code-style

Code style

Language

• Code, comments, identifiers, docstrings, commit messages: English.
• Agent rule files and briefs (.cursor/rules/*.mdc, .claude/rules/*.md, AGENTS.md, CLAUDE.md): English, unless the project owner asks otherwise; then switch every tree at once so the Rules Sync diff stays reviewable.
• User-facing product copy (the trip board, the user guide): Russian, following the microcopy rules in specs/05-interfeys.md.
• Chat replies to the user: Russian.

TypeScript

• Node >= 22.6, ESM only ("type": "module"). Relative imports carry the .ts extension; the toolchain runs TypeScript through Node's native type stripping, so only erasable syntax is allowed: no enum, no namespace, no parameter properties, no decorators. Use const objects with as const instead of enum.
• strict is on, together with noUncheckedIndexedAccess, exactOptionalPropertyTypes and verbatimModuleSyntax. Type-only imports use import type.
• any is forbidden and the linter enforces it. External payloads enter as unknown and are narrowed by an explicit parser in src/sources/. Everything downstream of that parser is a domain type.
• Prefer type aliases for data, discriminated unions over optional-field soup, and readonly arrays for anything crossing a module boundary.
• Named exports only; one clear responsibility per module. A file above roughly 300 lines is a signal to split, and a single file holding two thousand lines is an explicit reviewer complaint in specs/08-repozitoriy.md.

Errors and absence

• A missing field is undefined and stays visible as missing all the way to the UI. Never substitute a default, a guess or a web-search answer for data a source did not return. This is the product's core promise, not a style preference.
• Throw typed errors carrying the source name and the arguments that failed (class SourceError extends Error), not bare strings.
• Optional enrichment never throws outward: it resolves to undefined after its timeout and the caller renders the absence.