Develop a provider

While developing, install with a link so edits do not need a reinstall. A link install does not check the tree digest. It is for the local machine.

abx provider install ./my-cloud --link --yes
abx provider doctor my-cloud
abx provider test my-cloud

--link requires --yes. Without it the error is ProviderTrustError (E8012).

The Python SDK has the same commands (python -m agent_sandbox.providers install|doctor|test) and installs to the same directory. Both call the same plugin code. The CLI rejects a manifest whose kind is python.

To check what an SDK sees, start the engine (abx provider engine serve) and call GET /v1/providers, or run your Python code. The routes are in the CLI's Engine HTTP API.

What to look at

1. doctor checks the manifest, requires, configuration, and the handshake.
2. test runs the contract suite. Features you did not declare are skipped, not failed. A declared feature you did not implement fails. The suite covers lifecycle, exec, streaming, files, processes, timeouts, and error mapping.
3. A local fake TCP server should show the request path and the auth header, and that ABX_SANDBOX_API_KEY is not sent. For node plugins the CLI repository has an E2B-shaped mock (cli/tests/_support/e2b_mock.ts); an exec plugin should keep its own mock server and unit tests, as opensandbox/tests does.
4. With a real backend, the minimum live check is create, one command, one file round-trip, and kill. Without a backend, skip that check and name the missing variable. Do not borrow another provider's key.

abx provider test my-cloud needs no extra tools. python -m agent_sandbox.providers test my-cloud needs pytest and runs the same kit.

After the manifest changes

A link install reads the source directory. A normal install copies files to ~/.abx/providers/<id> and records a SHA-256 tree digest in .abx-install.json. Every file except data/ is in the digest. The digest is checked again on start. A mismatch is ProviderIntegrityError (E8011).

Use --link while developing. Before you hand the plugin to someone else, install once without --link and read the consent screen.

provider update re-fetches the recorded source. If the command, the security block, or the feature list changed, consent is required again. An install pinned to a 40-hex commit or --sha256 does not move; pass a new --ref to change it. If the new version fails its handshake, the previous files and data/ are restored.

Match the backend

Compare the adapter with that backend's current OpenAPI or official SDK, not with an old fake server in this repository. The fake server only shows that the adapter sent the request you told it to send.

After that, record three things in the provider's own docs/:

• which features are declared, and which path each one calls
• which calls raise E8004
• which calls ran against a real backend, and which were checked against docs only

The four official providers record that in their own docs/README.md. Differences that still need a real backend are collected in Catalog and review.

Skill for an agent

An agent that is writing a provider should load python-sdk/agent-sandbox-provider/SKILL.md, or SKILL.md in this catalog. Both say the same thing: pick a kind, list real features, do not touch the Express key, and do not claim a live run when the backend was not there.