fix(nix): parse Nix versions that omit the patch component

[mikeland73]

Summary

Fixes #2766.

Some Nix builds report a two-component version followed directly by a prerelease, e.g. nix (Nix) 2.33pre20251107_479b6b73 (note: 2.33pre…, not 2.33.0pre…). versionRegexp required a full major.minor.patch triple, so it failed to match these strings. Info.Version was then left empty and Devbox aborted every command with a confusing error where the version renders as empty:

Error: Devbox requires nix of version >= 2.12.0. Your version is . Please upgrade nix and try again.

Fix

• Make the patch component optional in versionRegexp.
• Normalize the parsed version by inserting a .0 patch when Nix omits it, so 2.33pre20251107_479b6b73 becomes 2.33.0pre20251107_479b6b73 (and a bare 2.33 becomes 2.33.0).

The normalization is necessary because a patch component is required for the version to be comparable as a semver — both directly and via AtLeast's prerelease coercion. Without it, AtLeast would coerce the version to 2.33-pre.20251107+479b6b73, which is not a valid semver (a prerelease requires a patch), so AtLeast(2.12.0) would still return false and the version would keep being rejected. Inserting the .0 makes the coerced form 2.33.0-pre.20251107+479b6b73, a valid semver that compares correctly.

All previously-supported version formats (2.21.2, 2.23.0pre20240526_7de033d6, 2.90.0-beta.1, …) are unchanged.

How was it tested?

• Added cases to TestParseVersionInfoShort asserting 2.33pre20251107_479b6b73 → 2.33.0pre20251107_479b6b73 and 2.33 → 2.33.0.
• Extended TestVersionInfoAtLeast so a patch-less prerelease (2.33.0pre20251107_479b6b73) is treated as >= 2.12.0 and >= MinVersion, and < 2.34.0.
• go test ./nix/ passes; go vet ./nix/, go build ./..., and gofmt -l are clean.

cc @Electrenator (issue reporter) — thanks for the detailed debug logs that pinpointed this.

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https://claude.ai/code/session_01VeatwKxvuw66rgQUnekx7J

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[Copilot]

Pull request overview

This PR fixes Devbox failing to detect certain Nix versions whose version string omits the patch component (e.g. 2.33pre... instead of 2.33.0pre...), which previously caused Info.Version to be empty and led to confusing “Your version is .” errors.

Changes:

• Updated the versionRegexp parser to allow an optional patch component in the Nix version.
• Added normalizeVersion to insert a .0 patch when Nix omits it, ensuring versions remain semver-comparable (including prerelease coercion in AtLeast).
• Extended unit tests to cover patch-less versions and patch-less prerelease normalization behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
nix/nix.go	Makes patch optional in version parsing and normalizes missing patch to .0 so version comparison works correctly.
nix/nix_test.go	Adds/extends test cases to validate parsing and AtLeast behavior for patch-less versions and prereleases.

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[mikeland73]

@claude please review this PR for correctness, and flag anything that would block merging.

[claude]

Claude finished @mikeland73's task in 1m 39s —— View job

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Review: fix(nix): parse Nix versions that omit the patch component

• Gather context (diff, related files)
• Review nix/nix.go changes for correctness
• Review nix/nix_test.go changes for coverage
• Check for edge cases / blocking issues
• Post final review

No blocking issues found. This is a clean, well-scoped fix.

