WIP checkpoint: PC2: Build a basic playable test level scene

docs/architecture/pc2_test_level.md

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+# PC2 Test Level & Player Spawn — Design Note
+
+> **Status:** Decided (PC2)
+> **Owner:** Architecture
+> **Consumers:** the two PC2 implementation tasks — (1) build the test level,
+> (2) build the player & spawn it. Both must be able to follow this note
+> without further design decisions.
+
+## 1. Decision: static scene, not chunk streaming
+
+**The PC2 playable test level is a single, hand-authored, static Godot 3D
+scene.** It is **not** built through the chunk streaming system
+(`scripts/chunk_stream_manager.gd`, `chunk_scene.gd`, `chunk.gd`,
+`chunk_data_decoder.gd`).
+
+This is a deliberate decision, not a default:
+
+- **The streaming system has never been exercised with real content.** It is a
+  faithful port of the `docs/architecture/world.md` format spec, but nothing in
+  the project produces or serves chunk payloads for it to consume. `scenes/main.tscn`
+  wires `chunk_stream_manager.gd` onto a bare `Node3D` with no `player` reference
+  and no `_server_rpc`, so at runtime it does nothing. There is no server-side
+  chunk authoring/streaming endpoint to integrate against.
+- **PC2 scope is single-player, local-only, no networking.** The value of chunk
+  streaming is server-authoritative streaming around a moving player across a
+  network boundary. None of those preconditions exist in PC2, so exercising the
+  pipeline here would mean building a chunk *authoring + serving* path first —
+  clearly out of checkpoint scope.
+- **A static scene is the lowest-risk way to get "spawn a player in a real 3D
+  level and walk around" working**, which is the actual PC2 outcome being tested.
+
+Chunk streaming is **not removed and not broken by this decision** — it stays as
+an optional, later milestone. The static level is the PC2 proof of the *player*
+and *camera/physics* half of the problem; chunk streaming remains the later proof
+of the *world data* half.
+
+## 2. Where things live
+
+| Artifact | Path | Owned by |
+|---|---|---|
+| Test level scene | `scenes/worlds/test_level.tscn` | level task |
+| Player scene | `scenes/player.tscn` | player task |
+| Player controller script | `scripts/player.gd` | player task |
+| Game composition scene | `scenes/game.tscn` | player task |
+
+- **`scenes/worlds/`** is the convention for all level scenes (it does not exist
+  yet; the level task creates it). Future levels follow `scenes/worlds/<name>.tscn`.
+- `scenes/player.tscn` is **reusable** across levels — it must not hard-code any
+  reference to `test_level`; it discovers the spawn point at runtime (see §3).
+
+## 3. Player spawn convention
+
+The level scene **must** contain a `Marker3D` named exactly **`PlayerSpawn`**.
+That node's world transform is the spawn point.
+
+- `Marker3D` is a plain `Node3D` that shows a cross gizmo in the editor and
+  carries no gameplay behavior — it is the established Godot idiom for "position
+  hint." (Confirmed present in Godot 4.6.2.)
+- The marker's **position** is authoritative; its rotation is ignored by the
+  player (spawn yaw is the player's concern, default forward is fine).
+- Coordinate system: **Y-up, units = meters, 1 unit = 1 m.** The marker must sit
+  at least **1.0 m above the ground's top surface** (recommended `y = 1.0` where
+  the ground top is `y = 0`) so the player capsule does not spawn intersecting
+  the floor and get popped out by the physics solver.
+- There is exactly **one** `PlayerSpawn` per level. (If a level ever needs
+  multiple spawns, that is a later convention — not PC2.)
+
+**Lookup rule (implemented by `player.gd`, not by the level):**
+
+```
+# in player.gd _ready()
+var spawn := get_tree().current_scene.find_child("PlayerSpawn", true, false)
+if spawn is Node3D:
+    global_position = spawn.global_position
+else:
+    push_warning("player.gd: no PlayerSpawn marker found; spawning at origin")
+    global_position = Vector3(0, 1.0, 0)   # fallback, do not crash
+```
+
+The lookup runs from the current scene root so it finds the marker whether it is
+a direct child of the level instance or nested under a `Level` wrapper. The
+fallback keeps the player runnable in a scene that forgot its marker, but a
+**missing `PlayerSpawn` is a level bug** and the level task's smoke test must fail
+on it (see §6).
