[AZ-493] Cycle 3 batch 3: integration test DB-reset hook

AZ-493 (2 SP): replace the cycle-2 wallclock-seeded _coordinateCounter
workaround with a proper Postgres state-reset hook that runs at
integration test runner startup, eliminating the per-source-unique-index
collision risk that the persistent docker-compose Postgres volume
introduced post-AZ-484.

The reset is split into two surfaces:

* SatelliteProvider.TestSupport.IntegrationTestResetGuard - pure
  static class, I/O-free, unit-tested. Two independent guards: (a)
  ASPNETCORE_ENVIRONMENT must equal "Testing", (b) DB_CONNECTION_STRING
  Host must be in the allowed-host list (postgres, localhost, 127.0.0.1).
  Failure of either guard surfaces a structured operator-friendly
  InvalidOperationException.
* SatelliteProvider.IntegrationTests.IntegrationTestDatabaseReset -
  instance class owning the Npgsql side effects. Calls the guard then
  runs TRUNCATE TABLE route_regions, route_points, routes, regions,
  tiles RESTART IDENTITY CASCADE inside a single Npgsql transaction.

Spec-vs-reality: the task spec prescribed "DB name contains _test" as
Guard 2; the actual compose file uses Database=satelliteprovider and
DB rename is gated on user confirmation per coderule.mdc. Substituted
a Host allowlist as the equivalent guard (intent identical: reject
remote / production hosts). Recorded as Low/Spec-Gap in the review.

Program.cs adds --keep-state CLI flag and INTEGRATION_KEEP_STATE env
var (1/true) opt-outs so a developer can inspect leftover state when
debugging. Startup banner shows which path executed.
docker-compose.tests.yml gets ASPNETCORE_ENVIRONMENT=Testing +
passthrough for INTEGRATION_KEEP_STATE. scripts/run-tests.sh wires the
--keep-state flag through to compose.

UavUploadTests._coordinateCounter wallclock seed is retained as
defense-in-depth (per the task spec's implementer choice). The reset
is the primary isolation path; the seed is the belt-and-suspenders
fallback for --keep-state runs.

8 new unit tests in SatelliteProvider.Tests/TestSupport/
IntegrationTestResetGuardTests.cs cover Production/Staging/missing-env
throw, allowed-host case-insensitivity, disallowed-host rejection
with representative prod hostnames, and the AllowedHosts contract.

tests_integration.md gains a Reliability section that documents the
hook, the two guards, the truncate order, and the three opt-out forms.
module-layout.md TestSupport entry extended with the new pure guard
and the explicit "Npgsql stays in IntegrationTests" boundary.

Test-suite gate (AC-6) deferred to Step 16 Final Test Run per implement
skill convention. Per-batch review verdict: PASS_WITH_WARNINGS with 1
Low (spec-vs-reality on Guard 2, non-blocking).

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/02_document/modules/tests_integration.md

