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

_show_authenticated() (the session-restore path, used when returning to
main_menu.tscn -- e.g. after clicking Back from world_list) only hid
EmailEdit/Over18Check, unlike _on_auth_complete() (the fresh-login path)
which hides the full form: UsernameEdit, PasswordEdit, EmailEdit,
Over18Check, AuthButton, AuthModeLabel. Play was correctly enabled and
the welcome message was correctly visible, so a check that stopped at
those two passed clean -- but the actual login fields were still on
screen, which is what a real user sees as "it's making me log in again."
Confirmed via live PC1 playtest today.

Reported by: real playtest, 2026-08-20 (yesterday's automated regression
test for this exact Play -> Back flow only asserted Play/welcome/auth
buttons row -- strengthened smoke_test_main_menu_back.gd to also check
the individual form fields, and confirmed it fails exactly this way with
the bug reintroduced before restoring the fix).

Verified against a live backend: 61/61 pytest (unaffected), 8/8 Godot
smoke tests (including 20/20 on the strengthened back-nav test).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M6rUEynmv2QmweocAQYARN

docs/architecture/pc2_test_level.md

@@ -0,0 +1,194 @@
+# 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 |

docs/testing/test_inventory.md

@@ -8,11 +8,12 @@ to know what "run the tests" actually checked.
 Run everything below in one shot with `scripts/run_checkpoint_tests.py`.
 
 Last verified against `main`: 2026-08-20 — full PC1 checkpoint run,
-migrations + pytest + all 6 Godot smoke tests + both platform exports, all
-clean. Two real bugs found and fixed via real playtesting this same day
-(not caught by the checkpoint suite as it stood before today): the main
-menu had no way to actually open the login/register form, and the world
-list's cards rendered at ~1px wide once real data existed. Both are now
+migrations + pytest + all 7 Godot smoke tests + both platform exports, all
+clean. Real bugs found and fixed via real playtesting this same day (not
+caught by the checkpoint suite as it stood before today): the main menu
+had no way to actually open the login/register form, the world list's
+cards rendered at ~1px wide once real data existed, and navigating Play →
+Back logged the user out despite a still-valid session. All three are now
 covered by the smoke tests below so they can't silently regress.
 
 ## Backend — `backend/tests/` (pytest)
@@ -52,7 +53,7 @@ these yet):
 
 ## Godot client — `scripts/smoke_test_*.gd`
 
-**6 smoke tests merged into `main`.** Each needs a live backend —
+**7 smoke tests merged into `main`.** Each needs a live backend —
 `AGP_API_BASE_URL` env var, falling back to the
 `application/agp/api_base_url` project setting (default
 `http://127.0.0.1:8000`) if unset.
@@ -65,6 +66,7 @@ these yet):
 | `smoke_test_world_list.gd` | Registers a user, **seeds a real world via `POST /api/worlds/`** (without this, `run_checkpoint_tests.py`'s always-fresh DB means the populated-card render path never actually runs in CI, only the empty-list path would), instantiates `world_list.tscn` as a real scene, waits for `_refresh_worlds()` to complete, confirms it reached the populated (not empty) state, and asserts **each rendered card's real computed width is >= 200px**. That last check is the one that matters: 2026-08-20, a real bug shipped where every card existed in the tree with a non-zero child count and no crash, but rendered at 1.0px wide (`ScrollContainer`'s `size_flags_horizontal`/`vertical` used the raw integer `4` = `Control.SIZE_SHRINK_CENTER` instead of `3` = `SIZE_EXPAND_FILL`) — invisible on screen, and a child-count-only check would never have caught it. Confirmed by deliberately reintroducing the bug: card width check correctly fails at 25px. |
 | `smoke_test_main_menu_ui.gd` | Instantiates `main_menu.tscn`, confirms the auth panel starts hidden, and confirms a **real signal emission** on LoginButton/RegisterButton (not calling the handler method directly) actually opens it. This is the check that would have caught 2026-08-20's real bug: the auth panel and its logic were fully correct, but nothing in the scene was ever wired to open it, so Login/Register were completely unreachable from the UI. |
 | `smoke_test_main_menu_full_flow.gd` | Full click-through: open the register form, fill it exactly as a user would, submit, confirm Play actually becomes enabled, the welcome message shows, and the auth buttons hide themselves. Calls the submit handler directly (awaited) rather than via `auth_button.pressed.emit()` — see the note at the top of the file: a synthetic `.emit()` on an `await`-using handler doesn't get driven forward reliably in `--script`/SceneTree headless mode the way real GUI input event dispatch does, confirmed by comparing direct-call vs `.emit()` behavior. Not a bug in the actual click-driven flow, just a headless-test-harness quirk to route around when writing tests. |
+| `smoke_test_main_menu_back.gd` | Regression test for Play → Back logging the user out even with a valid token still held. Registers a user, loads `main_menu.tscn` (asserts it restores the authenticated state via a real `auth_state_ready` signal wait, not a frame-count guess), clicks Play → `world_list.tscn`, clicks Back → `main_menu.tscn`, and asserts the menu is still authenticated. Checks `WelcomeLabel.is_visible_in_tree()`, not just `.visible` — the label lives inside AuthPanel, so `.visible` alone is a false positive if the panel itself is hidden (a real bug briefly present: `_show_authenticated()` hid AuthPanel while claiming the welcome label was visible, which rendered nothing). |
 
