refactor(modernize): apply safe modernize fixes

[p3ddd]

📝 Description

This PR applies safe, mechanical modernization fixes across the codebase using modernize.
Scope is limited to non-functional refactors (loop/style/stdlib modernizations), with no API or behavior changes intended.

This is a follow-up maintenance cleanup complementary to #435.

Not included in this PR:

• omitempty -> omitzero behavior-changing alternatives.

Reproducibility:

• Applied with: modernize -fix -omitzero=false ./...

🗣️ Type of Change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 📖 Documentation update
• ⚡ Code refactoring (no functional changes, no api changes)

🤖 AI Code Generation

• 🤖 Fully AI-generated (100% AI, 0% Human)
• 🛠️ Mostly AI-generated (AI draft, Human verified/modified)
• 👨‍💻 Mostly Human-written (Human lead, AI assisted or none)

🔗 Related Issue

N/A

📚 Technical Context (Skip for Docs)

• Reference URL:
  • https://go.dev/blog/gofix (Using go fix to modernize Go code, Alan Donovan, 17 February 2026)
• Reasoning:
  • After feat(fmt): Run formatters #435 , there were still reproducible modernize suggestions to address.
  • This PR keeps the modernization pass behavior-neutral and easy to review.
  • omitempty -> omitzero is intentionally deferred because it may change JSON serialization semantics.

🧪 Test Environment

• Hardware: Mac mini M4
• OS: macOS 26.3 (25D125)
• Model/Provider: N/A
• Channels: N/A

📸 Evidence (Optional)

Click to view Logs/Screenshots

➜ make check
all modules verified
ok      github.com/sipeed/picoclaw/cmd/picoclaw 0.744s
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal        (cached)
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/agent  1.247s
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/auth   (cached)
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/cron   (cached)
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/gateway        1.564s
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/migrate        (cached)
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/onboard        (cached)
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/skills 2.033s
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/status (cached)
ok      github.com/sipeed/picoclaw/cmd/picoclaw/internal/version        (cached)
ok      github.com/sipeed/picoclaw/pkg/agent    2.734s
ok      github.com/sipeed/picoclaw/pkg/auth     (cached)
?       github.com/sipeed/picoclaw/pkg/bus      [no test files]
ok      github.com/sipeed/picoclaw/pkg/channels 3.014s
ok      github.com/sipeed/picoclaw/pkg/config   3.521s
?       github.com/sipeed/picoclaw/pkg/constants        [no test files]
ok      github.com/sipeed/picoclaw/pkg/cron     (cached)
?       github.com/sipeed/picoclaw/pkg/devices  [no test files]
?       github.com/sipeed/picoclaw/pkg/devices/events   [no test files]
?       github.com/sipeed/picoclaw/pkg/devices/sources  [no test files]
?       github.com/sipeed/picoclaw/pkg/fileutil [no test files]
?       github.com/sipeed/picoclaw/pkg/health   [no test files]
ok      github.com/sipeed/picoclaw/pkg/heartbeat        (cached)
ok      github.com/sipeed/picoclaw/pkg/logger   (cached)
ok      github.com/sipeed/picoclaw/pkg/migrate  (cached)
ok      github.com/sipeed/picoclaw/pkg/providers        15.892s
ok      github.com/sipeed/picoclaw/pkg/providers/anthropic      4.416s
ok      github.com/sipeed/picoclaw/pkg/providers/openai_compat  3.889s
?       github.com/sipeed/picoclaw/pkg/providers/protocoltypes  [no test files]
ok      github.com/sipeed/picoclaw/pkg/routing  5.073s
ok      github.com/sipeed/picoclaw/pkg/session  (cached)
ok      github.com/sipeed/picoclaw/pkg/skills   5.167s
ok      github.com/sipeed/picoclaw/pkg/state    5.096s
ok      github.com/sipeed/picoclaw/pkg/tools    5.914s
ok      github.com/sipeed/picoclaw/pkg/utils    4.562s
?       github.com/sipeed/picoclaw/pkg/voice    [no test files]

☑️ Checklist

• My code/docs follow the style of this project.
• I have performed a self-review of my own changes.
• I have updated the documentation accordingly.

[mengzhuo]

LGTM, thanks

[yinwm]

@p3ddd please fix linter failed

[nikolasdehor]

Clean mechanical modernization pass. All changes are behavior-preserving:

• for range N replacing for i := 0; i < N; i++** (Go 1.22+) -- correct when the loop variable was unused
• slices.Contains/slices.Sort/slices.ContainsFunc replacing manual search loops -- correct, more readable
• strings.Cut/strings.CutPrefix/strings.CutSuffix replacing strings.HasPrefix + strings.TrimPrefix patterns -- correct, avoids the double-scan
• maps.Copy replacing manual map iteration -- correct
• strings.Builder replacing string concatenation -- correct, avoids quadratic allocation in parseResponse, listJobs, and NormalizeAgentID test
• max() builtin replacing manual min/max patterns -- correct (Go 1.21+)
• wg.Go() replacing wg.Add(1) + go func() -- correct (sync.WaitGroup.Go is Go 1.25+, and picoclaw uses Go 1.25)

The omitzero exclusion is sensible since it changes JSON serialization semantics.

All tests passing per the evidence. LGTM.

[p3ddd]

@nikolasdehor I’ve resolved the merge conflicts. Could you please approve/run the workflows for this fork PR when convenient? Thank you very much.

[p3ddd]

@yinwm CI is now green and conflicts are resolved. This PR is ready to merge when you have time. Thanks!

[xiaket]

should we add a step in CI to check this automatically?

[Orgmar]

@p3ddd Clean modernize pass. Keeping the codebase up to date with newer Go patterns and stdlib improvements without changing behavior is valuable maintenance work that often gets overlooked.

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