# Implementation Questions

**Purpose**: Track questions and ambiguities discovered during plan generation that require follow-up before or during implementation.

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## Open Questions

### Phase 0: Solution Skeleton

| # | Question | Context | Impact | Status |
|---|----------|---------|--------|--------|
| Q1 | What .NET version should we target? (.NET 8 LTS or .NET 9?) | Affects available APIs, Akka.NET compatibility, and support lifecycle. | Phase 0 — must decide before creating solution. | Open |
| Q2 | What Akka.NET version? (v1.5.x stable or preview features?) | Affects hosting APIs, serialization options, and cluster features. | Phase 0 — must decide before creating solution. | Open |
| Q3 | Should we use a monorepo (single .sln) or separate repos per component? | Affects CI/CD, versioning, and developer workflow. Monorepo recommended for a tightly coupled system. | Phase 0. | Open |
| Q4 | What CI/CD platform? (GitHub Actions, Azure DevOps, Jenkins, etc.) | Affects pipeline configuration in Phase 0. | Phase 0. | Open |

### Phase 1: Central Foundations

| # | Question | Context | Impact | Status |
|---|----------|---------|--------|--------|
| Q5 | What LDAP server will be used for dev/test? (Real AD, lightweight LDAP like OpenLDAP, or mock?) | Affects integration test setup for Security & Auth. | Phase 1 — needed for auth development. | Open |
| Q6 | What MS SQL version and hosting? (SQL Server 2019/2022, Azure SQL, local?) | Affects EF Core provider and connection string configuration. | Phase 1 — needed for Config DB. | Open |
| Q7 | Should the JWT signing key be stored in appsettings.json, Azure Key Vault, or elsewhere? | Affects security posture and operational procedures. Currently specified as "configuration." | Phase 1. | Open |

### Phase 3: Site Execution

| # | Question | Context | Impact | Status |
|---|----------|---------|--------|--------|
| Q8 | Is a real OPC UA server available for dev/test, or do we need a simulator? | Affects Data Connection Layer development. Best practices doc recommends mock protocol adapters. | Phase 3 — needed for DCL development. | Open |
| Q9 | What is the custom protocol? Is there an existing specification or SDK? | The design mentions "custom protocol" as a second adapter alongside OPC UA. Need details to implement. | Phase 3. | Open |
| Q10 | What is the target site hardware? (Server specs, network topology between nodes) | Affects performance tuning and Akka.NET dispatcher configuration. | Phase 3, Phase 8. | Open |

### Phase 7: Integrations

| # | Question | Context | Impact | Status |
|---|----------|---------|--------|--------|
| Q11 | Are there specific external systems (MES, recipe manager) to integrate with for initial testing? | Affects External System Gateway and Inbound API test scenarios. | Phase 7. | Open |
| Q12 | What Microsoft 365 tenant/app registration is available for SMTP OAuth2 testing? | Affects Notification Service OAuth2 implementation. | Phase 7. | Open |

### Cross-Phase

| # | Question | Context | Impact | Status |
|---|----------|---------|--------|--------|
| Q13 | Who is the development team? (Size, experience with Akka.NET, availability) | Affects phase sizing, parallelization, and timeline estimates. | All phases. | Open |
| Q14 | Is there an existing deployment target environment for early pilot testing? | Affects Phase 4 (minimal UI for pilot operations) timing. | Phase 4+. | Open |
| Q15 | Should the Machine Data Database schema be designed in this project, or is it out of scope? | HighLevelReqs 2.1 mentions it but no component owns it. | Phase 3 or later. | Open |

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## Resolved Questions

| # | Question | Resolution | Date |
|---|----------|------------|------|
| — | (none yet) | — | — |