MCP Rigor file extension

MCP Rigor plain-language tests use:

.mcpr

Examples:

smoke.mcpr
customer-regression.mcpr
transport-parity.mcpr

Why not .mcp?

The .mcp suffix predates Model Context Protocol and is already associated with other software, including Metrowerks CodeWarrior project files. Reusing it would create ambiguous editor, operating-system, MIME, and tooling associations.

MCP Rigor therefore uses the product-specific .mcpr suffix: MCP Rigor.

References checked during the decision:

• FileInfo: MCP file extension
• ReviverSoft file-extension registry

File-extension registries are not global standards authorities, but existing use is sufficient reason to avoid the collision.

Migration

Rename files without changing their contents:

mv tests/smoke.mcp tests/smoke.mcpr
mv tests/shared-flows.mcp tests/shared-flows.mcpr

Update flow imports:

Import flows from "./shared-flows.mcpr"

Update scripts and CI:

mcprigor check tests/smoke.mcpr
mcprigor test tests/smoke.mcpr

MCP Rigor now rejects .mcp files with an actionable rename message. YAML and JSON suite support is unchanged.