WIP checkpoint: Address review feedback: Fix: navigating Play -> Back logs the user out (should stay logged in)

The actual fix (main_menu.gd's _ready() checking ApiClient.has_token()
and restoring authenticated state via get_me()) was already correct --
verified this directly by instrumenting frame-by-frame state and seeing
it resolve properly in ~5 frames. The test wrapping it was the real
problem: _wait_for_menu_ready() only waited 2 frames total before
checking assertions, nowhere near enough for a real HTTP round-trip, so
every run failed on a fix that actually worked.

Root fix: added a real auth_state_ready signal to main_menu.gd, emitted
once _ready()'s session check has actually resolved (either branch --
authenticated or logged-out). The test now awaits that signal directly
instead of guessing from a frame count or from UI properties that are
ambiguous mid-await (AuthButtonsRow.visible is true both before the
check resolves AND in a genuine logged-out end state, which is exactly
what made an earlier polling-based fix attempt here also flaky).

Also fixed a second real bug in the test itself: unique_id used
Time.get_ticks_msec() (process-relative, not wall-clock), colliding
with a previous run's still-present data -- same flakiness class fixed
elsewhere this session, same fix (wall-clock ms + random suffix).

Verified: 12/12 passing across 3 consecutive runs against a real
backend.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/checkpoints/PC1.md

@@ -0,0 +1,72 @@
+# Package Checkpoint 1 (PC1)
+
+Validated 2026-08-20 against `main` commit `927f9bd`, from a genuinely fresh
+clone (not a reused agent workspace).
+
+## Automated validation
+
+Run with `scripts/run_checkpoint_tests.py` — see
+`docs/testing/test_inventory.md` for exactly what each suite covers.
+
+| Check | Result |
+|---|---|
+| Alembic migrations, fresh DB | PASS |
+| Backend pytest | 68/68 PASS |
+| Godot smoke tests (4 files) | ALL PASS |
+| Linux export (`agp-game.x86_64`) | Builds, verified as a real ELF64 binary |
+| Windows export (`agp-game.exe`) | Builds, verified as a real PE32+ binary |
+
+## Problems found during this checkpoint (fixed, tracked as tasks)
+
+- Roadmap showed the Godot Engine Scaffold feature amber despite 6/6 tasks
+  done — a historical data gap (a review-feedback follow-up task's
+  supersession link was never recorded, predating when that field started
+  being tracked). Backfilled in the PM database; confirmed green.
+- `docs/testing/test_inventory.md` was stale (said 38 backend tests,
+  actually 68; said no integration tests existed, 4 real ones had landed).
+  Fixed via task `398bf1a22a2d` / PR #40.
+
+## What's actually testable right now
+
+Login/register/browse-worlds only — there's no joinable gameplay yet. That's
+the real scope of PC1; don't expect more when playtesting.
+
+- Register a new account (18+ only, rejected otherwise)
+- Log out, log back in with the same credentials
+- Play → Browse Worlds — loads a (currently empty) world list with no errors
+
+## Manual playtest: backend on cloudbison, client on pinkbison
+
+As of 2026-08-20 this is dashboard-controlled — no terminal commands, no
+env vars, no editing files. Foolproof enough to hand to someone else.
+
+### 1. On cloudbison — the AGP dashboard
+
+Open the dashboard (`http://cloudbison:7070`, or its Tailscale address) and
+go to **PC1** in the nav bar (`/checkpoint/PC1`). Click **Start Backend** —
+it pulls the latest `main`, stands up Postgres, runs migrations, and starts
+the API server, all in one step. The page shows the LAN address it's
+reachable at once it's up (under a minute).
+
+When you're done playtesting, click **Stop & Clean Up** on the same page —
+it tears down everything that step started (API server, Postgres
+container, its volume and network). Nothing is left running or lying
+around afterward, even if the dashboard itself gets restarted in between.
+
+### 2. On pinkbison — download and run the .exe
+
+Same dashboard page: click **Build .exe** the first time (or **Rebuild** to
+pick up newer changes) — this pulls the latest `main` and exports a Windows
+binary with cloudbison's backend address already baked in. Click
+**Download agp-game.exe**, copy it to pinkbison, and just run it. No
+environment variable, no config file, no build step on pinkbison at all.
+
+### 3. Tear down when done
+
+**Stop & Clean Up** on the dashboard page. That's it.
+
+## Status
+
+`config/checkpoint_focus_feature_ids` in the AGP framework (`~/agp`) still
+restricts agent claiming to the 5 PC1-scope features. Agents will not move
+on to post-PC1 work until that's widened.

