# Neon Sprawl — Godot client

Open this **`client/`** directory as a project in **Godot 4.6** (4.x compatible). Use the **standard** Godot build (not the .NET build)—client code is **GDScript** (`.gd`).

- Main scene: `scenes/main.tscn` (bootstrap `scripts/main.gd`).
- Networking will use **WebSocket** or **TCP** to the C# server; authoritative logic stays on the server per [`docs/architecture/tech_stack.md`](../docs/architecture/tech_stack.md).

## Script organization (repo policy)

Do not grow an all-in-one **`main.gd`**. The main scene root should **compose** child nodes and scripts; put picking, server sync, and similar features in **dedicated scripts** (typically under `scripts/`) and connect via **signals** or small APIs. Use **Autoloads** only when several scenes truly need the same global. Full guidance for contributors and tooling: [`.cursor/rules/godot-client-script-organization.md`](../.cursor/rules/godot-client-script-organization.md).

**Tests with script changes:** Any PR that adds or changes GDScript under **`scripts/`** should **add or update** tests under **`test/`** in the same change set (see [`.cursor/rules/testing-expectations.md`](../.cursor/rules/testing-expectations.md)). CI runs them via **`.github/workflows/gdscript.yml`**.

## Follow camera (NEO-15)

The main scene uses **`World/IsometricFollowCamera`** (`scripts/isometric_follow_camera.gd`): client-local **isometric follow** for **`Player`** (`NodePath` **`../Player`**), with damped eye motion (`follow_smoothness`, exponential lerp) and **teleport snap** when the eye is farther than **`snap_distance`** from the desired pose (e.g. after **`snap_to_server`**). Framing exports **`follow_distance`**, **`pitch_elevation_deg`**, and **`presentation_yaw_deg`** match the pre–NEO-15 static camera at spawn. **Orbit is off in the prototype:** **`allow_yaw`** is false, **`CameraState.yaw`** stays **0**, and no rotate input is read—enable **`allow_yaw`** later and drive **`_orbit_yaw_rad`** from input on the rig (see **`docs/decomposition/modules/E1_M2_IsometricCameraController.md`**). **`CameraState`** (`scripts/camera_state.gd`) is refreshed every **`_physics_process`** tick on the rig (**`process_physics_priority`** after **`Player`**) so framing tracks **`move_and_slide`** without display-vs-physics jitter.

## Prototype district (NEON-29)

The default play space is a **45 × 45** unit flat floor (~2 000 sq units, ~5× the pre-NEON-29 footprint). All geometry lives under `World/NavigationRegion3D` in `scenes/main.tscn`; `main.gd` rebakes the nav mesh at startup so the scene-file vertices are intentionally stale.

### Props at a glance

Elevated walkables use **distinct albedo tints** in `scenes/main.tscn` so screenshots and discussion can name the right prop (`Mat_terrace_platform_a`, `Mat_terrace_b_step`, etc.). The main **floor** slab uses neutral gray (`Mat_floor_slab`). **Occluders** keep the default mesh gray.

| Node | Group | Tint | Size (m) | World XZ | Purpose |
|------|-------|------|----------|----------|---------|
| `Floor` | `walkable` | Neutral gray | 45 × 45 | (0, 0) | Main play surface |
| `PrototypeTerminal` | `walkable` | Slate blue | 0.9 × 0.4 | (0, 0) | Interaction target |
| `MoveRejectPedestal` | `walkable` | Orange | 1.5 × 1.5 | (7.5, −6.5) | NEON-7 vertical reject |
| `MoveRejectFarPad` | `walkable` | Blue-gray | 2.5 × 2.5 | (9, 9) | Near-floor walkable pad; no longer a reject target (horizontal limit removed NEON-29) |
| `Obstacle` | `occluder` | Default gray | 2 × 2 | (6, 5) | Occlusion policy demo |
| `ObstacleB` | `occluder` | Default gray | 3 × 3 | (−10, 5) | Second occluder (wider angle from spawn) |
| `ObstacleC` | `occluder` | Default gray | 2 × 4 | (5, −12) | Tall occluder, south quadrant |
| `ObstacleD` | `occluder` | Default gray | 3 × 2 | (−8, −16) | Far-south occluder |
| `TerracePlatformA` | `walkable` | **Teal** | 10 × 10, h=0.3 m | (13, −14) | Large SE pad; **three darker-teal approach treads per cardinal** (`TerracePlatformA_Approach` / `PAS_*`) — **1.0 m run** along the climb axis (~0.104 m rise each), wider than the **0.8 m** capsule diameter so the body is not wider than each tread |
| `TerraceStepB` | `walkable` | **Gold** | 6 × 3, h=0.3 m | (−15, 8.5) | NW approach step; **`TerraceStepB_Approach`** / `TSB_*` — three treads per **S/E/W** (darker gold), **1.0 m** run on NS arms |
| `TerracePlatformB` | `walkable` | **Violet** | 6 × 6, h=0.6 m | (−15, 13) | Upper NW terrace; **`TerracePlatformB_Approach`** / `TPB_*` — **six** treads per **N/E/W** (~0.104 m rise) for **0.6 m** to floor (**south** uses gold step, not violet treads) |
| `TerracePlatformC` | `walkable` | **Green** | 8 × 8, h=0.3 m | (14, 14) | NE pad; **`TerracePlatformC_Approach`** / `PCS_*` — same tread pattern as teal (`PAS_*`), darker green albedo |

