Corvint 0.5.0a4

Corvint 0.5.0a4 repairs OpenCode MCP initialization and improves automatic file-change handling.

• Core and test-validity MCP servers now support OpenCode's initialization handshake through --protocol-version 2025-11-25. All Corvint MCP servers retain MCP 2026-07-28 as their default.
• The OpenCode plugin provides task context and explicit outcomes alongside MCP status, query, tracked-Go impact and retained-test-evidence tools. An on-demand Corvint skill explains tool selection.
• Automatic events use the existing 2,000 ms limit by default and include the actual deadline in timeout diagnostics. Successful receipts can still report FALLBACK when frontier evidence is unavailable.
• Release checks now use the correct planning branch and roadmap interactions. The gate ledger hashes actual worktree content without trusting cached index timestamps.

Upgrade the separately installed MCP executables and OpenCode plugin as well as the core CLI. This release publishes four core CLI archives. The optional companion bundle is omitted because its installed console-browser qualification timed out; build the MCP executables and install the plugin from the tagged source. See integrations/opencode/README.md and mcp.example.json for the explicit compatibility configuration.

Developer preview: native OpenCode support remains FALLBACK, missing test evidence remains unsupported, and MCP repository roots retain their documented .git directory requirement. The unavailable reported work project has not been verified. This is an unsigned prerelease with publisher identity NOT_VERIFIED.