test(go): cover explicit harness provider factory paths

[aspire488]

Summary

Closes #404 (factory-test slice).

• Adds explicit factory coverage for the Claude Code provider.
• Adds explicit factory coverage for the OpenCode provider.
• Keeps the existing default, environment, precedence, blank-value, and unknown-provider coverage.

Scope

This takes only the factory_test.go slice explicitly offered by #404; no production code changes.

Validation

The tests are table-driven and assert the concrete provider type returned by BuildProvider.

[CLAassistant]

All committers have signed the CLA.

[santoshkumarradha]

The new cases are useful, but the table currently does not drive the expected type assertion. Please use the expected value from each row so the test fails if a provider is paired with the wrong concrete type.

[github-actions]

Performance

SDK	Memory	Δ	Latency	Δ	Tests	Status
Go	167 B	-40%	0.35 µs	-65%	✓	✓

✓ No regressions detected

[github-actions]

📊 Coverage gate

Thresholds from .coverage-gate.toml: per-surface ≥ 84%, aggregate ≥ 85%, max per-surface regression ≤ 1.0 pp, max aggregate regression ≤ 0.50 pp.

Surface	Current	Baseline	Δ
control-plane	87.90%	87.40%	↑ +0.50 pp	🟡
sdk-go	93.30%	92.00%	↑ +1.30 pp	🟢
sdk-python	94.72%	93.73%	↑ +0.99 pp	🟢
sdk-typescript	91.83%	90.42%	↑ +1.41 pp	🟢
web-ui	84.76%	84.79%	↓ -0.03 pp	🟡
aggregate	85.92%	85.75%	↑ +0.17 pp	🟡

✅ Gate passed

No surface regressed past the allowed threshold and the aggregate stayed above the floor.

[github-actions]

📐 Patch coverage gate

Threshold: 80% on lines this PR touches vs origin/main (from .coverage-gate.toml:thresholds.min_patch).

Surface	Touched lines	Patch coverage	Status
control-plane	0	—	➖ no changes
sdk-go	0	—	➖ no changes
sdk-python	0	—	➖ no changes
sdk-typescript	0	—	➖ no changes
web-ui	0	—	➖ no changes

✅ Patch gate passed

Every surface whose lines were touched by this PR has patch coverage at or above the threshold.

[aspire488]

Thanks — the current head already uses the table-driven expectation via assert.IsType(t, tt.want, provider), so the requested assertion change is addressed. Please re-review the current head (b2584224a7b03db05d1043a362bdfec684f6b1cb).

[santoshkumarradha]

Thanks for updating the table to drive the concrete type assertion. The focused factory tests and Go vet pass locally.

The contributor addressed this request in b258422; superseded by the approval on the current head.

[aspire488]

Huge thanks to the AgentField maintainers and reviewers for taking the time to review and merge #1073. 🙏

I really appreciate the feedback around making the factory tests assert the concrete provider types, and the chance to tighten the implementation before it landed.

This was a great contribution experience — clear review feedback, focused validation, and a clean path from issue → implementation → review → merge.

Looking forward to contributing more to AgentField and seeing where the project goes next. 🚀

And to future contributors reading this: keep shipping, keep the changes focused, and make the tests tell the story.