### Height variation notes

- **Single-step terraces (A, C):** 0.3 m rise — within `agent_max_climb = 0.35`, so the nav mesh routes directly from floor onto the pad; one steady WASD approach suffices. **`TerracePlatformA`** (teal) sits **12 mm** above the main floor slab and has **cardinal walkable treads** (`TerracePlatformA_Approach`) so movement does not rely on a bare vertical box lip; nav rebakes at startup.
- **Two-level terrace B:** floor → `TerraceStepB` (**gold**, 0.3 m) → `TerracePlatformB` (**violet**, +0.3 m). **`agent_max_climb = 0.35`** applies to the nav mesh **and** to **walk step assist**: you cannot cheese the violet deck from the floor in one move — use the **gold step** (or the platform after you are already on the step), not the violet top from below. **Approach treads** on gold (**`TSB_*`**) and on violet’s **north / east / west** (**`TPB_*`**, six risers for 0.6 m) match the teal convention.
- **QA / thin props:** **`PrototypeTerminal`**, **`MoveRejectPedestal`**, **`MoveRejectFarPad`** are unchanged (terminal kiosk, vertical reject demo, near-floor pad). Add ramps or treads later if they need full walk-up treatment.
- **Occluders** are plain `StaticBody3D` with no `walkable` tag; the nav bake excludes their top surfaces, so they remain true obstacles for routing.

### Designer / QA limits

- Floor bounds: **±22.5 m** in X and Z from world origin. Nav queries outside the `NavigationRegion3D` boundary (beyond the floor edge) fail as expected.
- The `MoveRejectPedestal` (orange box) top is ~2.5 m above the floor and will be rejected by the server's `MaxVerticalStep` (**2.2 m** by default) — the only remaining move-rejection criterion with default server config. Horizontal distance is never a rejection reason when `HorizontalStepEnabled` is false.
- New obstacles are tagged `"occluder"` so the NEON-27 occlusion policy applies automatically.

## Authoritative movement (NEO-7, NEO-11, NEO-22)

With the game server running ([`server/README.md`](../server/README.md)), **WASD** (input actions **`move_*`** in `project.godot`) drives **camera-relative XZ** wish direction on the **`Player`**, and **`main.gd`** periodically **`POST`**s **`/game/players/{id}/move-stream`** with the **latest** body-centre sample while you are moving (no stream while standing still, so idle anchor does not fight HTTP). **`PositionAuthorityClient`** coalesces to **one target per request** so a slow round-trip cannot apply a stale multi-step chain after the capsule has moved. The server validates each leg with the same rules as a single **`MoveCommand`**, applies **all targets in order** (reject = **no** partial apply), and returns **`PositionStateResponse`**. A successful **`move-stream`** response is treated as an **ack only** (no client teleport): the echoed position typically trails **`move_and_slide`** by roughly one RTT, so snapping it caused rubber-banding. **`authoritative_position_received`** is emitted only from **boot** `GET` so **`main.gd`** can **`snap_to_server`**. Left-click **ground pick / `POST /move`** has been removed from the client.