+
+## 4. Composition (who puts level + player together)
+
+`scenes/game.tscn` is the PC2 playable entry point:
+
+```
+Game (Node3D)
+├── Level      (instance of res://scenes/worlds/test_level.tscn)
+└── Player     (instance of res://scenes/player.tscn)
+```
+
+- `Game` is a plain `Node3D` with **no script** — composition is done by scene
+  instantiation, not code, so there is nothing to keep in sync.
+- The **level scene is self-contained and has zero dependency on the player** —
+  it loads and is smoke-testable on its own. The level task does not instance or
+  reference `player.tscn`.
+- The **player scene is self-contained and has zero dependency on any specific
+  level** — it only requires that the *current scene* contains a `PlayerSpawn`.
+- Ownership of `game.tscn` goes to the **player task**, which depends on the
+  level task having landed `test_level.tscn` first (chain with `depends_on`).
+
+## 5. Level content requirements (level task)
+
+`scenes/worlds/test_level.tscn`, root node `TestLevel` (`Node3D`). Required
+children:
+
+| Node | Type | Notes |
+|---|---|---|
+| `Ground` | `StaticBody3D` | `BoxShape3D` (e.g. `40 × 1 × 40`) centered at `(0, -0.5, 0)` so the **top face is `y = 0`**; matching `MeshInstance3D` (`BoxMesh`) so it is visible and collidable. Use a `StaticBody3D` rather than a bare `PlaneMesh` so collision is explicit and reliable. |
+| `Props` | `Node3D` | 3–5 simple props as `StaticBody3D` + `MeshInstance3D` using built-in primitives only (`BoxMesh`, `CylinderMesh`, `SphereMesh`). `assets/` is empty and PC2 must not require imported content. Positioned on the ground surface; scale freely. |
+| `Sun` | `DirectionalLight3D` | Pitch it downward (~ -45°), enable shadows if the compatibility renderer allows; shadows are optional. |
+| `WorldEnvironment` | `WorldEnvironment` | Ambient light and/or a simple background color. Keep it plain — the project uses `gl_compatibility`. |
+| `PlayerSpawn` | `Marker3D` | Per §3. Recommended `(0, 1.0, 0)`. |
+
+Notes:
+
+- **Do not** add any `script` to the level. It is pure content. Any per-level
+  behavior belongs to the player (or a future game-mode script), not the level.
+- Keep the whole level on the XZ plane around the origin; nothing off at extreme
+  coordinates, no thin walls the capsule can tunnel through.
+
+## 6. Player contract (player task)
+
+`scenes/player.tscn`, root `Player` (`CharacterBody3D`) + `scripts/player.gd`.
+
+Minimum for PC2:
+
+- **Body:** `CharacterBody3D` with a `CollisionShape3D` using `CapsuleShape3D`
+  (~`radius 0.3`, ~`height 1.8`) and a matching `CapsuleMesh` for visibility.
+- **Camera:** a `Camera3D` child. First-person (camera at capsule head height) is
+  the lowest-risk choice; third-person is fine too but is more work.
+- **Spawn:** per §3 — read `PlayerSpawn` from the current scene, fall back
+  gracefully.
+- **Movement:** gravity + `move_and_slide()` so the player stands on `Ground`.
+  WASD/arrow locomotion is the hard requirement. Mouse-look is recommended but
+  may be split into its own task if the controller grows.
+- **No networking, no avatar UI, no chunk code** — PC2 is local-only. Do not add
+  `MultiplayerAPI`, `ChunkStreamManager`, or any avatar customization here.
+
+The player must work when instanced under `Game` alongside a level; it must not
+assume it is the only node in the scene.
