feat(data): seed dataviewer frontend test foundation and per-section codecov flags

[WilliamBerryiii]

Summary

Establishes the dataviewer frontend test foundation called for in #210 and splits Codecov reporting into per-section vitest flags so coverage gaps surface by area instead of being averaged into a single number.

Closes #210.

Changes

• Add Radix DOM shims (typed ResizeObserver / IntersectionObserver) and shared test-utils QueryClient helpers so component tests render under React 19 + Happy DOM without bespoke setup.
• Split the Codecov vitest configuration into vitest-{components,features,lib,state,app} and wire the multi-flag upload through the workflow.
• Drop main.tsx from the vitest-app scope and add proof tests for StarRating and ProgressOverview to validate the new harness.
• Refresh copilot-instructions.md (L448) to document the per-section flag layout.
• Replace fragile plain-object fetch mocks in api-client.test.ts and use-joint-config.test.ts with a jsonResponse helper that builds a fresh Response per call, resolving the IV-001 single-consumption regression.

Validation

• npm test (frontend): full suite executed; the IV-001 surface (api-client.test.ts, use-joint-config.test.ts) plus adjacent files re-run in isolation passed 54/54 in 36.80s. Three unrelated cold-cache timeout flakes in the initial full run passed cleanly on isolated retry.
• Husky lint-staged ran on amend with no findings.

Related

• Issue: test(dataviewer): TypeScript frontend testing infrastructure and coverage — tracking issue #210

🧪 - Generated by Copilot

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.38%. Comparing base (0070b04) to head (9c28d20).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #594      +/-   ##
==========================================
+ Coverage   77.27%   77.38%   +0.11%     
==========================================
  Files         272      272              
  Lines       18140    18140              
  Branches     2493     2452      -41     
==========================================
+ Hits        14018    14038      +20     
+ Misses       3698     3677      -21     
- Partials      424      425       +1     

Flag	Coverage Δ		*Carryforward flag
pester	83.13% <ø> (ø)		Carriedforward from 8d407e0
pytest-data-pipeline	100.00% <ø> (ø)		Carriedforward from 8d407e0
pytest-dataviewer	93.60% <ø> (ø)		Carriedforward from 8d407e0
pytest-dm-tools	100.00% <ø> (ø)		Carriedforward from 8d407e0
pytest-evaluation	99.51% <ø> (ø)
pytest-fuzz	4.89% <ø> (ø)		Carriedforward from 8d407e0
pytest-inference	100.00% <ø> (ø)		Carriedforward from 8d407e0
pytest-training	93.32% <ø> (ø)		Carriedforward from 8d407e0
vitest	53.34% <ø> (+0.32%)	⬆️
vitest-app	53.34% <ø> (?)
vitest-components	53.34% <ø> (?)
vitest-features	53.34% <ø> (?)
vitest-lib	53.34% <ø> (?)
vitest-state	53.34% <ø> (?)

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
...tend/src/components/dashboard/ProgressOverview.tsx	100.00% <ø> (+71.42%)	⬆️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Snapshot Warnings

⚠️: No snapshots were found for the head SHA 9c28d20.

Ensure that dependencies are being submitted on PR branches and consider enabling retry-on-snapshot-warnings. See the documentation for more information and troubleshooting advice.

Scanned Files

None

[rezatnoMsirhC]

Thanks for the contribution — clean foundation. The DOM shims, real Response objects in fetch mocks, proof tests for StarRating and ProgressOverview, and the per-section Codecov flags are all solid. Left a couple of minor comments.

[katriendg]

Approving, two nit comments.

🔍 Locale-sensitive assertion fragility

File: data-management/viewer/frontend/src/components/dashboard/__tests__/ProgressOverview.test.tsx (L37)

screen.getByText('1,000') relies on .toLocaleString() producing comma-separated thousands under en-US. Happy DOM defaults to that locale today, but a CI locale drift would break this assertion silently.

Suggestion: Pin the locale in the component (toLocaleString('en-US')) or use a regex matcher in the test. Non-blocking nit.

---

💡 vitest-features flag scope documentation

File: codecov.yml (L230–L235)

vitest-features tracks 4 of 14 component subdirectories (dashboard/, annotation-panel/, frame-editor/, episode-viewer/). The remaining dirs are covered by the aggregate vitest-components flag so there's no gap — but a one-line comment noting these are the "most actively developed feature areas" (or whatever the intent is) would prevent future contributors from assuming something was missed.

[WilliamBerryiii]

Approving, two nit comments.

🔍 Locale-sensitive assertion fragility

File: data-management/viewer/frontend/src/components/dashboard/__tests__/ProgressOverview.test.tsx (L37)

screen.getByText('1,000') relies on .toLocaleString() producing comma-separated thousands under en-US. Happy DOM defaults to that locale today, but a CI locale drift would break this assertion silently.

Suggestion: Pin the locale in the component (toLocaleString('en-US')) or use a regex matcher in the test. Non-blocking nit.

💡 vitest-features flag scope documentation

File: codecov.yml (L230–L235)

vitest-features tracks 4 of 14 component subdirectories (dashboard/, annotation-panel/, frame-editor/, episode-viewer/). The remaining dirs are covered by the aggregate vitest-components flag so there's no gap — but a one-line comment noting these are the "most actively developed feature areas" (or whatever the intent is) would prevent future contributors from assuming something was missed.

Resolved in latest push.