 Run (once, to build the class cache): `godot --headless --path . --import`,
 then for each smoke test: `godot --headless --path . --script

scenes/worlds/test_level.tscn

@@ -0,0 +1,120 @@
+[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/main_menu.gd

@@ -6,6 +6,24 @@ extends Control
 ## The Login and Register buttons on the AuthButtonsRow directly set the panel's
 ## mode, so the user can switch between Login and Register at any time while
 ## the panel is open.
+##
+## On successful auth the token is stored via ApiClient, AuthButtonsRow hides,
+## the welcome label shows the username, and the Play button becomes enabled.
+## The auth form fields are hidden, leaving only the welcome message visible.
+##
+## When returning from another scene (e.g. world_list), _ready() checks whether
+## ApiClient already holds a valid token. If so, it restores the authenticated
+## UI state (Play enabled, welcome message visible) instead of forcing the user
+## back to the login form.
+
+
+## Emitted once _ready()'s session check (has_token() + the awaited
+## get_me() call) has actually resolved, whichever way -- lets a test (or
+## anything else) know the UI state is trustworthy now, rather than
+## guessing from a frame count or from UI properties that are ambiguous
+## mid-await (e.g. AuthButtonsRow.visible is true both before the check
+## resolves AND in a genuine logged-out end state).
+signal auth_state_ready
 
 # ─── UI references ────────────────────────────────────────────────────────────
 
@@ -47,7 +65,63 @@ func _ready() -> void:
 	_play_button = $CenterContainer/VBoxContainer/PlayButton
 	_quit_button = $CenterContainer/VBoxContainer/QuitButton
 
