# Game server (`NeonSprawl.Server`)

ASP.NET Core **.NET 10** host for authoritative simulation (prototype: HTTP + health + position state via in-memory **or** PostgreSQL).

## Prerequisites

- **.NET 10 SDK** (matches `TargetFramework` in `NeonSprawl.Server.csproj`). Check with `dotnet --list-sdks`.

## Run

```bash
cd server/NeonSprawl.Server
dotnet run
```

- Default URL is printed by Kestrel (see `Properties/launchSettings.json`, typically `http://localhost:5253`).
- Check `GET /health` for a JSON heartbeat.

## Position persistence (NEO-8)

When **`ConnectionStrings:NeonSprawl`** is set to a valid PostgreSQL connection string, the server uses the **`player_position`** table (relational columns `pos_x` … `sequence`, not JSONB). DDL lives in [`server/db/migrations/V001__player_position.sql`](../db/migrations/V001__player_position.sql); the app applies that script on startup and on first store use (idempotent `CREATE TABLE IF NOT EXISTS`). The configured dev player (`Game:DevPlayerId` / `Game:DefaultPosition`) is seeded once at host startup, matching the in-memory store’s constructor seed (not on every HTTP request).

If **`ConnectionStrings:NeonSprawl`** is missing or blank, behavior matches NEO-6/NEO-7 (**in-memory** only). The **test** project’s `postgres.runsettings` sets `ConnectionStrings__NeonSprawl` for the test host so Postgres integration tests run in CI/Rider/`dotnet test`; non-Postgres tests use `InMemoryWebApplicationFactory` and do not require a live DB. Remove or rename `postgres.runsettings` (and the `RunSettingsFilePath` property) if you want those three tests to **skip** again when the variable is unset.

**Environment variables** (typical — same mapping as other ASP.NET Core config):

| Mechanism | Example |
|-----------|---------|
| Shell / CI | `export ConnectionStrings__NeonSprawl='Host=localhost;Port=5432;Database=neon_sprawl;Username=neon_sprawl;Password=neon_sprawl_dev'` |
| User secrets | `dotnet user-secrets set ConnectionStrings:NeonSprawl "<connection string>"` (run from `server/NeonSprawl.Server`) |

Match credentials with [root `docker-compose.yml`](../../docker-compose.yml) for local development.

**Restart check (acceptance criteria):** start Postgres (`docker compose up -d` from repo root), set the connection string, `dotnet run`, `POST …/move`, stop the server, `dotnet run` again, `GET …/position` should return the last committed state.

**Postgres integration tests** require `ConnectionStrings__NeonSprawl` (set automatically in [`.github/workflows/dotnet.yml`](../../.github/workflows/dotnet.yml)). The test project sets this via **`NeonSprawl.Server.Tests/postgres.runsettings`** (`RunSettingsFilePath` in the `.csproj`) so **`dotnet test`** and **Rider** pick it up without shell `export`. **`launchSettings.json`** in the same project is for IDE launch profiles and is **not** the xUnit “config file” in Rider settings.

**Contributors / PRs:** With **`postgres.runsettings`** checked in, **`dotnet test`** always injects that connection string, so the **three Postgres integration tests run** (they are **not** skipped). If nothing is listening on Postgres and **Docker** cannot start Compose (or you have no DB), those tests **fail**—that is expected, not a random flake. **Mitigations:** `docker compose up -d` from the repo root (tests may auto-start Compose locally when not in CI), or temporarily remove **`RunSettingsFilePath`** from `NeonSprawl.Server.Tests.csproj` while hacking. **GitHub Actions** provides Postgres in [`.github/workflows/dotnet.yml`](../../.github/workflows/dotnet.yml), so merges stay green when the workflow runs.

**Rider:** Under **Settings → … → Unit Testing → xUnit.net**, leave **“Use specific configuration file”** off unless you add a real **`xunit.runner.json`**. Do **not** point that field at `launchSettings.json`.

