When code maps or normalizes external identifiers (tool names, locale tags, etc.), it must preserve the identifier’s real semantics and use canonical names. **Standards** - **Use canonical forms for identifiers and fixtures**: if an external system uses a specific naming pattern, mirror that pattern in tests/fixtures (e.g., `mcp____`), and only transform for *display* when needed. - **Avoid incorrect “helpful” aliasing**: alias maps (e.g., locale tag normalization) must reflect the true meaning of each tag. Do not silently route unrelated tags to the wrong category. - **Make normalization explicitly semantic-safe**: if normalization changes representation, document and enforce that it does not change semantics (unless the mapping is correct). - **Add regression tests for the canonical input**: ensure tests include the real/canonical external identifiers so the behavior matches production naming. **Example pattern (display-only normalization)** ```ts // Canonical external identifier (real MCP name) type McpToolName = 'mcp__filesystem__write_file' function displayTitle(toolName: McpToolName): string { // Safe display-only transformation; semantics preserved if (toolName === 'mcp__filesystem__write_file') return 'write_file' return toolName } ``` **Example anti-pattern (semantic-unsafe aliasing)** ```ts // ❌ Incorrect: Belarusian/Ukrainian/Kazakh tags mapped to Russian UI const LOCALE_ALIASES: Record = { be: 'ru', uk: 'ru', kk: 'ru' } // Fix by removing/correcting those mappings. ```