Prefill input context with resolved input variables

[Buckwich]

Closes #76
Closes camunda/camunda-modeler#5640

Proposed Changes

Note

PR still links to a git branch of variable resolver, will adjust to release version before merge. waiting on bpmn-io/variable-resolver#74

• prefill panel with variables provided by new variable resolver that contains variables needed in an expression
• adjust clear button to a reset button
  • resets the input to the determined empty prefill value
  • reset is now part of codemirror history (ie undoable)
  • enabled codemirror history
  • adjusted empty input default to {\n \n} to make it easier to get started editing the json

npx @bpmn-io/sr camunda/task-testing#5640_prefill-tasktesting

Checklist

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• Your contribution meets the definition of done
• Any new additions or modifications are consistent with the existing UI and UX patterns
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  • Link to related issue(s), i.e. Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}
  • Brief textual description of the changes
  • Screenshots or short videos showing UI/UX changes
  • Steps to try out, i.e. using the @bpmn-io/sr tool

[Copilot]

Pull request overview

This PR implements undoable reset-to-default functionality for the input panel by leveraging a new variable resolver that computes required variables from BPMN expressions. The "Clear" button has been replaced with a "Reset" button that populates the input with smart prefill values based on the element's variable requirements, and this reset operation is now undoable via CodeMirror's history extension.

Changes:

• Enabled CodeMirror undo/redo functionality (Ctrl+Z/Y) by adding history() and historyKeymap extensions
• Replaced "Clear" button with "Reset" button that prefills input with element-specific variable stubs
• Implemented automatic merging of variable requirements when BPMN model changes
• Changed default empty input from {} to {\n \n} for better UX

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
package.json	Updates @bpmn-io/variable-resolver to git branch (needs release version before merge)
package-lock.json	Lockfile updates for new variable-resolver and dependencies
lib/utils/prefill.js	New utility module implementing prefill logic with requirement merging
lib/ElementConfig.js	Added getDefaultInputForElement and getMergedInputConfigForElement methods
lib/ElementVariables.js	Added getInputRequirementsForElement method wrapping variable resolver
lib/components/Input/Input.jsx	Changed "Clear" button to "Reset" button
lib/components/Input/InputEditor.jsx	Enabled CodeMirror history and historyKeymap extensions
lib/components/TaskTesting/TaskTesting.js	Integrated prefill logic with auto-merge on variable changes
test/fixtures/prefill.bpmn	New BPMN test fixture with script tasks requiring variables
test/Prefill.spec.js	Comprehensive tests for prefill computation and merging logic
test/components/Input/Input.spec.js	Updated prop names from setInput/reset to onSetInput/onResetInput
test/ElementConfig.spec.js	Updated default empty config expectation to {\n \n}

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[jarekdanielak]

I can undo to the empty state, which I never actually had before. I think it's unexpected: