- Calls should be boring: complex decisions happen above; call args/object fields are names, literals, or simple property reads.

- Prefer early returns over nested condition pyramids. Split code into gather -> normalize -> decide -> act.

- Use named intermediates only for domain meaning or readability; avoid temp-variable soup.

- Code size matters. Prefer small clear code; maintainability includes not growing LOC without payoff.

- Refactors should delete about as much local complexity as they add. If LOC grows, the new ownership/API needs to clearly pay for it.

- Before adding helpers/files, check whether existing code can absorb the behavior with less new surface.

- Keep APIs narrow: export only current caller needs; keep types/helpers local by default.

- Return the smallest useful shape. Avoid broad result objects, flags, metadata unless callers use them.

- Avoid adapter layers that only rename fields. Move real responsibility or leave code local.

- Inline simple one-use objects/spreads when clearer. Extract only when it removes duplication or hard logic.

- Tests prove behavior/regressions, not every internal branch.

- For non-trivial refactors, check `git diff --numstat` before closeout. If LOC grew, trim or explain why.

- Dynamic import: no static+dynamic import for same prod module. Use `*.runtime.ts` lazy boundary. After edits: `pnpm build`; check `[INEFFECTIVE_DYNAMIC_IMPORT]`.

- Cycles: keep `pnpm check:import-cycles` + architecture/madge green.

- Classes: no prototype mixins/mutations. Prefer inheritance/composition. Tests prefer per-instance stubs.