Overview
dsh-web
WebRuntime (ctx.web) defines WHAT web access the harness has — search the web, fetch a URL — over multiple providers, without binding the model contract to one vendor's API shape.This is an atomic module already shipped with Harness, not a standalone profile layer.
Capabilities
What it contributes
README / EN
Package documentation
@deepseek-ai/dsh-web
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The WebRuntime (ctx.web) defines WHAT web access the harness has — search the web, fetch a URL — over multiple providers, without binding the model contract to one vendor's API shape.
This package owns the Service Definition role of the web capability. Unlike shell/fs it spans two operations (search and fetch) on one seam, with potentially multiple providers each:
| Package | Role |
|---|---|
@deepseek-ai/dsh-web (this) |
Service Definition: the service, provider registries, selection policy, request/result vocabulary, the WebError taxonomy |
@deepseek-ai/dsh-web-search-exa |
Search provider: Exa |
@deepseek-ai/dsh-web-search-perplexity |
Search provider: Perplexity |
@deepseek-ai/dsh-web-fetch-http |
Fetch provider: anonymous public HTTP(S) |
@deepseek-ai/dsh-tool-web |
Consumer: the model-facing web_search / web_fetch tool schemas over ctx.web |
Search and fetch share no request schema and no business logic, but they are deliberately one seam: ctx.web is a single web-access middle layer with one provider-selection policy owner, one abort/error vocabulary, and one product-facing "how this harness reaches the web" config surface. The Search/Fetch method pairs are deliberately parallel.
Service API (ctx.web)
| Member | Semantics |
|---|---|
registerSearchProvider(provider) / registerFetchProvider(provider) |
Register a backend. Throws WebError WEB_DUPLICATE_PROVIDER on a duplicate id within that capability kind. Returns a disposer. Disposed with the calling fiber. |
search(request, signal?) |
Resolve the search provider and run one search. Enforces request.maxResults on the result (truncates sources[], sets truncated). Throws WebError when the capability cannot run. |
fetch(request, signal?) |
Resolve the fetch provider and retrieve one URL. A non-2xx response is a result, not a throw. Throws WebError for failures to safely retrieve or represent the resource. |
Providers register capabilities, not tools. dsh-tool-web is the only owner of model-facing names, descriptions, prompt guidance, JSON schemas, and presentation.
Selection
Selection never depends on registration, config, or HMR order. A capability has an explicit provider id (config searchProvider/fetchProvider, or env $DSH_WEB_SEARCH_PROVIDER/$DSH_WEB_FETCH_PROVIDER feeding the same fields), or auto-selects when exactly one usable provider is registered. search()/fetch() resolve the provider at execution time:
| Situation | Execution |
|---|---|
configured id registered and available() |
runs that provider |
| configured id not registered | WEB_PROVIDER_CONFIGURED_MISSING |
| configured id registered but unavailable | WEB_PROVIDER_CONFIGURED_UNAVAILABLE |
| no id, exactly one registered usable provider | runs it |
| no id, no usable provider | WEB_PROVIDER_UNAVAILABLE |
| no id, multiple usable providers | WEB_PROVIDER_AMBIGUOUS |
The failure branches throw WebError, whose structured code (plus message detail — the missing id, the ambiguous candidate set) is the direct callers route on. A provider's own available() is a cheap local check (credential presence, parseable config) that feeds this execution-time selection and must not make network calls; dsh-tool-web never calls it — the tool executes through ctx.web.search()/fetch() and routes on the thrown codes, so provider selection has one owner.
Vocabulary
WebSearchRequest (query, maxResults?) → WebSearchResult (content?, sources[], truncated); each WebSearchSource has a required url and optional title/snippet/publishedAt (Perplexity citations may be URL-only). WebFetchRequest (url) → WebFetchResult (final url, statusCode, body, truncated); cancellation is a direct optional AbortSignal argument to search()/fetch(). WebFetchBody is a CLOSED discriminated union (html | text) owned here — consumers switch to exhaustiveness so a new kind breaks their compilation until handled. See src/types.ts for the full contracts and the WebError code taxonomy.
Model Experience
Indirectly, through dsh-tool-web, which retains bounded normalized provider data or the exact configured-provider, unavailable-provider, no-provider, multiple-provider, and Error: <message> failures while this registry contributes no prompt or schema itself.
KV Cache effect
No direct invalidation; the named consumer owns any request-prefix changes.
Known Limitations and Deferred Work
- No observation surface — no provider-change event and no capability-status query; availability is observed only by executing
search()/fetch()and routing the thrownWebErrorcodes, and the no-provider failure is the genericWEB_PROVIDER_UNAVAILABLEwith no per-provider reason enumeration (Agent Note). WebSearchRequestcarries onlyquery+maxResults— provider-neutral controls (recency, domain filters, regional hints, search depth) are deferred until Exa and Perplexity can both honor them honestly (seam Agent Note).WebFetchBodyhas nopdfarm — text-extractable PDF support is named deferred work; the closed union makes adding it a compile-enforced change across the three web packages.- Provider-backed page extraction is out of scope of
fetch()— a Firecrawl/Tavily-styleweb_extractcapability is deferred rather than widening the fetch operation.
LIMITATIONS
Known limitations
- **No observation surface** — no provider-change event and no capability-status query; availability is observed only by executing `search()`/`fetch()` and routing the thrown `WebError` codes, and the no-provider failure is the generic `WEB_PROVIDER_UNAVAILABLE` with no per-provider reason enumeration ([Agent Note](../../../.agents/notes/archived/simplification/2026-07-04-drop-unconsumed-web-observation-surface.md)). - **`WebSearchRequest` carries only `query` + `maxResults`** — provider-neutral controls (recency, domain filters, regional hints, search depth) are deferred until Exa and Perplexity can both honor them honestly ([seam Agent Note](../../../.agents/notes/implemented/architecture/2026-06-24-web-capability-seam.md)). - **`WebFetchBody` has no `pdf` arm** — text-extractable PDF support is named deferred work; the closed union makes adding it a compile-enforced change across the three web packages. - **Provider-backed page extraction is out of scope of `fetch()`** — a Firecrawl/Tavily-style `web_extract` capability is deferred rather than widening the fetch operation.
