[Bug][http-proxy][0.2.1-alpha.2] A blank proxy variable makes every Node child connect directly while the host proxies

[heaven999b]

中文摘要：用户环境里某个代理变量“已设置但为空”（如 http_proxy= 与 HTTP_PROXY=http://proxy 并存，或 HTTPS_PROXY=）时，proxyEnvironmentForChild() 把空串当作用户值透传，并因此撤掉 NODE_USE_ENV_PROXY，MCP stdio server、子 agent 等 Node 子进程静默直连；修复为空白值按未设置处理。

Summary

With a proxy exported and one proxy variable exported but empty, the host process proxies correctly, but every Node child spawned through scrubbedParentEnv() connects directly, with no diagnostic. Examples of the second variable: http_proxy= beside HTTP_PROXY=http://proxy:8080, or HTTPS_PROXY= beside HTTP_PROXY. Those children include stdio MCP servers, subagent CLIs, and any other dsh-subprocess spawn. On a network that only allows egress through the proxy, those children fail to reach the network, or reach it around a corporate proxy.

The package documents the opposite: README L50 says the policy reads the variables "with a blank value treated as unset". readEnv does exactly that for this process, but the child-environment overlay does not.

Shells often leave such empty exports behind, for example export http_proxy=$CORP_PROXY with the variable unset, or a proxy toggle that clears only one casing.

Environment

• dsh 0.2.1-alpha.2, source checkout at d743267388 (current master)
• macOS 14.4.1 arm64, Node v24.11.1. Any Node with NODE_USE_ENV_PROXY support (22.21+, 24+) behaves the same.
• Reproduces in a fresh session. On Windows the http_proxy=/HTTP_PROXY pair folds into one variable, but HTTPS_PROXY= alone reproduces there too.

Reproduction

export HTTP_PROXY=http://127.0.0.1:3128   # any reachable HTTP proxy
export HTTPS_PROXY=                       # exported but empty
dsh --profile headless "…"                # any task that starts a stdio MCP server

The host's own requests go through the proxy, but each child environment contains HTTPS_PROXY= and no NODE_USE_ENV_PROXY, so the MCP server connects directly. The same happens with http_proxy= plus HTTP_PROXY=http://127.0.0.1:3128.

As a unit test, the case added to packages/util/http-proxy/tests/install.spec.ts:

for (const exported of [{ http_proxy: '', HTTP_PROXY: proxyUrl }, { HTTP_PROXY: proxyUrl, HTTPS_PROXY: ' ' }]) {
  await withCleanProxyEnv(async () => {
    Object.assign(process.env, exported)
    const { dispose } = await install(env(exported))
    try {
      expect(proxyEnvironmentForChild().NODE_USE_ENV_PROXY).toBe('1')
    } finally {
      await dispose()
    }
  })
}

On d743267388 it fails with expected undefined to be '1'. A spawned node -e "http.get('http://origin.test/')" with the overlay applied never reaches the proxy, while the parent's proxyRouteFor() reports proxied: true.

Root cause

install.ts L271-L277:

const named = field !== 'noProxy' && names.some(name => inherited[name] !== undefined)
for (const name of names) overlay[name] = named ? inherited[name] : resolved
// …
if (parsedByNode.some(name => overlay[name] !== undefined && !isSupportedProxyUrl(overlay[name]))) {
  delete overlay.NODE_USE_ENV_PROXY
}

inherited is the snapshot of what the user exported. An empty string is !== undefined, so it claims the scheme and is copied to the child verbatim. isSupportedProxyUrl('') is false, so the refused-value guard intended for SOCKS URLs kept for curl then withholds NODE_USE_ENV_PROXY, and a child Node ignores every proxy variable. In the http_proxy= case, the empty lowercase name would also shadow the uppercase one for tools that read lowercase first.

Fix

Branch: heaven999b/deepseek-harness@fix/http-proxy-blank-env (compare with master) (one commit, fix(http-proxy): treat blank proxy variables as unset for children).