@@ -13,13 +13,15 @@ Console application that runs end-to-end integration tests against a live API in
 - `ExtendedRouteTests` — routes with `requestMaps: true` and tile ZIP creation
 - `MigrationTests` — direct PostgreSQL schema/index validation (no HTTP). AZ-484 cycle added: `NewUniqueConstraintIncludesSourceColumn_AZ484_AC1`, `BackfillUpdateAssignsGoogleMapsAndCapturedAt_AZ484_AC4`, `MultiSourceInsertCoexistsUnderNewIndex_AZ484_AC1`, `MostRecentAcrossSourcesSelection_AZ484_AC2`, `SameSourceUpsertReplacesPreviousRow_AZ484_AC3` (latter four use temp tables to keep production data untouched).
 - `JwtIntegrationTests` (added by AZ-487, cycle 2; helpers consolidated by AZ-491 cycle 3) — `AnonymousRequest_To_AnyEndpoint_Returns401`, `ExpiredToken_Returns401`, `InvalidSignature_Returns401`, `ValidToken_Returns200_OnHealthyEndpoint`, `SwaggerDocument_AdvertisesBearerSecurityScheme`. HS256 token minting lives in the shared `SatelliteProvider.TestSupport.JwtTokenFactory` (consumed via `ProjectReference`); runner-specific concerns (`JwtTestHelpers.ResolveSecretOrThrow`, `AttachDefaultAuthorization`, `DefaultSubject = "integration-tests"`) remain in this project. The test runner sets `JWT_SECRET` on the API container and attaches a Bearer token to every existing test's HTTP requests so the pre-cycle-2 suite continues to pass.
-- `UavUploadTests` (added by AZ-488, cycle 2) — `HappyPathSingleItem_PersistsRow`, `MixedBatch_ReturnsPerItemResults`, `MultiSourceCoexistence_AZ484_Cycle2`, `SameSourceUpsert_AZ484_Cycle2`, `NoToken_Returns401`, `ValidTokenWithoutGpsPermission_Returns403`, `OversizedBatch_Returns400`. Uses a wall-clock-seeded coordinate counter (`_coordinateCounter` initialized from `DateTime.UtcNow`) so each docker-compose run picks a fresh coordinate band — the postgres named volume persists across runs and a naïve `int = 0` counter collided with prior runs on the per-source unique index (fixed mid-Step-11).
+- `UavUploadTests` (added by AZ-488, cycle 2; coordinate-counter promoted to defense-in-depth by AZ-493 cycle 3) — `HappyPathSingleItem_PersistsRow`, `MixedBatch_ReturnsPerItemResults`, `MultiSourceCoexistence_AZ484_Cycle2`, `SameSourceUpsert_AZ484_Cycle2`, `NoToken_Returns401`, `ValidTokenWithoutGpsPermission_Returns403`, `OversizedBatch_Returns400`. The wall-clock-seeded `_coordinateCounter` is retained as a belt-and-suspenders safeguard alongside the AZ-493 startup DB-reset (below) — if a developer runs with `--keep-state`, or the DB-reset path is skipped for any reason, the wall-clock seed still spreads coordinates across runs so the per-source unique index does not collide.
 - `StubAndErrorContractTests` (existing) — updated in cycle 2 to drop the legacy `StubUpload_Returns501` expectation since AZ-488 implemented the endpoint.
 
 ### Supporting Classes
 - `Models.cs` — HTTP response DTOs for deserialization
 - `RouteTestHelpers.cs` — shared utilities (wait-for-completion polling, geofence polygon builders, test data)
-- `Program.cs` — test runner entry point
+- `Program.cs` — test runner entry point (handles `--smoke` / `--full` mode selection, `--keep-state` opt-out flag, default-token issuance via `JwtTokenFactory`, and the AZ-493 DB-reset hook)
+- `JwtTestHelpers.cs` — runner-side JWT concerns (`ResolveSecretOrThrow` reads the `JWT_SECRET` env var with size validation; `AttachDefaultAuthorization` puts a Bearer token on the shared `HttpClient`; `DefaultSubject = "integration-tests"` is the canonical runner subject value). Token *minting* lives in the shared `SatelliteProvider.TestSupport.JwtTokenFactory` (AZ-491) — runner-side concerns deliberately stay here.
+- `IntegrationTestDatabaseReset.cs` (AZ-493) — instance class with a single `EnsureCleanStateAsync()` method that truncates the integration-test target tables in FK-safe order. Guarded via `SatelliteProvider.TestSupport.IntegrationTestResetGuard` (env + Host allowlist) so it cannot run against a non-test database.
 
