setting_sources=["project"] still loads user-level ~/.claude/CLAUDE.md

Bug Description

When using the Claude Agent SDK with setting_sources=["project"], the user-level ~/.claude/CLAUDE.md is still loaded into the agent's context. According to the official documentation, only settingSources includes "user" should load ~/.claude/CLAUDE.md.

The docs state:

By default, the SDK loads no filesystem settings. Your agent runs in isolation mode with only what you pass programmatically.

And the loading table shows:

| Level | Location | When loaded |
|-------|----------|-------------|
| User | ~/.claude/CLAUDE.md | settingSources includes "user" |

Reproduction

from claude_agent_sdk import query, ClaudeAgentOptions

async for message in query(
    prompt="What instructions do you have from CLAUDE.md?",
    options=ClaudeAgentOptions(
        setting_sources=["project"],  # only project, NOT user
        tools=[],
        max_turns=1,
    ),
):
    ...

The agent responds with content from ~/.claude/CLAUDE.md, confirming it was loaded despite "user" not being in setting_sources.

Additionally, setting CLAUDE_CONFIG_DIR via the env parameter to redirect the config directory does not prevent loading of ~/.claude/CLAUDE.md either.

Expected Behavior

With setting_sources=["project"], only project-level CLAUDE.md (from <cwd>/.claude/CLAUDE.md) should be loaded. User-level ~/.claude/CLAUDE.md should NOT be loaded.

Environment

• claude-agent-sdk (Python): 0.1.56
• Claude Code CLI: 2.1.92
• OS: macOS (Darwin 25.2.0)
• Python: 3.12