/migrate compare — Compare Migration Approaches

Compare migration approaches side-by-side. The user provides a comparison topic as an argument (e.g., /migrate compare PaaS vs IaaS, /migrate compare SQL MI vs SQL VM).

Instructions

1. Parse the Comparison Topic

The user's argument describes what to compare. Common comparisons include:

• PaaS vs IaaS — Azure App Service vs Azure VMs for Sitecore hosting
• SQL MI vs SQL VM — Azure SQL Managed Instance vs SQL Server on Azure VM
• Solr vs Azure Search — Solr on VM/AKS vs Azure Cognitive Search
• Front Door vs App Gateway — Azure Front Door vs Application Gateway for CD traffic
• Redis tiers — Basic vs Standard vs Premium vs Enterprise Azure Cache
• VM vs AKS — VM-based deployment vs containerized on AKS
• ExpressRoute vs VPN — Private connectivity options
• Blob vs DB media — Azure Blob Storage vs database for Sitecore media

If the comparison topic is unclear, ask the user to clarify.

2. Load Context

1. Call get_assessment with project_path (current working directory). Fall back to .migration/assessment.json for project context.
2. Call get_discovery with the assessment ID for relevant discovery data. Fall back to reading .migration/discovery/ files.
3. Read relevant knowledge files from skills/migrate-knowledge/knowledge/
4. Read skills/migrate-knowledge/heuristics/base-effort-hours.json for effort differences

3. Build Comparison

For each approach being compared, evaluate:

Migration Effort

• Base hours for each approach
• Additional complexity or simplification
• Skills required (different role mix?)

Operational Cost

• Estimated monthly Azure cost range
• Cost scaling characteristics (linear vs step)
• Reserved instance / savings plan applicability

Risk

• Migration risk (what can go wrong during migration)
• Operational risk (what can go wrong in steady state)
• Vendor lock-in considerations

Sitecore Compatibility

• Official support status
• Known limitations or workarounds
• Community experience and documentation

Timeline Impact

• Does this approach change the critical path?
• Setup/provisioning lead time
• Learning curve for the team

Operational Complexity

• Day-to-day management overhead
• Monitoring and alerting differences
• Patching and update responsibilities
• Scaling behavior

4. Generate Recommendation

Based on the project's specific context (topology, scale, requirements):

• Identify which approach best fits THIS migration
• Explain why, referencing specific discovery data
• Note any conditions that would change the recommendation
• Present trade-offs honestly — there's rarely a universally "right" answer

5. Write Comparison File

Write .migration/comparisons/<comparison-name>.json:

{
  "generated_at": "ISO date",
  "topic": "SQL MI vs SQL VM",
  "options": [
    {
      "name": "Azure SQL Managed Instance",
      "migration_effort": { "hours_delta": 0, "notes": "Baseline approach" },
      "monthly_cost_range": "$X - $Y",
      "risk_level": "medium",
      "sitecore_compatibility": "Full — near-100% SQL Server compatibility",
      "timeline_impact": "Standard",
      "pros": ["Managed service", "Built-in HA", "Automated backups", "No OS patching"],
      "cons": ["Higher base cost", "Some SQL features unavailable", "Dedicated subnet required"],
      "best_when": "Standard Sitecore deployment without exotic SQL features"
    },
    {
      "name": "SQL Server on Azure VM",
      "migration_effort": { "hours_delta": 16, "notes": "Additional OS-level DB management setup" },
      "monthly_cost_range": "$X - $Y",
      "risk_level": "medium",
      "sitecore_compatibility": "Full — identical to on-prem SQL Server",
      "timeline_impact": "Slightly longer due to OS-level setup",
      "pros": ["Full SQL Server feature set", "Lower base cost at small scale", "Full control"],
      "cons": ["OS patching responsibility", "Manual HA setup", "Manual backup config"],
      "best_when": "Requires SQL features not in MI, or team prefers full control"
    }
  ],
  "recommendation": {
    "preferred": "Azure SQL Managed Instance",
    "rationale": "For this deployment with...",
    "conditions": "Would change to SQL VM if..."
  },
  "context_factors": {
    "database_count": 12,
    "ha_required": true,
    "total_size_gb": 150
  }
}

6. Present Results

Display as a side-by-side comparison:

Comparison: SQL MI vs SQL Server on Azure VM
════════════════════════════════════════════

                    SQL Managed Instance    SQL Server on VM
─────────────────   ────────────────────    ────────────────
Migration Effort    Baseline               +16 hours
Monthly Cost        $X–$Y/mo               $X–$Y/mo
Risk Level          Medium                  Medium
Sitecore Compat.    Full (near-100%)        Full (100%)
HA Approach         Built-in (BC tier)      Manual Always On AG
Patching            Automated               Manual
Timeline Impact     Standard                +1 week

Recommendation: SQL Managed Instance
Rationale: ...

If the user didn't specify a comparison topic or the argument is empty, show available comparison topics and ask them to choose.