diff --git a/CLAUDE.md b/CLAUDE.md
index 4909bf8..a417da0 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -29,6 +29,7 @@ godot --headless --path . res://tools/diag_loot.tscn          # drop -> pick up
 godot --headless --path . res://tools/diag_upgrades.tscn      # level -> choice -> taken at the NPC -> new stats
 godot --headless --path . --script tools/bench.gd             # sim cost per tick
 python3 tools/build_local_assets.py                           # rebuild the local-only bullet atlas
+SHOT_DIR=/tmp/shots godot --path . res://tools/screenshot.tscn # capture the menus and HUD (needs a display)
 ```
 
 `diag_progression`, `diag_loot` and `diag_upgrades` exist because the bot smoke
@@ -105,6 +106,8 @@ and `tests/integration/test_replica_parity.gd` pin this down.
 | `src/instances/` | Lobby hub and dungeon runs. |
 | `src/view/`, `src/ui/` | Read-only rendering. Never decides anything. |
 | `src/core/settings.gd` | Client-local preferences: key bindings and volumes. Never reaches the server. |
+| `src/core/credits.gd` | Every third-party asset and its licence. Two are CC BY, so this is a legal requirement, not a nicety. |
+| `src/view/ui_theme.gd` | The control theme, built in code from the UI pack. |
 | `src/autoload/net.gd` | The only autoload. RPC surface. |
 | `tools/` | Headless tooling. |
 
@@ -137,7 +140,15 @@ ticks in milliseconds with no SceneTree.
    coordinate even on an anchored control; `offset_left`/`offset_top` are the
    anchor-relative ones. This combination silently broke the main menu and
    three pieces of the HUD.
-6. **`ProjectSettings.save()` drops settings equal to the engine default** and
+6. **A Control's theme is inherited from Control ANCESTORS only.** The chain
+   breaks at the first parent that is a plain `Node` or a `CanvasLayer`, which
+   here is every screen: they hang off `main.gd` or off a CanvasLayer. Setting
+   `get_window().theme` therefore compiles, runs, changes the property — and
+   styles nothing. Apply the theme to each screen's own root Control
+   (`UiTheme.themed_root()`). `tests/unit/test_ui_theme.gd` instantiates every
+   screen and asks what its buttons actually resolve, because this failure is
+   invisible to every other kind of check.
+7. **`ProjectSettings.save()` drops settings equal to the engine default** and
    strips comments. Anything load-bearing (the 60 Hz tick) is asserted in code
    in `src/main.gd` instead of trusted to `project.godot`.
 
diff --git a/CREDITS.md b/CREDITS.md
index 1bbd0b0..41e7786 100644
--- a/CREDITS.md
+++ b/CREDITS.md
@@ -1,8 +1,14 @@
 # Credits
 
 Every third-party asset pack used or bundled during development, credited
-regardless of whether its licence requires it. Two of them do not — they are
-here because the work deserves it.
+regardless of whether its licence requires it. Some of them do not require it —
+they are here because the work deserves it.
+
+**This file is not the only place credit appears.** Two of the packs are CC BY
+4.0, which asks for attribution "in any reasonable manner", and a markdown file
+in a source repository is not reasonable for someone who downloaded a build. The
+game carries the same list on its own credits screen (Settings → Credits), built
+from `src/core/credits.gd`; `tests/unit/test_credits.gd` asserts the two agree.
 
 ## In the game
 
@@ -11,6 +17,12 @@ Terrain, player, enemies and boss sprites.
 [CC0 1.0](https://creativecommons.org/publicdomain/zero/1.0/) — public domain.
 *Credit not required.*
 
+**Complete UI Essential Pack** — [Crusenho Agus Hennihuno](https://crusenho.itch.io/complete-ui-essential-pack)
+Buttons, panels, bars and inventory slots. Used unmodified; a subset of the
+pack's individual sprites is committed under `assets/sprites/ui/`.
+[CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
+**Credit required by licence.**
+
 **Pixel Combat SFX** — [Helton Yan](https://heltonyan.itch.io/pixelcombat)
 All sound effects. Converted to 16-bit / 44.1 kHz mono and trimmed.
 [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
diff --git a/assets/README.md b/assets/README.md
index ec19961..18fa410 100644
--- a/assets/README.md
+++ b/assets/README.md
@@ -12,6 +12,17 @@ The split exists so that adding a 3.9 GB pack of source material costs the
 repository and the import step nothing, while the handful of files the game
 loads stay reviewable.
 
-Nothing is here yet — the game currently draws itself from primitives and one
-runtime-generated dot texture ([src/view/bullet_renderer.gd](../src/view/bullet_renderer.gd)).
-Art is Stage 2 of [docs/ROADMAP.md](../docs/ROADMAP.md).
+What is here:
+
+| Path | What | Source |
+| --- | --- | --- |
+| `sprites/dungeon_tileset.png` | terrain, characters, bosses, item icons | 0x72, CC0 |
+| `sprites/ui/` | buttons, panels, bars, inventory slots | Crusenho, CC BY 4.0 |
+| `audio/sfx/` | every sound the game plays | Helton Yan, CC BY 4.0 |
+| `local/` | bullet and impact art — **gitignored**, licence forbids redistribution | bdragon1727 |
+
+Sprite rects and sound paths are declared in
+[src/view/art.gd](../src/view/art.gd); UI textures in
+[src/view/ui_theme.gd](../src/view/ui_theme.gd). Attribution lives in
+[CREDITS.md](../CREDITS.md) and on the game's own credits screen — see
+[docs/ASSETS.md](../docs/ASSETS.md) for the licence findings.