Correctness

• versionRegexp (nix/nix.go:180): making the patch group (?:\.(?P<patch>0|[1-9]\d*))? optional is a minimal, correct change — group numbering/matches[2] (the full version substring) is unaffected, so the existing len(matches) < 3 check and info.Name = matches[1] logic still hold.
• normalizeVersion (nix/nix.go:291-301): since major/minor are captured verbatim from the start of matches[2], majorMinor is always a true prefix of version, so strings.TrimPrefix can never silently no-op on a mismatch — there's no ambiguity here even for multi-digit major/minor values.
• Traced through both new cases by hand:
  • 2.33pre20251107_479b6b73 → patch empty → "2.33" + ".0" + "pre20251107_479b6b73" = 2.33.0pre20251107_479b6b73 ✓.
  • 2.33 → patch empty → "2.33" + ".0" + "" = 2.33.0 ✓.
• The AtLeast reasoning in the PR description is correct: preReleaseRegexp requires a semver-valid base to coerce to -pre.$date+$commit, and without the inserted patch, 2.33-pre.20251107+479b6b73 is not a valid semver (per semver.IsValid), so AtLeast would keep returning false. Inserting .0 fixes this.
• Checked all other call sites of Info.Version/nix.Version() (internal/nix/install.go, internal/telemetry/{telemetry,segment}.go) — they just display or log the string, so normalizing 2.33pre... → 2.33.0pre... is a harmless, arguably more-correct cosmetic change, not a behavioral regression.
• All previously-supported formats (2.21.2, 2.23.0pre..., 2.90.0-beta.1) are unaffected since patch is non-empty for them and normalizeVersion returns early.

Tests

• TestParseVersionInfoShort and TestVersionInfoAtLeast additions directly cover the new normalization and the AtLeast comparison against Version2_12, MinVersion, and an upper bound (2.34.0) — good coverage of the reported bug and the fix's correctness claim.

Note

I was not able to execute go test/go vet/go build in this sandboxed environment (commands required approval that wasn't available), so I verified correctness by manual trace/regex analysis instead of running the suite. The PR description states go test ./nix/, go vet ./nix/, go build ./..., and gofmt -l were run locally and pass — if you'd like me to actually execute them here, the --allowedTools for this job would need to permit go test/go vet/go build.

Minor (non-blocking) observations

• normalizeVersion calls versionRegexp.SubexpIndex("patch") (and again for major/minor) on every parse; this is a linear name lookup but happens once per nix --version invocation (memoized via sync.Once), so it's not a real perf concern.
• Nothing else stood out — the doc comments are accurate and the fix is narrowly targeted at the reported issue (Devbox unable to detect version #2766).

[mikeland73]

Review: correct, and I don't see a correctness blocker

I re-reviewed the change (nix/nix.go, nix/nix_test.go) against the PR head. Summary of what I verified:

Correctness — the fix is complete, not just the regex half. The bug has two layers, and both are handled:

1. versionRegexp required a major.minor.patch triple, so 2.33pre20251107_479b6b73 didn't match → Info.Version empty → the gate in internal/nix/install.go (nix.AtLeast(MinVersion), MinVersion = 2.18.0) rejected it. Making patch optional fixes matching.
2. But an extracted 2.33pre… still wouldn't compare: AtLeast coerces prereleases to 2.33-pre.20251107+479b6b73, which is not a valid semver (a prerelease requires a patch), so semver.Compare would return -1 and the version would keep being rejected. normalizeVersion inserting .0 (→ 2.33.0pre… → coerced 2.33.0-pre.…, valid) is what actually makes the gate pass. I confirmed this against MinVersion (2.18.0), not just the 2.12.0 in the error string.

Edge cases checked:

• normalizeVersion's TrimPrefix(version, major.minor) is safe: it only runs when the patch group is empty (so there's no numeric .patch after the minor to confuse it), and capture group 2 always begins with exactly major.minor.
• Bare 2.33 → 2.33.0; all previously-supported formats (2.21.2, 2.23.0pre…, 2.90.0-beta.1) are unchanged. Tests cover these plus the two new patch-less cases.

Local verification: go test ./nix/ passes, go vet ./nix/ and go build ./... clean, gofmt -l empty.

Non-blocking notes:

• The branch is behind main (which has advanced since this was opened, including "ci: test against Nix 2.35.2"), but main hasn't touched nix/nix.go/nix/nix_test.go, so there's no merge conflict. A rebase is optional — happy to rebase if you'd prefer the branch current before merge.
• This PR is currently in draft. I've left it as-is — I won't mark it ready for review unless you ask me to.

Net: I'd consider this mergeable on correctness grounds. The only merge gate is the draft status (a maintainer decision).

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