**Local Docker (optional automation):** When **not** in CI (`CI`, `GITHUB_ACTIONS`, `GITLAB_CI`, `TF_BUILD`), the Postgres test harness tries to connect first. If the server is unreachable, it runs **`docker compose up -d`** from the repo root (same compose file as [root `docker-compose.yml`](../../docker-compose.yml)), waits for the DB, runs tests, then runs **`docker compose down`** **only if** it started Compose itself. If Postgres was already listening (existing container or native install), tests do **not** stop your database afterward. Initialization is **async** (no sync-over-async on the xUnit sync context) so **Rider** / **Visual Studio** do not leave Postgres tests stuck **Pending** after Compose starts.

## Position state (NEO-6)

Authoritative player position is served over HTTP whether the backing store is **in memory** or **PostgreSQL** (NEO-8). The HTTP JSON shape is versioned with top-level `schemaVersion` (see XML docs on `PositionStateResponse` in the server project). Path `{id}` is **trimmed** and matched **case-insensitively** against stored players; `playerId` in the JSON body echoes the path segment from the request. Stored player ids use **invariant lowercase + trim** in Postgres for lookup parity.

Example (dev player id defaults to `dev-local-1` in `appsettings.json`):

```bash
curl -s http://localhost:5253/game/players/dev-local-1/position
```

Sample response (default spawn matches Godot capsule and NEO-9 walk-in range demo):

```json
{"schemaVersion":1,"playerId":"dev-local-1","position":{"x":-5,"y":0.9,"z":-5},"sequence":0}
```

Unknown player ids return **404**. Full zone sync / replication is still out of scope for these spikes.

## Move command (NEO-7, NEO-10)

**`POST /game/players/{id}/move`** with JSON body applies a v1 **MoveCommand**: authoritative position **snaps** to `target` immediately; `sequence` in responses increases by one per successful apply.

**`POST /game/players/{id}/move-stream` (NEO-22):** JSON body **`MoveStreamRequest`** (`schemaVersion` **1**, **`targets`**: ordered array of world positions, max **24** per request). The server **validates the entire chain** against **`Game:MovementValidation`** (same rules as a single move) **before** applying anything, then applies each target in order; **`sequence`** increases by **one per applied target**. Response body matches **`PositionStateResponse`**. On the first failing leg the handler returns **400** with **`MoveCommandRejectedResponse`** and **does not** change stored position.

**Client navigation (NEO-11):** The Godot prototype uses a **baked navigation mesh** for **local** vertical routing / step assist when applicable; **WASD** sends **`move-stream`** samples and the server validates **straight-line** legs (NEO-10) from the **last authoritative position** to each **requested** position. The server does **not** simulate navmesh. Cheating or divergent paths are out of scope for this slice.

**NEO-10 validation (reject-only):** Before applying, the server checks the move against **`Game:MovementValidation`**. Limits use **horizontal** distance on **X/Z** only and **|ΔY|** separately (see `MoveCommandValidation`). Unknown players return **404** before validation.

| Config key | Meaning | Default (see `appsettings.json`) |
|------------|---------|-----------------------------------|
| `Game:MovementValidation:MaxHorizontalStep` | Max XZ displacement per command (m); inclusive at limit | `18` |
| `Game:MovementValidation:MaxVerticalStep` | Max absolute Y delta per command (m); inclusive | `2.2` |
| `Game:MovementValidation:DistrictBoundsEnabled` | Axis-aligned box on **target** (inclusive min/max) | `false` |
| `Game:MovementValidation:DistrictMinX` … `DistrictMaxZ` | District extents when enabled | ±12 / Y −2…24 |

**Manual QA (Godot `main.tscn`):** **Green bumps** are **two random short cylinders** each run (~**8–14 cm** rise) and stay under default `MaxVerticalStep` from the dev spawn; **orange reject pedestal** top is ~**2.5 m** above floor so **`move-stream`** from the floor into the pedestal still yields **`vertical_step_exceeded`** (default `MaxVerticalStep` is **2.2 m**); the **physics ramp test block** top is **2 m** so streaming from it toward the floor is **accepted**. **Far pad** is beyond default horizontal reach for **`horizontal_step_exceeded`** when horizontal limits are enabled.

