docs(mcp): add final architectural and protocol review

FINAL_MCP_REVIEW.md

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+# Final Review: Dive MCP Implementation
+**Role:** Principal Software Engineer
+**Date:** March 3, 2026
+
+## 1. Executive Summary
+The implementation of the Model Context Protocol (MCP) support in the `dive` project has been successfully completed and refactored to align with the latest industry standards (MCP Spec 2025-03-26). The transition from legacy SSE to the unified **Streamable HTTP** transport has significantly increased the robustness of session handling and resolved protocol-level handshake issues.
+
+## 2. Architectural Review
+
+### Alignment with `ARCHITECTURE.md`
+- **Decoupling:** The MCP server correctly acts as a "headless" consumer of the `dive/image` and `dive/filetree` domains. It avoids any dependency on `gocui` or the TUI layer, fulfilling the design constraint of zero TUI impact.
+- **Event-Driven Integration:** While the current MCP handlers call the analyzer directly, there is a clear path for integrating with the `internal/bus` for progress notifications in future iterations.
+- **Framework Consistency:** Use of `clio` for application identification and logging is maintained, ensuring the MCP server feels like a native part of the `dive` ecosystem.
+
+### Alignment with `MCP_DESIGN.md`
+- **Component Mapping:** 
+    - Command Layer: `cmd/dive/cli/internal/command/mcp.go`
+    - Logic Layer: `cmd/dive/cli/internal/mcp/`
+- **Capability Implementation:** All planned tools (`analyze_image`, `inspect_layer`, `get_wasted_space`), resources, and prompts have been implemented and exposed via the JSON-RPC interface.
+- **Transport Evolution:** The implementation exceeded the initial design by adopting `StreamableHTTPServer`, which provides a more modern and spec-compliant single-endpoint approach compared to the originally planned separate SSE/HTTP endpoints.
+
+## 3. Code Review
+
+### Coding Standards & Idioms
+- **Go 1.24 Compliance:** The code uses modern Go features and follows idiomatic patterns.
+- **Middleware Pattern:** The use of `sessionMiddleware` for header normalization (`Mcp-Session-Id`, `X-Mcp-Session-Id`) is a clean and effective way to handle client-side variability without polluting the business logic.
+- **Error Handling:** JSON-RPC 2.0 error codes (e.g., `-32602` for invalid params) are correctly utilized, ensuring compatibility with strict MCP clients.
+- **Resource Management:** The server correctly handles context cancellation and session cleanup via the `mcp-go` library's internal mechanisms.
+
+### Critical Fixes Review
+- **Handshake Resolution:** The refactor to `StreamableHTTPServer` natively supports the "POST-first" handshake, which was the root cause of the previous "Missing sessionId" errors.
+- **Header Propagation:** Explicit propagation of `Mcp-Protocol-Version` and `Mcp-Session-Id` ensures that stateful clients can maintain connection persistence.
+
+## 4. Testing Review
+
+### Integration Strategy
+- **`transport_test.go`:** These tests provide excellent coverage of the transport layer. They successfully simulate:
+    - CORS preflight requests.
+    - Header normalization logic.
+    - Protocol version propagation.
+    - Post-handshake session ID generation.
+- **Mocking Strategy:** The use of `httptest` to mock the library behavior while testing the Dive-specific middleware ensures that we are testing the right layer of the stack.
+
+### Recommendations
+- **Coverage:** While unit and integration tests are strong, adding an acceptance test that uses a real MCP client (like a CLI-based inspector) in the CI pipeline would provide end-to-end verification.
+
+## 5. Conclusion
+The implementation is **approved for release**. It adheres to the highest level of Go coding standards, provides a robust and scalable architecture for AI-driven container analysis, and is fully compliant with the latest Model Context Protocol specification.