MCP 2026-07-28 — published artifact activation readiness checkpoint

Date: 2026-10-20

Status: Production activation blocked. Evidence review only.

Verified published inputs

• Specification: final 2026-07-28, published MCP specification.
• Python SDK: stable mcp==2.2.0 from PyPI, consumed by kicad-mcp-pro==4.3.0 under the published dependency range mcp[cli]>=2.2.0,<3.0.0. This is the server SDK, not the Studio client runtime.
• npm protocol schemas: published @oaslananka/kicad-protocol-schemas@2.0.0, used in both Studio package manifests and the pnpm lockfile without bypassing the seven-day minimum release age.
• Server: published and signed PyPI kicad-mcp-pro==4.3.0, GitHub source tag mcp-server-v4.3.0 at 282c7499f67457bb247d2390379410f05e96a3e8. Both wheel and sdist passed independent PyPI publisher signature verification, SHA-256 comparison with the GitHub Release, and GitHub-signed CycloneDX SBOM attestation matching the source tag and workflow; recorded evidence.
• Published server final protocol: KiCad MCP Pro ADR-0006 and server issue #924 record native SDK v2 and the public 2026-07-28 contract. The retained 2026-07-28-rc server selector is an optional strict conformance profile, not the public protocol revision.

Exact-reviewed Studio acceptance

All PRs below were merged after required checks and confirmed successful on the exact merge SHA, not just a PR head:

Gate	Source review and evidence	Result
Published schema and final client envelope	PR #806	Passed
Negative tool/header contracts	PR #807, #808	Passed
Published mixed-peer VS Code Extension Host	PR #809	Passed
MRTR rejection, invalid discovery, HTTP failures and timeout	PR #810	Passed
Signed PyPI artifact provenance enforced in CI	PR #811	Passed
Published 2026 to 2025 isolated rollback and metadata/session isolation	PR #812	Passed
Published final GA on normal server protocol lane, strict canary, and 2025 fallback	PR #813, main@fb1170bdd3d7985ed8c4c3a118f511409ea8befc	Passed, 10/10 postmerge workflows

Final published server 4.3.0 completed the real Studio adapter/transport test with 24 tools in each of three lanes: normal final 2026 stateless, strict final 2026 canary stateless, and legacy 2025 session; each completed a read-only kicad_get_version call and refused an unknown tool. These tests use KICAD_MCP_STATEFUL_HTTP=0 for both 2026 lanes; they do not prove every default HTTP configuration is stateless or a VSIX release is ready.

Production cutover is still blocked

1. Studio adapter registry: the compiled final adapter is intentionally nonselectable; the product currently selects 2025-11-25. Production registration, full client integration and protected tests must happen in the coordinated activation change.
2. Version support promise: Studio still advertises >=3.5.2 <5.0.0 as a compatible MCP server range. That includes older servers without the published native 2026 contract. Do not activate final 2026 against this old range; either narrow the new active-protocol minimum to reviewed published 4.3.0, or implement and prove safe version-aware client negotiation before enabling it.
3. Production switch and rollback: isolated 2026-to-2025 Host recovery is proven, but the actual production adapter selection, default Studio extension lifecycle, protected cross-platform CI, and versioned product rollback/metadata are not yet accepted together.
4. Source versus published release: signing, extension VSIX packaging, support docs and Marketplace publication require a separate release decision after activation gates are complete. There was no release in the acceptance PR series.

compatibility.yaml continues to declare 2025-11-25 active and 2026-07-28 blocked; ADR 0008 remains Proposed. This record fills factual evidence fields without granting permission to turn on the final adapter. Keep issue #777 OPEN until the production cutover and release gates are independently passed.