Request body (example):

```bash
curl -s -X POST http://localhost:5253/game/players/dev-local-1/move \
  -H "Content-Type: application/json" \
  -d '{"schemaVersion":1,"target":{"x":1.5,"y":0,"z":-2}}'
```

- **200** — body matches **`PositionStateResponse`** (same shape as `GET` … `/position`).
- **400** — malformed command (missing/invalid body or wrong `schemaVersion`) **or** move rejected by NEO-10 rules. Rejection responses are JSON **`MoveCommandRejectedResponse`**: `schemaVersion` (`1`) + **`reasonCode`** (`horizontal_step_exceeded`, `vertical_step_exceeded`, `out_of_bounds`). Malformed requests return **400** with **no** rejection body.
- **404** — unknown player id.

See XML on `MoveCommandRequest`, `PositionStateResponse`, and `MoveCommandRejectedResponse` in the server project.

For a **PR-ready** contract blurb (formatted JSON + field table), see the [NEO-6 implementation plan — Pull request description](../../docs/plans/NEO-6-implementation-plan.md#pull-request-description-linear-ac) (GET shape) and [NEO-7 implementation plan](../../docs/plans/NEO-7-implementation-plan.md#pull-request-description-linear-ac--draft-for-merge) (MoveCommand + sequence semantics). NEO-10: [NEO-10 implementation plan](../../docs/plans/NEO-10-implementation-plan.md).

## Interaction (NEO-9)

**`POST /game/players/{id}/interact`** with a versioned **InteractionRequest** body asks whether the given player may use a prototype interactable **now**. The server reads **authoritative** `PositionState` from `IPositionStateStore` (same id rules as position APIs: trim + ordinal case-insensitive match). **Horizontal reach** uses **X and Z only**; **Y is ignored** for distance (floor-plane prototype). See `HorizontalReach` in `NeonSprawl.Server/Game/World/` and `PrototypeInteractableRegistry` in `Game/Interaction/`.

Request (example):

```bash
curl -s -X POST http://localhost:5253/game/players/dev-local-1/interact \
  -H "Content-Type: application/json" \
  -d '{"schemaVersion":1,"interactableId":"prototype_terminal"}'
```

**HTTP**

| Status | Meaning |
|--------|---------|
| **200** | Body is **InteractionResponse** v1: `allowed: true` (optional `payload`, `interactableId` echo) or `allowed: false` with required **`reasonCode`**. |
| **400** | Not a valid v1 attempt (bad/missing `schemaVersion`, malformed JSON, missing **`interactableId`**, or empty after trim). |
| **404** | Unknown **player** only (no row in the position store). |

**`reasonCode` (v1, when `allowed` is false)**

| Code | When |
|------|------|
| `out_of_range` | Horizontal distance on X/Z is **greater than** the interactable’s `interactionRadius` (on the radius is **allowed** — inclusive `<=`). |
| `unknown_interactable` | Id not in the prototype registry (after trim + case-insensitive lookup). |

When **`allowed` is `true`**, **`reasonCode` is omitted** (clients must not require it on success). Unknown player never returns this JSON — use **404**.

Contract details and PR blurb: [NEO-9 implementation plan](../../docs/plans/NEO-9-implementation-plan.md).

## Targeting (NEO-23)

Authoritative **combat target lock** (prototype): **`GET /game/players/{id}/target`** returns **`PlayerTargetStateResponse`** v1; **`POST /game/players/{id}/target/select`** accepts **`TargetSelectRequest`** v1 and returns **`TargetSelectResponse`** v1. Player id rules match position/interact (trim + ordinal case-insensitive lookup in the in-memory store). **Horizontal lock range** uses **`HorizontalReach`** on **X/Z only** (inclusive radius), same floor-plane policy as NEO-9.

