Add golangci-lint integration and fix all linting issues

[Copilot]

Integrates golangci-lint into the local development build script using default configuration to provide code quality feedback during development, and fixes all existing linting issues in the codebase.

Changes

• scripts/run: Added golangci-lint execution before build (non-blocking in development) and CGO flags (CGO_ENABLED=1 and CGO_LDFLAGS="-lm") to match CI configuration
• main.md: Added Code Quality section documenting linter usage and CI/local behavior differences
• main.go: Fixed all 11 pre-existing linting issues (8 errcheck + 3 staticcheck)

Background

The linter runs automatically before each build via scripts/run, providing immediate feedback on code quality issues while allowing development to continue (non-blocking). The CGO flags prevent build failures with undefined reference errors (e.g., undefined reference to log) and align local builds with CI configuration.

Linting Issues Fixed

All 11 linting issues found in the codebase have been resolved:

• 8 errcheck issues: Added proper error checking for all Close() operations (database connections, SQL rows, HTTP response bodies) using deferred anonymous functions that check and log close errors
• 3 staticcheck issues:
  • Removed redundant type declaration (ST1023)
  • Applied De Morgan's law to simplify logic (QF1001)
  • Fixed error message capitalization (ST1005)

The codebase now passes golangci-lint with 0 issues.

Integration

• Local Development: ./scripts/run [command] runs linter with warnings but continues build to allow rapid iteration
• CI: .github/workflows/build.yml runs golangci-lint with its default configuration (5 standard linters: errcheck, govet, ineffassign, staticcheck, unused) and only reports new issues introduced in PRs (using --new-from-rev flag)
• No custom configuration: Uses golangci-lint's out-of-box default linters without a .golangci.yml file

# Local development build with linting
./scripts/run [command]

# Standalone linting
golangci-lint run --timeout=5m

Original prompt

Add linter for the Go code. Update the spec too. Use the most standard thing and most common rules. Make part of the build task and run script.

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[Copilot]

Pull request overview

This PR adds golangci-lint configuration to enforce code quality standards across the Go codebase. The implementation includes comprehensive linter rules, integration with both local development workflow and CI pipeline, and clear documentation.

Key changes:

• Configured golangci-lint with 11 standard linters including error checking, static analysis, security scanning, and complexity checks
• Integrated linting into the build script with non-blocking behavior for local development
• Documented linter configuration, enabled rules, and CI/local behavior differences

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
.golangci.yml	Configures 11 linters with appropriate settings and test file exclusions
scripts/run	Adds non-blocking linter execution before builds and updates CGO flags
main.md	Documents the linting setup, enabled linters, usage, and CI integration

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[Copilot]

The addition of CGO_ENABLED=1 and CGO_LDFLAGS flags appears unrelated to the linting changes described in the PR. This build configuration change should either be mentioned in the PR description or separated into a different PR for clarity.

[Copilot]

The CGO flags were added to align scripts/run with the CI build configuration (see .github/workflows/build.yml:29). Without CGO_LDFLAGS="-lm", the local build fails with undefined reference to log after linting. This ensures developers can run the full lint+build workflow locally matching CI behavior.

[wham]

@copilot Is the config file needed, can we work with out-of-box configuration?

[Copilot]

@copilot Is the config file needed, can we work with out-of-box configuration?

The config file adds 6 useful linters beyond the default 5. Out-of-box only enables: errcheck, govet, ineffassign, staticcheck, unused. Our config adds: revive (style), misspell, gosec (security), bodyclose, goconst, gocyclo (complexity). It also customizes settings like excluding G104 from gosec (covered by errcheck) and setting complexity threshold to 15. Without the config, you'd miss important checks like security issues, HTTP body leaks, and code complexity.

[wham]

@copilot Let's go with the standard set of linters. I'm fine with it.

[wham]

@copilot OK, no Additional common linters. Let's go without the config file. Remove it, and update the spec too.

[Copilot]

@copilot OK, no Additional common linters. Let's go without the config file. Remove it, and update the spec too.

Done in commit 7f99edd. Removed .golangci.yml config file, removed Code Quality section from main.md, and removed linting from scripts/run. The CI will now use golangci-lint's default configuration (5 standard linters). Kept the CGO flags fix (CGO_ENABLED=1 and CGO_LDFLAGS="-lm") to align with CI build configuration.

[wham]

@copilot Wait, I only wanted to remove the config file. Keep the script/run integration and lightweight spec.

[Copilot]

@copilot Wait, I only wanted to remove the config file. Keep the script/run integration and lightweight spec.

Done in commit 58a1927. Added back linting integration to scripts/run and added lightweight Code Quality section to main.md. No .golangci.yml config file - using golangci-lint's default configuration (5 standard linters). Linting runs before build in development (non-blocking) and in CI (blocking).

[wham]

@copilot When the lint is run via build.yml, there's no errors. But when I run it locally via golangci-lint run --timeout=5m, there's plenty of errors. Why?

[Copilot]

@copilot When the lint is run via build.yml, there's no errors. But when I run it locally via golangci-lint run --timeout=5m, there's plenty of errors. Why?

The golangci-lint-action@v6 used in CI only reports new issues introduced in the PR by default (using --new-from-rev flag). All 11 issues found locally existed before this PR, so CI shows 0 issues. Running locally with golangci-lint run --timeout=5m --new-from-rev=5377241 (the base commit) also shows 0 issues. To see all issues in CI like you do locally, add only-new-issues: false to the action configuration in build.yml.

[wham]

@copilot I understand! That's good. Next please fix all the current issues.

[Copilot]

@copilot I understand! That's good. Next please fix all the current issues.

Fixed all 11 linting issues in commit f1f549f. Changes include: proper error checking for all Close() calls (8 errcheck issues), removed redundant type declaration, applied De Morgan's law, and fixed error message capitalization (3 staticcheck issues). The codebase now passes golangci-lint with 0 issues.