**Boot** `sync_from_server()` **snaps** once so spawn matches the server.

**Tradeoff (prototype):** Horizontal motion is a **direct XZ bee-line** toward the server’s verified target. The baked **`NavigationMesh`** is still used when **vertical routing** is latched **and** the capsule is inside the **nav column** hysteresis band (`NAV_COLUMN_STEER_ENTER_DIST` / `EXIT`) **and** **`is_on_floor()`** — terraces / steps then steer along **`get_current_navigation_path()`** using the first waypoint at least **`NAV_PATH_STEER_MIN_LOOKAHEAD`** (~22 cm) away in XZ (unlike a **5 cm** scan or raw **`get_next_path_position()`**, which both sat inside Jolt’s per-tick slide and could flip velocity **180°** every tick). While **airborne**, column path steering is **off** so horizontal motion stays a bee-line toward the movement goal (avoids fall-time XZ oscillation). **No descend bypass** for gravity while on an upper deck (same as before). While walking, **gravity** still runs when **`is_on_floor()`** is false; if **snap / lip contacts** keep **`is_on_floor()`** true over open space (e.g. gold deck → gray floor), **`player.gd`** casts **several short down rays** under the **foot disk** (center + offsets along move direction so the **leading** edge off a deck is tested) and applies **gravity** when **none** hit upward-facing ground within **`WALK_SUPPORT_PROBE_DEPTH`**. In that case **`floor_snap_length`** is set to **0** for the tick so **moving snap** does not cancel **`velocity.y`** on every physics step. **Automatic routing around tall obstacles in one straight push is still not guaranteed** — steer around e.g. the gray **`Obstacle`** with WASD as needed.

**NEO-10 / movement QA bumps:** On **run**, **`spawn_short_random_bumps`** adds **two** green cylinders, each on its own **`StaticBody3D`** **sibling** of **`Floor`** under **`NavigationRegion3D`** (**`walkable`** on bump roots — avoids compound **internal-edge** jitter vs floor+cylinder on one body). Bump meshes use Godot group **`random_floor_bump_mesh`**. **Collision radius** = mesh **+ `COLLISION_RADIUS_EXTRA`** (see **`scripts/random_floor_bump_collision_constants.gd`**, capped by **`COLLISION_RADIUS_MAX`**). **`bake_navigation_mesh(false)`** after spawn.

**Idle stability (NEO-14 / NEON-16):** **Jolt Physics**; **TPS** **120**. **`physics/common/physics_interpolation`** is **off** — with **on**, small physics **position** changes on bump **edges** were **blended** across render frames and looked like **ghosting / extra jitter**. **`snap_to_server()`** still calls **`reset_physics_interpolation()`** for compatibility if you turn interpolation on later. **`floor_max_angle`** **~50°** walking / **~35°** idle; **loose** angle **~0.8 s** after walk stops. **Walk step assist**. **Idle rim / straddle:** **moving** `floor_max_angle` when floor normal is **shallow** or slide hits mix **floor + wall**. One idle **`move_and_slide()`**, rim **settle**, **`random_floor_bump_mesh`** **lip / rim / vertical-wall** escape (**`IDLE_BUMP_ESCAPE_STEP`**, **`PLAYER_CAPSULE_RADIUS`**, collider fudge from **`random_floor_bump_collision_constants.gd`**). **Flat idle hardening:** when support is already effectively level (floor normal almost **`Vector3.UP`** and no post-arrival loose-floor window), **`player.gd`** now skips the corrective idle slide / escape loop instead of nudging the capsule anyway, even if physics reports incidental extra contacts on an otherwise flat support. In that stable grounded state the player also keeps an **idle x/z anchor**, so any residual horizontal creep is clamped away until movement resumes or support stops looking stable. **Uniform shallow ramps** can latch stable idle; **nav-column path steering** is gated to flatter floors so ramp ribbons do not flip velocity each tick. Goal arrival and descend-bypass checks both use the capsule **feet height** rather than the body origin, so flat-floor arrivals clear and route normally instead of lingering in a straight-line obstacle push. **`Player`:** interp **Off**, **`avoidance_enabled`** **false**, **`floor_block_on_wall`** **true** — do **not** rewrite **`global_transform`** in **`_process`** (can **ghost** **`CharacterBody3D`**). **`_snap_capsule_upright()`** now short-circuits when the basis is already identity. Idle **`FLOOR_SNAP_IDLE`** ~**11 cm**; walking **`FLOOR_SNAP_MOVING`** ~**0.32**. **Rendering:** **`Mat_player_capsule`**, **`cast_shadow = 0`**, capsule mesh **+Y ~3.4 cm** (visual-only vs **`CapsuleShape3D`** — less **z-fight** vs floor/bump tops), **`light_specular = 0`**, **`msaa_3d = 2`**. **`safe_margin`** **0.055**.

