pi-python v0.4.0

Added

• Phase 6 (git context): pi_agent_cli injects a bounded, read-only <git_status> block into the system prompt on every turn. Disable with [git] enabled = false or headless --no-git-context. Non-repos, timeouts, and git failures omit the section. MCP stays out of the product path; callers still adapt langchain-mcp-adapters tools with from_langchain_tool().
• Provider matrix: opt-in live tests for OpenAI, Anthropic, DeepSeek, and SiliconFlow (pytest -m real_llm pi_agent_core/tests/test_provider_matrix.py). Manual workflow .github/workflows/provider-matrix.yml (workflow_dispatch only; missing secrets skip).
• Phase 7 extension packages are built and published with the release: pi-web-access-py, pi-goal-x-py, pi-dynamic-workflows-py. CI and the pre-release test job install all three.

Changed

• pi-agent-core-lc, pi-agent-harness-lc, and pi-agent-cli-lc are version 0.4.0.