docs/testing/test_inventory.md

@@ -7,9 +7,13 @@ 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 (commit `927f9bd`) — full PC1
-checkpoint run, fresh clone, migrations + pytest + all 4 Godot smoke tests +
-both platform exports, all clean.
+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
+covered by the smoke tests below so they can't silently regress.
 
 ## Backend — `backend/tests/` (pytest)
 
@@ -48,7 +52,7 @@ these yet):
 
 ## Godot client — `scripts/smoke_test_*.gd`
 
-**4 smoke tests merged into `main`.** Each needs a live backend —
+**6 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.
@@ -58,7 +62,9 @@ these yet):
 | `smoke_test_api.gd` | Exercises `ApiClient.health_check()` against a live backend. Verifies the real HTTP request path (`HTTPRequest` node lifecycle, JSON parse, result-dictionary contract). Exits 1 on failure. |
 | `smoke_test_auth.gd` | Tests the full auth flow via `ApiClient` autoload: register unique user (201), duplicate username (409), under-18 registration (400), correct login (200), wrong password (401), nonexistent user (401). |
 | `smoke_test_e2e.gd` | End-to-end flow: health check → register → login → worlds list. Verifies the full request chain with a fresh user, including token storage and `get_worlds()` with auth header. |
-| `smoke_test_world_list.gd` | Instantiates `world_list.tscn` as a real scene, adds to tree (catches `@onready` node-path bugs), waits for `_refresh_worlds()` to complete, confirms the screen reaches a real end state (world cards, empty-list message, or error label — not stuck loading). |
+| `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. |
 
 Run (once, to build the class cache): `godot --headless --path . --import`,
 then for each smoke test: `godot --headless --path . --script
@@ -66,14 +72,18 @@ res://scripts/smoke_test_<name>.gd` — **no `--quit`**, it kills these before
 their awaited HTTP calls finish.
 
 **Known gaps:**
-- No smoke tests for the main menu scene (`main_menu.tscn`).
 - No smoke tests for chunk loading/streaming (`chunk.gd`, `chunk_scene.gd`).
 - No smoke tests for dynamic/static object nodes.
 - All smoke tests require a live backend; no offline/unit smoke tests exist.
-- `smoke_test_world_list.gd` is the only one that exercises a real `.tscn`
-  scene instantiation — others only test the `ApiClient` autoload.
+- `smoke_test_world_list.gd` and `smoke_test_main_menu_*.gd` are the only
+  ones that exercise a real `.tscn` scene instantiation — others only test
+  the `ApiClient` autoload directly.
 - `get_me()` (`GET /auth/me`) is implemented in `scripts/api_client.gd` but
   has no smoke coverage yet.
+- The Login path (as opposed to Register) through `main_menu.gd` isn't
+  separately smoke-tested — it shares the same `_on_auth_button_pressed()`/
+  `_on_auth_complete()` code path already exercised for Register, but that's
+  inference, not a direct check.
 
 ## Client export
 

export_presets.cfg

@@ -21,7 +21,7 @@ script_export_mode=2
 custom_template/debug=""
 custom_template/release=""
 debug/export_console_wrapper=1
-binary_format/embed_pck=false
+binary_format/embed_pck=true
 texture_format/bptc=true
 texture_format/s3tc=true
 texture_format/etc=false
@@ -52,7 +52,7 @@ script_export_mode=2
 custom_template/debug=""
 custom_template/release=""
 debug/export_console_wrapper=1
-binary_format/embed_pck=false
+binary_format/embed_pck=true
 texture_format/bptc=true
 texture_format/s3tc=true
 texture_format/etc=false

scenes/main_menu.tscn

@@ -29,6 +29,21 @@ text = "AGP Game"
 horizontal_alignment = 1
 theme_override_font_sizes/font_size = 72
 
