Reduce deps

[soraxas]

This PR refactors the spz and spz-pywrapper crates:

• point spz-pywrapper/Cargo.toml to the spz crate in the same repo
• remove dependencies on anyhow and tokio, introduces a custom error type (SpzError), and cleans up the codebase to use more explicit error handling
• Removed unnecessary dependencies on anyhow, tokio, libc, rayon, and clap (probably got auto-pulled in with LLM due to your AGENTS.md? (as they are mentioned in the md, but never needed in the actual code base)
  • this reduce spz's deps from ~91 to ~49 on my machine
• we don't need to pull the whole async runtime tokio setup (as there's also multiple runtime exists out there); we only need the trait to support async reading

The arbitary derive is hidden behind feature as it's only needed for testing

[Jackneill]

• Thank you for the pull request.

---

1. Please resolve the merge conflicts first and pull in main.
2. bin/spz.rs has errors.
3. error handling: you left context out with thiserror when using the SpzError type, whereas with anyhow they were there. i see SpzError type has them, why not use them?
   1. example: thiserror doc .
4. ci has errors

[Copilot]

Pull request overview

This PR significantly reduces dependencies in the spz crate by removing anyhow, tokio, libc, rayon, clap, rustversion, and serde_json, reducing the total dependency count from ~91 to ~49. The changes introduce a custom error type (SpzError) for more explicit error handling, replace the full tokio async runtime with lightweight futures traits, and make the arbitrary dependency optional behind a fuzzing feature flag.

Key changes:

• Introduced custom SpzError type replacing anyhow::Error for explicit error handling
• Replaced tokio async runtime with futures traits for async I/O operations
• Made arbitrary dependency optional, controlled by the fuzzing feature
• Updated builder API to accept file path in load() method instead of storing it in the builder

Reviewed changes

Copilot reviewed 17 out of 18 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/spz/Cargo.toml	Removed unnecessary dependencies (anyhow, tokio, clap, rayon, libc, rustversion, serde_json); made arbitrary optional
crates/spz/src/errors.rs	Added custom SpzError enum with specific error variants
crates/spz/src/lib.rs	Exported SpzError in prelude
crates/spz/src/packed.rs	Migrated from anyhow to SpzError; added conditional arbitrary derives
crates/spz/src/unpacked.rs	Made arbitrary derive conditional on fuzzing feature
crates/spz/src/header.rs	Simplified error handling with SpzError
crates/spz/src/gaussian_splat.rs	Replaced tokio with futures traits; updated builder API to accept filepath in load()
crates/spz/src/coord.rs	Made arbitrary derive conditional on fuzzing feature
crates/spz/src/compression.rs	Migrated to SpzError with automatic io::Error conversion
crates/spz/src/mmap.rs	Updated error handling to use SpzError
crates/spz/tests/test.rs	Updated to use new builder API pattern
crates/spz/examples/load_spz.rs	Updated examples for new API and async patterns
crates/spz/benches/util/mod.rs	Removed async benchmark helper; updated for new API
crates/spz/benches/benchmarks/load.rs	Removed tokio-based async benchmark
crates/spz-pywrapper/Cargo.toml	Changed to use local path dependency instead of crates.io version
crates/spz-pywrapper/src/lib.rs	Updated module paths to match new spz crate structure
fuzz/Cargo.toml	Enabled fuzzing feature for spz dependency
Cargo.lock	Reflected removal of unnecessary transitive dependencies

---

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[Copilot]

The original error from Mmap::map() is being discarded here. This loses valuable information like the specific I/O error that occurred (e.g., permission denied, out of memory). Consider wrapping the io::Error or using a more specific error variant that preserves the underlying cause.

Suggested change

	Mmap::map(&infile).map_err(|_| {
	SpzError::LoadPackedError("unable to open file with mmap()".to_string())
	Mmap::map(&infile).map_err(|e| {
	SpzError::LoadPackedError(format!("unable to open file with mmap(): {e}"))

[Copilot]

The underlying I/O error from gzip decompression is being discarded. Since SpzError has an IoError variant with #[from], you should preserve the original error by using a different error variant that wraps io::Error or by adding more specific error types that can preserve the cause chain.

Suggested change

	crate::compression::gzip_to_bytes(data, &mut decompressed).map_err(|_| {
	SpzError::LoadPackedError("unable to decompress gzip data".to_string())
	})?;
	crate::compression::gzip_to_bytes(data, &mut decompressed)?;

[Copilot]

The specific SpzError from the try_into conversion is being discarded and replaced with a generic message. The underlying error likely contains useful details about why parsing failed (e.g., invalid magic number, unsupported version). Consider preserving the original error instead of discarding it.

Suggested change

	let packed: PackedGaussians = decompressed.try_into().map_err(|_| {
	SpzError::LoadPackedError(
	"unable to parse packed gaussian data".to_string(),
	)
	})?;
	let packed: PackedGaussians = decompressed.try_into()?;

[codacy-production]

Codacy found an issue: Method to_packed_gaussians has 125 lines of code (limit is 50)

[codacy-production]

Codacy found an issue: Method to_packed_gaussians has a cyclomatic complexity of 12 (limit is 8)

[codacy-production]

Codacy found an issue: Detected 'unsafe' usage, please audit for secure usage