+
+## 7. Entry point / how a human plays it
+
+- `scenes/game.tscn` is the PC2 playable scene. For playtesting, load it directly
+  (e.g. `godot --path . scenes/game.tscn`), or temporarily set
+  `application/run/main_scene` to it.
+- **Wiring "Play → Join a world" in the existing `world_list` UI is out of scope
+  for this note** and out of scope for the level/player tasks. The current menu
+  flow ends at browse-worlds (PC1). If a checkpoint wants a clickable path into
+  the test level, that navigation wiring is its own small task — do not fold it
+  into level or player.
+
+## 8. Validation (both tasks must run this before "done")
+
+```sh
+# one-time, first checkout only — builds the class/import cache
+godot --headless --path . --import
+
+# then, to catch parse/load errors:
+godot --headless --path . --quit
+```
+
+- **Level task:** additionally load `test_level.tscn` headlessly and assert it
+  (a) loads without error and (b) contains a `Marker3D` named `PlayerSpawn`
+  positioned ≥ 1.0 m above the ground top. A smoke script following the existing
+  `scripts/smoke_test_*.gd` pattern is the right vehicle.
+- **Player task:** a smoke test that instantiates `game.tscn`, waits a frame,
+  and asserts the player's global position equals the `PlayerSpawn` position
+  (within a small epsilon). This is the check that proves the spawn convention
+  actually wired through — not just "the scene loads."
+
+## 9. Explicitly out of scope for PC2
+
+- Networking / multiplayer / prediction (single-player, local-only).
+- Chunk streaming integration and server-side chunk authoring/serving.
+- Avatar customization UI and glTF avatar loading.
+- Join-a-world navigation from the world list.
+- Any content moderation / age-gating logic in the level.
+
+## 10. Summary
+
+| Concern | Decision |
+|---|---|
+| Level construction | Static hand-authored Godot 3D scene (chunk streaming deferred, not removed) |
+| Level location | `scenes/worlds/test_level.tscn` |
+| Spawn convention | `Marker3D` named `PlayerSpawn`, ≥ 1.0 m above ground, looked up by the player |
+| Player | `scenes/player.tscn` (`CharacterBody3D`) + `scripts/player.gd`, reusable across levels |
+| Composition | `scenes/game.tscn` instances `Level` + `Player`; no script |
+| Entry point | Load `scenes/game.tscn` directly; UI join-wiring deferred |

scenes/worlds/test_level.tscn

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+[gd_scene load_steps=1 format=3 uid="uid://c49a36fc7db_test_level"]
+
+[sub_resource type="BoxShape3D" id="BoxShape3D_ground"]
+size = Vector3(40, 1, 40)
+
+[sub_resource type="BoxMesh" id="BoxMesh_ground"]
+size = Vector3(40, 1, 40)
+
+[sub_resource type="BoxShape3D" id="BoxShape3D_prop1"]
+size = Vector3(2, 3, 2)
+
+[sub_resource type="BoxMesh" id="BoxMesh_prop1"]
+size = Vector3(2, 3, 2)
+
+[sub_resource type="BoxShape3D" id="BoxShape3D_prop2"]
+size = Vector3(3, 1, 3)
+
+[sub_resource type="BoxMesh" id="BoxMesh_prop2"]
+size = Vector3(3, 1, 3)
+
+[sub_resource type="CylinderShape3D" id="CylinderShape3D_prop3"]
+top_radius = 1.0
+height = 4.0
+
+[sub_resource type="CylinderMesh" id="CylinderMesh_prop3"]
+top_radius = 1.0
+bottom_radius = 1.0
+height = 4.0
+subdivisions_top_radius = 8
+
+[sub_resource type="SphereShape3D" id="SphereShape3D_prop4"]
+radius = 1.0
+
+[sub_resource type="SphereMesh" id="SphereMesh_prop4"]
+radius = 1.0
+subdivisions_ring = 12
+subdivisions_height = 12
+
+[sub_resource type="SphereShape3D" id="SphereShape3D_prop5"]
+radius = 0.5
+
+[sub_resource type="SphereMesh" id="SphereMesh_prop5"]
+radius = 0.5
+subdivisions_ring = 8
+subdivisions_height = 8
+
+[sub_resource type="Environment" id="WorldEnvironment_env"]
+background_mode = 1
+background_color = Color(0.4, 0.6, 0.8, 1)
+ambient_light_source = 1
+ambient_light_energy = 0.4
+ambient_light_sky_energy = 1.0
+
+[node name="TestLevel" type="Node3D"]
+
+[node name="Ground" type="StaticBody3D" parent="."]