diff --git a/assets/sprites/ui/Banner01a.png b/assets/sprites/ui/Banner01a.png
new file mode 100644
index 0000000..e168334
Binary files /dev/null and b/assets/sprites/ui/Banner01a.png differ
diff --git a/assets/sprites/ui/Banner01a.png.import b/assets/sprites/ui/Banner01a.png.import
new file mode 100644
index 0000000..2027173
--- /dev/null
+++ b/assets/sprites/ui/Banner01a.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://m2nhvybbia58"
+path="res://.godot/imported/Banner01a.png-79d54606f6c5efa37ca262c86fb3c88b.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Banner01a.png"
+dest_files=["res://.godot/imported/Banner01a.png-79d54606f6c5efa37ca262c86fb3c88b.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Bar01a.png b/assets/sprites/ui/Bar01a.png
new file mode 100644
index 0000000..544bc84
Binary files /dev/null and b/assets/sprites/ui/Bar01a.png differ
diff --git a/assets/sprites/ui/Bar01a.png.import b/assets/sprites/ui/Bar01a.png.import
new file mode 100644
index 0000000..ce84653
--- /dev/null
+++ b/assets/sprites/ui/Bar01a.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://b4w7eso648lkb"
+path="res://.godot/imported/Bar01a.png-4fa78ad3d34ea11ebad35ea23bc8ff70.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Bar01a.png"
+dest_files=["res://.godot/imported/Bar01a.png-4fa78ad3d34ea11ebad35ea23bc8ff70.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/BarFill01f.png b/assets/sprites/ui/BarFill01f.png
new file mode 100644
index 0000000..c2c08ae
Binary files /dev/null and b/assets/sprites/ui/BarFill01f.png differ
diff --git a/assets/sprites/ui/BarFill01f.png.import b/assets/sprites/ui/BarFill01f.png.import
new file mode 100644
index 0000000..5b4a42b
--- /dev/null
+++ b/assets/sprites/ui/BarFill01f.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://0txc40f6u7pc"
+path="res://.godot/imported/BarFill01f.png-8f813e9f1aea22470c4cd1a20dc14300.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/BarFill01f.png"
+dest_files=["res://.godot/imported/BarFill01f.png-8f813e9f1aea22470c4cd1a20dc14300.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Button01a_1.png b/assets/sprites/ui/Button01a_1.png
new file mode 100644
index 0000000..1bb31b8
Binary files /dev/null and b/assets/sprites/ui/Button01a_1.png differ
diff --git a/assets/sprites/ui/Button01a_1.png.import b/assets/sprites/ui/Button01a_1.png.import
new file mode 100644
index 0000000..f7b32d8
--- /dev/null
+++ b/assets/sprites/ui/Button01a_1.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://dk2bbq73k8h27"
+path="res://.godot/imported/Button01a_1.png-2cddde3a12e70b9f65fa9b0cba03379d.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Button01a_1.png"
+dest_files=["res://.godot/imported/Button01a_1.png-2cddde3a12e70b9f65fa9b0cba03379d.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Button01a_2.png b/assets/sprites/ui/Button01a_2.png
new file mode 100644
index 0000000..fd62ab2
Binary files /dev/null and b/assets/sprites/ui/Button01a_2.png differ
diff --git a/assets/sprites/ui/Button01a_2.png.import b/assets/sprites/ui/Button01a_2.png.import
new file mode 100644
index 0000000..e726125
--- /dev/null
+++ b/assets/sprites/ui/Button01a_2.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://b8nsxodlmgomt"
+path="res://.godot/imported/Button01a_2.png-35c4875fe9ac1c69211a75ffbcc0fd8c.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Button01a_2.png"
+dest_files=["res://.godot/imported/Button01a_2.png-35c4875fe9ac1c69211a75ffbcc0fd8c.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Button01a_3.png b/assets/sprites/ui/Button01a_3.png
new file mode 100644
index 0000000..14d6589
Binary files /dev/null and b/assets/sprites/ui/Button01a_3.png differ
diff --git a/assets/sprites/ui/Button01a_3.png.import b/assets/sprites/ui/Button01a_3.png.import
new file mode 100644
index 0000000..1ad8639
--- /dev/null
+++ b/assets/sprites/ui/Button01a_3.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://cvj6idjcu0j1s"
+path="res://.godot/imported/Button01a_3.png-3896dc57fbcbb9c973f680df22c8b858.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Button01a_3.png"
+dest_files=["res://.godot/imported/Button01a_3.png-3896dc57fbcbb9c973f680df22c8b858.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Button01a_4.png b/assets/sprites/ui/Button01a_4.png
new file mode 100644
index 0000000..bb9ca2c
Binary files /dev/null and b/assets/sprites/ui/Button01a_4.png differ
diff --git a/assets/sprites/ui/Button01a_4.png.import b/assets/sprites/ui/Button01a_4.png.import
new file mode 100644
index 0000000..2cfc35b
--- /dev/null
+++ b/assets/sprites/ui/Button01a_4.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://dj0kffckj1iug"
+path="res://.godot/imported/Button01a_4.png-9c12b7189c542159f43a7e003d114d95.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Button01a_4.png"
+dest_files=["res://.godot/imported/Button01a_4.png-9c12b7189c542159f43a7e003d114d95.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Frame01a.png b/assets/sprites/ui/Frame01a.png
new file mode 100644
index 0000000..b8cc060
Binary files /dev/null and b/assets/sprites/ui/Frame01a.png differ
diff --git a/assets/sprites/ui/Frame01a.png.import b/assets/sprites/ui/Frame01a.png.import
new file mode 100644
index 0000000..5309101
--- /dev/null
+++ b/assets/sprites/ui/Frame01a.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://bybgrl0ye24w0"
+path="res://.godot/imported/Frame01a.png-626104f1220a56d01a83a690493b113d.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Frame01a.png"
+dest_files=["res://.godot/imported/Frame01a.png-626104f1220a56d01a83a690493b113d.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/Frame02a.png b/assets/sprites/ui/Frame02a.png
new file mode 100644
index 0000000..e273c79
Binary files /dev/null and b/assets/sprites/ui/Frame02a.png differ
diff --git a/assets/sprites/ui/Frame02a.png.import b/assets/sprites/ui/Frame02a.png.import
new file mode 100644
index 0000000..3820cb2
--- /dev/null
+++ b/assets/sprites/ui/Frame02a.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://y42352ti7y2t"
+path="res://.godot/imported/Frame02a.png-ac57f8ba2960b573fe171292b8a7c378.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/Frame02a.png"
+dest_files=["res://.godot/imported/Frame02a.png-ac57f8ba2960b573fe171292b8a7c378.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/FrameSlot01a.png b/assets/sprites/ui/FrameSlot01a.png
new file mode 100644
index 0000000..3774d38
Binary files /dev/null and b/assets/sprites/ui/FrameSlot01a.png differ
diff --git a/assets/sprites/ui/FrameSlot01a.png.import b/assets/sprites/ui/FrameSlot01a.png.import
new file mode 100644
index 0000000..3a1a440
--- /dev/null
+++ b/assets/sprites/ui/FrameSlot01a.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://btuhdrpfr8td3"
+path="res://.godot/imported/FrameSlot01a.png-069d1091d125c87d7c14afba6400418d.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/FrameSlot01a.png"
+dest_files=["res://.godot/imported/FrameSlot01a.png-069d1091d125c87d7c14afba6400418d.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/FrameSlot01b.png b/assets/sprites/ui/FrameSlot01b.png
new file mode 100644
index 0000000..dde41de
Binary files /dev/null and b/assets/sprites/ui/FrameSlot01b.png differ
diff --git a/assets/sprites/ui/FrameSlot01b.png.import b/assets/sprites/ui/FrameSlot01b.png.import
new file mode 100644
index 0000000..a37573d
--- /dev/null
+++ b/assets/sprites/ui/FrameSlot01b.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://btf5al7f07nl"
+path="res://.godot/imported/FrameSlot01b.png-bd6ad2d53ba974202493dbaf3f360ea5.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/FrameSlot01b.png"
+dest_files=["res://.godot/imported/FrameSlot01b.png-bd6ad2d53ba974202493dbaf3f360ea5.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/assets/sprites/ui/InputField01a.png b/assets/sprites/ui/InputField01a.png
new file mode 100644
index 0000000..c3327e1
Binary files /dev/null and b/assets/sprites/ui/InputField01a.png differ
diff --git a/assets/sprites/ui/InputField01a.png.import b/assets/sprites/ui/InputField01a.png.import
new file mode 100644
index 0000000..7737d59
--- /dev/null
+++ b/assets/sprites/ui/InputField01a.png.import
@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://cb41i0vnvjmri"
+path="res://.godot/imported/InputField01a.png-d4cf01240254dbae255720ff161f1d6a.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://assets/sprites/ui/InputField01a.png"
+dest_files=["res://.godot/imported/InputField01a.png-d4cf01240254dbae255720ff161f1d6a.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1
diff --git a/docs/ASSETS.md b/docs/ASSETS.md
index 8722de1..314315d 100644
--- a/docs/ASSETS.md
+++ b/docs/ASSETS.md
@@ -12,22 +12,24 @@ can be referenced from a scene or script. Files are copied into `res://assets/`
 in game-ready form, and only then imported. The tree is 3.9 GB and
 `tools/check.sh` runs `--import`, which would otherwise walk all of it every run.
 
-What is in the game today totals **548 KB** across seven files: three sprite
-sheets and four sounds. Sprite rects and sound paths are all declared in one
+What is in the game today is three sprite sheets, four sounds and twelve small
+UI sprites. Sprite rects and sound paths are all declared in one
 place, [src/view/art.gd](../src/view/art.gd), and
 `tests/unit/test_art.gd` asserts every rect lands inside its texture — a wrong
 atlas coordinate does not error, it silently draws the wrong pixels.