-	# Initial state.
+	# Default to Play being gated. When a token exists, the async session
+	# check below may take several frames (a real get_me() round-trip);
+	# keeping the button disabled until validation succeeds prevents a fast
+	# click from navigating to world_list with an expired/invalid token.
+	_play_button.disabled = true
+
+	# Check whether a valid session already exists (e.g. user logged in,
+	# navigated to world_list, then clicked Back). If so, restore the
+	# authenticated UI state instead of forcing the login form again.
+	if ApiClient.has_token():
+		var me_result: Dictionary = await ApiClient.get_me()
+		if me_result.ok and me_result.data is Dictionary:
+			var username: String = str((me_result.data as Dictionary).get("username", ""))
+			if username != "":
+				_show_authenticated(username)
+				auth_state_ready.emit()
+				return
+
+	# Token missing or invalid — fall through to logged-out state.
+	_reset_to_logged_out()
+	auth_state_ready.emit()
+
+
+## Restore the UI to the authenticated state (Play enabled, welcome message
+## visible, auth buttons hidden). AuthPanel itself stays visible -- the
+## welcome label lives inside it, so hiding the panel hides the label too
+## even when the label's own `visible` is true (real bug, 2026-08-20: a
+## review caught the panel being hidden here while the label claimed to be
+## visible, which is a no-op UI-wise since Control.visible doesn't override
+## an ancestor's hidden state).
+func _show_authenticated(username: String) -> void:
+	_auth_panel.visible = true
+	_status_label.visible = false
+	_welcome_label.text = "Welcome, %s!" % username
+	_welcome_label.visible = true
+	# Hide the same full set of form fields _on_auth_complete() hides right
+	# after a fresh login/register -- this path (session restore on scene
+	# reload, e.g. after Play -> Back) used to only hide EmailEdit/
+	# Over18Check, leaving UsernameEdit/PasswordEdit/AuthButton/
+	# AuthModeLabel visible on top of the welcome message. Real bug: Play
+	# was enabled and the welcome label was correct, so it wasn't caught by
+	# checks for those alone -- the login fields being back on screen is
+	# what a user actually sees as "it's making me log in again."
+	_username_edit.visible = false
+	_password_edit.visible = false
+	_email_edit.visible = false
+	_over_18_check.visible = false
+	_auth_button.visible = false
+	_auth_mode_label.visible = false
+	_play_button.disabled = false
+	_auth_buttons_row.visible = false
+	print("Restored authenticated session for: ", username)
+
+
+## Reset the UI to the logged-out state (Play disabled, auth panel hidden,
+## login/register buttons visible).
+func _reset_to_logged_out() -> void:
 	_auth_panel.visible = false
 	_status_label.visible = false
 	_welcome_label.visible = false
@@ -158,12 +232,16 @@ func _on_auth_complete(result: Dictionary) -> void:
 	_is_authenticating = false
 
 	if result.ok:
-		# Success — show welcome, enable Play, hide the now-redundant
-		# Login/Register entry points (the auth panel itself stays open,
-		# showing the welcome message in place of the form).
+		# Success — hide the auth form fields, show only the welcome label.
+		_username_edit.visible = false
+		_password_edit.visible = false
+		_email_edit.visible = false
+		_over_18_check.visible = false
+		_auth_button.visible = false
+		_auth_mode_label.visible = false
+		_status_label.visible = false
 		_welcome_label.text = "Welcome, %s!" % _username_edit.text.strip_edges()
 		_welcome_label.visible = true
-		_status_label.visible = false
 		_play_button.disabled = false
 		_auth_buttons_row.visible = false
 		print("Auth successful. Token stored.")