- **Scripts:** `scripts/position_authority_client.gd` (`PositionAuthorityClient`: boot `GET`, `move-stream` `POST`), `scripts/player.gd` (WASD locomotion + nav assist when a goal exists), `scripts/isometric_follow_camera.gd` + `scripts/camera_state.gd` (NEO-15 follow), thin `scripts/main.gd` (nav bake on first frame, then wiring).
- **Scene:** `scenes/main.tscn` — walkable **`StaticBody3D`** geometry lives under **`World/NavigationRegion3D`**. `main.gd` waits one **`process_frame`**, spawns **random test bumps** on **`Floor`**, then **`bake_navigation_mesh(false)`** (main-thread bake), then waits two **`physics_frame`**s so **`NavigationServer3D`** has a map before agents query paths. The baked **`NavigationMesh`** asset in the scene file is **stale** until you run or re-bake in the editor.
- **Inspector:** select **`PositionAuthorityClient`** on the main scene to set **`base_url`** (default `http://127.0.0.1:5253`) and **`dev_player_id`** (default `dev-local-1`, must match server `Game:DevPlayerId`).

### Manual check (NEO-7 + NEO-11 + NEO-22)

1. From repo root: `cd server/NeonSprawl.Server && dotnet run` (note the URL/port, usually `http://localhost:5253`).
2. If the port differs, set **`base_url`** on **`PositionAuthorityClient`** accordingly (e.g. `http://127.0.0.1:5253`).
3. Open the client in Godot and run the main scene (**F5**). The player should **snap** to the server’s default position (e.g. **(-5, 0.9, -5)** per `Game:DefaultPosition` / NEO-9 walk demo).
4. **WASD:** walk on the floor; the HUD position label should update and the server should accept **`move-stream`** steps (watch server logs or use a proxy if needed). **Release keys** and confirm the capsule settles to **idle** without runaway drift.
5. Walk to the **orange reject pedestal** and try to climb it with WASD; **`move-stream`** should return **`vertical_step_exceeded`** when a requested step exceeds **`MaxVerticalStep`** (watch the **`MoveRejectLabel`** or server logs). The `MoveRejectFarPad` (blue pad at (9, 9)) remains a normal walkable surface.
6. After movement, **stand idle** for **10+ seconds** and confirm the capsule does **not** visibly vibrate or drift in **x/z** on flat floor, then repeat on the **random green bumps** (positions change each run).

If the server is **down**, boot **`GET`** fails silently (check Output for warnings). **`move-stream`** submissions are skipped while the HTTP client is busy, then resume.

## Interaction + range preview (NEO-9 + NEO-25)

On boot, **`InteractablesCatalogClient`** **`GET`s** **`/game/world/interactables`**; **`interactable_world_builder.gd`** spawns **walkable** prototype props plus **two** small glow markers per row under **`World/InteractionMarkers`**. **`interaction_radius_indicators.gd`** compares the snapped **`CharacterBody3D`** **`global_position`** to each descriptor’s **`anchor`** on **X/Z** with the same **`interactionRadius`** and inclusive **`<=`** rule as the server — **preview only**; **`POST /game/players/{id}/interact`** remains authoritative.

- **`InteractionRequestClient`**: **`interact`** (**E**) → **`prototype_terminal`**; **`interact_secondary`** (**R**) → **`prototype_resource_node_alpha`** (stable ids; must match `PrototypeInteractableRegistry.cs`). **Output** prints `allowed` / `reasonCode` per response (lines prefixed with `Interaction [<id>]: …`). Only one HTTP POST runs at a time; if you press **E** then **R** while the first request is still in flight, the **latest** id is remembered and sent **immediately after** the first completes (last-wins coalescing — not a silent drop).
- **Inspector:** match **`base_url`** on **`InteractablesCatalogClient`**, **`InteractionRequestClient`**, and **`PositionAuthorityClient`** to the running server.
- **No server:** catalog **GET** fails → **Output** errors; props and glow markers do not spawn (expected prototype degradation).

