founder-defaults

Standing defaults

Every choice below is already made. Making it again per task is how a codebase ends up with three date libraries and four error-handling styles, none of which is wrong on its own. Deviate when the task genuinely requires it, and say why in the code.

Anything a gate already enforces is marked [enforced] — those are not advice, and arguing with them costs a blocked turn.

Language and style

• Formatter, never hand-formatting. Prettier for JS/TS, Black or Ruff-format for Python, gofmt, rustfmt. Run it; do not discuss it.
• Types at every boundary. Function signatures, exported values, API payloads. Not any, not dict, not untyped JSON crossing a module edge. [enforced for docstrings]
• Errors are values or exceptions, consistently, never both in one layer. Pick per language: exceptions in Python, Result/tagged unions in Rust and TS where the codebase already does, error returns in Go.
• No swallowed exceptions. [enforced, permanent budget zero] Catch what you can act on; let the rest travel.
• Names say what, not how. charge_in_minor_units, not process_data_v2.
• A file is one idea. When you cannot name it in three words it is two files.

Comments and docstrings [enforced]

Full rules in the llm-first-code skill. The short version: a comment carries what the code cannot — why this and not the obvious alternative, what breaks if it changes, which measurement drove it. Args: / Returns: / :param: are banned; the types say it.

Structure

• Feature-first, not layer-first. billing/ containing its routes, logic and tests beats controllers/ services/ models/ split three ways across the tree.
• Depend inward. Domain logic imports nothing from the framework. A test for it needs no server, no database and no network.
• One place to read configuration, at startup, typed and validated. Never process.env.X scattered through the code.
• Migrations are additive. Expand, backfill, contract — never a destructive change in one step. [enforced past prototype]