# Configurable Route Table - Static Files Serving

## Module
Gateway

## Status
VERIFIED

## Description
The Gateway supports a `StaticFiles` route type that serves directory contents mapped to a URL prefix. Configured via `StellaOpsRoute` with `Type = StaticFiles`, `Path` = URL prefix, `TranslatesTo` = physical directory path. Supports SPA fallback (serving `index.html` for extensionless paths) when the route's `Headers["x-spa-fallback"]` is set to `"true"`. Files are served with correct MIME types via `FileExtensionContentTypeProvider`. Multiple StaticFiles routes can coexist with isolated path scopes.

## Implementation Details
- **Modules**: `src/Router/__Libraries/StellaOps.Router.Gateway/`, `src/Router/StellaOps.Gateway.WebService/`
- **Key Classes**:
  - `StellaOpsRoute` (`src/Router/__Libraries/StellaOps.Router.Gateway/Configuration/StellaOpsRoute.cs`) - Route model with `StellaOpsRouteType.StaticFiles`
  - `StellaOpsRouteResolver` (`src/Router/StellaOps.Gateway.WebService/Routing/StellaOpsRouteResolver.cs`) - First-match-wins route resolution engine
  - `RouteDispatchMiddleware` (`src/Router/StellaOps.Gateway.WebService/Middleware/RouteDispatchMiddleware.cs`) - `HandleStaticFiles` method uses `PhysicalFileProvider` and `FileExtensionContentTypeProvider`
  - `GatewayOptionsValidator` (`src/Router/StellaOps.Gateway.WebService/Configuration/GatewayOptionsValidator.cs`) - Validates StaticFiles route has non-empty TranslatesTo directory path
- **Tests**:
  - `RouteTableIntegrationTests` (`src/Router/__Tests/StellaOps.Gateway.WebService.Tests/Integration/RouteTableIntegrationTests.cs`) - 8 StaticFiles integration tests
  - `GatewayOptionsValidatorTests` (`src/Router/__Tests/StellaOps.Gateway.WebService.Tests/Configuration/GatewayOptionsValidatorTests.cs`) - StaticFiles validation tests

## E2E Test Plan
- [ ] Serve a file from a mapped directory: `GET /app/index.html` returns HTML content with 200 and `Content-Type: text/html`
- [ ] Serve a nested file: `GET /app/assets/style.css` returns CSS content with 200 and `Content-Type: text/css`
- [ ] Return 404 for missing file: `GET /app/missing.txt` returns 404
- [ ] Verify MIME types: `.html` -> `text/html`, `.css` -> `text/css`, `.js` -> `application/javascript`, `.json` -> `application/json`
- [ ] SPA fallback: `GET /app/some/route` (extensionless) returns `index.html` when `x-spa-fallback=true`
- [ ] Multiple mappings isolation: `/app/` and `/docs/` serve from different directories without interference

## Verification
- **Run ID**: run-001
- **Date**: 2026-02-12
- **Method**: Tier 0 source verification + Tier 1 build/code review (224/224 tests pass) + Tier 2a live HTTP API testing
- **Build**: PASS (0 errors, 0 warnings)
- **Tests**: PASS (224/224 Gateway tests pass)
- **Tier 2a Evidence**: `docs/qa/feature-checks/runs/gateway/configurable-route-table-static-files-serving/run-001/tier2-api-check.json`
- **Verdict**: PASS