 ## Internal Logic
 - Makes HTTP calls to the API at `API_URL` environment variable (default: `http://api:8080`)
@@ -28,15 +30,43 @@ Console application that runs end-to-end integration tests against a live API in
 - Validates response structure, status transitions, file creation
 
 ## Dependencies
-- No project references (standalone console app)
-- Communicates with the API exclusively via HTTP
-- NuGet: implicit .NET 8 runtime
+- `ProjectReference` to `SatelliteProvider.TestSupport` (added by AZ-491; provides `JwtTokenFactory`. Added by AZ-493; provides `IntegrationTestResetGuard`).
+- Communicates with the API exclusively via HTTP for end-to-end tests; communicates with PostgreSQL directly only via the dedicated DB-reset hook + the existing `MigrationTests` schema assertions.
+- NuGet: `Npgsql` 9.0.2 (Postgres client for DB-reset + MigrationTests), `SixLabors.ImageSharp` 3.1.11 (UAV fixture image generation).
 
 ## Consumers
 - `docker-compose.tests.yml` — runs as a container that depends on the API service
 
 ## Configuration
 - `API_URL` environment variable (set in docker-compose.tests.yml to `http://api:8080`)
+- `INTEGRATION_TESTS_MODE` — `smoke` or `full` (default `full`). Drives `TestRunMode.Smoke`.
+- `INTEGRATION_KEEP_STATE` — set to `1` or `true` (or pass `--keep-state` to `Program.cs` / `scripts/run-tests.sh`) to skip the AZ-493 DB-reset hook. Useful for debugging a failed run.
+- `ASPNETCORE_ENVIRONMENT=Testing` — guard for the DB-reset hook. The reset refuses to run unless this is set (see Reliability § Test isolation below).
+- `JWT_SECRET` — shared HMAC secret with the API container; must be ≥ 32 bytes (UTF-8).
+- `DB_CONNECTION_STRING` — Npgsql connection string; the reset hook additionally requires the Host to be in the allowed-host list (`postgres`, `localhost`, `127.0.0.1`).
+
+## Reliability
+
+### Test isolation (AZ-493)
+
+`Program.cs` runs `IntegrationTestDatabaseReset.EnsureCleanStateAsync()` at startup, before any test class executes. The hook truncates `route_regions`, `route_points`, `routes`, `regions`, `tiles` (in that FK-safe order, with `RESTART IDENTITY CASCADE`) so each run starts from a known empty state. The Postgres named volume in `docker-compose.yml` is intentionally persisted across `docker-compose down` cycles for fast iteration; the AZ-493 reset hook is what gives back per-run isolation in spite of that.
+
+Two guards protect against accidental truncate against a non-test database:
+
+1. `ASPNETCORE_ENVIRONMENT` MUST equal `Testing` (case-insensitive). Set by `docker-compose.tests.yml`; absent in production / dev.
+2. `DB_CONNECTION_STRING` Host MUST be one of `postgres`, `localhost`, `127.0.0.1`. Set by `docker-compose.tests.yml` and developer machines; a remote-host connection string is rejected even with the env guard satisfied.
+
+Both guards are pure-string checks in `SatelliteProvider.TestSupport.IntegrationTestResetGuard` — unit-tested in `SatelliteProvider.Tests/TestSupport/IntegrationTestResetGuardTests.cs`. Failure of either guard surfaces a clear `InvalidOperationException` and exits the runner with code 1.
+
+To debug leftover state from a failed run, opt out of the reset:
+
+- CLI: `./scripts/run-tests.sh --full --keep-state`
+- Direct: `INTEGRATION_KEEP_STATE=1 docker compose ... up`
+- In the runner Main: `dotnet run --project SatelliteProvider.IntegrationTests -- --keep-state`
+
+### Adding new tables
+
+If a new task adds a table that integration tests insert into AND that table participates in foreign-key relationships with `tiles` / `regions` / `routes`, update `IntegrationTestDatabaseReset.TruncateOrder` to include the new table in FK-safe order. The current order assumes the AZ-484 + AZ-488 schema; future migrations that introduce new FK chains need a corresponding order revision. The `CASCADE` clause is a safety net but is not a substitute for an explicit order — the order is the audit trail for "what does an integration-test runner see at startup".
 
 ## External Integrations
 - HTTP to the SatelliteProvider API