• packages/util/http-proxy/src/install.ts: read inherited names the way resolution does. A blank (whitespace-only) value is unset: it no longer claims its scheme, and the blank name is removed from the child (undefined in the overlay). The child receives the other casing's value when the user set one; otherwise it receives the resolved value, the same as a scheme named in neither casing. The flag stays. Non-blank values still pass through exactly as written, and refused values such as SOCKS URLs still withhold the flag.
• JSDoc for proxyEnvironmentForChild() and README / README.zh (+ i18n record): state that blank values are unset for children too.
• tests/install.spec.ts: a regression case for both shapes, with assertions that hold whether or not the platform folds the two casings.

Verification

• New test fails on d743267388 (expected undefined to be '1') and passes with the fix.
• vitest run packages/util/http-proxy/tests --coverage --coverage.include='packages/util/http-proxy/src/**/*.ts': 3 files, 90 tests passed; every src file at 100% statements/branches/functions/lines.
• vitest run packages/subprocess/subprocess/tests/egress.spec.ts (the scrubbedParentEnv() consumer): 5/5 passed.
• tsc -b packages/util/http-proxy/tsconfig.json and tsc -b tsconfig.host.json (includes the specs): clean. Staged oxlint, verify-translation-pairing, verify-md-wrap and git diff --check: pass.
• An end-to-end repro (a real child node process with the overlay applied; run on 5badb15009, and install.ts / policy.ts are unchanged in d743267388) now reaches the fake proxy in both scenarios: child http status 200; proxy saw=["GET http://origin.test/a"]. Before the fix, the proxy saw nothing.

Related

• [Windows] Case-duplicate proxy variables in the child environment break PowerShell Env: provider #6426 / dsh help me find some bugs about itself #7055: Windows case-duplicate proxy variables in the child environment. Different defect, same overlay.
• [bug][http-proxy] 导出给子进程的 NO_PROXY 携带方括号条目 [::1],Python httpx 直接拒收整个变量(0.1.5-rc.1 复现) #6098 / [Bug] dsh-http-proxy 把 undici 专用的 `[::1]` 写进通用 NO_PROXY，Python httpx 等非 Node 子进程直接构不出 client #8056 / Bug: `[::1]` in child `NO_PROXY` breaks Python/httpx before any request #8410: bracketed [::1] in the child NO_PROXY. Different defect, same overlay.
• [feat request] 主进程launch时自注入NODE_USE_ENV_PROXY,使得llm-pi-ai可以走代理端口 #1171: original request for NODE_USE_ENV_PROXY in children.

[PerryLink]

这条成立，而且因果链可以一句话读完 —— 只依赖 packages/util/http-proxy 里的两个文件。你三处引用全部逐字命中（这是我这批里见过最干净的一份报告）。

1. 一条成文契约，被父进程遵守、被子进程违反

契约在 packages/util/http-proxy/README.md:50（你引的 L50 逐字命中）：

http_proxy, https_proxy, no_proxy, and all_proxy, lowercase first and uppercase as the fallback, with a blank value treated as unset.

主进程侧确实按它实现了 —— packages/util/http-proxy/src/policy.ts:109-118：

for (const name of [lower, lower.toUpperCase()]) {
  const value = env.get(name)?.value.trim()
  if (value !== undefined && value !== '') return { value, name }
}
return undefined

.trim() + !== '' ⇒ 空白视为未设置。

但子进程侧只判 undefined —— packages/util/http-proxy/src/install.ts:271-272：

const named = field !== 'noProxy' && names.some(name => inherited[name] !== undefined)
for (const name of names) overlay[name] = named ? inherited[name] : resolved

空串 !== undefined ⇒ named = true ⇒ 空串被原样透传。输入来自 snapshotProxyEnv()（:99-105，直接取 process.env[name]），而 :80-81 的 inheritedProxyEnv = previousInherited ?? snapshotProxyEnv()。

2. 二次伤害：空串把 NODE_USE_ENV_PROXY 撤掉了

install.ts:274-277（你引的这段逐字命中）：

const parsedByNode = [...POLICY_ENV_NAMES.httpProxy, ...POLICY_ENV_NAMES.httpsProxy]
if (parsedByNode.some(name => overlay[name] !== undefined && !isSupportedProxyUrl(overlay[name]))) {
  delete overlay.NODE_USE_ENV_PROXY
}