### Manual check (NEO-9 + NEO-25)

1. Run the game server and client as in NEO-7.
2. **F5** in Godot: after catalog load, two interactable sites appear (center + **+X / −Z** floor, anchor **(12, 0.5, −6)** — clear of the gray **Obstacle** near **(6, 1, 5)**). Default spawn **(-5, 0.9, -5)** is out of range of the **center** node (3 m); markers near **origin** stay **dim** until you **WASD** within horizontal **3** m of **(0, 0.5, 0)** on X/Z — then that pair **brightens**.
3. Press **E** (**`interact`**): Output **`allowed=true`** when the **terminal** pair glows; **`allowed=false`** / **`out_of_range`** when dim. Walk toward **(12, −6)** until the **second** pair glows; press **R** (**`interact_secondary`**) for **`allowed=true`** on the resource node.
4. **E** / **R** are handled in **`main.gd`** **`_unhandled_key_input`** and forwarded to **`InteractionRequestClient`** (same pattern as dev keys) so they still register in the embedded **Game** dock; click the game view if the editor had focus elsewhere.

Full checklist: [`docs/manual-qa/NEO-25.md`](../manual-qa/NEO-25.md).

## Target lock + tab cycle (NEO-24)

`scripts/target_selection_client.gd` wires the server targeting API from [NEO-23](../docs/plans/NEO-23-implementation-plan.md) to a tab-cycle input and a HUD overlay.

- **Bindings** (in `project.godot`): **`target_tab`** → **Tab** cycles targets in the order defined by **`scripts/prototype_target_constants.gd`** (`prototype_target_alpha`, then `prototype_target_beta`; matches `PrototypeTargetRegistry.cs` ascending id), wrapping from last → first. When the player reference is wired (via `set_freshness_kick`, which `main.gd` does), Tab **skips client-computed out-of-range anchors** and selects the first in-range id in cycle order so pressing Tab while visibly standing next to an anchor actually locks it instead of trying the next-in-order id that happens to be across the map. Falls back to the plain cycle when nothing is in range so the server still picks the denial reason. **`target_clear`** → **Esc** POSTs with `targetId` omitted to clear the server lock.
- **HUD:** `UICanvas/TargetLockLabel` shows the last **server-acknowledged** state: `lockedTargetId` (or **`—`** when no lock), `validity` (`none` / `ok` / `out_of_range` / `invalid_target`), `sequence`, one **display-only** line per known target in the form `<id>: <dist> m / <radius> (in|out)` (computed client-side from the live capsule position against `prototype_target_constants.gd`), and (on denials) `Denied: <reasonCode>` on the last line. **UI never shows an optimistic lock the server denied** — it always paints from the authoritative `targetState` echoed by each `200` response. Distance lines are a lag diagnostic: if the HUD shows `Validity: ok` but `alpha: 7.1 m / 6.0 (out)`, the server's position snapshot is lagging the visible capsule, and the next `authoritative_ack` refresh will reconcile. `UICanvas/PlayerPositionLabel` also shows the last **server-acknowledged** world position + horizontal delta from the visible capsule — when that `Δ` is large, targeting denials are being evaluated against a stale server snapshot.
- **`positionHint` on select (NEO-24 follow-up #5):** when `TargetSelectionClient.set_freshness_kick(authority, player)` is wired (as `main.gd` does), every `POST /target/select` body also carries `positionHint: {x,y,z}` = the live capsule position. The server uses the hint for the radius check and for the `validity` field in the echoed `targetState`, eliminating the cross-request race between `move-stream` and `target/select` POSTs — a Tab pressed several seconds after stopping (with an old stored snap on the server) now still succeeds when you are visibly in range. The hint is advisory (server never writes it to the position store); `move-stream` remains the sole write path. Tests that omit `set_freshness_kick(...)` fall back to the no-hint code path.
- **Freshness kick (ancillary):** alongside the hint, `set_freshness_kick(...)` also has the target client nudge the authority with `submit_stream_targets([player.global_position])` before each select POST. That write is no longer load-bearing for denial correctness (the hint handles that), but it keeps the stored snap reasonably fresh so the movement-triggered validity GET that runs on the next `authoritative_ack` sees current data.
- **Visible anchors:** `scripts/prototype_target_markers.gd` (under `World/PrototypeTargetMarkers`) spawns a small colored mast + a flat translucent ring at every `ANCHORS` entry so the lock radius is visible in-world. All prototype targets share a single radius (`PrototypeTargetConstants.SHARED_LOCK_RADIUS` = `PrototypeTargetRegistry.SharedLockRadius` = **6 m**); anchors are placed at `(-3, 0.5, -3)` and `(3, 0, 3)` so the two rings overlap at origin (~3.5 m wide), letting you flip between targets with Tab without locomotion. The script and `prototype_target_constants.gd` mirror the server's `PrototypeTargetRegistry.cs` — change them together in the same commit so the markers never drift from server authority. Per-target radii will return with real combat design (E5.M1).
- **Soft lock refresh:** the client does **not** poll on a timer. It refreshes via `GET …/target` on boot, on every `POST …/target/select` response (body already carries `targetState`), and — while a lock is currently held — on **`authoritative_ack`** from `PositionAuthorityClient`, throttled to at most one GET per **250 ms**. `authoritative_ack` fires on every server-confirmed position (boot `GET` 200 **and** successful `move-stream` 200), so a held lock revalidates during normal WASD locomotion without re-introducing snap rubber-banding. Boot is naturally skipped because no lock exists yet. Purely server-driven state flips (future PvP / combat categories) would require revisiting this policy; today NEO-23 has none.
- **Inspector:** match **`base_url`** / **`dev_player_id`** on the `TargetSelectionClient` node to the other HTTP clients / `Game:DevPlayerId`.