scripts/smoke_test_main_menu_back.gd

@@ -0,0 +1,170 @@
+extends SceneTree
+## Regression test for the Play -> Back navigation bug.
+##
+## The reported bug: after logging in and clicking Play, the user lands on
+## world_list.tscn; clicking Back returns to main_menu.tscn, but the menu
+## reset to a fully logged-out state (Play disabled, login form showing)
+## even though ApiClient still held a valid token. main_menu.gd's _ready()
+## used to unconditionally reset the UI on every scene load.
+##
+## This test drives the real navigation flow (change_scene_to_file) against
+## a live backend:
+##   1. Register a unique user so ApiClient holds a valid token.
+##   2. Load main_menu.tscn and assert it restores the authenticated state.
+##   3. Click Play -> world_list.tscn.
+##   4. Click Back -> main_menu.tscn.
+##   5. Assert the menu is STILL authenticated (Play enabled, welcome label
+##      actually visible in the tree, login/register buttons hidden).
+##
+## Run with:
+##     godot --headless --path . --script res://scripts/smoke_test_main_menu_back.gd
+##
+## Requires the backend to be running (default base URL
+## `application/agp/api_base_url` -> http://127.0.0.1:8000).
+
+const USERNAME := "backnav_%d"
+const EMAIL := "backnav_%d@test.example.com"
+const PASSWORD := "BackNav123!"
+
+var passed := 0
+var failed := 0
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	await process_frame
+
+	var api := root.get_node("ApiClient")
+	if api == null:
+		printerr("FAIL: ApiClient autoload not found")
+		quit(1)
+		return
+
+	# 1. Establish a real, valid session exactly the way a user would.
+	randomize()
+	var unique_id: int = int(Time.get_unix_time_from_system() * 1000) + randi() % 100000
+	var username := USERNAME % unique_id
+	var email := EMAIL % unique_id
+	print("\n=== Setup: register ", username, " ===")
+	var register_result: Dictionary = await api.register(username, email, PASSWORD, true)
+	if not _check("register succeeds", register_result.ok):
+		print("  detail: ", register_result.detail)
+		_finish()
+		return
+	_check("ApiClient stores token after register", api.has_token())
+
+	# 2. First visit to the main menu: should already show the authenticated
+	#    state (no login form, Play enabled).
+	change_scene_to_file("res://scenes/main_menu.tscn")
+	# change_scene_to_file defers the actual swap -- a couple frames is
+	# plenty for the scene object itself to exist (unlike the real
+	# get_me() network round-trip afterward, which is what auth_state_ready
+	# actually waits for below).
+	for i in 5:
+		await process_frame
+		if current_scene is Control:
+			break
+
+	var menu: Control = current_scene
+	if menu == null or not menu is Control:
+		printerr("FAIL: main_menu.tscn did not become current_scene")
+		_finish()
+		return
+	await menu.auth_state_ready
+	_check("first main menu visit restores authenticated state", _is_authenticated(menu))
+
+	# 3. Play -> world_list.tscn (real button press).
+	var play_button: Button = menu.get_node("CenterContainer/VBoxContainer/PlayButton")
+	play_button.pressed.emit()
+	await _wait_for_scene_change(menu)
+
+	var world_list_scene := current_scene
+	if world_list_scene == null or world_list_scene == menu:
+		printerr("FAIL: world_list.tscn did not become current_scene after Play")
+		_finish()
+		return
+
+	# 4. Back -> main_menu.tscn (real button press).
+	var back_button: Button = world_list_scene.get_node("VBoxContainer/HeaderHBox/BackButton")
+	back_button.pressed.emit()
+	await _wait_for_scene_change(world_list_scene)
+
+	menu = current_scene
+	if menu == null or not menu is Control:
+		printerr("FAIL: main_menu.tscn did not become current_scene after Back")
+		_finish()
+		return
+
+	# The new main_menu instance's own _ready() is *also* awaiting a real
+	# get_me() call -- _wait_for_scene_change only confirms the scene
+	# object exists, not that its authenticated-state fields have been
+	# set yet. Wait for the real signal, not a guess.
+	await menu.auth_state_ready
+
+	# 5. THE regression assertion: still logged in after returning.
+	_check("main menu stays authenticated after Play -> Back", _is_authenticated(menu))
+
+	_finish()
+
+
+func _is_authenticated(menu: Control) -> bool:
+	var play_button: Button = menu.get_node("CenterContainer/VBoxContainer/PlayButton")
+	var welcome_label: Label = menu.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/WelcomeLabel")
+	var auth_buttons_row: HBoxContainer = menu.get_node("CenterContainer/VBoxContainer/AuthButtonsRow")
+	var auth_panel: PanelContainer = menu.get_node("CenterContainer/VBoxContainer/AuthPanel")
+	var username_edit: LineEdit = menu.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/UsernameEdit")
+	var password_edit: LineEdit = menu.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/PasswordEdit")
+	var auth_button: Button = menu.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthButton")
+	var auth_mode_label: Label = menu.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthModeLabel")
+
+	_check("Play enabled", not play_button.disabled)
+	# WelcomeLabel lives inside AuthPanel, so `.visible` alone is a
+	# false-positive: the label can have visible=true while its parent is
+	# hidden and it renders as nothing. `is_visible_in_tree()` is the
+	# check that proves the user can actually see the welcome message.
+	_check("Welcome label visible in tree", welcome_label.is_visible_in_tree())
+	_check("Auth buttons row hidden", not auth_buttons_row.visible)
+	_check("Auth panel visible (it contains the welcome label)", auth_panel.visible)
+	# Real bug, 2026-08-20: the session-restore path (this one, after
+	# Play -> Back) hid EmailEdit/Over18Check but never the rest of the
+	# login form -- Play enabled + welcome label visible were both still
+	# true, so a check that stopped there passed while the user was
+	# looking at the login fields again on top of the welcome message.
+	_check("Username field hidden", not username_edit.visible)
+	_check("Password field hidden", not password_edit.visible)
+	_check("Auth button hidden", not auth_button.visible)
+	_check("Auth mode label hidden", not auth_mode_label.visible)
+
+	return (not play_button.disabled) \
+		and welcome_label.is_visible_in_tree() \
+		and not auth_buttons_row.visible \
+		and auth_panel.visible \
+		and not username_edit.visible \
+		and not password_edit.visible \
+		and not auth_button.visible \
+		and not auth_mode_label.visible
+
+
+func _wait_for_scene_change(previous_scene: Node) -> void:
+	for i in 20:
+		await process_frame
+		if current_scene != previous_scene and current_scene != null:
+			return
+
+
+func _check(description: String, condition: bool) -> bool:
+	if condition:
+		print("  PASS: ", description)
+		passed += 1
+	else:
+		printerr("  FAIL: ", description)
+		failed += 1
+	return condition
+
+
+func _finish() -> void:
+	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])
+	quit(0 if failed == 0 else 1)