+[node name="AuthButtonsRow" type="HBoxContainer" parent="CenterContainer/VBoxContainer"]
+layout_mode = 1
+theme_override_constants/separation = 16
+alignment = 1
+
+[node name="LoginButton" type="Button" parent="CenterContainer/VBoxContainer/AuthButtonsRow"]
+layout_mode = 1
+text = "Login"
+size_flags_horizontal = 3
+
+[node name="RegisterButton" type="Button" parent="CenterContainer/VBoxContainer/AuthButtonsRow"]
+layout_mode = 1
+text = "Register"
+size_flags_horizontal = 3
+
 [node name="AuthPanel" type="PanelContainer" parent="CenterContainer/VBoxContainer"]
 layout_mode = 1
 visible = false
@@ -106,6 +121,8 @@ layout_mode = 1
 text = "Quit"
 size_flags_horizontal = 4
 
+[connection signal="pressed" from="CenterContainer/VBoxContainer/AuthButtonsRow/LoginButton" to="." method="_on_login_button_pressed"]
+[connection signal="pressed" from="CenterContainer/VBoxContainer/AuthButtonsRow/RegisterButton" to="." method="_on_register_button_pressed"]
 [connection signal="pressed" from="CenterContainer/VBoxContainer/PlayButton" to="." method="_on_play_button_pressed"]
 [connection signal="pressed" from="CenterContainer/VBoxContainer/QuitButton" to="." method="_on_quit_button_pressed"]
 [connection signal="toggled" from="CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/ModeToggle" to="." method="_on_mode_toggle_toggled"]

scenes/world_list.tscn

@@ -11,14 +11,17 @@ grow_vertical = 2
 script = ExtResource("1_wl")
 
 [node name="VBoxContainer" type="VBoxContainer" parent="."]
-layout_mode = 3
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
 theme_override_constants/separation = 8
-size_flags_horizontal = 4
-size_flags_vertical = 4
 
 [node name="HeaderHBox" type="HBoxContainer" parent="VBoxContainer"]
 layout_mode = 3
-size_flags_horizontal = 4
+size_flags_horizontal = 3
 theme_override_constants/separation = 16
 
 [node name="BackButton" type="Button" parent="VBoxContainer/HeaderHBox"]
@@ -30,7 +33,7 @@ size_flags_horizontal = 0
 layout_mode = 3
 text = "Browse Worlds"
 horizontal_alignment = 1
-size_flags_horizontal = 4
+size_flags_horizontal = 3
 theme_override_font_sizes/font_size = 28
 
 [node name="RefreshButton" type="Button" parent="VBoxContainer/HeaderHBox"]
@@ -40,15 +43,14 @@ size_flags_horizontal = 0
 
 [node name="ScrollContainer" type="ScrollContainer" parent="VBoxContainer"]
 layout_mode = 3
-size_flags_horizontal = 4
-size_flags_vertical = 4
+size_flags_horizontal = 3
+size_flags_vertical = 3
 horizontal_mode = 2
 vertical_mode = 2
 
 [node name="WorldList" type="VBoxContainer" parent="VBoxContainer/ScrollContainer"]
 layout_mode = 3
-size_flags_horizontal = 4
-size_flags_vertical = 4
+size_flags_horizontal = 3
 theme_override_constants/separation = 8
 
 [node name="LoadingLabel" type="Label" parent="VBoxContainer"]

scripts/main_menu.gd

@@ -1,17 +1,33 @@
 extends Control
 ## Main menu with login/register UI wired to the backend auth API.
 ##
-## The AuthPanel is hidden by default. When the user clicks "Login" or "Register"
-## (the existing Play/Quit buttons), the auth panel slides in. The ModeToggle
-## switches between Login and Register modes, showing/hiding the email and DOB
-## fields accordingly.
+## The AuthPanel is hidden by default. When the user clicks the LoginButton or
+## RegisterButton (AuthButtonsRow, above the panel), the auth panel slides in.
+## The ModeToggle switches between Login and Register modes, showing/hiding
+## the email and DOB fields accordingly.
 ##
-## On successful auth the token is stored via ApiClient, the welcome label
-## shows the username, and the Play button becomes enabled.
+## On successful auth the token is stored via ApiClient, AuthButtonsRow hides,
+## the welcome label shows the username, and the Play button becomes enabled.
+##
+## 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 label visible) instead of forcing the user
+## back to the login form.
 
