Nix Processor

File: src/processors/nix.py

Priority: 48

Name: nix

Summarize Nix build and store-transfer output with counts while retaining recognized diagnostics and plan summaries.

Supported commands

nix build, nix develop, nix run, nix eval, nix shell, nix flake subcommands, nix-build, nix-shell, and nix-env.

What it keeps

Keeps recognized plan summaries, warnings, errors, hints, and nonempty lines that do not match build or transfer noise.

What it drops or summarizes

Counts derivation builds, copied paths, fetch operations, and standalone store paths. Individual store paths can therefore be omitted from long output. Output with 15 lines or fewer passes through unchanged.

Example

Input: 16 building '/nix/store/example.drv' lines followed by error: build failed.

Processor output:

error: build failed
[16 derivations built]

Configuration and failure handling

This processor has no dedicated configuration keys. Global engine thresholds still apply. It handles non-zero exits and has a representative failure fixture in the precision tests. These fixtures cover known output shapes, not every possible tool version.

See the FAQ for error-preservation limits, or return to the processor reference.