 
 ## Licence findings
 
-Checked against each pack's itch.io page. **Two of the four forbid
-redistribution**, which is what publishing a repository containing them would
-be — so they are not in the repository.
+Checked against each pack's itch.io page, and against the licence file the pack
+itself ships where there is one. **Two of the five forbid redistribution**,
+which is what publishing a repository containing them would be — so they are not
+in the repository.
 
 | Pack | Licence | Commercial | Credit | In this repo? |
 | --- | --- | --- | --- | --- |
 | [0x72 DungeonTileset II](https://0x72.itch.io/dungeontileset-ii) | **CC0 1.0** (public domain) | Yes | Not required | **Yes** — `assets/sprites/dungeon_tileset.png` |
 | [Helton Yan Pixel Combat](https://heltonyan.itch.io/pixelcombat) | **CC BY 4.0** | Yes | **Required** | **Yes** — `assets/audio/sfx/` |
+| [Complete UI Essential Pack](https://crusenho.itch.io/complete-ui-essential-pack) | **CC BY 4.0** | Yes | **Required** | **Yes** — `assets/sprites/ui/` |
 | [Fire Pixel Bullet 16x16](https://bdragon1727.itch.io/fire-pixel-bullet-16x16) | Custom | Free tier non-commercial; **paid tier allows commercial** | Encouraged | **No, at any tier** — local only |
 | [750+ Effect and FX Pixel All](https://bdragon1727.itch.io/750-effect-and-fx-pixel-all) | Custom | Free tier non-commercial; **paid tier allows commercial** | Encouraged | **No, at any tier** — local only |
 
@@ -56,12 +58,30 @@ passes 156/156 and the game runs.
 This is also why nothing there may be `preload()`ed — `preload` resolves at
 compile time and would fail the build on every machine that lacks the files.
 
+### The UI pack is the easy case
+
+Crusenho's *Complete UI Essential Pack* ships its own `License.txt` naming
+CC BY 4.0 outright, with the licensor and store link spelled out. That permits
+redistribution and commercial use, so unlike the bullet and FX packs a subset of
+it is committed — twelve PNGs, 48 KB, under `assets/sprites/ui/`, listed in
+`UiTheme.TEXTURES`.
+
+Only what the game uses was copied rather than all 98 sprites: each committed
+PNG costs a Godot `.import` sidecar, and a directory of files nothing references
+is a directory nobody prunes. The rest stays in the untracked pack.
+
+The obligation it creates is the same one the audio creates — see below.
+
 ### Two obligations this creates
 
-1. **Helton Yan's CC BY 4.0 requires attribution**, and it is not satisfied by
-   a file in the source tree once the game ships. Players need to be able to
-   see it. [CREDITS.md](../CREDITS.md) records it for now; an in-game credits
-   screen is a todo.
+1. **Two packs are CC BY 4.0 and require attribution** — Helton Yan's audio and
+   Crusenho's UI art. A file in the source tree does not satisfy that once the
+   game ships, because a player who downloaded a build never sees it. **Done:**
+   Settings → Credits shows the same list, built from
+   [src/core/credits.gd](../src/core/credits.gd), including a link to the
+   licence text as CC BY asks. `tests/unit/test_credits.gd` asserts every source
+   there also appears in [CREDITS.md](../CREDITS.md) and in this file, so the
+   three cannot drift apart.
 2. **Both bdragon packs are non-commercial in their free tier.** Buying the
    full tier *does* fix that — confirmed verbatim from the FX pack's paid
    licence: "You may use these assets in personal, commercial or
diff --git a/docs/ROADMAP.md b/docs/ROADMAP.md
index 571c3db..2271e7b 100644
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -20,13 +20,17 @@ What "everything passes" currently means. Numbers move; the shape does not.
 | Gate | Covers | Runtime |
 | --- | --- | --- |
 | `tools/check.sh` | every script parses and type-checks | ~5s |
-| `tools/test.sh` | 439 GUT tests, no SceneTree | ~4s |
+| `tools/test.sh` | 460 GUT tests, no SceneTree | ~4s |
 | `tools/smoke.sh` | 23 assertions over a real ENet socket: handshake, auth, character creation and persistence, both dungeon kinds, escape, hard kill, polite disconnect | ~40s |
 | `diag_prediction.tscn` | client-prediction gap, with injected clock drift | ~10s |
 | `diag_progression.tscn` | kill → xp → level → health, death → retire → roster, swap guards | ~10s |
 | `diag_loot.tscn` | drop → snapshot → pick up → persist → use → drop, and both loot visibilities on the wire | ~10s |
 | `diag_upgrades.tscn` | level → banked choice → refused in a dungeon and away from the NPC → taken → new stats → persisted → **survives every zone change** | ~10s |
 
+`tools/screenshot.tscn` is a **manual** check, not a gate: it needs a display,
+and it is the only thing in the project that can tell you the interface
+actually rendered. Run it after touching `src/ui/`.
+
 The four diagnostics exist because the smoke test structurally cannot reach
 what they cover: bots are poor shots (so they neither level up, produce drops,
 nor walk to the quartermaster), and a listen server cannot drift its own clock
@@ -129,8 +133,10 @@ play off server events. Enough to prove the pipeline, not a finished look.
 | Impact/death VFX animation | todo | `Art.IMPACT` is loaded and validated but nothing plays it yet |
 | Directional sprites, hit flashes, screen shake | todo | |
 | Rebindable controls | done | [src/ui/settings_screen.gd](../src/ui/settings_screen.gd), [src/core/settings.gd](../src/core/settings.gd) |
+| Themed controls from a UI pack | done | [src/view/ui_theme.gd](../src/view/ui_theme.gd), art in `assets/sprites/ui/` |
+| Textured HUD bars and inventory slots | done | `HUD._bar`, `HUD._draw_inventory` |
 | Audio buses and a volume setting | done | `Settings`, an SFX bus created at runtime, sliders in the settings screen |
-| **In-game credits screen** | **todo** | Not cosmetic: the SFX are CC BY 4.0 and attribution is a licence *requirement*. [CREDITS.md](../CREDITS.md) is not reachable by a player. |
+| **In-game credits screen** | **done** | Settings → Credits, from [src/core/credits.gd](../src/core/credits.gd). Two packs are CC BY 4.0 and attribution is a licence *requirement* — [CREDITS.md](../CREDITS.md) is not reachable by a player. |
 | Replace the two non-redistributable packs | todo | Bullet and FX art is local-only and non-commercial. CC0 replacements would let them into the repo and unblock a commercial release. See [ASSETS.md](ASSETS.md). |
 
 ## Stage 2 — Characters, persistence, levels · *done*
diff --git a/docs/WORKFLOW.md b/docs/WORKFLOW.md
index f15e40e..8c1cad3 100644
--- a/docs/WORKFLOW.md
+++ b/docs/WORKFLOW.md
@@ -251,3 +251,24 @@ the output, which is worth doing after any change to startup.
 `smoke.sh` now asserts no plain engine errors either, excluding by name the one
 line Godot prints on every clean exit — naming it means anything else that turns
 up is a real finding rather than noise to be squinted past.
+
+### Nothing automated can see the screen
+
+Every gate passed — 458 tests, a clean smoke run, no engine errors — while the
+entire interface rendered in Godot's default style and none of the UI pack was
+visible. A Control inherits its theme from Control *ancestors only*, and the
+chain breaks at the first plain `Node` or `CanvasLayer`; every screen in this
+game hangs off one. `get_window().theme = ...` set the property, changed
+nothing, and looked correct in the code.
+
+It took `tools/screenshot.tscn` — boot the client, save a PNG, open it — to
+find. The same run then showed **Fire bound to the right mouse button**, which
+was the test suite writing the player's real `user://settings.cfg`, because
+rebinding calls `save()` and nothing had redirected the path.