 
-# ── UI references ────────────────────────────────────────────────────────────
+## 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 ────────────────────────────────────────────────────────────
+
+var _auth_buttons_row: HBoxContainer
+var _login_button: Button
+var _register_button: Button
 var _auth_panel: PanelContainer
 var _auth_mode_label: Label
 var _username_edit: LineEdit
@@ -29,10 +45,13 @@ var _is_register_mode: bool = false
 var _is_authenticating: bool = false
 
 
-# ── Lifecycle ────────────────────────────────────────────────────────────────
+# ─── Lifecycle ────────────────────────────────────────────────────────────────
 
 func _ready() -> void:
 	# Cache node references.
+	_auth_buttons_row = $CenterContainer/VBoxContainer/AuthButtonsRow
+	_login_button = $CenterContainer/VBoxContainer/AuthButtonsRow/LoginButton
+	_register_button = $CenterContainer/VBoxContainer/AuthButtonsRow/RegisterButton
 	_auth_panel = $CenterContainer/VBoxContainer/AuthPanel
 	_auth_mode_label = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthModeLabel
 	_username_edit = $CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/UsernameEdit
@@ -46,7 +65,46 @@ 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 label,
+## auth buttons hidden).
+func _show_authenticated(username: String) -> void:
+	_auth_panel.visible = true
+	_status_label.visible = false
+	_welcome_label.text = "Welcome, %s!" % username
+	_welcome_label.visible = true
+	_email_edit.visible = false
+	_dob_edit.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
@@ -56,7 +114,7 @@ func _ready() -> void:
 	_update_auth_mode_ui()
 
 
-# ── Play / Quit ──────────────────────────────────────────────────────────────
+# ─── Play / Quit ─────────────────────────────────────────────────────────────
 
 func _on_play_button_pressed() -> void:
 	if _play_button.disabled:
@@ -70,24 +128,25 @@ func _on_quit_button_pressed() -> void:
 	get_tree().quit()
 
 
-# ── Auth panel toggle ────────────────────────────────────────────────────────
+# ─── Auth panel toggle ───────────────────────────────────────────────────────
 
 func _on_login_button_pressed() -> void:
-	"""Show the auth panel (called from a future Login button on the main menu)."""
+	"""Show the auth panel, called from AuthButtonsRow/LoginButton."""
 	_auth_panel.visible = true
-	_auth_panel.grab_focus()
+	_username_edit.grab_focus()
 
 
 func _on_register_button_pressed() -> void:
-	"""Show the auth panel in register mode."""
+	"""Show the auth panel in register mode, called from AuthButtonsRow/RegisterButton."""
 	_auth_panel.visible = true
 	_is_register_mode = true
 	_mode_toggle.button_pressed = true
 	_update_auth_mode_ui()
 	_clear_status()
+	_username_edit.grab_focus()
 
 
-# ── Mode toggle (Login / Register) ───────────────────────────────────────────
+# ─── Mode toggle (Login / Register) ──────────────────────────────────────────
 
 func _on_mode_toggle_toggled(button_pressed: bool) -> void:
 	_is_register_mode = button_pressed
@@ -109,7 +168,7 @@ func _update_auth_mode_ui() -> void:
 		_dob_edit.visible = false
 
 
-# ── Auth submission ──────────────────────────────────────────────────────────
+# ─── Auth submission ─────────────────────────────────────────────────────────
 
 func _on_auth_button_pressed() -> void:
 	"""Handle login or register button press."""
@@ -166,18 +225,21 @@ func _on_auth_complete(result: Dictionary) -> void:
 	_is_authenticating = false
 
 	if result.ok:
-		# Success — show welcome, enable Play.
+		# 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).
 		_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.")
 	else:
 		# Failure — show backend error detail.
 		_show_status(result.detail)
 
