Crate harness_web 

Web access for prompts: a Plugin that gives a run two tools, one that fetches a page and one that searches the web.

A Host registers Web in its Plugin registry. A prompt turns it on with one frontmatter line, plugins: [promptforge/web]. The run then gets both tools: promptforge/web/fetch, which fetches a URL and returns its content as text, and promptforge/web/search, which runs a search through the Host’s SearchProvider. The two tools always come together.

The Host also provides two services beside the Plugin. Its SearchProvider is registered under the key SEARCH_PROVIDER. The tokio runtime handle that every fetch is spawned onto is registered under the key TOKIO_RUNTIME. A run gets the web tools only when both services are registered.

The fetch tool is security-critical. The model supplies the URL, so the tool is the server-side request forgery (SSRF) boundary between an untrusted argument and the network. A Host can replace the default fetch policy with a FetchConfig built by FetchConfigBuilder. A configuration problem is reported as a ConfigError.

The fetch tool sends a GET request and chooses how to render the response from its Content-Type. For an HTML page, it extracts the main article with readabilityrs and renders it to markdown. When a page yields too little article text, htmd converts the whole page to markdown. Any other text body, such as JSON, XML, or plain text, is decoded and returned verbatim. The tool refuses every other type.

The search tool validates the model’s arguments into a SearchQuery and hands it to the provider. It returns the provider’s SearchResults as compact JSON, marked untrusted. The JSON matches the Gateway’s search output: an object with the query and a results array. Each result has a title, url, and description, plus age, site_name, and extra_snippets when present. The provider owns the transport and its deadline, so a search vendor’s credential stays wherever the provider keeps it.

Invariants

• Every URL selected by the model or a tool, and every resolved address, is validated again on each redirect hop. A non-global address is denied unless the fetch policy grants an exact host-and-address exception.
• No fetch includes an ambient identity on any hop. The client has no proxy, no cookie store, no automatic Referer header, and no default credentials.
• Every fetch runs on the Host’s runtime handle, and dropping the call aborts it.

Structs

ConfigError

The error reported when a fetch configuration fails validation or its HTTP client fails to build.

FetchConfig

The security policy for the web fetch tool, promptforge/web/fetch.

FetchConfigBuilder

A builder for a custom FetchConfig.

SearchError

The error a SearchProvider returns when a search fails.

SearchQuery

The validated arguments of one promptforge/web/search call.

SearchResult

One result in SearchResults: a title, a URL, a description, and optional extras.

SearchResults

The results a SearchProvider returns for one search, with the query it ran.

Web

A Plugin that gives a run web access: one tool that fetches a page and one that searches the web.

Enums

Freshness

How recent the results of a SearchQuery must be.

SafeSearch

The SafeSearch filtering level of a SearchQuery.

SearchErrorKind

Which part of a search failed: the transport or the backend.

Constants

SEARCH_PROVIDER

The service key for the Host’s search provider.

TOKIO_RUNTIME

The service key for the Host’s tokio runtime handle.

Traits

SearchProvider

A backend that runs web searches for the promptforge/web/search tool.