### SelectionEvent (NEO-26)

- **`TargetSelectionClient`** emits **`selection_event(event: Dictionary)`** only when the server-acknowledged **`lockedTargetId`** changes (not on **`validity`-only** updates; those stay on **`target_state_changed`**).
- Payload keys: **`previous`** ([String] or `null`), **`next`** (same), **`cause`** (`tab` \| `clear` \| `server_correction`), **`sequence`** (int from the new state). **`POST …/target/select`** from **`request_select_target_id`** (including the path used by Tab) uses cause **`tab`**; **`request_clear_target`** uses **`clear`**; every **`GET …/target`** completion uses **`server_correction`** (including boot sync).
- **Slice 3 telemetry hook (NEO-27):** this selection transition maps to product event name **`target_changed`**; with **`log_selection_events`** enabled, Godot Output prints the `target_changed` token for manual verification. **TODO(E9.M1):** replace dev log with cataloged telemetry emit.
- **Ability cast hooks (NEO-27 + NEO-31 + NEO-28):** digit keys **`hotbar_slot_1` … `hotbar_slot_8`** (defaults **1**–**8**) issue a prototype cast via `scripts/ability_cast_client.gd`. **`ability_cast_requested`** is printed from `main.gd` only when **`request_cast`** returns **`true`** (HTTP POST successfully queued). **`ability_cast_denied`** is logged as `push_warning` from the client on deny responses, and **NEO-28** mirrors the same outcome on the **`CastFeedbackLabel`** HUD line (`ability_cast_denied: <reasonCode>` or `Cast: accepted`) via **`AbilityCastClient.cast_result_received`** (TODO(E9.M1): telemetry).
- **E1.M4+:** connect to **`$TargetSelectionClient.selection_event`** (or your scene’s path to that node) without reshaping the payload.

Full checklist: [`docs/manual-qa/NEO-26.md`](../docs/manual-qa/NEO-26.md).

