Add data mutation helpers

[titouanmathis]

Summary

• add toggle(), increment(), and cycle() helpers to DataBind
• normalize comparisons across DOM string coercion, dates, and arrays
• keep all mutations routed through set() so scalar and scoped groups continue to dispatch normally
• document Action usage and helper semantics
• cover custom/default toggles, numeric recovery, negative steps, value cycling, scoped state, and Action integration

This is an independent stacked follow-up to #511 and should be reviewed against feature/data-scope. Once #511 merges, this PR can be retargeted to main.

Validation

• npm run test — 47 files passed, 305 tests passed, 3 skipped, 1 todo
• focused npm run test -- -- Data Action — 9 files passed, 55 tests passed, 1 todo
• npm run lint:types — passed
• npm run lint:static — passed with 15 pre-existing warnings and no errors
• npm run lint:prettier — passed
• npm run build — passed

No local docs build was run.

Follow-up to #510.
Depends on #511.

[codecov]

Codecov Report

❌ Patch coverage is 88.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.41%. Comparing base (7d58c48) to head (ad143cd).

Files with missing lines	Patch %	Lines
packages/ui/Data/DataBind.ts	88.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@                   Coverage Diff                    @@
##             feature/data-scope     #514      +/-   ##
========================================================
- Coverage                 79.45%   78.41%   -1.04%     
  Complexity                  145      145              
========================================================
  Files                       100       94       -6     
  Lines                      3008     2845     -163     
  Branches                    532      499      -33     
========================================================
- Hits                       2390     2231     -159     
+ Misses                      542      537       -5     
- Partials                     76       77       +1     

Flag	Coverage Δ
unittests	78.41% <88.00%> (-1.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/ui/Data/DataBind.ts	96.50% <88.00%> (-1.81%)	⬇️

... and 13 files with indirect coverage changes

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[github-actions]

Code Review

Risk: Low — no blocking issues; safe to merge aside from nits.

This MR adds toggle(), increment(), and cycle() to DataBind, documents the new API, and extends the test suite with helper, scoped-state, and Action integration coverage. The implementation generally follows the stated intent of routing mutations through set(), but one unsupported toggle shape is still accepted and does not round-trip correctly.

Still open from earlier reviews (1 finding):

• packages/ui/Data/DataBind.ts:255 — issue: Custom toggle values do not round-trip on checkboxes

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Review usage: 111,081 in (89,088 cached) / 8,996 out tokens — $0.2122 (cloudflare-ai-gateway/gpt-5.4, thinking: medium)

Reviewed by @weareikko/code-review v0.8.2 for commit ad143cd.

Previous review runs

Previous run archived 2026-07-15T15:37:32Z

Code Review

Risk: Medium — issues that should be addressed before merge.

Adds toggle(), increment(), and cycle() to DataBind, introduces a shared value comparison helper for DOM/string/date/array cases, and expands the API docs. The test suite now covers the new helpers, Action integration, and scoped state propagation.

1 issue found:

• issue — packages/ui/Data/DataBind.ts:245 — Custom toggle values do not round-trip on checkboxes

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Review usage: 120,167 in (86,016 cached) / 11,191 out tokens — $0.2747 (cloudflare-ai-gateway/gpt-5.4, thinking: medium)

Reviewed by @weareikko/code-review v0.8.2 for commit 27a8fbb.