Tianyi Cui
8ca82d03ab
master's web_search/web_fetch tools were authored against the old ToolCallPresentation bag; the render-intent union replaces it with a card-tagged discriminated union. Both are simple generic cards, so they declare card:'generic' explicitly.
77 lines
3.5 KiB
TypeScript
77 lines
3.5 KiB
TypeScript
/**
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* The model-facing `web_fetch` tool: retrieve the content of a specific URL.
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* Execution goes through `ctx.web` — this module owns the model-facing schema,
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* argument validation, and PRESENTATION (HTML→markdown, truncation formatting),
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* while the fetch provider owns safe retrieval (transport, redirects, caps).
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*/
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import type { Context } from 'cordis'
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import { defineTool } from '@deepseek-ai/dsh-tools'
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import type { GenericCallView } from '@deepseek-ai/dsh-tools'
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import type { ContentBlock } from '@deepseek-ai/dsh-llm'
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import type { WebFetchBody, WebFetchResult } from '@deepseek-ai/dsh-web'
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import { assertNever } from '@deepseek-ai/dsh-llm'
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import type {} from '@deepseek-ai/dsh-system-prompt'
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import { htmlToMarkdown } from './html.ts'
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/** Validate value constraints the schema DSL can't express. */
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export function parseFetchArgs(args: { url: string; timeout_ms?: number }): { url: string; timeoutMs?: number } {
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if (args.url.trim().length === 0) throw new Error('url must be a non-empty string')
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if (args.timeout_ms !== undefined && (!Number.isFinite(args.timeout_ms) || args.timeout_ms <= 0)) {
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throw new Error('timeout_ms must be a positive number')
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}
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return { url: args.url, ...args.timeout_ms !== undefined ? { timeoutMs: args.timeout_ms } : {} }
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}
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/** Render a fetched body to model-facing markdown text. */
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export function renderBody(body: WebFetchBody): string {
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switch (body.kind) {
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case 'html':
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return htmlToMarkdown(body.content)
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case 'text':
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return body.content
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/* v8 ignore next 2 -- WebFetchBody is a closed union; this arm is unreachable and only makes adding a kind a compile error. */
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default:
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return assertNever(body, 'unhandled web fetch body kind')
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}
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}
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/** Format a fetch result as one model-facing text block. */
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export function formatFetchOutput(result: WebFetchResult): string {
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const header = `Fetched ${result.url} (HTTP ${result.statusCode})`
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const footer = result.truncated ? '\n\n(Content truncated. Fetch a more specific URL or section for the full text.)' : ''
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return `${header}\n\n${renderBody(result.body)}${footer}`
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}
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/** Pending-call presentation: a fetch card titled by the URL. */
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export function presentFetchCall(args: { url: string; timeout_ms?: number }): GenericCallView {
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return { card: 'generic', title: args.url, kind: 'fetch', rawInput: args.url }
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}
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/** Register the `web_fetch` tool and its system-prompt guidance. */
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export function applyWebFetchTool(ctx: Context): void {
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ctx.systemPrompt.section({
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name: 'tool:web_fetch',
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order: 111,
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text: 'Use the web_fetch tool to retrieve the content of a specific HTTP(S) URL (for example a result from web_search). It returns the page content decoded to text. Cite the URL as a markdown link when you use its content.',
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})
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ctx.tools.register(defineTool({
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name: 'web_fetch',
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description: 'Fetch the content of a specific HTTP(S) URL and return it decoded to text.',
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parameters: {
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url: { type: 'string', required: true, description: 'The HTTP(S) URL to fetch.' },
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timeout_ms: { type: 'number', description: 'Optional fetch timeout in milliseconds (capped by the provider).' },
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},
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async execute(args, exec): Promise<ContentBlock[]> {
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const input = parseFetchArgs(args)
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const result = await ctx.web.fetch(
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{ url: input.url, ...input.timeoutMs !== undefined ? { timeoutMs: input.timeoutMs } : {} },
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exec.signal ? { signal: exec.signal } : undefined,
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)
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return [{ type: 'text', text: formatFetchOutput(result) }]
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},
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presentCall: presentFetchCall,
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}))
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}
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