## Hotbar loadout hydration (NEO-29)

`scripts/hotbar_loadout_client.gd` fetches server-owned `HotbarLoadout` state and applies it to `scripts/hotbar_state.gd`:

- On `main.gd` startup, `_setup_hotbar_loadout_sync()` creates `HotbarState` + `HotbarLoadoutClient` nodes, mirrors `base_url`/`dev_player_id` from `PositionAuthorityClient`, and calls `request_sync_from_server()`.
- `HotbarState` keeps a fixed **8-slot** local mirror (`Array` indexed `0..7`) with nullable ability ids.
- `HotbarLoadoutClient.request_bind_slot(slot_index, ability_id)` POSTs one slot update to `/game/players/{id}/hotbar-loadout`; denials emit `loadout_update_denied(reason_code, loadout)` so future UI can surface machine-readable errors directly.

This story hydrates bindings only; cast execution and cooldown behavior stay in later E1.M4 / E5.M1 stories.

## Ability cast request (NEO-31 + NEO-28)

- **`POST /game/players/{id}/ability-cast`** — JSON body `schemaVersion`, `slotIndex` (0–7), `abilityId`, **`targetId`** (must match server lock + prototype registry + range for `accepted: true`; see `server/README.md` and `AbilityCastApi.cs`).
- **Client:** `main.gd` reads `HotbarState.slots_snapshot()` and `TargetSelectionClient.cached_state()` (`lockedTargetId`) so cast payloads use **server-acknowledged** target context, not camera guessing. **Tab-lock a target** before expecting a successful cast at the default spawn.

Full checklist: [`docs/manual-qa/NEO-31.md`](../docs/manual-qa/NEO-31.md) · cast deny/accept HUD: [`docs/manual-qa/NEO-28.md`](../docs/manual-qa/NEO-28.md).

### Manual check (NEO-24)

1. Run the server and client as in NEO-7 / NEO-9; confirm spawn snap at `(-5, 0.9, -5)`.
2. Press **Tab**: HUD → `Target: prototype_target_alpha`, `Validity: ok` (spawn is ~2.83 m from alpha's anchor `(-3, -3)`, well inside the shared 6 m radius).
3. Press **Tab** again: server denies (beta anchor `(3, 3)` is ~11.3 m from spawn, outside 6 m). The range-aware picker skips the currently-locked alpha and falls back to the cycle so the server gets a clean "swap to beta" request and can deny it; per NEO-23 soft-lock policy the persisted lock does not change, so HUD stays at `Target: prototype_target_alpha, Validity: ok` with `Denied: out_of_range` appended.
4. **WASD** away from spawn past ~6 m horizontally from alpha; HUD flips to `Validity: out_of_range` on the next movement-triggered refresh (≤250 ms cadence) while `lockedTargetId` stays `alpha` — this is the **soft lock** round-tripped from the server.
5. Walk to the **origin** (both rings visibly overlap): HUD shows `alpha` and `beta` distance lines both `(in)` (~4.24 m each). Press **Tab** to flip alpha → beta → alpha → … without moving. This is the main overlap sanity.
6. Walk toward beta (inside `(3, 3)` within 6 m, outside alpha's ring) and press **Tab** from a cleared lock: the range-aware picker skips alpha and locks beta directly. A further **Tab** from beta-only-in-range wraps to `alpha` and the server denies (same soft-lock behavior as step 3).
7. Press **Esc**: HUD → `Target: —`, `Validity: none`, sequence advances.

## Movement prototype (NEO-5 → NEO-11)

**`player.gd`** steers **XZ** toward the authoritative goal and uses **`NavigationAgent3D`**’s **current path** only for the **vertical-routing** case above (on sufficiently flat floor); **`move_and_slide()`** does the motion. **`snap_to_server()`** remains for **boot** (and would apply for any future hard reconcile).

- The avatar is on **physics layer 2** with **collision_mask** **3** (scans layers **1** and **2** so all walkables/occluders pair reliably). Environment **StaticBody3D** nodes stay on **collision_layer** **1** with **collision_mask** **3** as well.

### Manual check (remnants)

1. Run the main scene (**F5**) **with server running** for movement behavior above.
2. Without the server, startup sync does not apply authoritative position; behavior is undefined for this repo’s intended demo—**run the server** for the demo path.

## First run

1. Install [Godot 4.x](https://godotengine.org/download).
2. In the project manager, **Import** and select `client/project.godot`.
3. Press **F5** to run the main scene.

