A11y | Bump design-system for D3 divider color

[BrianGenisio]

Summary

Closes #59. This app now consumes the design-system D3 Split Panel change: the divider line is Neutral-800 at ≥3:1 against both pane surfaces. D2 name and 24×24 hit target are unchanged.

Also records A17 as closed (PR #60) on the issue map. That number is not on the D3 or bump D3 rows.

Changes

Submodule public/design-system points at 0e02e04 (DS PR #33). No app widget changes.

Characterization locks the divider ::after so it cannot regain #2b3b52.

Axe floor stays color-contrast 1 (Sort empty-dropzone placeholder, A21). Split-shell scenarios had 0 violations.

Test plan

• npm test — D2 hit target/name still hold; D3 token lock passes
• PORT=3010 A11Y_BASE_URL=http://127.0.0.1:3010 SIM_PORT=8081 SIM_ORIGIN=http://127.0.0.1:8081 npm run a11y:ci — baseline unchanged
• Split markdown / sim in light and dark: line is visible, drag and arrow keys still resize

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: cd62668c-653e-4983-ae41-50c8006b086c

📥 Commits

Reviewing files that changed from the base of the PR and between 67290c3 and ae861e2.

📒 Files selected for processing (3)

• a11y-audits/8-13-26/wave-4-plan.md
• public/design-system
• test/a11y-characterization.test.js

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📝 Walkthrough

Walkthrough

The design-system submodule now points to the merged D3 revision. A characterization test verifies that the split-panel divider uses the Neutral-800 token through --Colors-Split-Panel-Divider-Line and no longer uses #2b3b52. The Wave 4 plan records A17 as completed through PR #60 and sets the D3 consumer bump before A16.

Merge Risk: ⚪ Minimal · up to ae861

The PR makes a localized design-system reference update and adds a focused divider-color characterization check. No actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: bumping the design-system for the D3 divider color.
Description check	✅ Passed	The description directly explains the design-system bump, divider token change, characterization test, A17 issue-map update, and validation results.
Linked Issues check	✅ Passed	For [#59], the PR bumps the submodule to the D3 revision, verifies the semantic divider token, preserves D2 behavior, runs the required automated checks, and avoids app widget changes.
Out of Scope Changes check	✅ Passed	All changes support the linked objectives. The submodule bump, divider characterization test, and A17 issue-map update are related to the stated accessibility work.

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