scripts/smoke_test_main_menu_full_flow.gd

@@ -1,9 +1,8 @@
 extends SceneTree
 ## Full click-through simulation of the real user flow: press Register,
 ## fill the form exactly as a human would, submit, confirm Play actually
-## becomes clickable. This is the check that would have caught the
-## original bug (no way to even open the form) and would catch a repeat
-## of it.
+## becomes clickable. Also verifies that after successful auth the auth
+## form fields are hidden, leaving only the welcome message visible.
 
 var passed := 0
 var failed := 0
@@ -28,6 +27,7 @@ func _run() -> void:
 	var email_edit: LineEdit = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/EmailEdit")
 	var over_18_check: CheckBox = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/Over18Check")
 	var auth_button: Button = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthButton")
+	var auth_mode_label: Label = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthModeLabel")
 	var welcome_label: Label = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/WelcomeLabel")
 	var play_button: Button = instance.get_node("CenterContainer/VBoxContainer/PlayButton")
 
@@ -60,9 +60,19 @@ func _run() -> void:
 	await instance._on_auth_button_pressed()
 
 	_check("Play became enabled after real register submission", not play_button.disabled)
-	_check("Welcome label visible", welcome_label.visible)
+	_check("Welcome label visible in tree", welcome_label.is_visible_in_tree())
 	_check("Auth buttons row hid itself after success", not auth_buttons_row.visible)
 
+	# Verify the auth form fields are hidden after successful auth,
+	# leaving only the welcome message visible within the panel.
+	_check("Username edit hidden after auth", not username_edit.visible)
+	_check("Password edit hidden after auth", not password_edit.visible)
+	_check("Email edit hidden after auth", not email_edit.visible)
+	_check("Over18 checkbox hidden after auth", not over_18_check.visible)
+	_check("Auth button hidden after auth", not auth_button.visible)
+	_check("Auth mode label hidden after auth", not auth_mode_label.visible)
+	_check("Welcome label contains username", welcome_label.text.begins_with("Welcome, mainmenu_e2e_"))
+
 	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])
 	quit(0 if failed == 0 else 1)
 

scripts/smoke_test_test_level.gd

@@ -0,0 +1,125 @@
+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)