+
+Two lessons, and the second is the general one:
+
+- After touching `src/ui/`, look at it. There is no substitute.
+- A test that exercises a code path which writes to user state **will write to
+  user state**. Redirect the path in the fixture, and assert the default is
+  still the real one so the redirect cannot escape.
diff --git a/src/core/credits.gd b/src/core/credits.gd
new file mode 100644
index 0000000..f50148c
--- /dev/null
+++ b/src/core/credits.gd
@@ -0,0 +1,76 @@
+class_name Credits
+extends RefCounted
+## Every third-party asset the game ships, and the terms it ships under.
+##
+## This is not decoration. Two of these packs are CC BY 4.0, which requires
+## attribution "in any reasonable manner" -- a file in the repository is not
+## reasonable for a player who downloaded a build, so the game has to say so
+## itself. See [CreditsScreen].
+##
+## `tests/unit/test_credits.gd` asserts every entry here also appears in
+## CREDITS.md, so the two cannot drift apart.
+
+## Each entry: what it is, who made it, the licence, a link, and what it is
+## used for. `required` marks the ones the licence obliges us to show.
+const SOURCES: Array[Dictionary] = [
+	{
+		"name": "16x16 DungeonTileset II",
+		"author": "0x72 (Robert Norenberg)",
+		"licence": "CC0 1.0 (public domain)",
+		"url": "https://0x72.itch.io/dungeontileset-ii",
+		"used_for": "Terrain, characters, bosses, item icons",
+		"required": false,
+	},
+	{
+		"name": "Complete UI Essential Pack",
+		"author": "Crusenho Agus Hennihuno",
+		"licence": "CC BY 4.0",
+		"url": "https://crusenho.itch.io/complete-ui-essential-pack",
+		"used_for": "Buttons, panels, bars, inventory slots",
+		"required": true,
+	},
+	{
+		"name": "Pixel Combat SFX",
+		"author": "Helton Yan",
+		"licence": "CC BY 4.0",
+		"url": "https://heltonyan.itch.io/pixelcombat",
+		"used_for": "All sound effects",
+		"required": true,
+	},
+	{
+		"name": "Fire Pixel Bullet 16x16",
+		"author": "bdragon1727",
+		"licence": "Custom - not redistributable",
+		"url": "https://bdragon1727.itch.io/fire-pixel-bullet-16x16",
+		"used_for": "Bullet sprites (local builds only)",
+		"required": false,
+	},
+	{
+		"name": "750+ Effect and FX Pixel All",
+		"author": "bdragon1727",
+		"licence": "Custom - not redistributable",
+		"url": "https://bdragon1727.itch.io/750-effect-and-fx-pixel-all",
+		"used_for": "Impact effects (local builds only)",
+		"required": false,
+	},
+]
+
+## CC BY asks for a link to the licence itself, not only to the work.
+const LICENCE_LINKS := {
+	"CC BY 4.0": "https://creativecommons.org/licenses/by/4.0/",
+	"CC0 1.0 (public domain)": "https://creativecommons.org/publicdomain/zero/1.0/",
+}
+
+
+## The packs whose licence actually obliges us to credit them. Everything else
+## in [constant SOURCES] is there because the work deserves it.
+static func required() -> Array[Dictionary]:
+	var out: Array[Dictionary] = []
+	for entry in SOURCES:
+		if bool(entry["required"]):
+			out.append(entry)
+	return out
+
+
+static func licence_url(licence: String) -> String:
+	return String(LICENCE_LINKS.get(licence, ""))
diff --git a/src/core/credits.gd.uid b/src/core/credits.gd.uid
new file mode 100644
index 0000000..374b6a4
--- /dev/null
+++ b/src/core/credits.gd.uid
@@ -0,0 +1 @@
+uid://drpadmmsrvoax
diff --git a/src/core/settings.gd b/src/core/settings.gd
index 406d84e..378b249 100644
--- a/src/core/settings.gd
+++ b/src/core/settings.gd
@@ -10,7 +10,14 @@ extends RefCounted
 ## tool has no main loop and cannot resolve autoload names, and the settings
 ## file is something a headless test may well want to read.
 
-const PATH := "user://settings.cfg"
+const DEFAULT_PATH := "user://settings.cfg"
+
+## Where preferences are read from and written to. A variable rather than a
+## constant so tests can point it at a scratch file: rebinding calls save(),
+## and a suite run was otherwise rewriting the player's real settings -- which
+## it did, silently, until a screenshot showed Fire bound to the right mouse
+## button.
+static var path: String = DEFAULT_PATH
 
 ## Actions the settings screen offers, in the order it lists them. Anything not
 ## here keeps whatever `tools/setup_input_map.gd` gave it and cannot be changed
@@ -54,7 +61,7 @@ static var _defaults_captured: bool = false
 static func load_and_apply() -> void:
 	_capture_defaults()
 	var cfg := ConfigFile.new()
-	if cfg.load(PATH) == OK:
+	if cfg.load(path) == OK:
 		master_volume = clampf(float(cfg.get_value("audio", "master", master_volume)), 0.0, 1.0)
 		sfx_volume = clampf(float(cfg.get_value("audio", "sfx", sfx_volume)), 0.0, 1.0)
 		bindings.clear()
@@ -81,9 +88,9 @@ static func save() -> void:
 	cfg.set_value("audio", "sfx", sfx_volume)
 	for action in bindings:
 		cfg.set_value("input", action, bindings[action])
-	var err := cfg.save(PATH)
+	var err := cfg.save(path)
 	if err != OK:
-		GameLog.warn("settings", "could not write %s (error %d)" % [PATH, err])
+		GameLog.warn("settings", "could not write %s (error %d)" % [path, err])
 
 
 # --- Audio -------------------------------------------------------------------
diff --git a/src/game.tscn b/src/game.tscn
index 594c40e..a801f79 100644
--- a/src/game.tscn
+++ b/src/game.tscn
@@ -1,4 +1,4 @@
-[gd_scene load_steps=10 format=3]
+[gd_scene load_steps=11 format=3]
 
 [ext_resource type="Script" path="res://src/view/game_scene.gd" id="1"]
 [ext_resource type="Script" path="res://src/view/world_view.gd" id="2"]
@@ -9,6 +9,7 @@
 [ext_resource type="Script" path="res://src/ui/character_select.gd" id="7"]
 [ext_resource type="Script" path="res://src/ui/upgrade_screen.gd" id="8"]
 [ext_resource type="Script" path="res://src/ui/settings_screen.gd" id="9"]
+[ext_resource type="Script" path="res://src/ui/credits_screen.gd" id="10"]
 
 [node name="Game" type="Node2D"]
 script = ExtResource("1")
@@ -37,3 +38,6 @@ script = ExtResource("8")
 
 [node name="SettingsScreen" type="CanvasLayer" parent="."]
 script = ExtResource("9")
+
+[node name="CreditsScreen" type="CanvasLayer" parent="."]