 
-# ── Status helpers ───────────────────────────────────────────────────────────
+# ─── Status helpers ──────────────────────────────────────────────────────────
 
 func _show_status(message: String) -> void:
 	_status_label.text = message
@@ -189,7 +251,7 @@ func _clear_status() -> void:
 	_status_label.visible = false
 
 
-# ── Validation ───────────────────────────────────────────────────────────────
+# ─── Validation ──────────────────────────────────────────────────────────────
 
 func _is_valid_date(date_str: String) -> bool:
 	"""Check if a string looks like a valid YYYY-MM-DD date."""

scripts/smoke_test_main_menu_back.gd

@@ -0,0 +1,154 @@
+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!"
+const DOB := "2000-01-01"
+
+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, DOB)
+	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")
+
+	_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)
+
+	return (not play_button.disabled) \
+		and welcome_label.is_visible_in_tree() \
+		and not auth_buttons_row.visible \
+		and auth_panel.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

@@ -0,0 +1,76 @@
+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.
+
+var passed := 0
+var failed := 0
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	await process_frame
+
+	var packed: PackedScene = load("res://scenes/main_menu.tscn")
+	var instance: Control = packed.instantiate()
+	root.add_child(instance)
+	await process_frame
+
+	var register_button: Button = instance.get_node("CenterContainer/VBoxContainer/AuthButtonsRow/RegisterButton")
+	var auth_buttons_row: HBoxContainer = instance.get_node("CenterContainer/VBoxContainer/AuthButtonsRow")
+	var username_edit: LineEdit = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/UsernameEdit")
+	var password_edit: LineEdit = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/PasswordEdit")
+	var email_edit: LineEdit = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/EmailEdit")
+	var dob_edit: LineEdit = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/DOBEdit")
+	var auth_button: Button = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/AuthButton")
+	var welcome_label: Label = instance.get_node("CenterContainer/VBoxContainer/AuthPanel/MarginContainer/AuthVBox/WelcomeLabel")
+	var play_button: Button = instance.get_node("CenterContainer/VBoxContainer/PlayButton")
+
+	_check("Play starts disabled", play_button.disabled)
+
+	# Click Register -- a real signal emission is fine here since
+	# _on_register_button_pressed() is synchronous (no await), same as a
+	# real click's GUI event dispatch would drive it.
+	register_button.pressed.emit()
+	await process_frame
+
+	_check("auth panel opened in register mode", instance.get_node("CenterContainer/VBoxContainer/AuthPanel").visible)
+
+	# Fill the form exactly as a user would type into it.
+	var unique_id := int(Time.get_unix_time_from_system() * 1000)
+	username_edit.text = "mainmenu_e2e_%d" % unique_id
+	password_edit.text = "TestPass123!"
+	email_edit.text = "mainmenu_e2e_%d@test.example.com" % unique_id
+	dob_edit.text = "2000-01-01"
+
+	# Call the submit handler directly (awaited) rather than via
+	# auth_button.pressed.emit() -- a synthetic .emit() in --script/
+	# SceneTree headless mode doesn't drive an await-using handler's
+	# coroutine forward the same way real GUI input event dispatch does
+	# (confirmed via a direct-call vs emit() comparison: the direct call
+	# always resolves, the synthetic emit sometimes doesn't advance past
+	# its own await point even after 50 real process_frame waits). This
+	# is a headless-mode test-harness limitation, not a bug in the actual
+	# click-driven flow.
+	await instance._on_auth_button_pressed()
+
+	_check("Play became enabled after real register submission", not play_button.disabled)
+	_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)
+
+	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])
+	quit(0 if failed == 0 else 1)
+
+
+func _check(description: String, condition: bool) -> void:
+	if condition:
+		print("  PASS: ", description)
+		passed += 1
+	else:
+		printerr("  FAIL: ", description)
+		failed += 1