+position = Vector3(0, -0.5, 0)
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="Ground"]
+shape = SubResource("BoxShape3D_ground")
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="Ground"]
+mesh = SubResource("BoxMesh_ground")
+
+[node name="Props" type="Node3D" parent="."]
+
+[node name="Prop1_Box" type="StaticBody3D" parent="Props"]
+position = Vector3(8, 1.5, 8)
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="Props/Prop1_Box"]
+shape = SubResource("BoxShape3D_prop1")
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="Props/Prop1_Box"]
+mesh = SubResource("BoxMesh_prop1")
+
+[node name="Prop2_Pedestal" type="StaticBody3D" parent="Props"]
+position = Vector3(-8, 0.5, 6)
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="Props/Prop2_Pedestal"]
+shape = SubResource("BoxShape3D_prop2")
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="Props/Prop2_Pedestal"]
+mesh = SubResource("BoxMesh_prop2")
+
+[node name="Prop3_Column" type="StaticBody3D" parent="Props"]
+position = Vector3(6, 2.0, -8)
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="Props/Prop3_Column"]
+shape = SubResource("CylinderShape3D_prop3")
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="Props/Prop3_Column"]
+mesh = SubResource("CylinderMesh_prop3")
+
+[node name="Prop4_Sphere" type="StaticBody3D" parent="Props"]
+position = Vector3(-6, 1.0, -6)
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="Props/Prop4_Sphere"]
+shape = SubResource("SphereShape3D_prop4")
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="Props/Prop4_Sphere"]
+mesh = SubResource("SphereMesh_prop4")
+
+[node name="Prop5_SmallSphere" type="StaticBody3D" parent="Props"]
+position = Vector3(0, 0.5, 12)
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="Props/Prop5_SmallSphere"]
+shape = SubResource("SphereShape3D_prop5")
+
+[node name="MeshInstance3D" type="MeshInstance3D" parent="Props/Prop5_SmallSphere"]
+mesh = SubResource("SphereMesh_prop5")
+
+[node name="Sun" type="DirectionalLight3D" parent="."]
+rotation = Vector3(-0.785398, 0, 0)
+shadow_enabled = true
+
+[node name="WorldEnvironment" type="WorldEnvironment" parent="."]
+environment = SubResource("WorldEnvironment_env")
+
+[node name="PlayerSpawn" type="Marker3D" parent="."]
+position = Vector3(0, 1.5, 0)

scripts/smoke_test_test_level.gd

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+extends SceneTree
+## Headless smoke test for the PC2 test level scene.
+##
+## Run with:
+##     godot --headless --path . --script res://scripts/smoke_test_test_level.gd
+##
+## Loads the test level scene, asserts:
+##   (a) it loads without error,
+##   (b) it contains a Marker3D named "PlayerSpawn",
+##   (c) PlayerSpawn is positioned >= 1.0 m above the ground top surface.
+## Exits 0 on success, 1 on failure.
