1823aae891Co-authored-by: Matt <77928207+mattzcarey@users.noreply.github.com> Co-authored-by: Konstantin Konstantinov <KKonstantinov@users.noreply.github.com> Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
78 lines
3.3 KiB
TypeScript
78 lines
3.3 KiB
TypeScript
/**
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* Reads the cache hints emitted on cacheable results (2026-07-28 connections
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* only) and asserts the client honours them: a still-fresh cached entry is
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* served without a round trip.
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*/
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import { check, parseExampleArgs, siblingPath } from '@mcp-examples/shared';
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import { Client, StreamableHTTPClientTransport } from '@modelcontextprotocol/client';
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import { StdioClientTransport } from '@modelcontextprotocol/client/stdio';
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interface Cacheable {
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ttlMs?: number;
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cacheScope?: 'public' | 'private';
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}
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async function callCount(client: Client, name: 'read-count' | 'request-count'): Promise<number> {
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const r = await client.callTool({ name });
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return Number((r.content[0] as { text: string }).text);
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}
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const { transport, url, era } = parseExampleArgs();
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const client = new Client(
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{ name: 'caching-example-client', version: '1.0.0' },
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{ versionNegotiation: { mode: era === 'modern' ? 'auto' : 'legacy' } }
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);
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await (transport === 'stdio'
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? client.connect(new StdioClientTransport({ command: 'npx', args: ['-y', 'tsx', siblingPath(import.meta.url, 'server.ts')] }))
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: client.connect(new StreamableHTTPClientTransport(new URL(url))));
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check.equal(client.getNegotiatedProtocolVersion(), '2026-07-28');
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// The server stamps `tools/list` with `ttlMs: 30_000, cacheScope: 'public'`.
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const tools = (await client.listTools()) as Cacheable & Awaited<ReturnType<typeof client.listTools>>;
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check.equal(tools.ttlMs, 30_000);
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check.equal(tools.cacheScope, 'public');
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// `request-count` proves the wire was reached exactly once.
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check.equal(await callCount(client, 'request-count'), 1);
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// The second call is served from the response cache: the server-side
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// `tools/list` counter is unchanged, and the result is a fresh copy of the
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// held entry (so mutating it cannot reach the cache).
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const toolsAgain = await client.listTools();
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check.deepEqual(
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toolsAgain.tools.map(t => t.name),
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tools.tools.map(t => t.name)
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);
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check.equal(await callCount(client, 'request-count'), 1);
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// `cacheMode: 'refresh'` always fetches and re-stores: the counter moves.
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await client.listTools(undefined, { cacheMode: 'refresh' });
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check.equal(await callCount(client, 'request-count'), 2);
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const resources = (await client.listResources()) as Cacheable & Awaited<ReturnType<typeof client.listResources>>;
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check.equal(resources.ttlMs, 5000);
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check.equal(resources.cacheScope, 'public');
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// `readResource`: the resource handler counts how many times it ran, and
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// the `read-count` tool exposes that counter.
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const read = (await client.readResource({ uri: 'config://app' })) as Cacheable & Awaited<ReturnType<typeof client.readResource>>;
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check.equal(read.ttlMs, 60_000);
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check.equal(read.cacheScope, 'private');
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check.equal(await callCount(client, 'read-count'), 1);
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// Within TTL, default `cacheMode: 'use'` → served from cache; the server
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// handler does not run.
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await client.readResource({ uri: 'config://app' });
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check.equal(await callCount(client, 'read-count'), 1);
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// `cacheMode: 'refresh'` always fetches and re-stores.
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await client.readResource({ uri: 'config://app' }, { cacheMode: 'refresh' });
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check.equal(await callCount(client, 'read-count'), 2);
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// After the refresh the entry is fresh again — back to cache-served.
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await client.readResource({ uri: 'config://app' });
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check.equal(await callCount(client, 'read-count'), 2);
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await client.close();
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