scripts/smoke_test_main_menu_ui.gd

@@ -0,0 +1,60 @@
+extends SceneTree
+## Verifies the main menu's Login/Register buttons actually open the auth
+## panel via a real signal emission (not calling the handler method
+## directly) -- that's the exact gap that shipped without ever being
+## caught: the AuthPanel and its logic were all correct, but nothing in
+## the scene was ever wired to open it.
+
+
+func _initialize() -> void:
+	_run()
+
+
+func _run() -> void:
+	await process_frame
+
+	var passed := 0
+	var failed := 0
+
+	var packed: PackedScene = load("res://scenes/main_menu.tscn")
+	var instance: Control = packed.instantiate()
+	root.add_child(instance)
+	await process_frame
+
+	var login_button: Button = instance.get_node("CenterContainer/VBoxContainer/AuthButtonsRow/LoginButton")
+	var register_button: Button = instance.get_node("CenterContainer/VBoxContainer/AuthButtonsRow/RegisterButton")
+	var auth_panel: PanelContainer = instance.get_node("CenterContainer/VBoxContainer/AuthPanel")
+
+	if _check("auth panel starts hidden", not auth_panel.visible):
+		passed += 1
+	else:
+		failed += 1
+
+	login_button.pressed.emit()
+	await process_frame
+
+	if _check("auth panel visible after a real LoginButton press signal", auth_panel.visible):
+		passed += 1
+	else:
+		failed += 1
+
+	# Reset and check RegisterButton independently too.
+	auth_panel.visible = false
+	register_button.pressed.emit()
+	await process_frame
+
+	if _check("auth panel visible after a real RegisterButton press signal", auth_panel.visible):
+		passed += 1
+	else:
+		failed += 1
+
+	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])
+	quit(0 if failed == 0 else 1)
+
+
+func _check(description: String, condition: bool) -> bool:
+	if condition:
+		print("  PASS: ", description)
+	else:
+		printerr("  FAIL: ", description)
+	return condition

scripts/smoke_test_world_list.gd

@@ -16,15 +16,27 @@ extends SceneTree
 ##
 ## Tests:
 ##   1. Register + log in a fresh user (so get_worlds() has a valid token).
-##   2. Instantiate world_list.tscn, add to tree -- @onready resolution
+##   2. POST a real world via the API so the populated-card path actually
+##      gets exercised -- run_checkpoint_tests.py always starts from a
+##      genuinely empty DB, so without this the card-rendering code below
+##      would never run in CI at all, only the empty-list path would.
+##   3. Instantiate world_list.tscn, add to tree -- @onready resolution
 ##      must not error.
-##   3. Wait for _refresh_worlds()'s awaited request to complete.
-##   4. Confirm the screen reached a real end state (world cards, or the
-##      empty-list message -- either is fine, a crash/stuck-loading isn't).
+##   4. Wait for _refresh_worlds()'s awaited request to complete.
+##   5. Confirm it actually reached the populated (not empty) state, and
+##      that the rendered card has a real width -- not just non-zero
+##      child_count. 2026-08-20: a real bug shipped where every card
+##      technically existed in the tree (child_count > 0, no error, no
+##      crash) but rendered at 1.0px wide because size_flags_horizontal/
+##      vertical used the raw integer 4 (Control.SIZE_SHRINK_CENTER)
+##      instead of 3 (Control.SIZE_EXPAND_FILL) on ScrollContainer -- a
+##      child-count check alone would never catch that, only a real size
+##      assertion does.
 ##
 ## Exits 0 on full pass, 1 on any failure.
 
 const WORLD_LIST_SCENE := "res://scenes/world_list.tscn"
+const MIN_SANE_CARD_WIDTH := 200.0  # a real screen is at minimum a few hundred px wide
 
 
 func _initialize() -> void:
@@ -52,6 +64,19 @@ func _run() -> void:
 		quit(1)
 		return
 
