Summary

• Problem: external channel plugin startup could import OpenClaw's packaged Undici proxy helpers on a clean no-proxy path, changing process-level fetch behavior before the plugin called globalThis.fetch.
• Why it matters: openclaw channels login --channel openclaw-weixin failed for @tencent-weixin/openclaw-weixin@2.4.1 with TypeError: fetch failed even though the same request worked in plain Node fetch.
• What changed: lazy-load Undici dispatcher/proxy dependencies only when OpenClaw actually creates a proxy fetch or proxy dispatcher, while keeping the guarded-fetch timeout bridge and proxy reset behavior intact.
• What did NOT change (scope boundary): no plugin code is changed, no proxy env contract is removed, and no configured proxy path is intentionally bypassed.

Change Type (select all)

• Bug fix
• Feature
• Refactor required for the fix
• Docs
• Security hardening
• Chore/infra

Scope (select all touched areas)

• Gateway / orchestration
• Skills / tool execution
• Auth / tokens
• Memory / storage
• Integrations
• API / contracts
• UI / DX
• CI/CD / infra

Linked Issue/PR

• Closes Regression: external channel plugin fetch() fails with TypeError: fetch failed in 2026.5.4 #78007
• Related Ignore unsupported proxy schemes for env dispatcher #78040
• This PR fixes a bug or regression

Real behavior proof (required for external PRs)

• Behavior or issue addressed: Tencent Weixin channel login failed before QR startup because the plugin's plain fetch request was rejected after OpenClaw loaded packaged Undici helpers.
• Real environment tested: source checkout on macOS with isolated HOME, isolated OPENCLAW_STATE_DIR, and @tencent-weixin/openclaw-weixin@2.4.1 installed through openclaw plugins install.
• Exact steps or command run after this patch:
  1. pnpm openclaw plugins install @tencent-weixin/openclaw-weixin@2.4.1 --pin
  2. pnpm openclaw channels login --channel openclaw-weixin --verbose
• Evidence after fix:

[plugins] loading openclaw-weixin from /private/tmp/openclaw-78007.Ez0VWR/.openclaw/npm/node_modules/@tencent-weixin/openclaw-weixin/dist/index.js
[plugins] loaded 1 plugin(s) (1 attempted) in 1516.5ms
用手机微信扫描以下二维码，以继续连接：
若二维码未能显示或无法使用，你可以访问以下链接以继续：
https://liteapp.weixin.qq.com/q/7GiQu1?qrcode=3e04d58f044ba6b007fc02cca258bf48&bot_type=3

• Observed result after fix: the login flow reaches QR startup instead of failing at TypeError: fetch failed.
• What was not tested: scanning the QR code and completing the Weixin account-linking flow.
• Before evidence:

Failed to start login: TypeError: fetch failed
Channel login failed: Error: Failed to start login: TypeError: fetch failed

Trace before fix showed the underlying cause:

UND_ERR_INVALID_ARG: invalid content-length header

Root Cause (if applicable)

• Root cause: src/infra/net/proxy-fetch.ts imported Undici at module load time. That module is exported through plugin runtime helper surfaces, so loading external plugin code could initialize Undici's package dispatcher state even when no proxy was configured. With the current Undici dependency, that changed Node global fetch behavior and caused plugin requests with explicit Content-Length to fail.
• Missing detection / guardrail: there was no regression test proving clean no-proxy startup does not initialize Undici global dispatcher state.
• Contributing context (if known): the affected plugin sends an explicit Content-Length header; plain Node fetch accepts the request, but OpenClaw's import side effect made the same request fail.

Regression Test Plan (if applicable)

• Coverage level that should have caught this:
  • Unit test
  • Seam / integration test
  • End-to-end test
  • Existing coverage already sufficient
• Target test or file:
  • src/infra/net/undici-global-dispatcher.test.ts
  • src/infra/net/proxy-fetch.test.ts
  • src/infra/net/fetch-guard.ssrf.test.ts
• Scenario the test should lock in: no-proxy timeout setup and proxy helper import must not initialize Undici global dispatcher state; proxy fetch and env proxy paths must still lazy-load and use Undici when needed.
• Why this is the smallest reliable guardrail: the regression was an import-time side effect, so a subprocess assertion against the global dispatcher symbol catches the exact failure class without requiring live third-party auth.
• Existing test that already covers this (if any): none before this PR.
• If no new test is added, why not: N/A.

