[Hona]

Fixes #26602

On Node, a provider that sends nothing for 5 minutes is disconnected with UND_ERR_HEADERS_TIMEOUT, even with headerTimeout: false. Node's built-in fetch applies undici's default 300s headersTimeout and bodyTimeout. Bun has the same deadline, and Core already turns it off with timeout: false. This PR turns off the Node deadline in the same way.

• Who is affected: the Node CLI (opencode2-node) and Core embedded in a Node process. Desktop 2.0.x starts the bundled Bun CLI (opencode-cli serve --service), the same service the TUI uses, so it already behaves correctly.
• What still limits a request: the provider settings headerTimeout (default 300s), chunkTimeout (default 900s), and timeout (no default), on every runtime.

sequenceDiagram
  participant S as opencode service (Node)
  participant P as Provider (Ollama, router, ...)
  S->>P: POST /v1/chat/completions
  Note over P: reads a long prompt, sends no bytes
  Note over S: 300s: undici headersTimeout fires
  S--xP: socket closed: UND_ERR_HEADERS_TIMEOUT
  S->>P: retry about 2s later, same result (up to 10 retries)

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Change

Both provider request paths (native routes through RequestExecutor, AI SDK routes through aisdk.ts) now get their fetch from a runtime-conditioned import, like #sqlite and #pty:

flowchart LR
  N[Native routes<br/>RequestExecutor] --> R{"#runtime-fetch"}
  A[AI SDK routes<br/>aisdk.ts] --> R
  R -->|bun| B["ambient fetch + timeout: false<br/>(unchanged behavior)"]
  R -->|node| U["undici fetch + EnvHttpProxyAgent<br/>headersTimeout: 0, bodyTimeout: 0"]
  R -->|workerd| W[platform fetch]

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// packages/core/src/effect/runtime-fetch.node.ts
const dispatcher = new EnvHttpProxyAgent({ headersTimeout: 0, bodyTimeout: 0 })

export function withoutRuntimeTimeouts(runtime: Fetch): Fetch {
  if (runtime !== globalThis.fetch) return runtime
  return Object.assign(
    (input: Parameters<Fetch>[0], init?: RequestInit) =>
      input instanceof Request || init?.body instanceof FormData
        ? runtime(input, init)
        : (fetch(input, { ...init, dispatcher } as Parameters<typeof fetch>[1]) as unknown as Promise<Response>),
    { preconnect: runtime.preconnect },
  )
}

• Undici's fetch, not the built-in one: Node 24's built-in fetch rejects an agent from undici 8 (UND_ERR_INVALID_ARG), so the agent is paired with undici's own fetch.
• FormData and Request keep the built-in fetch: undici's fetch does not recognize the built-in classes. For example, it sends a built-in FormData as the text [object FormData], which would break image and transcription uploads.
• Proxy variables: EnvHttpProxyAgent honors HTTP_PROXY, HTTPS_PROXY, and NO_PROXY, like Bun's fetch and Core's WebSocket transport on Node.
• Injected fetch stays in charge: a fetch from provider settings, a host, or the test network guard is never replaced on Node. On Bun it still receives timeout: false.
• Bundles: Bun and workerd do not load undici. The Node CLI bundles it through a Vite alias. Without the alias, Vite (which runs under Bun, where undici is a builtin) leaves it external and the executable fails at startup with Cannot find package 'undici'.

Before and after

A real V2 server and an OpenAI-compatible provider that waits 330s before it sends response headers, with headerTimeout: false:

Service runtime	Before	After
Bun (Desktop 2.0.29, TUI)	Answered after 330s	Answered after 330s
Node 26.4 (opencode2-node)	Disconnected after 305s: UND_ERR_HEADERS_TIMEOUT: Headers Timeout Error, then retried	Answered after 330s

With headerTimeout: 20000 and a 60s provider delay, patched Node still ends the request after 20s with Timed out waiting for response headers.

Relation to #54793

#54793 by @Yedigaryan found the same cause. This PR differs in three places:

• Undici is loaded only under the node condition, so it stays out of the Bun and workerd graphs (the review note on fix(core): lift undici's 300s timeouts on Node #54793).
• FormData and Request inputs keep the built-in fetch.
• The Node CLI bundle includes undici; otherwise the executable cannot start.

---

Added by the opencode bot (AI-generated).

Public API: On Node, provider requests now honour HTTP_PROXY/HTTPS_PROXY/NO_PROXY, matching Bun (behaviour change, no API surface change)

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[opencode-agent]

Looks good. I reproduced the problem on Node 24: against a server that waits 310s before sending headers, the built-in fetch fails at 300s with UND_ERR_HEADERS_TIMEOUT, and the new withoutRuntimeTimeouts fetch returns 200 at 310s. The --bundle-only Node CLI build bundles undici and opencode2-node starts. The core tests closest to the change (aisdk, aisdk-native, request hooks, app-node-platform) and typecheck for core and cli all pass.

Public API: no SDK, HTTP, plugin, config or CLI changes. One behaviour change on Node: provider requests now honour HTTP_PROXY, HTTPS_PROXY and NO_PROXY through EnvHttpProxyAgent. The built-in fetch only did that with NODE_USE_ENV_PROXY, so Node users who have those variables set will now send provider traffic through the proxy, as Bun already does.

I have no blocking concerns.