ID 61: Replace FHIRPath-based bundle reference traversal with core fhir_navigation handling

[abhinandan2012]

Summary

Replaces the FHIRPath-based bundle reference traversal in PAS bundle validation with the shared FHIRResourceNavigation module from Inferno core.

This refactor removes the dependency on evaluate_fhirpath (an external HTTP call to a FHIRPath server) and switches the traversal flow to metadata-driven in-process navigation using resolve_path. Extension slice references are now resolved automatically through extracted profile metadata, removing the need for manual FHIRPath workarounds.

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Changes

Navigation Module (pas_bundle_validation.rb)

• Adds ReferenceNavigationContext wrapper class that includes Inferno::DSL::FHIRResourceNavigation with metadata accessible.

• Replaces evaluate_fhirpath in process_reference_element with reference_values_for_element which uses resolve_path from the navigation module. The new approach:

  • Runs in-process (no external HTTP call)
  • Returns FHIR::Reference objects directly instead of JSON hashes
  • Handles value[x] choice types natively
  • Resolves extension slice paths automatically via metadata

• Adds profile_metadata parameter to process_reference_element so the navigation context has access to must_supports[:extensions] for automatic extension URL resolution.

• Adds supporting navigation methods:

  • reference_values_for_element — resolves references using the navigation module, filters to FHIR::Reference objects with a present reference, and returns their reference strings.
  • navigation_path_for_reference — orchestrates path conversion from metadata format to navigation-compatible format.
  • resource_relative_reference_path — strips resource type prefix from paths (e.g. Claim.patient → patient) since resolve_path starts from the resource itself.
  • navigation_compatible_reference_path — processes each path segment and converts extension slice notation to where(url='...') syntax.
  • normalized_reference_path_segment — converts extension slice segments like extension:encounter to extension.where(url='http://...') by looking up the URL from must_supports[:extensions] in the profile metadata.
  • extension_url_for_reference_path — looks up extension URL from profile metadata must_supports[:extensions].
  • extension_url_without_version — strips version suffix from profile URLs before use in navigation paths.
  • reference_navigation_context — factory method for ReferenceNavigationContext.

• Removes manual Claim.extension:encounter FHIRPath workaround from handle_claim_profile. The navigation module now resolves this automatically:

  Claim.extension:encounter
    → normalized_reference_path_segment looks up must_supports[:extensions]
    → finds { id: "Claim.extension:encounter",
               url: "http://hl7.org/fhir/5.0/StructureDefinition/extension-Claim.encounter" }
    → produces: extension.where(url='http://hl7.org/fhir/5.0/...')
    → resolve_path navigates to Encounter/SurgicalEncounterExample
    → profile-encounter assigned 

• Updates handle_claim_profile requestedService path to use value[x] suffix for compatibility with the navigation module's choice type handling:

  # Before
  path: 'Claim.item.extension.value'

  # After
  path: 'Claim.item.extension:requestedService.value[x]'

The navigation module normalizes this to:

  item.extension.where(url='...requestedService...').value[x]

Operation Type Helpers

• Adds submit_operation?, inquire_operation?, and request_operation
  helper methods to replace direct string comparisons of request_type.

• Fixes a bug where request_type == 'submit' comparisons were
  silently failing because request_type is a compound string like
  submit_request — not just submit. This caused incorrect validation
  path selection and resources falling through to US Core profiles
  incorrectly. The new helpers correctly extract the operation type:

  def request_operation(request_type)
    request_type.to_s.split('_').first  # "submit_request" → "submit"
  end

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Behavior Changes

Before

• Bundle traversal depended on external FHIRPath evaluation.
• Claim.extension:encounter traversal required a manual FHIRPath workaround in handle_claim_profile.
• Extension slice traversal was not metadata-driven.
• request_type == 'submit' comparisons were silently failing for compound request type strings.

After

• Bundle traversal uses shared Inferno core navigation, in-process.
• Extension slice traversal is resolved automatically through extracted metadata.
• Encounter/SurgicalEncounterExample is discovered through metadata-driven navigation without any manual workaround.
• Operation type detection correctly handles compound request type strings.

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Unit Testing

bundle exec rspec
bundle exec rubocop

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UI Testing Steps

Use the v2.2 client and server suites run against each other locally.

What To Verify

PAS profile precedence — must NOT fall back to US Core:

• Encounter/SurgicalEncounterExample → validates against profile-encounter. No 6.1.0 reference should appear.
• ServiceRequest/ReferralRequestExample → validates against profile-servicerequest. No us-core-servicerequest should appear.
• Patient/SubscriberExample → validates against profile-subscriber.

US Core via declared meta.profile:

• DocumentReference/episode-summary → validates against us-core-documentreference|6.1.0.

General:

• No resource that has a PAS profile should fall through to US Core.
• No new errors should appear that were not present before this change.

Regression Check

Run the PAS v2.0.1 suite and confirm:

• No us-core-* profiles appear in validation messages.
• No 6.1.0 references appear anywhere.
• Behavior is identical to before this change.

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Notes

This PR only changes traversal and navigation handling, and operation profile selection logic. The existing validation logic, profile precedence order, US Core fallback behavior, and bundle entry profile map were not modified.