# Fixture conventions

Fixtures are immutable inputs grouped by the verifier that owns their format. Use descriptive lowercase directory names and commit expected outputs beside inputs when exact bytes matter. A fixture directory must contain a `fixture.toml` with `schema`, `case`, and `expected` fields; paths in that file are relative to its directory.

Positive and negative cases remain separate. Negative cases name the rejected condition and assert the stable error category, not incidental wording. Physical and failure fixtures also record the verification level, durable checkpoint, and exact identity fields under test. Generated, downloaded, host-specific, credential-bearing, and mutable runtime data are not fixtures.

Tests must copy writable inputs to a test-owned temporary directory and remove it on success or failure. Retained corpus updates are reviewed as input changes; tests never rewrite committed expected output.