Validate ACP cohort-method recommendations before script generation

[rkboyce]

Problem

The cohort-method shell accepts ACP recommendations from the free-text analytic-parameters step and converts them into effective_analytic_settings, but there is no dedicated validation layer between the ACP response and downstream script generation.

This means malformed, incomplete, or semantically inconsistent ACP output can still flow into:

• analysis-settings/cm_analytic_settings_recommendation.json
• effective_analytic_settings
• generated 06_cm_spec.R
• generated analysisSpecification.json

Current behavior

• ACP recommendations are converted through shell_settings_from_acp_recommendation(...)
• If ACP returns source = acp_flow and status = ok, the mapped settings are used downstream
• There is no explicit schema/semantic validation pass that confirms:
  • required settings are present
  • values are in supported ranges
  • combinations are coherent
  • unsupported fields are surfaced clearly

Risk

• invalid generated scripts
• silent fallback to partial defaults
• hard-to-debug user experience when ACP output is plausible-looking but not executable

Requested change

Add a validation layer for cohort-method analytic recommendations before they are committed to shell state or used for script generation.

Acceptance criteria

• ACP recommendation objects are validated before conversion/use
• validation distinguishes:
  • schema errors
  • unsupported fields
  • semantically inconsistent settings
• the shell surfaces clear actionable messages when validation fails
• invalid recommendations do not silently produce executable-looking output
• tests cover valid, partially valid, and invalid ACP recommendation payloads