CLI validation probe paginates entire catalog, causing timeout on large registries

Summary

thv registry list times out with "context deadline exceeded" when the registry contains more than ~97 servers. The CLI's validation probe inadvertently paginates the entire catalog instead of fetching a single page.

Root cause

When creating an APIRegistryProvider, the CLI runs a validation probe (provider_api.go:62):

_, err = client.ListServers(ctx, &api.ListOptions{Limit: 1})

The intent is to fetch one server to verify the API works. However, ListServers always paginates through the entire catalog — Limit only controls page size, not total results. The method loops until nextCursor is empty (client.go:134-146):

for {
    servers, nextCursor, err := c.fetchServersPage(ctx, cursor, opts)
    // ...
    if nextCursor == "" {
        break
    }
    cursor = nextCursor
}

With Limit: 1 and 100+ servers, the probe makes 100+ sequential HTTP requests, exceeding the 10-second context timeout.

Reproduction

# Point at a registry with 50+ servers (e.g. the full ToolHive catalog)
thv config set-registry https://registry.example.com/registry/toolhive
thv registry list
# Error: failed to get registry provider: custom registry API at
# https://registry.example.com/registry/toolhive is not reachable:
# API endpoint not functional: failed to fetch servers: context deadline exceeded

The registry endpoint itself works fine via curl — this is purely a client-side issue.

Affected versions

Confirmed on v0.12.4 and current main (v0.13.1).

Suggested fix

The validation probe should fetch one page, not paginate the entire catalog. Options:

1. Call fetchServersPage directly instead of ListServers (currently unexported)
2. Add a MaxPages or NoPaginate option to ListOptions
3. Use a simpler health check (e.g. confirm a 200 with valid JSON from a single request)

Related

• stacklok/ai-toolkit#78 (tracking issue from PoC deployment)

Start at provider_api.go:62, where APIRegistryProvider performs the validation probe, then trace ListServers in client.go:134-146 and its pagination behavior. Reproduce with a registry containing 50+ servers and compare the probe's requests; done means validation fetches only one page and does not time out on a large catalog.