Online demo on Render

The repository’s render.yaml builds the frontend into the Rust binary and runs it as a native Rust web service on Render’s Free instance. The ledger lives in S3-compatible storage; no persistent disk or database is needed on Render.

Prepare read-only storage

1. Use a dedicated bucket containing only public demo data. For a first demo, upload examples/main.zhang as main.zhang. Upload any included files, attachments and plugin modules with their relative paths preserved.
2. Give the service credentials read and list access to that bucket, with no write or delete access. Keep the credentials used to upload or maintain the sample separate from those used by Render.
   • Cloudflare R2: create an S3 API token with Object Read only, scoped to the demo bucket. Use its Access Key ID and Secret Access Key, the S3 endpoint https://<account_id>.r2.cloudflarestorage.com, and region auto. Use the jurisdiction-specific endpoint if your bucket requires one. The bucket can remain private; Zhang serves its contents to visitors. See R2 authentication.
   • Amazon S3: use a dedicated IAM identity with s3:GetObject on the demo objects and s3:ListBucket on the demo bucket. If the ledger is encrypted with a customer-managed KMS key, also allow decryption with that key. Use the bucket’s actual region and its regional S3 endpoint. See S3 policy examples.

Read-only credentials protect the source files even when a visitor sends a write request directly to the API. They do not hide editing controls in the web UI: saving a file, creating or updating a transaction, uploading a document or registering a passkey fails because storage refuses the write. Browsing, queries and CSV exports work normally. Leave password and passkey authentication disabled for an anonymous demo.

Deploy the Blueprint

1. Push the deployment files to a GitHub branch. The demo can deploy from a pull request branch; merging is not required.

2. In the Render Dashboard, select New → Blueprint, connect the repository, and select that branch. Keep the Blueprint path render.yaml.

3. Fill in the variables Render prompts for:

   Variable	Value
   ZHANG_S3_BUCKET	The demo bucket’s name.
   ZHANG_S3_ENDPOINT	The S3 API endpoint, not a public download URL.
   ZHANG_S3_REGION	auto for R2; the actual bucket region for AWS S3.
   ZHANG_S3_ACCESS_KEY_ID	The read-only Access Key ID.
   ZHANG_S3_SECRET_ACCESS_KEY	The read-only Secret Access Key.

4. Review the service: Rust, Free, Singapore, and no disk or database. Deploy it.

5. If your ledger is not at the bucket root, set ZHANG_S3_ROOT to its prefix (for example /accounting). If its main file is not main.zhang, set ZHANG_DEMO_ENDPOINT. Save these changes before deploying, or redeploy afterwards. A .bean endpoint also works. For temporary AWS credentials, add ZHANG_S3_SESSION_TOKEN; renew the credentials before they expire.

6. Open the service’s onrender.com URL and verify that the expected accounts and transactions appear. Also run an Explore query and export its CSV. To verify storage permissions, use the demo credentials to attempt writing a separate scratch object and confirm that storage rejects it.

The build script pins pnpm 9, builds the UI, and compiles only the zhang binary with the embedded-frontend feature. The start script validates the required settings and listens on 0.0.0.0:$PORT. /api/info is the health check; inspect the accounts as well, because a missing main file can yield an empty ledger with a successful health check.

Automatic deployments are disabled to avoid spending build minutes on every commit. Use Manual Deploy after updating the branch. When you update the bucket’s files, use Zhang’s reload button or restart the service: Zhang does not watch remote storage. Source files remain in the bucket across Render redeploys and restarts; local document and plugin caches can be rebuilt.

Free-tier limits

Render Free services sleep after 15 minutes without incoming traffic and take about a minute to wake. A workspace has 750 free instance hours per month, shared by its Free services. Free services also consume build minutes and outbound bandwidth. Without a payment method, exceeding the included quotas suspends services or disables builds instead of billing for additional usage. If the workspace already has a payment method, review its billing and spend settings separately: plan: free does not by itself disable every usage charge. See Render’s free-tier limits.

R2 Standard storage has a monthly free allowance, including 10 GB-months of storage, 1 million Class A operations and 10 million Class B operations; direct R2 egress is free. Usage beyond the allowance is billed, so read-only access does not mean unlimited free storage or requests. See R2 pricing.