而 :266 的初值是 { NODE_USE_ENV_PROXY: '1' }；policy.ts:180-183 的 isSupportedProxyUrl 用 URL.parse ⇒ isSupportedProxyUrl('') === false、(' ') === false。

⇒ 空串触发了原本为 SOCKS 保留的守卫（其正当理由见 install.ts:250-254 的注释），于是那面旗被 delete。子进程里：既带着空白的代理变量、又没有了让 Node 去读代理变量的开关 ⇒ Node 完全不读代理变量，静默直连、无任何诊断。

3. ⭐ 一条你没点破、但决定修法位置的细节

applyPolicyEnv（install.ts:79-92）在 writeProxyEnv 之前做快照 ⇒ 被记住的是用户原始态（含空串），而不是 policy 回写后的值。

这正是 bug 的成因，也决定了修复必须落在「读取侧」（把空白按未设置处理），而不能落在「写入侧」（policy 已经写对了）。这条建议写进你的 Fix 段落，否则容易被理解成"再规范化一遍".

4. 你的 Windows 限定是对的，而且理由比你说的更硬

你写"On Windows the http_proxy=/HTTP_PROXY pair folds into one variable, but HTTPS_PROXY= alone reproduces there too"——

install.ts:114-116 的注释明说 Windows 折叠环境变量名的大小写，而 process.env 在 Windows 上本身就是大小写不敏感的 ⇒ 那两个名字在 Windows 真的是同一个变量，不可能一个空一个有值。

⇒ 跨平台可复现形态应写成单个名字空白，例如 HTTPS_PROXY=（或 https_proxy=）。建议在报告里保留你这个限定，别改成 POSIX 式的成对写法，否则 Windows 复现不出来。

5. 一处措辞建议

你写"the host process proxies correctly"。在 HTTPS_PROXY= 且无其它 HTTPS 来源时，resolveScheme 的回退链会让 HTTPS 落到 HTTP 代理（README:50 的 "HTTPS falls back to the HTTP proxy last"）—— 那种配置下父子都不代理 https，不是"父代理、子直连"。

要让你的叙事严格成立，用你给的两个例子（HTTP_PROXY=<url> + 另一个 scheme 名为空白）就对了。建议把这句收窄成"父进程按契约忽略了空白值"，更准也更难被挑。

6. 最小修复（单一函数内）

在 proxyEnvironmentForChild() 里用与 readEnv 相同的方式读 inherited：

• 值先 .trim()，空串视为未设置 ⇒ 不 claim 该 scheme，且在 overlay 里置 undefined（让 subprocess 侧把它从子进程 env 里删掉）
• 非空值仍原样透传（保住"SOCKS 留给 curl"的设计意图）
• 被拒的值仍然撤旗（那面旗的原有理由不变）

packages/subprocess/subprocess/src/index.ts:66-79 的 scrubbedParentEnv() 已经处理了 undefined 的删除语义（Reflect.deleteProperty），所以置 undefined 就能生效。

7. 验证口径

• 新用例断言 proxyEnvironmentForChild().NODE_USE_ENV_PROXY === '1'（复用 tests/install.spec.ts:66-68 的 env() 与 :85-96 的 withCleanProxyEnv()）
• 既有约定可对照：tests/install.spec.ts:303 expect(child.NODE_USE_ENV_PROXY).toBe('1')、:311/:323 的 'withholds NODE_USE_ENV_PROXY when the child receives %s…'、:284 的 SOCKS 场景
• 再用 packages/subprocess/subprocess/tests/egress.spec.ts 或真实子进程确认确实路由到假代理

8. 用户侧 workaround（零改码，今天可用）

别留空的代理变量 —— unset HTTPS_PROXY https_proxy http_proxy no_proxy，或把空的那些也显式设成同一个代理 URL。启动 dsh 前 env | grep -i proxy 自查一遍。

9. 版本

你标 0.2.1-alpha.2 / d743267388 —— 我复核了 git rev-list --count d743267388..origin/master = 0，你标的就是当前 origin/master。所以这帖不存在"先升级再复现"的空间，上述每一处都是最新代码。