[🐞] V2 cursors: inconsistent state changes for multiple items

[thejackshelton]

Which component is affected?

Qwik Runtime

Describe the bug

When multiple actions are performed on several instances via context, the item state is inconsistent

Reproduction

https://github.com/thejackshelton/cursors-checklist-bug

Steps to reproduce

Reproduction Steps:

1. Run pnpm install
2. Run pnpm dev
3. Open http://localhost:5173 in your browser
4. Click the Select All checkbox (top level)
5. Notice how all get checked
6. Uncheck the Select All checkbox
7. Notice how only one of the items get unchecked, and it's at random.

Expected Output

Clicking the Select All checkbox should check all items, and unclicking it should uncheck all items.

When the select all checkbox is checked, all items should be checked.
When the select all checkbox is unchecked, all items should be unchecked.
When the select all checkbox is in a mixed state, some items should be checked, and some should be unchecked.
When all items are checked, the select all checkbox should be checked.

System Info

System:
    OS: macOS 26.1
    CPU: (16) arm64 Apple M4 Max
    Memory: 2.09 GB / 48.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.18.0 - /usr/local/bin/node
    Yarn: 1.22.22 - /usr/local/bin/yarn
    npm: 10.9.3 - /usr/local/bin/npm
    pnpm: 10.19.0 - /Users/jackshelton/.nvm/versions/node/v24.9.0/bin/pnpm
    bun: 1.1.7 - /Users/jackshelton/.bun/bin/bun
    Deno: 2.1.4 - /opt/homebrew/bin/deno
  Browsers:
    Brave Browser: 141.1.83.120
    Chrome: 143.0.7499.170
    Firefox: 145.0.2
    Safari: 26.1
  npmPackages:
    typescript: 5.4.5 => 5.4.5 
    undici: * => 7.16.0 
    vite: 7.2.6 => 7.2.6

Additional Information

No response

[thejackshelton]

Closing as existing logic was incorrect, but previous inconsistencies made it appear correct. The new version made those issues clear.