**Soft lock:** the server keeps the persisted **`lockedTargetId`** until clear or a successful swap. If the player moves out of stub range, **`validity`** becomes **`out_of_range`** on **`GET`** and on **`POST`** echoes until they move back in range, clear, or select another valid target (see [NEO-23 implementation plan](../../docs/plans/NEO-23-implementation-plan.md)).

Stub registry: `PrototypeTargetRegistry` in `NeonSprawl.Server/Game/Targeting/` — ids **`prototype_target_alpha`**, **`prototype_target_beta`** (ascending id order for future tab cycle).

**`GET /game/players/{id}/target`**

| Field | Meaning |
|--------|--------|
| `schemaVersion` | `1` |
| `playerId` | Echo of route `{id}` |
| `lockedTargetId` | Lowercase stub id when locked; JSON **`null`** when no lock (**key always present**) |
| `validity` | `none` (no lock), `ok`, `out_of_range`, or `invalid_target` (unknown id in store — should not occur in normal use) |
| `sequence` | Increments when the persisted lock **id** changes (clear or swap); unchanged on idempotent re-select of the same id |

**`POST /game/players/{id}/target/select`** — body `schemaVersion` (`1`), optional **`targetId`**. Omit **`targetId`** or send JSON **`null`** to **clear** the lock. Non-null **`targetId`** is trimmed; **whitespace-only** after trim → **400**.

Examples:

```bash
curl -s http://localhost:5253/game/players/dev-local-1/target
```

```bash
curl -s -X POST http://localhost:5253/game/players/dev-local-1/target/select \
  -H "Content-Type: application/json" \
  -d '{"schemaVersion":1,"targetId":"prototype_target_alpha"}'
```

**HTTP**

| Status | Meaning |
|--------|---------|
| **200** | **GET:** `PlayerTargetStateResponse` v1. **POST:** `TargetSelectResponse` v1 with **`targetState`** always set; **`selectionApplied`** `true` or `false`; when `false`, required **`reasonCode`**. |
| **400** | Invalid v1 body (wrong `schemaVersion`, malformed JSON, or **`targetId`** whitespace-only when provided). |
| **404** | Unknown **player** only (same as interact). |

**`reasonCode` (POST v1, when `selectionApplied` is `false`)**

| Code | When |
|------|------|
| `unknown_target` | Id not in the prototype target registry (after trim + case-insensitive lookup). |
| `out_of_range` | Horizontal distance on X/Z is **greater than** the target’s `lockRadius` (on the radius is **allowed** — inclusive `<=`). |

When **`selectionApplied` is `true`**, **`reasonCode` is omitted** (clients must not require it on success).

## Solution

From repo root: `dotnet build NeonSprawl.sln` and `dotnet test NeonSprawl.sln`.

## CI

Pull requests targeting `main` run build and tests via [`.github/workflows/dotnet.yml`](../.github/workflows/dotnet.yml) on GitHub Actions (`ubuntu-latest` runner, **Release** configuration).

## Linux + Rider: “only 8.x in /usr/share/dotnet”

If the debugger prints **`.NET location: /usr/share/dotnet`** and **cannot find `Microsoft.NETCore.App` 10.x** while you have .NET 10 under **`~/.dotnet`**:

- **`launchSettings.json` `environmentVariables`** (e.g. `DOTNET_ROOT`) often do **not** apply to the **native apphost** Rider launches first; the host probes `/usr/share/dotnet` before your app starts.
- This repo sets **`<UseAppHost>false</UseAppHost>`** for **Debug** builds so the IDE runs **`dotnet …/NeonSprawl.Server.dll`** using the **.NET CLI** you configured in the toolchain (**`/home/don/.dotnet/dotnet`**), which then loads the 10.x shared runtime from the same install.
- Alternatives: install [.NET 10 into the default location](https://learn.microsoft.com/en-us/dotnet/core/install/linux) so `/usr/share/dotnet` has 10.x, or add **`DOTNET_ROOT=/home/don/.dotnet`** in **Run → Edit Configurations → Environment variables** (IDE-level, not only `launchSettings.json`).