feat: support --remote-config for loading config from URL

[neilkuan]

Summary

Support loading config from a remote URL by auto-detecting URL in the existing positional argument:

# local (existing behavior, unchanged)
agent-broker config.toml

# remote (new — auto-detected by http:// or https:// prefix)
agent-broker https://example.com/config.toml

Motivation

Currently the broker only reads config from a local file path (defaults to ./config.toml). In containerized or multi-node deployments, it's common to host a shared config on a central server (e.g. S3, internal HTTP service, Git raw URL). Auto-detecting URLs in the existing positional arg removes the need to pre-download or mount the file manually, while keeping the CLI simple — no extra flags needed.

Proposed Behavior

• If the positional config arg starts with http:// or https://, fetch the TOML content via HTTP(S) GET before parsing.
• Otherwise, treat the arg as a local file path (existing behavior, unchanged).
• No separate --remote-config flag — the daemon just takes one config source and it can be either a path or a URL.
• Existing env-var expansion (${VAR}) should still work on the fetched content.
• Reasonable timeout (e.g. 10s) and clear error message on fetch failure.

Design Rationale

agent-broker is a daemon (starts and stays running), not a client CLI. This is more like dockerd / kubelet — it starts up with a config and runs. A kubectl apply -f-style subcommand structure fits client tools better. Future client-side subcommands (e.g. session management) would be a separate concern (agent-broker-ctl or similar).

Implementation Notes

• Add reqwest dependency
• In main.rs, check if the arg starts with http:// / https:// → fetch, otherwise → read_to_string
• Same expand_env_vars + toml::from_str pipeline either way
• 10s timeout + clear error on fetch failure
• Works with S3 pre-signed URLs, raw GitHub URLs, etc. — anything that returns TOML over HTTP(S)

Acceptance Criteria

• agent-broker https://... fetches and uses remote config via auto-detection
• Env-var expansion works on remote config content
• Clear error on network failure / non-200 response / invalid TOML
• Existing local file config path remains the default behavior

[thepagent]

Interesting idea! This is essentially the same UX as kubectl apply -f <URL> — the config source becomes a URL instead of a local path, but the content is still just TOML going through the same parsing pipeline.

One thought: instead of a separate --remote-config flag, we could also consider letting the existing positional arg auto-detect URLs (i.e. if the arg starts with http:// or https://, fetch it; otherwise treat it as a local path). That would give a more kubectl-like experience:

# local (existing)
agent-broker config.toml

# remote (new — auto-detected)
agent-broker https://example.com/config.toml

Either approach works — explicit flag vs auto-detect. Happy to discuss which fits better.

We welcome PRs for this! 🙌

[thepagent]

After some more thought — since agent-broker is a daemon (starts and stays running), not a client CLI, we think the simplest approach is to just let the existing positional arg auto-detect URLs:

# local (existing behavior, unchanged)
agent-broker config.toml

# remote (new — auto-detected by http:// or https:// prefix)
agent-broker https://example.com/config.toml

No need for a separate --remote-config flag or a run subcommand — the daemon just takes one config source and it can be either a path or a URL.

We considered a kubectl apply -f-style subcommand structure, but that pattern fits client tools better. agent-broker is more like dockerd / kubelet — it starts up with a config and runs. Future client-side subcommands (e.g. session management) would likely be a separate concern (agent-broker-ctl or similar).

Implementation-wise this is minimal:

• Add reqwest dependency
• In main.rs, check if the arg starts with http:// / https:// → fetch, otherwise → read_to_string
• Same expand_env_vars + toml::from_str pipeline either way
• 10s timeout + clear error on fetch failure

We welcome PRs for this! 🙌

[chaodu-agent]

Hi @neilkuan,

Clean proposal — auto-detecting URL prefix keeps the CLI simple. PR #87 is already open with the implementation. Will review there.