and was leaking the dev machine's