[brenorb]

When a configured .simf file cannot be parsed, simplex build currently warns and exits successfully. A malformed-only project publishes empty metadata; a mixed project publishes only its valid contracts. Callers therefore receive a false-green build result.

Propagate the source path and parser diagnostic as BuildError::SourceParse, so discovery fails before artifact generation. Every matched source must parse; valid helpers without main remain excluded. Existing artifacts stay intact when discovery fails.

Fixes #175.

Validation:

• Reproduced malformed-only and mixed-source false successes on upstream a1bf060 in fresh disposable projects.
• Added four real CLI regressions. Before the fix, the two malformed-source cases fail and both repaired/helper controls pass. After the fix, all four pass, including preservation of previous metadata and the absence of newly generated partial bindings.
• cargo test --locked --offline -p smplx-build -p smplx-cli: 50 tests pass.
• cargo clippy --locked --offline -p smplx-build -p smplx-cli --all-targets -- -D warnings, cargo fmt --all --check, and the build crate's --no-default-features check pass.
• Independent agent review found no blocking issue. Full workspace and fixture checks run in CI.

Written by Codex.

[Arvolear]

LGTM!