+script = ExtResource("10")
diff --git a/src/main.gd b/src/main.gd
index 9be0ae5..69f654f 100644
--- a/src/main.gd
+++ b/src/main.gd
@@ -11,6 +11,7 @@ const CONNECT_TIMEOUT_SEC := 8.0
 
 var _menu: Control = null
 var _settings: CanvasLayer = null
+var _credits: CanvasLayer = null
 var _game: Node = null
 var _ticks: int = 0
 var _connecting: bool = false
@@ -151,10 +152,19 @@ func _open_settings() -> void:
 	if _settings == null:
 		_settings = preload("res://src/ui/settings_screen.gd").new()
 		_settings.closed.connect(func() -> void: _settings.visible = false)
+		_settings.credits_requested.connect(_open_credits)
 		add_child(_settings)
 	_settings.open()
 
 
+func _open_credits() -> void:
+	if _credits == null:
+		_credits = preload("res://src/ui/credits_screen.gd").new()
+		_credits.closed.connect(func() -> void: _credits.visible = false)
+		add_child(_credits)
+	_credits.open()
+
+
 func _clear_game() -> void:
 	if _game != null:
 		_game.queue_free()
diff --git a/src/ui/character_select.gd b/src/ui/character_select.gd
index a3a3a6a..d7c828f 100644
--- a/src/ui/character_select.gd
+++ b/src/ui/character_select.gd
@@ -24,8 +24,7 @@ var _selected: String = ""
 func _ready() -> void:
 	layer = 30
 	_rng.randomize()
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	var scrim := ColorRect.new()
diff --git a/src/ui/credits_screen.gd b/src/ui/credits_screen.gd
new file mode 100644
index 0000000..988e15d
--- /dev/null
+++ b/src/ui/credits_screen.gd
@@ -0,0 +1,94 @@
+extends CanvasLayer
+## Attribution, in the game rather than only in the repository.
+##
+## CC BY 4.0 requires credit "in any reasonable manner", and a markdown file
+## nobody who downloads a build will ever see does not clear that bar. Two of
+## the packs the game ships are CC BY, so this screen is a licence obligation
+## and not a nicety -- which is why its contents come from [Credits] and a test
+## asserts nothing in there is missing from it.
+
+signal closed
+
+var _list: VBoxContainer
+
+
+func _ready() -> void:
+	layer = 34
+	visible = false
+	var root := UiTheme.themed_root()
+	add_child(root)
+
+	var scrim := ColorRect.new()
+	scrim.color = Color(0.03, 0.03, 0.06, 0.95)
+	scrim.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	scrim.mouse_filter = Control.MOUSE_FILTER_STOP
+	root.add_child(scrim)
+
+	var centre := CenterContainer.new()
+	centre.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	root.add_child(centre)
+
+	var panel := VBoxContainer.new()
+	panel.custom_minimum_size = Vector2(620.0, 0.0)
+	panel.add_theme_constant_override("separation", 8)
+	centre.add_child(panel)
+
+	var title := Label.new()
+	title.text = "CREDITS"
+	title.add_theme_font_size_override("font_size", 26)
+	panel.add_child(title)
+
+	var intro := Label.new()
+	intro.text = "Third-party work this game is built from. " \
+		+ "Credited whether or not the licence asks."
+	intro.add_theme_font_size_override("font_size", 12)
+	intro.add_theme_color_override("font_color", Color(0.6, 0.65, 0.78))
+	intro.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	intro.custom_minimum_size = Vector2(620.0, 0.0)
+	panel.add_child(intro)
+
+	var scroll := ScrollContainer.new()
+	scroll.custom_minimum_size = Vector2(620.0, 340.0)
+	panel.add_child(scroll)
+	_list = VBoxContainer.new()
+	_list.custom_minimum_size = Vector2(600.0, 0.0)
+	_list.add_theme_constant_override("separation", 12)
+	scroll.add_child(_list)
+	for entry in Credits.SOURCES:
+		_add_entry(entry)
+
+	var close := Button.new()
+	close.text = "Close"
+	close.custom_minimum_size = Vector2(160.0, 34.0)
+	close.pressed.connect(func() -> void: closed.emit())
+	panel.add_child(close)
+
+
+func _add_entry(entry: Dictionary) -> void:
+	var block := VBoxContainer.new()
+	block.add_theme_constant_override("separation", 1)
+	_list.add_child(block)
+
+	var heading := Label.new()
+	heading.text = "%s  —  %s" % [entry["name"], entry["author"]]
+	heading.add_theme_font_size_override("font_size", 16)
+	block.add_child(heading)
+
+	var detail := Label.new()
+	var licence := String(entry["licence"])
+	var link := Credits.licence_url(licence)
+	# The licence LINK, not just its name: CC BY asks for one, and a player
+	# reading this screen has no other way to reach the terms.
+	detail.text = "%s  ·  %s%s\n%s" % [
+		entry["used_for"], licence,
+		"  ·  " + link if not link.is_empty() else "",
+		entry["url"]]
+	detail.add_theme_font_size_override("font_size", 12)
+	detail.add_theme_color_override("font_color", Color(0.62, 0.67, 0.8))
+	detail.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	detail.custom_minimum_size = Vector2(600.0, 0.0)
+	block.add_child(detail)
+
+
+func open() -> void:
+	visible = true
diff --git a/src/ui/credits_screen.gd.uid b/src/ui/credits_screen.gd.uid
new file mode 100644
index 0000000..6b88f64
--- /dev/null
+++ b/src/ui/credits_screen.gd.uid
@@ -0,0 +1 @@
+uid://bo3xikvfahke5
diff --git a/src/ui/game_menu.gd b/src/ui/game_menu.gd
index 0470aa4..5a25ba5 100644
--- a/src/ui/game_menu.gd
+++ b/src/ui/game_menu.gd
@@ -23,8 +23,7 @@ var _open: bool = false
 
 func _ready() -> void:
 	layer = 20
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	# Dim the game behind the menu so it is obvious the world is still running.
diff --git a/src/ui/hud.gd b/src/ui/hud.gd
index fcd4d6d..da9d45b 100644
--- a/src/ui/hud.gd
+++ b/src/ui/hud.gd
@@ -6,8 +6,17 @@ const MARGIN := 24.0
 const BAR_W := 260.0
 const BAR_H := 16.0
 ## Inventory slot box, and the gap between boxes.
-const SLOT := 46.0
+##
+## Exactly twice the 32px source sprite. A non-integer scale on pixel art with
+## nearest filtering gives uneven pixel widths, which on a 1px border reads as
+## a wobble along the edge of every slot.
+const SLOT := 64.0
 const SLOT_GAP := 8.0
+## Source-pixel width of the caps on the bar sprite. The bar is stretched only
+## horizontally, so the ends are drawn at their own size and the middle takes
+## whatever is left -- a plain stretched draw would smear a 1px border out to
+## eight.
+const BAR_CAP := 6.0
 ## How far above the bottom of the screen the inventory row sits.
 const SLOT_BOTTOM := 26.0
 
@@ -31,6 +40,7 @@ func _ready() -> void:
 	# and the death-message centering down with it, since all three read
 	# _canvas.size. set_anchors_and_offsets_preset() sets both correctly.
 	_canvas.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	UiTheme.apply_to(_canvas)
 	_canvas.mouse_filter = Control.MOUSE_FILTER_IGNORE
 	_canvas.draw.connect(_draw_hud)
 	add_child(_canvas)
@@ -44,7 +54,10 @@ func _ready() -> void:
 	# here means "56px above the bottom anchor", which is what "-56" was meant
 	# to say in the first place.
 	_hint.offset_left = MARGIN
-	_hint.offset_top = -56.0
+	# Above the inventory row, not through it. Derived from the row's own
+	# geometry rather than written down, because the slots grew from 46px to 64
+	# and a hardcoded -56 put the control hints straight across them.
