[BUG] 1M context unavailable in corporate proxy environment

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

1M context (opus[1m]) is unavailable in a corporate proxy environment with a valid Max 20x subscription. Since v2.1.75, 1M context is enabled by default for Max, Team, and Enterprise plans. Despite this, the feature remains inaccessible behind a corporate proxy.

Observed behavior:

• Home network (no proxy): Removing CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC and DISABLE_TELEMETRY → cachedGrowthBookFeatures in ~/.claude.json populated → opus[1m] works immediately
• Corporate proxy: Same changes → cachedGrowthBookFeatures stays null → opus[1m] still unavailable

Network verification via curl:

| Domain | Via proxy | Direct (no proxy) |
|---|---|---|
| api.anthropic.com | OK (404) | Blocked (000) |
| cdn.growthbook.io | OK (200) | Blocked (000) |
| statsig.anthropic.com | 403 | Blocked (000) |

cdn.growthbook.io is reachable through the proxy, but Claude Code fails to fetch feature flags. This suggests that GrowthBook requests may not be routed through the configured HTTPS_PROXY.

What Should Happen?

Feature flag requests (GrowthBook, Statsig) should respect HTTPS_PROXY / HTTP_PROXY environment variables, consistent with how the Anthropic API SDK handles proxy configuration.

Error Messages/Logs

❯ /model opus[1m]
  ⎿  Opus 4.6 with 1M context is not available for your account. Learn more: https://code.claude.com/docs/en/model-config#extended-context-with-1m

❯ cat ~/.claude.json | jq '.cachedGrowthBookFeatures'
null

Steps to Reproduce

1. Set up a corporate proxy environment where direct outbound connections are blocked
2. Configure HTTPS_PROXY in ~/.claude/settings.json (API calls to api.anthropic.com work correctly)
3. Remove CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC and DISABLE_TELEMETRY from environment
4. Restart Claude Code in a new terminal session
5. Run /model opus[1m]
6. Observe error: "Opus 4.6 with 1M context is not available for your account"
7. Verify: cat ~/.claude.json | jq '.cachedGrowthBookFeatures' returns null

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.76 (Claude Code

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

cdn.growthbook.io and statsig.anthropic.com are not listed in the enterprise network configuration allow-list, making it difficult for IT teams to configure correctly.

Related issues:

• #11220 — Statsig SDK not respecting HTTPS_PROXY
• #15212 — Claude Code intermittently ignores HTTP_PROXY on startup
• #29015 — GrowthBook feature flag restrictive defaults when unreachable
• #33119 — DISABLE_NONESSENTIAL_TRAFFIC silently disables GrowthBook evaluation
• #28777 — Stale Statsig cache workaround