Spec: Complete Deep History Validation

Status: done Priority: P2 Created: 2026-02-08 Owner: history-validator Completed: 2026-02-09

Context

The invalid-history-elements function in chart.cljc:412 has a TODO comment: "Validate deep history." Shallow history validation exists (though buggy, see history-validation-bug spec) but deep history has no static validation.

The W3C SCXML spec Section 3.11 defines requirements for deep history that should be validated:

• Deep history records full descendant configuration
• Transition target requirements differ from shallow history
• Must be child of a compound state

Requirements

1. Research exact W3C requirements for deep history nodes
2. Implement static validation rules
3. Add to existing invalid-history-elements function
4. This depends on history-validation-bug being fixed first

Affected Modules

• src/main/com/fulcrologic/statecharts/chart.cljc:412 - Add validation

Implementation Summary

Enhanced invalid-history-elements function in chart.cljc:

• Added validation that history must be child of compound state
• Added deep history target must be proper descendant of parent
• Wired validation into statechart construction (throws on invalid charts)
• Added comprehensive tests in chart_validation_spec.cljc

##Verification

1. [x] Deep history in compound state passes validation
2. [x] Deep history outside compound state fails validation
3. [x] Deep history transition target rules validated
4. [PENDING] All existing deep history tests still pass - needs REPL to run tests