Vendor crates through fetchCargoVendor

[thedavidmeister]

Refs rainlanguage/rainix#377

What

cargoLock replaced by cargoDeps = fetchCargoVendor with the vendor hash. Same move rainix made for rainix-static and wasm-bindgen-cli.

Why

cargoLock fetches every crate from crates.io/api/v1/crates/<name>/<version>/download, which now answers 403 to any User-Agent starting with curl/, and nixpkgs fetchurl sends curl/<v> Nixpkgs/<v>. Every consumer that has to rebuild rain on a store miss (raindex git-clean on main, and every local devshell for rain.dia, rain.flare, rain.pyth, rain.merkle, rainlang, rainlang.deploy, rain.erc4626.words this weekend) fails with cannot download crate-<name>.tar.gz from any mirror. fetchCargoVendor downloads from the static.crates.io CDN, which has no User-Agent gate.

QA

• Discriminating tests: n/a, a packaging change with no Rust source change; the proof is the build itself.
• Mutations applied: n/a, no logic changed.
• Oracle: from a shell, the API download URL returns 403 for curl/8.11.1 Nixpkgs/25.11 and 302 for Nixpkgs/25.11; nix build .#rain on this branch fetched the vendor set and produced the binary on a host where the cargoLock path 403s.
• Category check: rainix#377 asks for rain-cli rebuilds to stop 403ing on crate fetches; covered for rain.cli. rainix itself already vendors through the CDN.

Local: nix build .#rain succeeds, vendor hash sha256-TrZzMmDnC07lhfjKdKfwNtrzbeRcxKewqTqmiZD2fic=. Consumers pick this up on their next flake.lock bump of the rain input.

🤖 Generated with Claude Code

https://claude.ai/code/session_01V8ViHcKLVk2YoS2joH4HdN

Summary by CodeRabbit

• Chores
  • Updated package dependency retrieval to use a more reliable source.
  • Added a fixed dependency vendor hash to improve reproducibility during builds.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Advanced

Run ID: e930e04b-6440-4d57-8c6b-db48ebbaa848

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Reviewing files that changed from the base of the PR and between 2481470 and 103ff2c.

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• flake.nix

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Walkthrough

The Nix package now vendors Rust dependencies with fetchCargoVendor and a fixed hash instead of using cargoLock.

Changes

Rust dependency vendoring

Layer / File(s)	Summary
Nix dependency source update flake.nix	Replaces cargoLock settings with pkgs.rustPlatform.fetchCargoVendor, using the package source, name, and fixed hash. Comments document the CDN selection.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 103ff

This packaging-only change switches dependency retrieval to the static crates.io CDN with fixed-output hashing; no concrete build or runtime failure is established.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main packaging change: using fetchCargoVendor to vendor the Rust crates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-09-14-fetch-cargo-vendor

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