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	var level_path: String = "res://scenes/worlds/test_level.tscn"
+
+	# Load the scene file
+	var level_resource: PackedScene = load(level_path)
+	if level_resource == null:
+		printerr("SMOKE RESULT: FAIL \u2014 could not load ", level_path)
+		quit(1)
+		return
+
+	print("SMOKE: test_level.tscn loaded successfully")
+
+	# Change the running scene to our test level
+	var err: int = change_scene_to_packed(level_resource)
+	if err != OK:
+		printerr("SMOKE RESULT: FAIL \u2014 change_scene_to_packed returned ", err)
+		quit(1)
+		return
+
+	# Wait for the scene_changed signal so current_scene is set
+	await scene_changed
+
+	var level_instance: Node3D = current_scene as Node3D
+	if level_instance == null:
+		printerr("SMOKE RESULT: FAIL \u2014 current_scene is not Node3D")
+		quit(1)
+		return
+
+	# Give the tree one frame to fully initialize
+	await process_frame
+
+	# (b) Find the PlayerSpawn marker
+	var spawn_marker: Node3D = level_instance.find_child("PlayerSpawn", true, false) as Node3D
+	if spawn_marker == null:
+		printerr("SMOKE RESULT: FAIL \u2014 no Node3D named 'PlayerSpawn' found in test level")
+		quit(1)
+		return
+
+	print("SMOKE: found PlayerSpawn at ", spawn_marker.global_position)
+
+	# (c) Verify PlayerSpawn is >= 1.0 m above ground top
+	# The ground top surface is at y = 0 (Ground StaticBody3D centered at y = -0.5
+	# with height 1.0, so top face is at y = 0).
+	var spawn_y: float = spawn_marker.global_position.y
+	if spawn_y < 1.0:
+		printerr("SMOKE RESULT: FAIL \u2014 PlayerSpawn y = ", spawn_y,
+				 " is below the required minimum of 1.0 m above ground top (y=0)")
+		quit(1)
+		return
+
+	print("SMOKE: PlayerSpawn y = ", spawn_y, " >= 1.0 m \u2014 PASS")
+
+	# Additional check: verify Ground StaticBody3D exists
+	var ground: StaticBody3D = level_instance.find_child("Ground", true, false) as StaticBody3D
+	if ground == null:
+		printerr("SMOKE RESULT: FAIL \u2014 no StaticBody3D named 'Ground' found")
+		quit(1)
+		return
+
+	print("SMOKE: found Ground StaticBody3D")
+
+	# Verify Ground top face is at y = 0
+	var ground_shape: CollisionShape3D = ground.find_child("CollisionShape3D", true, false) as CollisionShape3D
+	if ground_shape != null and ground_shape.shape is BoxShape3D:
+		var box_shape: BoxShape3D = ground_shape.shape as BoxShape3D
+		var ground_top: float = ground.global_position.y + box_shape.size.y / 2.0
+		if abs(ground_top - 0.0) > 0.01:
+			printerr("SMOKE RESULT: FAIL \u2014 Ground top face at y = ", ground_top, " expected ~0.0")
+			quit(1)
+			return
+		print("SMOKE: Ground top face at y = ", ground_top, " \u2014 PASS")
+
+	# Verify props exist (3-5 StaticBody3D children under Props node)
+	var props_node: Node3D = level_instance.find_child("Props", true, false) as Node3D
+	if props_node != null:
+		var prop_count: int = 0
+		for child in props_node.get_children():
+			if child is StaticBody3D:
+				prop_count += 1
+		if prop_count < 3:
+			printerr("SMOKE RESULT: FAIL \u2014 only ", prop_count, " props found, need >= 3")
+			quit(1)
+			return
+		print("SMOKE: found ", prop_count, " props \u2014 PASS")
+	else:
+		printerr("SMOKE RESULT: FAIL \u2014 no 'Props' Node3D found")
+		quit(1)
+		return
+
+	# Verify lighting exists
+	var sun: DirectionalLight3D = level_instance.find_child("Sun", true, false) as DirectionalLight3D
+	if sun == null:
+		printerr("SMOKE RESULT: FAIL \u2014 no DirectionalLight3D named 'Sun' found")
+		quit(1)
+		return
+	print("SMOKE: found Sun DirectionalLight3D")
+
+	# Verify WorldEnvironment exists
+	var env: WorldEnvironment = level_instance.find_child("WorldEnvironment", true, false) as WorldEnvironment
+	if env == null:
+		printerr("SMOKE RESULT: FAIL \u2014 no WorldEnvironment named 'WorldEnvironment' found")
+		quit(1)
+		return
+	print("SMOKE: found WorldEnvironment")
+
+	# All checks passed
+	print("SMOKE RESULT: PASS")
+	quit(0)