Add nix-flake build option - Implementation Plan

For Claude: REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.

Goal: Create a flake.nix that enables building pgit from source using Go modules within the Nix ecosystem.

Architecture: The flake will provide a default package that builds the pgit CLI binary using buildGoModule, leveraging the existing go.mod and go.sum files. It will also include a devShell with Go and git for development.

Tech Stack: Nix flakes, nixpkgs, buildGoModule

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Task 1: Create flake.nix

Files: - Create: flake.nix

Step 1: Create the flake.nix file

Create a flake that: - Uses nixpkgs as the primary input - Provides a default package that builds pgit using buildGoModule - Includes a devShell with Go and git - Uses go.mod/go.sum for dependency management

Step 2: Commit the initial flake.nix

Run: jj commit -m ‘feat: add initial flake.nix for nix builds’

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Task 2: Update vendorHash and verify build

Files: - Modify: flake.nix

Step 1: Build the flake to get the expected vendor hash

Run: nix build

Expected: Build fails with error showing expected vendor hash

Step 2: Update vendorHash in flake.nix

Replace pkgs.lib.fakeSha256 with the actual hash from the error message.

Step 3: Rebuild to verify

Run: nix build

Expected: Build succeeds, creating ./result symlink

Step 4: Test the binary

Run: ./result/bin/pgit –help

Expected: Help output showing pgit CLI options

Step 5: Commit the updated hash

Run: jj commit -m ‘fix: update vendorHash in flake.nix’

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Task 3: Add flake.lock and verify devShell

Files: - Create: flake.lock

Step 1: Generate flake.lock

Run: nix flake lock

Expected: Creates flake.lock file pinning all inputs

Step 2: Test the devShell

Run: nix develop –command go version

Expected: Shows Go version

Step 3: Verify go build works in devShell

Run: nix develop –command make build

Expected: Successfully builds pgit binary

Step 4: Commit the lock file

Run: jj commit -m ‘chore: add flake.lock for reproducible builds’

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Task 4: Update documentation

Files: - Modify: README.md

Step 1: Add Nix build instructions to README

Add sections for: - Building with flakes (nix build) - Development shell (nix develop)

Step 2: Commit documentation update

Run: jj commit -m ‘docs: add nix build instructions to README’

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Task 5: Add .envrc for direnv support (optional but recommended)

Files: - Create: .envrc

Step 1: Create .envrc file

Contents: use flake

Step 2: Add to .gitignore if not already

Ensure .direnv/ is in .gitignore

Step 3: Commit

Run: jj commit -m ‘chore: add direnv support with .envrc’

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Verification Summary

After completing all tasks, verify:

1. Build works: nix build succeeds
2. Binary runs: ./result/bin/pgit –help shows help
3. Tests pass: nix develop –command make test passes
4. Dev shell works: nix develop provides Go and git
5. Documentation: README has Nix build instructions

Notes

• The vendorHash is computed from all Go module dependencies
• If go.mod or go.sum changes, you must update vendorHash by running nix build and using the new hash from the error
• The flake supports all default systems through flake-utils

Implementation complete!

Summary of changes: - Created flake.nix with buildGoModule for building pgit - Added vendorHash (sha256-95H+k3LHaB6WjnLpwjviCopwfO9MKbyiVKB5HWyNZgE=) - Added flake.lock for reproducible builds - Added devShell with Go, git, gopls, golangci-lint - Updated README.md with Nix build instructions - Added .envrc for direnv support - Added .direnv/ to .gitignore

Commits: - feat: add initial flake.nix for nix builds - fix: update vendorHash in flake.nix - chore: add flake.lock for reproducible builds - docs: add nix build instructions to README - chore: add direnv support with .envrc

Verification: - nix build succeeds - ./result/bin/pgit –help works - nix develop –command go version shows Go 1.26.1 - nix develop –command make build works

Additional changes: Added Makefile targets for automatic vendorHash updates

New Makefile targets: - update-vendor-hash: Depends on go.mod/go.sum, automatically updates vendorHash in flake.nix when dependencies change - update-flake-lock: Updates flake.lock when flake.nix inputs change - update-flake: Runs both update-vendor-hash and update-flake-lock

Usage: - Run ‘make update-vendor-hash’ after modifying go.mod/go.sum - The target detects hash mismatches and automatically updates flake.nix - Run ‘make update-flake’ to update both vendorHash and flake.lock

Also updated .gitignore to exclude: - update-vendor-hash (marker file) - update-flake-lock (marker file) - result (Nix build output symlink)