Add web capability seam: ctx.web, search/fetch providers, web tools

Introduce web access as a first-class capability seam so the model-facing web tools stay stable while backends change. dsh-web owns ctx.web as a provider registry with registration-order-independent selection and the WebError taxonomy; dsh-web-search-exa, dsh-web-search-perplexity, and dsh-web-fetch-local register capabilities into it; dsh-tool-web is the sole owner of the model-facing web_search/web_fetch schemas, prompt sections, and HTML-to-markdown presentation. Search and fetch are deliberately one seam. Providers ship as namespace plugins that register into ctx.web (like an LlmAdapter into ctx.llm), not key-owning services, since multiple search providers cannot each own the key. Tool registration follows product enablement, not backend availability, so load order/credentials never enter the model contract; the seam resolves the provider at execution time and surfaces a structured WebError otherwise. Moves the RFC to implemented/ amended to match what shipped. Example/app configs are intentionally not wired yet (RFC migration step 6).
2026-06-25 15:04:12 +08:00
parent a4091daa3d
commit d01f5f73b7
50 changed files with 3610 additions and 8 deletions
@@ -0,0 +1,105 @@
+/**
+ * The model-facing `web_search` tool: discover current information on the web.
+ * Execution goes through `ctx.web` — this module owns only the model-facing
+ * schema, argument validation, the result-count bound, and result formatting,
+ * never provider selection or network access.
+ *
+ * @module @deepseek-ai/dsh-tool-web/search
+ */
+
+import type { Context } from 'cordis'
+import { defineTool } from '@deepseek-ai/dsh-tools'
+import type { ToolCallPresentation } from '@deepseek-ai/dsh-tools'
+import type { ContentBlock } from '@deepseek-ai/dsh-llm'
+import type { WebSearchResult } from '@deepseek-ai/dsh-web'
+import type {} from '@deepseek-ai/dsh-system-prompt'
+
+/**
+ * Default upper bound on returned sources. Owned by the consumer (not the
+ * provider or model), mirroring `dsh-tool-fs`'s `READ_LIMIT`/`GREP_LIMIT`. The
+ * model just asks a question; the product controls how much context returns.
+ * The default `8` aligns with OpenCode's Exa default.
+ */
+export const WEB_SEARCH_MAX_RESULTS = 8
+
+/** Validate value constraints the schema DSL can't express. */
+export function parseSearchArgs(args: { query: string }): { query: string } {
+  if (args.query.trim().length === 0) throw new Error('query must be a non-empty string')
+  return { query: args.query }
+}
+
+/** Display label for a source: its title, else its hostname. */
+function sourceLabel(url: string, title: string | undefined): string {
+  if (title !== undefined && title.length > 0) return title
+  try {
+    return new URL(url).hostname
+  } catch {
+    // A provider should return a valid URL, but never let a malformed one throw
+    // out of pure formatting — fall back to the raw string.
+    return url
+  }
+}
+
+/** Format a search result as one model-facing text block. */
+export function formatSearchOutput(result: WebSearchResult): string {
+  const parts: string[] = []
+  if (result.content !== undefined && result.content.length > 0) parts.push(result.content)
+
+  if (result.sources.length > 0) {
+    const lines = result.sources.map((source) => {
+      const label = sourceLabel(source.url, source.title)
+      const meta: string[] = []
+      if (source.snippet !== undefined && source.snippet.length > 0) meta.push(source.snippet)
+      if (source.publishedAt !== undefined && source.publishedAt.length > 0) meta.push(`(${source.publishedAt})`)
+      const suffix = meta.length > 0 ? ` — ${meta.join(' ')}` : ''
+      return `- [${label}](${source.url})${suffix}`
+    })
+    parts.push(`Sources:\n${lines.join('\n')}`)
+  } else if (result.content === undefined || result.content.length === 0) {
+    parts.push('No results found.')
+  }
+
+  if (result.truncated) parts.push(`(Showing the first ${result.sources.length} sources. Refine the query for more.)`)
+  parts.push('Cite the relevant URLs above as markdown links in your answer.')
+  return parts.join('\n\n')
+}
+
+/** Pending-call presentation: a search card titled by the query. */
+export function presentSearchCall(args: { query: string }): ToolCallPresentation {
+  return { title: args.query, kind: 'search', rawInput: args.query }
+}
+
+/** Register the `web_search` tool and its system-prompt guidance. */
+export function apply(ctx: Context): void {
+  ctx.systemPrompt.section({
+    name: 'tool:web_search',
+    order: 110,
+    text: 'Use the web_search tool to discover current information on the web. It returns an optional answer plus a list of source URLs. Follow up with web_fetch when you need the full content of a specific result, and cite the relevant URLs as markdown links.',
+  })
+
+  ctx.tools.register(defineTool({
+    name: 'web_search',
+    description: 'Search the web for current information. Returns an optional summary answer and a list of source URLs.',
+    parameters: {
+      query: { type: 'string', required: true, description: 'The search query.' },
+    },
+    async execute(args, exec): Promise<ContentBlock[]> {
+      const input = parseSearchArgs(args)
+      const result = await ctx.web.search(
+        { query: input.query, maxResults: WEB_SEARCH_MAX_RESULTS },
+        exec.signal ? { signal: exec.signal } : undefined,
+      )
+      return [{ type: 'text', text: formatSearchOutput(result) }]
+    },
+    presentCall: presentSearchCall,
+  }))
+}
+
+/** Cordis plugin name used by loader diagnostics. */
+export const name = 'web-search'
+
+/** Services required by the `web_search` tool plugin. */
+export const inject = ['tools', 'web', 'systemPrompt']
+
+/** Named helper for direct registration in the root plugin and tests. */
+export const applyWebSearchTool = apply