+	_hint.offset_top = -(SLOT_BOTTOM + SLOT + 34.0)
 
 	# A real Button rather than something drawn in _draw_hud: this is the one
 	# HUD element the player has to actually click, and it starts disabled so
@@ -126,13 +139,13 @@ func _draw_hud() -> void:
 	var origin := Vector2(MARGIN, MARGIN + 28.0)
 	_bar(origin, float(client.my_hp) / float(maxi(client.my_max_hp, 1)),
 		Color(0.35, 0.9, 0.6), Color(0.1, 0.15, 0.18))
-	_draw_xp_bar(origin + Vector2(0.0, BAR_H + 3.0))
+	_draw_xp_bar(origin + Vector2(0.0, BAR_H + 4.0))
 
 	if client.my_escaping:
-		_bar(origin + Vector2(0.0, BAR_H + 8.0), client.my_escape,
+		_bar(origin + Vector2(0.0, (BAR_H + 4.0) * 2.0), client.my_escape,
 			Color(0.5, 0.85, 1.0), Color(0.1, 0.15, 0.2))
 		_canvas.draw_string(ThemeDB.fallback_font,
-			origin + Vector2(BAR_W + 12.0, BAR_H + 8.0 + BAR_H),
+			origin + Vector2(BAR_W + 12.0, (BAR_H + 4.0) * 2.0 + BAR_H - 3.0),
 			"ESCAPING", HORIZONTAL_ALIGNMENT_LEFT, -1, 14, Color(0.5, 0.85, 1.0))
 
 	_draw_boss_bar()
@@ -195,15 +208,15 @@ func _draw_inventory() -> void:
 		var at := origin + Vector2(float(i) * (SLOT + SLOT_GAP), 0.0)
 		var item := Items.by_index(int(client.my_inventory[i]))
 		var def := Items.get_def(item)
-		var frame_col := Color(0.55, 0.6, 0.72, 0.75) if i == held \
-			else Color(0.3, 0.33, 0.42, 0.6)
-		_canvas.draw_rect(Rect2(at, Vector2(SLOT, SLOT)), Color(0.07, 0.08, 0.12, 0.72))
-		_canvas.draw_rect(Rect2(at, Vector2(SLOT, SLOT)), frame_col, false, 1.5)
+		# The held slot uses the pack's pressed-in slot art rather than a
+		# recoloured border, so "this is the one the key is on" reads the same
+		# way every other pressed thing in the interface does.
+		var slot_art := UiTheme.texture("slot_active" if i == held else "slot")
+		_canvas.draw_texture_rect(slot_art, Rect2(at, Vector2(SLOT, SLOT)), false)
 		# The slot number, because the key that uses it is the only thing the
 		# player actually needs to know about a slot.
-		_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(4.0, 13.0),
-			str(i + 1), HORIZONTAL_ALIGNMENT_LEFT, -1, 11,
-			Color(0.5, 0.55, 0.68))
+		_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(6.0, 17.0),
+			str(i + 1), HORIZONTAL_ALIGNMENT_LEFT, -1, 12, UiTheme.INK_DIM)
 		if def == null:
 			continue
 		var icon := Art.item_icon(item)
@@ -248,13 +261,12 @@ func _draw_xp_bar(at: Vector2) -> void:
 	var capped := level >= Progression.MAX_LEVEL
 	var progress := Progression.level_progress(client.my_total_xp)
 	var tint := Color(1.0, 0.85, 0.4) if capped else Color(0.6, 0.55, 1.0)
-	_canvas.draw_rect(Rect2(at, Vector2(BAR_W, 5.0)), Color(0.1, 0.12, 0.18))
-	_canvas.draw_rect(Rect2(at, Vector2(BAR_W * progress, 5.0)), tint)
+	_bar(at, progress, tint, Color.BLACK)
 	# The number as well as the bar: "how far to the next level" is a question
 	# a bar answers vaguely and a percentage answers exactly.
 	var text := "MAX" if capped else "%d%% to level %d" % [
 		int(floor(progress * 100.0)), level + 1]
-	_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(BAR_W + 10.0, 6.0),
+	_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(BAR_W + 10.0, 13.0),
 		text, HORIZONTAL_ALIGNMENT_LEFT, -1, 12, tint)
 
 
@@ -299,8 +311,13 @@ func _draw_boss_bar() -> void:
 	var w := 560.0
 	var pos := Vector2((_canvas.size.x - w) * 0.5, MARGIN)
 	var frac := clampf(float(b["hp"]) / float(client.boss_def.max_hp), 0.0, 1.0)
-	_canvas.draw_rect(Rect2(pos, Vector2(w, BAR_H)), Color(0.12, 0.08, 0.1))
-	_canvas.draw_rect(Rect2(pos, Vector2(w * frac, BAR_H)), Color(0.95, 0.35, 0.45))
+	var rect := Rect2(pos, Vector2(w, BAR_H))
+	_hslice(UiTheme.texture("bar"), rect, Color.WHITE)
+	var inner := Rect2(rect.position + Vector2(3.0, 3.0),
+		Vector2((w - 6.0) * frac, BAR_H - 6.0))
+	if inner.size.x > 0.5:
+		_canvas.draw_texture_rect(UiTheme.texture("bar_fill"), inner, false,
+			Color(0.95, 0.35, 0.45))
 	var phase_index := int(b["phase"])
 	var phase_name := ""
 	if phase_index < client.boss_def.phases.size():
@@ -310,9 +327,45 @@ func _draw_boss_bar() -> void:
 		HORIZONTAL_ALIGNMENT_LEFT, -1, 14, Color(1.0, 0.75, 0.8))
 
 
-func _bar(pos: Vector2, frac: float, fill: Color, back: Color) -> void:
-	_canvas.draw_rect(Rect2(pos, Vector2(BAR_W, BAR_H)), back)
-	_canvas.draw_rect(Rect2(pos, Vector2(BAR_W * clampf(frac, 0.0, 1.0), BAR_H)), fill)
+## A bar in the pack's art: the frame stretched horizontally, the fill tinted.
+##
+## [param back] is no longer a colour -- the frame sprite is the background --
+## but the signature keeps it so callers read the same and a future flat-bar
+## fallback has somewhere to go.
+func _bar(pos: Vector2, frac: float, fill: Color, _back: Color) -> void:
+	var rect := Rect2(pos, Vector2(BAR_W, BAR_H))
+	_hslice(UiTheme.texture("bar"), rect, Color.WHITE)
+	var inset := 3.0
+	var inner := Rect2(rect.position + Vector2(inset, inset),
+		Vector2((rect.size.x - inset * 2.0) * clampf(frac, 0.0, 1.0),
+			rect.size.y - inset * 2.0))
+	if inner.size.x > 0.5:
+		# The fill sprite is a flat strip, so tinting it is the whole palette --
+		# one texture covers health, experience, the escape channel and the
+		# boss.
+		_canvas.draw_texture_rect(UiTheme.texture("bar_fill"), inner, false, fill)
+
+
+## Draw a horizontally stretchable sprite as three slices: left cap, stretched
+## middle, right cap. Godot's nine-patch lives on nodes rather than on the
+## immediate-mode API, and the HUD is drawn rather than built out of controls.
+func _hslice(tex: Texture2D, rect: Rect2, tint: Color) -> void:
+	if tex == null:
+		return
+	var src := Vector2(tex.get_size())
+	var cap := minf(BAR_CAP, src.x * 0.5)
+	var draw_cap := cap * (rect.size.y / src.y)
+	_canvas.draw_texture_rect_region(tex,
+		Rect2(rect.position, Vector2(draw_cap, rect.size.y)),
+		Rect2(0.0, 0.0, cap, src.y), tint)
+	_canvas.draw_texture_rect_region(tex,
+		Rect2(rect.position + Vector2(draw_cap, 0.0),
+			Vector2(maxf(rect.size.x - draw_cap * 2.0, 0.0), rect.size.y)),
+		Rect2(cap, 0.0, src.x - cap * 2.0, src.y), tint)
+	_canvas.draw_texture_rect_region(tex,
+		Rect2(rect.position + Vector2(rect.size.x - draw_cap, 0.0),
+			Vector2(draw_cap, rect.size.y)),
+		Rect2(src.x - cap, 0.0, cap, src.y), tint)
 
 
 func flash_hit() -> void:
diff --git a/src/ui/main_menu.gd b/src/ui/main_menu.gd
index 0c75090..3707fd9 100644
--- a/src/ui/main_menu.gd
+++ b/src/ui/main_menu.gd
@@ -24,6 +24,7 @@ func _ready() -> void:
 	# what actually caused the "menu stuck in the top-left corner" bug --
 	# set_anchors_and_offsets_preset() sets both halves correctly in one call.
 	set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	UiTheme.apply_to(self)
 