## Godot CLI (Linux smoke test)

For agents and CI, use the **official Linux x86_64 editor binary** (matches **`config/features`** `4.6` in `project.godot`):

1. Download [Godot_v4.6-stable_linux.x86_64.zip](https://github.com/godotengine/godot/releases/download/4.6-stable/Godot_v4.6-stable_linux.x86_64.zip) from the [4.6-stable release](https://github.com/godotengine/godot/releases/tag/4.6-stable).
2. Unzip and put the binary on your **`PATH`**, e.g. `~/.local/opt/godot-4.6-stable/` and `ln -s …/Godot_v4.6-stable_linux.x86_64 ~/.local/bin/godot`.
3. Ensure **`~/.local/bin`** is on **`PATH`**, then from **`client/`**:

```bash
godot --version
godot --headless --path . --quit-after 5
```

A clean checkout has **`client/.godot/`** gitignored, so scripts intentionally avoid **`class_name`** global types that require a full editor import before headless can resolve them.

## Automated tests (GDScript, NEO-12)

**Framework:** **[GdUnit4](https://github.com/godot-gdunit-labs/gdUnit4)** **v6.1.2** is vendored under **`addons/gdUnit4/`** (plugin enabled in `project.godot`). Test suites live in **`test/`** (`*_test.gd` files extending `GdUnitTestSuite`).

**Editor:** Open the project in Godot 4.6; use the **GdUnit** dock to run tests, or run headless (below).

**Headless (Linux, from `client/`):** Use the same **4.6-stable** binary as in [Godot CLI](#godot-cli-linux-smoke-test). On a fresh clone you may need a one-time import so `.godot` exists:

```bash
godot --headless --import --path . --quit-after 8
godot --headless --path . -s res://addons/gdUnit4/bin/GdUnitCmdTool.gd --ignoreHeadlessMode -a res://test
```

On **Linux** (including GitHub Actions), the path must be **`gdUnit4`** with a capital **`U`**; `gdunit4` does not resolve.

**CI:** The **GDScript** workflow fails the job if Godot prints **`SCRIPT ERROR:`** or **`ERROR: Failed to load script`** while running GdUnit. GdUnit alone can still exit **0** when a test file fails to parse (that suite is skipped); the workflow guards against that.

**Scope:** Unit tests cover **`player.gd`**, **`player_locomotion_wasd.gd`** (pure WASD seam helpers), **`position_authority_client.gd`**, **`isometric_follow_camera.gd`** (eye math + effective zoom distance), **`camera_state.gd`**, and **`zoom_band_config.gd`**. **`main.gd`** and scene wiring are **not** automated here—use manual checks above.

**Camera zoom:** Input actions **`camera_zoom_in`** / **`camera_zoom_out`** (mouse wheel, **`=`** / **`-`**, keypad **+** / **−**) are defined in **`project.godot`**. On layouts where **`+`** requires **Shift**, remap or add a binding under **Project → Project Settings → Input Map** if needed.

**Dev (NEO-18):** **`dev_toggle_occluder_obstacle`** (default **Ctrl+Shift+K**) toggles the prototype `Obstacle` visibility/collision in **`main.gd`**. **F9** / **F10** are used by the embedded debugger; use this action instead when the game is running in the editor.

**Git hooks (recommended):** install the repo’s local hooks from the repo root (once per clone):

```bash
./scripts/install-git-hooks.sh
```

On **Windows** (PowerShell), same hook:

```powershell
pwsh -File scripts/install-git-hooks.ps1
```

This installs:

- **pre-commit**: blocks commits when `client/scripts/*.gd` changes lack matching `client/test/*_test.gd` updates, or when server route/contract files change without corresponding `server/NeonSprawl.Server.Tests/` and `bruno/neon-sprawl-server/**/*.bru` updates.
- **pre-push**: runs **`gdlint client/scripts client/test`** and **`gdformat --check client/scripts client/test`**.

The pre-push hook prefers **`.venv-gd/bin/`** (Unix) or **`.venv-gd/Scripts/`** (Windows venv) when present; without that venv or a global install, the hook **fails** and blocks the push — same as CI.

**If CI fails gdlint but your push succeeded:** the hook was not installed, **`gdlint`/`gdformat` were missing** when the hook ran, or push bypassed hooks (`--no-verify`).

**Reports:** GdUnit writes under **`reports/`** (gitignored); ignore locally generated HTML/XML when committing.
