# Architecture Compliance Baseline

**Date**: 2026-05-10
**Mode**: Baseline (Phase 1 + Phase 7)
**Scope**: Full existing codebase
**Verdict**: PASS_WITH_WARNINGS (baseline) → all findings resolved by epic AZ-309

## Findings

| # | Severity | Category | File:Line | Title | Status |
|---|----------|----------|-----------|-------|--------|
| 1 | High | Architecture | SatelliteProvider.Services/TileService.cs:11 | Concrete dependency on GoogleMapsDownloaderV2 bypasses ISatelliteDownloader | Resolved (pre-AZ-309 cleanup) |
| 2 | High | Architecture | SatelliteProvider.Common/Interfaces/ISatelliteDownloader.cs | ISatelliteDownloader interface is dead code | Resolved (pre-AZ-309 cleanup) |
| 3 | Medium | Architecture | SatelliteProvider.Api/Program.cs:141 | API endpoint directly injects concrete downloader + repository | **Resolved by AZ-310 + AZ-311** (commit 8b0ddae's parent) |
| 4 | Medium | Architecture | SatelliteProvider.Services/ | No physical boundary between logical components in shared project | **Resolved by AZ-312 + AZ-313 + AZ-314** (commit `8b0ddae`) |
| 5 | Low | Architecture | module-layout.md | DataAccess documented as importing Common but actually has zero cross-project dependencies | **Resolved by AZ-315** (this commit) — module-layout.md now reflects the actual no-import layout |

## Finding Details

**F1: Concrete dependency on GoogleMapsDownloaderV2** (High / Architecture)
- Location: `SatelliteProvider.Services/TileService.cs:11`
- Description: `TileService` depends on the concrete class `GoogleMapsDownloaderV2` instead of `ISatelliteDownloader`. DI registration is also concrete (`AddSingleton<GoogleMapsDownloaderV2>()`). This couples the entire tile pipeline to a single provider.
- Impact: Adding a new satellite imagery provider requires modifying TileService and Program.cs DI wiring rather than just registering a new implementation.
- Suggestion: Have `GoogleMapsDownloaderV2` implement `ISatelliteDownloader`, update DI to register via interface, inject interface into TileService.

**F2: ISatelliteDownloader is dead code** (High / Architecture)
- Location: `SatelliteProvider.Common/Interfaces/ISatelliteDownloader.cs`
- Description: The interface exists (declares `GetTiles(GeoPoint, double, int, CancellationToken)`) but NO class implements it and NO code references it. The actual downloader method used is `GoogleMapsDownloaderV2.GetTilesWithMetadataAsync()` which has a different signature.
- Impact: The provider-agnostic abstraction doesn't function. Interface and implementation have diverged.
- Suggestion: Update `ISatelliteDownloader` to match the actual API surface needed by consumers, then implement it in `GoogleMapsDownloaderV2`.

**F3: API endpoint bypasses service layer** (Medium / Architecture) — **RESOLVED**
- Location: `SatelliteProvider.Api/Program.cs:141` (`ServeTile`) and `:206` (`GetTileByLatLon`)
- Description: Two API endpoints directly inject `GoogleMapsDownloaderV2` and `ITileRepository` instead of using `ITileService`. This bypasses the service layer and creates a shortcut from Layer 4 to Layer 2.
- Impact: Business logic (caching, dedup) in TileService is bypassed for these endpoints; tile download logic is duplicated.
- Suggestion: Route all tile operations through `ITileService`.
- **Resolution (AZ-310 + AZ-311)**: `ITileService` extended with `GetOrDownloadTileAsync` and `DownloadAndStoreSingleTileAsync`; both endpoints now inject only `ITileService`. Caching (IMemoryCache), repository lookup, and downloader fallback consolidated inside TileService. Verified by 5 new unit tests + smoke integration.

**F4: No physical boundary in Services project** (Medium / Architecture) — **RESOLVED**
- Location: `SatelliteProvider.Services/` (all files)
- Description: Three logical components (TileDownloader, RegionProcessing, RouteManagement) share one `.csproj`. No compiler-enforced boundary prevents direct cross-component coupling.
- Impact: Over time, services may accumulate hidden coupling that's hard to detect without code review.
- Suggestion: Accept as-is for current scale; consider splitting into separate projects if the codebase grows significantly.
- **Resolution (AZ-312 + AZ-313 + AZ-314, commit `8b0ddae`)**: Project split into `SatelliteProvider.Services.TileDownloader`, `SatelliteProvider.Services.RegionProcessing`, `SatelliteProvider.Services.RouteManagement`. None of the three references another sibling — cross-sibling calls now flow exclusively through interfaces in `SatelliteProvider.Common.Interfaces`. `RateLimitException` relocated to `SatelliteProvider.Common.Exceptions` to keep the sibling boundary clean. Per-component DI extension methods (`AddTileDownloader`, `AddRegionProcessing`, `AddRouteManagement`) registered from `Program.cs`. Verified by 0 build errors, 40/40 unit tests, and full smoke integration suite passing post-split.

**F5: module-layout.md incorrect — DataAccess has no Common dependency** (Low / Architecture) — **RESOLVED**
- Location: `_docs/02_document/module-layout.md`
- Description: DataAccess was documented as "Imports from: Common" but `SatelliteProvider.DataAccess.csproj` has no ProjectReference to Common and no `using SatelliteProvider.Common` in any file.
- Impact: Documentation inaccuracy; no code impact.
- Suggestion: Correct module-layout.md.
- **Resolution (AZ-315)**: `module-layout.md` now lists DataAccess Imports from: (none); the §Verification section calls out the no-Common-dependency invariant explicitly.

## Summary

| Severity | Count (baseline) | Count (post AZ-309) |
|----------|------------------|---------------------|
| Critical | 0 | 0 |
| High | 2 | 0 |
| Medium | 2 | 0 |
| Low | 1 | 0 |

The two High findings both relate to the same root cause: the `ISatelliteDownloader` abstraction was created but never wired into the system. The concrete `GoogleMapsDownloaderV2` is used directly everywhere. This is the primary architecture gap — addressing it would enable the provider-agnostic design the system intends to have.

## Post-AZ-309 Status

Epic AZ-309 (architecture coupling refactor) closes all five baseline findings:
- F1, F2 — pre-AZ-309 cleanup (interface implementation + DI rewire).
- F3 — AZ-310 + AZ-311 (route tile endpoints through `ITileService`).
- F4 — AZ-312 + AZ-313 + AZ-314 (split monolithic Services csproj into three per-component csprojs with compiler-enforced sibling boundary).
- F5 — AZ-315 (this commit; documentation now matches actual ProjectReference graph).

No new Architecture findings were introduced by the refactor. The baseline is now clean.