 	# A CenterContainer recomputes its child's centered position itself, every
 	# time the child's minimum size or the window size changes -- no manual
diff --git a/src/ui/settings_screen.gd b/src/ui/settings_screen.gd
index cf6d40b..31abb08 100644
--- a/src/ui/settings_screen.gd
+++ b/src/ui/settings_screen.gd
@@ -6,6 +6,7 @@ extends CanvasLayer
 ## game's state that should change what it can do.
 
 signal closed
+signal credits_requested
 
 var _rows: Dictionary[String, Button] = {}
 var _status: Label
@@ -20,8 +21,7 @@ var _listening: String = ""
 func _ready() -> void:
 	layer = 32
 	visible = false
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	var scrim := ColorRect.new()
@@ -81,6 +81,11 @@ func _ready() -> void:
 		_status.text = "controls reset"
 		refresh())
 	buttons.add_child(reset)
+	var credits := Button.new()
+	credits.text = "Credits"
+	credits.custom_minimum_size = Vector2(160.0, 34.0)
+	credits.pressed.connect(func() -> void: credits_requested.emit())
+	buttons.add_child(credits)
 	var close := Button.new()
 	close.text = "Close"
 	close.custom_minimum_size = Vector2(160.0, 34.0)
diff --git a/src/ui/upgrade_screen.gd b/src/ui/upgrade_screen.gd
index a9a5de0..c2a1947 100644
--- a/src/ui/upgrade_screen.gd
+++ b/src/ui/upgrade_screen.gd
@@ -31,8 +31,7 @@ var _status: Label
 func _ready() -> void:
 	layer = 28
 	visible = false
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	var scrim := ColorRect.new()
diff --git a/src/view/game_scene.gd b/src/view/game_scene.gd
index 12a40c3..a63f992 100644
--- a/src/view/game_scene.gd
+++ b/src/view/game_scene.gd
@@ -10,6 +10,7 @@ extends Node2D
 @onready var characters: CanvasLayer = $CharacterSelect
 @onready var upgrades: CanvasLayer = $UpgradeScreen
 @onready var settings: CanvasLayer = $SettingsScreen
+@onready var credits: CanvasLayer = $CreditsScreen
 
 var _bound: ClientRuntime = null
 ## Opened deliberately from the menu, as opposed to forced open by having no
@@ -37,6 +38,8 @@ func _ready() -> void:
 	upgrades.closed.connect(func() -> void: _upgrades_open = false)
 	menu.settings_requested.connect(func() -> void: settings.open())
 	settings.closed.connect(func() -> void: settings.visible = false)
+	settings.credits_requested.connect(func() -> void: credits.open())
+	credits.closed.connect(func() -> void: credits.visible = false)
 	upgrades.choose_requested.connect(func(i: int) -> void: Net.choose_upgrade(i))
 
 
diff --git a/src/view/ui_theme.gd b/src/view/ui_theme.gd
new file mode 100644
index 0000000..8383795
--- /dev/null
+++ b/src/view/ui_theme.gd
@@ -0,0 +1,116 @@
+class_name UiTheme
+extends RefCounted
+## The game's control theme, built in code from Crusenho's UI pack.
+##
+## Built rather than authored as a .tres for the same reason [Content] is code:
+## it is a readable diff, there are no resource UIDs churning in version
+## control, and a test can build it without the editor.
+##
+## Applied to each screen's root Control ([method apply_to]). It cannot be
+## applied once to the Window instead: Godot's theme lookup walks a Control's
+## ancestors, and the chain BREAKS at the first plain Node -- which for every
+## screen here is `main.gd` or a CanvasLayer. Setting `window.theme` looked like
+## it worked and changed nothing.
+
+const DIR := "res://assets/sprites/ui/"
+
+## Every texture the theme needs. Named so a test can assert they all load: a
+## missing file gives a null texture and a silently unstyled control, which
+## looks like the theme never being applied at all.
+const TEXTURES := {
+	"button": DIR + "Button01a_1.png",
+	"button_hover": DIR + "Button01a_2.png",
+	"button_pressed": DIR + "Button01a_3.png",
+	"button_disabled": DIR + "Button01a_4.png",
+	"panel": DIR + "Frame01a.png",
+	"panel_accent": DIR + "Frame02a.png",
+	"slot": DIR + "FrameSlot01a.png",
+	"slot_active": DIR + "FrameSlot01b.png",
+	"bar": DIR + "Bar01a.png",
+	"bar_fill": DIR + "BarFill01f.png",
+	"field": DIR + "InputField01a.png",
+	"banner": DIR + "Banner01a.png",
+}
+
+## The art is cream with a black outline, so text on it has to be dark. Every
+## label the game draws over the dark world stays light; only controls that sit
+## on this pack's own surfaces flip.
+const INK := Color(0.12, 0.11, 0.13)
+const INK_DIM := Color(0.42, 0.40, 0.44)
+
+static var _theme: Theme = null
+
+
+static func texture(key: String) -> Texture2D:
+	return load(TEXTURES[key]) as Texture2D
+
+
+## One shared instance. Themes are pure data and every control only reads them,
+## so building a second would be waste rather than isolation.
+static func get_theme() -> Theme:
+	if _theme != null:
+		return _theme
+	var t := Theme.new()
+	t.default_font_size = 14
+
+	t.set_stylebox("normal", "Button", _box("button", 8, 12, 7))
+	t.set_stylebox("hover", "Button", _box("button_hover", 8, 12, 7))
+	t.set_stylebox("pressed", "Button", _box("button_pressed", 8, 12, 7))
+	t.set_stylebox("disabled", "Button", _box("button_disabled", 8, 12, 7))
+	# Focus deliberately reuses the hover art rather than adding an outline:
+	# the pack has no focus state, and an invented one would be the only thing
+	# on screen that is not from the set.
+	t.set_stylebox("focus", "Button", _box("button_hover", 8, 12, 7))
+	t.set_color("font_color", "Button", INK)
+	t.set_color("font_hover_color", "Button", INK)
+	t.set_color("font_pressed_color", "Button", INK)
+	t.set_color("font_disabled_color", "Button", INK_DIM)
+	t.set_color("font_focus_color", "Button", INK)
+
+	t.set_stylebox("panel", "Panel", _box("panel", 8, 10, 10))
+	t.set_stylebox("panel", "PanelContainer", _box("panel", 8, 10, 10))
+
+	t.set_stylebox("normal", "LineEdit", _box("field", 8, 10, 6))
+	t.set_stylebox("focus", "LineEdit", _box("field", 8, 10, 6))
+	t.set_color("font_color", "LineEdit", INK)
+	t.set_color("font_placeholder_color", "LineEdit", INK_DIM)
+	t.set_color("caret_color", "LineEdit", INK)
+
+	_theme = t
+	return _theme
+
+
+## Give [param root] the theme. Everything under it inherits, so one call per
+## screen covers that screen.
+##
+## Per-screen rather than once on the Window, because theme inheritance only
+## travels Control-to-Control: a Control whose parent is a plain Node or a
+## CanvasLayer resolves against the default theme however the Window is set.
+## Every screen in this game hangs off one or the other.
+static func apply_to(root: Control) -> void:
+	if root != null:
+		root.theme = get_theme()
+
+
+## A full-rect Control with the theme already on it -- the root every screen
+## built in code starts from. Using this rather than a bare Control is what
+## stops a new screen quietly rendering unstyled.