User-visible / Behavior Changes

External channel plugins that use plain fetch() no longer inherit OpenClaw's packaged Undici dispatcher behavior on clean no-proxy startup. This fixes the Weixin QR login regression in #78007.

Diagram (if applicable)

Before:
plugin load -> SDK/runtime helper import -> proxy-fetch imports Undici -> plugin fetch fails

After:
plugin load -> SDK/runtime helper import -> no Undici import unless proxy fetch is created -> plugin fetch reaches QR login

Security Impact (required)

• New permissions/capabilities? No
• Secrets/tokens handling changed? No
• New/changed network calls? No
• Command/tool execution surface changed? No
• Data access scope changed? No
• If any Yes, explain risk + mitigation: N/A

Repro + Verification

Environment

• OS: macOS local checkout; Blacksmith Testbox for remote validation
• Runtime/container: source checkout, Node 24, pnpm 10
• Model/provider: N/A
• Integration/channel: @tencent-weixin/openclaw-weixin@2.4.1
• Relevant config (redacted): isolated state dir with only the installed plugin enabled

Steps

1. Install @tencent-weixin/openclaw-weixin@2.4.1 into an isolated state dir.
2. Run pnpm openclaw channels login --channel openclaw-weixin --verbose.
3. Confirm the command reaches QR login output instead of failing with TypeError: fetch failed.

Expected

• The Weixin login request reaches QR login startup.

Actual

• After this patch, the command reaches QR login startup.

Evidence

• Failing test/log before + passing after
• Trace/log snippets
• Screenshot/recording
• Perf numbers (if relevant)

Human Verification (required)

What I personally verified:

• pnpm test src/infra/net/proxy-fetch.test.ts src/infra/net/undici-global-dispatcher.test.ts src/infra/net/fetch-guard.ssrf.test.ts
• Same targeted test command passed in Blacksmith Testbox.
• pnpm exec oxfmt --check --threads=1 CHANGELOG.md src/infra/net/proxy-fetch.ts src/infra/net/proxy-fetch.test.ts src/infra/net/undici-runtime.ts src/infra/net/undici-global-dispatcher.ts src/infra/net/undici-global-dispatcher.test.ts src/infra/net/fetch-guard.ssrf.test.ts
• git diff --check
• Real isolated openclaw channels login --channel openclaw-weixin --verbose reached QR login output.

Edge cases checked:

• No-proxy timeout setup does not initialize Undici global dispatcher state.
• Env proxy setup still installs EnvHttpProxyAgent.
• Proxy fetch still creates ProxyAgent lazily.
• FormData normalization still strips stale content-length/content-type in proxy fetch paths.
• Clearing a proxy dispatcher installed by OpenClaw still restores a direct dispatcher.

What I did not verify:

• Full Weixin account-linking after QR scan.
• Full repo test suite.

Note: pnpm check:changed was run in Blacksmith Testbox after rebase and failed in tsgo:core:test on src/agents/model-fallback.test.ts, which this PR does not touch:

src/agents/model-fallback.test.ts(1091,22): error TS2339: Property 'expectedReason' does not exist on type ...
src/agents/model-fallback.test.ts(1093,60): error TS2339: Property 'expectedReason' does not exist on type ...

Review Conversations

• I replied to or resolved every bot review conversation I addressed in this PR.
• I left unresolved only the conversations that still need reviewer or maintainer judgment.

Compatibility / Migration

• Backward compatible? Yes
• Config/env changes? No
• Migration needed? No
• If yes, exact upgrade steps: N/A

Risks and Mitigations

• Risk: proxy paths could stop loading Undici too early.
  • Mitigation: proxy fetch and env proxy dispatcher tests assert lazy creation still loads and uses the expected Undici agents.
• Risk: direct guarded fetches could lose timeout propagation.
  • Mitigation: guarded fetch tests still assert the timeout bridge is inherited by direct guarded dispatchers.