+	# --- Seed a real world so the populated-card path is actually exercised ---
+	print("\n=== Setup: seed a real world ===")
+	var world_body := JSON.stringify({
+		"name": "Smoke Test World %d" % unique_id,
+		"description": "Seeded by smoke_test_world_list.gd to exercise the populated-card render path.",
+		"visibility": "public",
+	})
+	var create_result: Dictionary = await api.request(HTTPClient.METHOD_POST, "/api/worlds/", world_body, "application/json", true)
+	if not _check("setup: world created", create_result.ok):
+		print("  detail: ", create_result.detail)
+		quit(1)
+		return
+
 	# --- Test 1: Instantiate the real scene ---
 	print("\n=== Test 1: Instantiate world_list.tscn ===")
 	var packed_scene: PackedScene = load(WORLD_LIST_SCENE)
@@ -99,10 +124,31 @@ func _run() -> void:
 
 	if error_label.visible:
 		printerr("  Note: ended in error state: ", error_label.text)
-	elif world_list_node.visible:
-		print("  Note: rendered %d world card(s)" % world_list_node.get_child_count())
 	elif empty_label.visible:
-		print("  Note: ended in empty-list state")
+		# We just seeded a world -- ending up empty means GET /api/worlds
+		# isn't actually seeing what POST /api/worlds/ just created.
+		_check("ended in populated state, not empty (a world was just seeded)", false)
+		failed += 1
+	elif world_list_node.visible:
+		var card_count := world_list_node.get_child_count()
+		print("  Note: rendered %d world card(s)" % card_count)
+
+		if _check("at least one card rendered", card_count > 0):
+			passed += 1
+		else:
+			failed += 1
+
+		# The actual bug this test exists to catch: a card can be present
+		# in the tree, not crash, and still be visually nothing because
+		# it rendered at ~1px wide. Check every card's real computed size,
+		# not just that it exists.
+		for i in range(card_count):
+			var card: Control = world_list_node.get_child(i)
+			var wide_enough := card.size.x >= MIN_SANE_CARD_WIDTH
+			if _check("card %d has a real width (%.0fpx >= %.0fpx)" % [i, card.size.x, MIN_SANE_CARD_WIDTH], wide_enough):
+				passed += 1
+			else:
+				failed += 1
 
 	# --- Summary ---
 	print("\n=== SMOKE RESULT: %d/%d passed ===" % [passed, passed + failed])

scripts/world_list.gd

@@ -88,10 +88,26 @@ func _refresh_worlds() -> void:
 
 ## Create a visual card for a single world entry.
 func _create_world_card(world_dict: Dictionary) -> Control:
+	# PanelContainer for the background, not a ColorRect moved to child index
+	# 0 of a VBoxContainer -- a VBoxContainer lays out ALL its children in a
+	# vertical sequence, it has no concept of "float this one child behind
+	# the others as an overlay". That version rendered as an empty dark bar
+	# sitting above the text, not a background behind it.
+	var panel := PanelContainer.new()
+	panel.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	panel.custom_minimum_size = Vector2(0, 80)
+	var style := StyleBoxFlat.new()
+	style.bg_color = Color(0.15, 0.15, 0.15, 1.0)
+	style.content_margin_left = 12
+	style.content_margin_right = 12
+	style.content_margin_top = 8
+	style.content_margin_bottom = 8
+	panel.add_theme_stylebox_override("panel", style)
+
 	var card := VBoxContainer.new()
-	card.size_flags_horizontal = Control.SIZE_FILL
-	card.custom_minimum_size = Vector2(0, 80)
+	card.size_flags_horizontal = Control.SIZE_EXPAND_FILL
 	card.add_theme_constant_override("separation", 4)
+	panel.add_child(card)
 
 	var name_label := Label.new()
 	name_label.text = world_dict.get("name", "Unnamed World")
@@ -123,13 +139,4 @@ func _create_world_card(world_dict: Dictionary) -> Control:
 	card.add_child(desc_label)
 	card.add_child(meta_label)
 
-	# Subtle background for the card
-	var bg := ColorRect.new()
-	bg.color = Color(0.15, 0.15, 0.15, 1.0)
-	bg.size_flags_horizontal = Control.SIZE_FILL
-	bg.size_flags_vertical = Control.SIZE_FILL
-	bg.custom_minimum_size = Vector2(0, 80)
-	card.add_child(bg)
-	card.move_child(bg, 0)
-
-	return card
+	return panel