soldr 0.7.0

Instant tools. Instant builds. One command.

soldr

Instant tools. Instant builds. One command.

soldr = crgx + zccache in a single tool.

In soldering, flux removes the oxide so the joint bonds clean. soldr removes the friction between you and your build: no waiting for tool installs, no waiting for recompilation.

The point of soldr is not to invent some brand-new primitive. The point is to combine the pieces that already work into one tool that people can actually rely on every day.

zccache is already excellent. crgx already proved the value of instant Rust tooling. soldr turns those into one front door:

• get the right Rust tool for the job
• get the right Windows ABI without thinking about it
• get transparent compilation caching without separate setup

That is the same reason uv is compelling. uv did not win because it invented packaging, virtual environments, or Python installation. It won because it made the whole workflow feel like one tool instead of a pile of separate ones.

soldr aims for the same outcome in the Rust toolchain world.

Current release line:

• 0.5.x is the secure front-door, tool-fetch, and built-in zccache-backed cache release line
• 1.0.0-rc remains reserved for broader release hardening and bootstrap validation
• the supported external integration boundary remains the soldr executable, not the internal Rust crates; see docs/API_BOUNDARY.md

Why soldr exists

On Windows, the real problem is not "how do I cache builds?" or "how do I download a tool binary?" in isolation.

The real problem is that the execution path is messy:

• the wrong cargo can win on PATH
• the wrong Windows target can get selected
• GNU can leak in where MSVC should have been used
• users end up debugging their toolchain instead of shipping code

soldr exists to make that path boring.

When you run soldr, the tool should do the obvious thing:

• pick MSVC on Windows by default
• fetch the tool you asked for
• cache it locally
• fetch and manage zccache so Rust builds get transparent caching without manual wrapper setup

If soldr solves that one problem well, it becomes a super tool: the command you reach for first, because it makes the rest of the stack behave.

• Tool acquisition (the crgx half): Need maturin, cargo-dylint, or any crate binary? soldr fetches a pre-built binary from GitHub Releases in seconds. No cargo install from source. Cached locally for instant reuse. On 0.5.x, this is still an upstream trust decision rather than a repo-side trust guarantee; see docs/TRUST_BOUNDARIES.md.

• Compilation caching (the zccache half): soldr cargo ... now fetches and manages a pinned zccache release for Rust builds. soldr owns the zccache daemon/session wiring; zccache's artifact store still uses its current default cache root.

# Build through soldr's front door:
soldr cargo build --release
soldr cargo test
soldr --no-cache cargo test

# Fetch and run any Rust tool instantly:
soldr maturin build --release
soldr cargo-dylint check
soldr rustfmt src/main.rs

How it works

soldr cargo build --release
  +-- resolve the real cargo binary
  +-- fetch/start managed zccache when cache is enabled
  +-- set soldr as the compiler wrapper for this build
  +-- have soldr wrapper mode delegate to managed zccache
  +-- delegate to cargo with your existing flags

soldr maturin build --release
  +-- maturin cached? --> run instantly
  +-- not cached?     --> download pre-built binary (2s) --> run

Design goals

• One obvious command: Fetch tools, pick the right Windows target, and run through managed zccache through the same entry point.
• Front-door builds: soldr cargo ... is the primary build UX.
• Invisible caching: soldr cargo ... uses a soldr-managed zccache by default, with soldr --no-cache cargo ... as the opt-out.
• Real cache controls: soldr status, soldr cache, and soldr clean report and manage the soldr-managed zccache state instead of placeholder behavior.
• One cache boundary, eventually: soldr keeps its own tools and zccache session state in ~/.soldr/. Current zccache artifacts still live in zccache's default cache root until upstream exposes a supported cache-dir override.
• Pre-built first: Download a pre-built binary before compiling from source. Fall back gracefully.
• Cargo-compatible: soldr preserves normal cargo arguments instead of forcing a separate workflow.
• Cross-platform: Linux, macOS, Windows (x86_64 + aarch64).
• MSVC by default on Windows: Always targets x86_64-pc-windows-msvc (or aarch64-pc-windows-msvc) unless the active project explicitly selects another target in .cargo/config.toml, .cargo/config, or rust-toolchain.toml. MSVC links against vcruntime140.dll which ships with every modern Windows install. The GNU target requires shipping libgcc_s_seh-1.dll and libwinpthread-1.dll with every binary, which is extra baggage for no benefit. This matches the Rust ecosystem default: rustup, cargo-binstall, and nearly all published release binaries target MSVC. crgx gets this wrong by baking the target at compile time, causing it to look for GNU binaries when compiled under MSYS2.

Architecture

soldr/
|-- crates/
|   |-- soldr-core/      # Shared types, config, cache directory layout
|   |-- soldr-fetch/     # Binary resolution + download (the crgx half)
|   |-- soldr-cache/     # Compilation caching (the zccache half)
|   `-- soldr-cli/       # CLI entry point + wrapper mode
|-- src/soldr/           # Python package (maturin bin bindings)
`-- tests/

Crate	Role
soldr-core	Cache paths, config, version types
soldr-fetch	Resolve crate binaries from crates.io metadata and GitHub Releases. Download and cache.
soldr-cache	zccache integration helpers, cache policy, session plumbing.
soldr-cli	Mode detection, cargo front door, built-in commands (status, clean, config, cache), tool fetch dispatch.

These workspace crates are implementation details. They are not a supported public Rust library API.

Prior art

Built on lessons from:

• zccache - 2.4x faster warm builds than sccache (benchmark)
• crgx - the npx of Rust, instant tool execution
• cargo-binstall - pre-built binary resolution
• sccache - the original Rust compilation cache

Security And Verification

• SECURITY.md describes the current hardening posture and release policy.
• docs/API_BOUNDARY.md defines the supported machine-facing integration boundary.
• docs/PYPI_TRUSTED_PUBLISHING.md describes the optional Trusted Publishing path for hardened PyPI wheels.
• RELEASE.md documents the intended maximum-security release setup and owner workflow.
• docs/RELEASE_VERIFICATION.md explains how to verify published release artifacts.
• docs/TRUST_BOUNDARIES.md inventories the external systems and artifacts soldr currently trusts, including the current 0.5.x limits of runtime fetched-binary trust.

License

BSD-3-Clause