Emit Claude Code plugin hint at module load time

[johno-stripe]

Why?

Claude Code supports a plugin hint protocol: if an SDK writes a specific XML tag to stderr at import time, Claude Code picks it up and loads the associated plugin automatically. Adding this hint to stripe-python means any user running Claude Code against Python code that imports stripe will get the Stripe plugin loaded without any manual setup.

What?

• Adds _claude_code_hint() and _emit_claude_code_hint() to stripe/_util.py. Both are internal and not re-exported from the package.
• Calls _emit_claude_code_hint() from stripe/__init__.py at module load time, just before the generated section. Gated on CLAUDECODE or CLAUDE_CODE_CHILD_SESSION being set, wrapped in try/except so it can never raise.
• Adds TestEmitClaudeCodeHint to tests/test_util.py with three cases: emits on CLAUDECODE, emits on CLAUDE_CODE_CHILD_SESSION, silent when neither is set.
• Updates assert_output in tests/test_exports.py to strip the hint line from stderr before asserting it's clean, so existing import tests pass whether or not Claude env vars are set in the outer process (for example, if a Stripe is editing this SDK using Claude Code).

See Also

• Claude Code plugin hints docs
• Symmetric change in stripe-node: Emit Claude Code plugin hint at module load time stripe-node#2805

Changelog

• Emits new Claude Code plugin hint when CLAUDECODE or CLAUDE_CODE_CHILD_SESSION environment variables are detected.