docs: document git2 automated context binding in design and instructions

design.md

@@ -152,4 +152,7 @@ To trace binary provenances during rapid deployment cycles, all binaries embed d
 ## 16. Testing Architecture (Native Rust E2E)
 Historically, the project relied on a complex Python testing suite (\pytest\ + \mcp_client.py\) to validate the server over HTTP/SSE. This has been fully deprecated in favor of **Native Rust End-to-End Testing**.
 *   **Unit Tests:** Handlers and business logic are tested directly inside \server/src/handlers.rs\ using native \	okio::test\ constructs.
-*   **E2E Tests:** Integration and full-system tests run via \stub/tests/e2e.rs\ and \win-nvim/tests/integration_test.rs\, ensuring type safety, faster execution, and eliminating Python environment dependencies.
+*   **E2E Tests:** Integration and full-system tests run via \stub/tests/e2e.rs\ and \win-nvim/tests/integration_test.rs\, ensuring type safety, faster execution, and eliminating Python environment dependencies.
+## 17. Automated Git Context Binding (git2)
+Instead of forcing the LLM client to manually run `git rev-parse HEAD` and pass `git_branch` / `git_commit` arguments for every single code change, the server integrates the native **`git2`** C bindings. 
+When engineering endpoints (`log_code_change`, `log_error_fix`, `log_tech_debt`) are invoked, the server asynchronously discovers the surrounding Git repository, peels the HEAD reference, and automatically injects the current commit hash, commit message, and branch name directly into the stored entities and audit logs. This guarantees airtight VCS traceability without wasting LLM tokens or relying on the agent's memory.