+static func themed_root() -> Control:
+	var root := Control.new()
+	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	apply_to(root)
+	return root
+
+
+## A nine-patch stylebox. [param margin] is the corner size in source pixels;
+## the middle is what stretches.
+static func _box(key: String, margin: int, pad_x: int, pad_y: int) -> StyleBoxTexture:
+	var sb := StyleBoxTexture.new()
+	sb.texture = texture(key)
+	for side in [SIDE_LEFT, SIDE_TOP, SIDE_RIGHT, SIDE_BOTTOM]:
+		sb.set_texture_margin(side, float(margin))
+	sb.set_content_margin(SIDE_LEFT, float(pad_x))
+	sb.set_content_margin(SIDE_RIGHT, float(pad_x))
+	sb.set_content_margin(SIDE_TOP, float(pad_y))
+	sb.set_content_margin(SIDE_BOTTOM, float(pad_y))
+	return sb
diff --git a/src/view/ui_theme.gd.uid b/src/view/ui_theme.gd.uid
new file mode 100644
index 0000000..7b75081
--- /dev/null
+++ b/src/view/ui_theme.gd.uid
@@ -0,0 +1 @@
+uid://ddaj0c8xfjitx
diff --git a/tests/unit/test_credits.gd b/tests/unit/test_credits.gd
new file mode 100644
index 0000000..42e3d7c
--- /dev/null
+++ b/tests/unit/test_credits.gd
@@ -0,0 +1,76 @@
+extends GutTest
+## Attribution. Two of the packs this game ships are CC BY 4.0, which requires
+## credit -- so these are licence-compliance tests, not tidiness ones.
+
+
+func test_every_source_is_completely_described() -> void:
+	for entry in Credits.SOURCES:
+		for field in ["name", "author", "licence", "url", "used_for"]:
+			assert_false(String(entry[field]).strip_edges().is_empty(),
+				"%s has no %s" % [entry.get("name", "?"), field])
+		assert_true(String(entry["url"]).begins_with("http"),
+			"%s has no usable link" % entry["name"])
+
+
+## The whole point of the flag: it marks the entries a licence obliges us to
+## show, as opposed to the ones credited because the work deserves it.
+func test_the_cc_by_packs_are_marked_as_required() -> void:
+	var required := Credits.required()
+	assert_gt(required.size(), 0)
+	for entry in Credits.SOURCES:
+		var is_cc_by := String(entry["licence"]).begins_with("CC BY")
+		assert_eq(bool(entry["required"]), is_cc_by,
+			"%s is %s but marked required=%s" % [
+				entry["name"], entry["licence"], entry["required"]])
+
+
+## CC BY asks for a link to the licence itself, not only to the work. A player
+## reading the in-game screen has no other way to reach the terms.
+func test_every_creative_commons_licence_links_to_its_terms() -> void:
+	for entry in Credits.SOURCES:
+		var licence := String(entry["licence"])
+		if not licence.begins_with("CC"):
+			continue
+		assert_true(Credits.licence_url(licence).begins_with(
+			"https://creativecommons.org/"),
+			"%s has no link to its terms" % licence)
+
+
+## The repository file and the in-game screen have to say the same thing. They
+## are maintained separately, so this is what stops one of them going stale --
+## and a stale attribution is a licence problem, not a documentation one.
+func test_the_credits_file_names_every_source() -> void:
+	var f := FileAccess.open("res://CREDITS.md", FileAccess.READ)
+	assert_not_null(f, "CREDITS.md should be readable")
+	var text := f.get_as_text()
+	f.close()
+	for entry in Credits.SOURCES:
+		assert_true(text.contains(String(entry["name"])),
+			"CREDITS.md never mentions %s" % entry["name"])
+		assert_true(text.contains(String(entry["author"])),
+			"CREDITS.md never credits %s" % entry["author"])
+		assert_true(text.contains(String(entry["url"])),
+			"CREDITS.md has no link for %s" % entry["name"])
+
+
+func test_the_asset_document_covers_every_source_too() -> void:
+	var f := FileAccess.open("res://docs/ASSETS.md", FileAccess.READ)
+	assert_not_null(f)
+	var text := f.get_as_text()
+	f.close()
+	for entry in Credits.SOURCES:
+		assert_true(text.contains(String(entry["url"])),
+			"docs/ASSETS.md has no entry for %s" % entry["name"])
+
+
+## Every pack in the repository's own asset directories must be accounted for.
+## Committing art without recording where it came from is how a project ends up
+## unable to say whether it may ship.
+func test_the_committed_ui_art_is_attributed() -> void:
+	assert_true(DirAccess.dir_exists_absolute("res://assets/sprites/ui"),
+		"the UI art should be committed")
+	var names := ""
+	for entry in Credits.SOURCES:
+		names += String(entry["name"])
+	assert_true(names.contains("Complete UI Essential Pack"),
+		"the UI pack has to be credited before its art is shipped")
diff --git a/tests/unit/test_credits.gd.uid b/tests/unit/test_credits.gd.uid
new file mode 100644
index 0000000..d16e4e9
--- /dev/null
+++ b/tests/unit/test_credits.gd.uid
@@ -0,0 +1 @@
+uid://tb74xt0r3x5s
diff --git a/tests/unit/test_settings.gd b/tests/unit/test_settings.gd
index fe90778..5cf9fa9 100644
--- a/tests/unit/test_settings.gd
+++ b/tests/unit/test_settings.gd
@@ -8,6 +8,7 @@ const SCRATCH := "user://test_settings_%d.cfg"
 var _saved_bindings: Dictionary[String, Dictionary] = {}
 var _saved_master: float = 0.0
 var _saved_sfx: float = 0.0
+var _scratch: String = ""
 
 
 func before_each() -> void:
@@ -16,6 +17,12 @@ func before_each() -> void:
 	_saved_bindings = Settings.bindings.duplicate()
 	_saved_master = Settings.master_volume
 	_saved_sfx = Settings.sfx_volume
+	# And rebinding SAVES. Without redirecting the file, running the suite
+	# rewrote the player's own settings -- it really did, and it took a
+	# screenshot of the settings screen showing Fire on the right mouse button
+	# to notice.
+	_scratch = SCRATCH % randi()
+	Settings.path = _scratch
 
 
 func after_each() -> void:
@@ -23,6 +30,8 @@ func after_each() -> void:
 	Settings.master_volume = _saved_master
 	Settings.sfx_volume = _saved_sfx
 	Settings.apply_input()
+	Settings.path = Settings.DEFAULT_PATH
+	DirAccess.remove_absolute(ProjectSettings.globalize_path(_scratch))
 
 
 func _key_event(code: Key) -> InputEventKey:
@@ -226,3 +235,22 @@ func test_a_settings_file_missing_keys_loads_without_complaint() -> void:
 	# default, which is what made this log an engine error per missing action.
 	assert_false(loaded.has_section_key("input", "move_up"))
 	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))
+
+
+## The redirect above is a test fixture. If it were ever left in place -- or the
+## default changed to something under a scratch directory -- players would
+## silently stop keeping their settings.
+func test_the_default_path_is_the_players_own_file() -> void:
+	assert_eq(Settings.DEFAULT_PATH, "user://settings.cfg")
+	assert_true(Settings.DEFAULT_PATH.begins_with("user://"))
+
+
+## Saving has to actually reach the file the path points at, or the redirect
+## above would hide a broken save rather than isolate a working one.
+func test_saving_writes_to_the_configured_path() -> void:
+	Settings.master_volume = 0.33
+	Settings.save()
+	assert_true(FileAccess.file_exists(_scratch), "nothing was written")
+	var cfg := ConfigFile.new()
+	assert_eq(cfg.load(_scratch), OK)
+	assert_almost_eq(float(cfg.get_value("audio", "master")), 0.33, 0.001)
diff --git a/tests/unit/test_ui_theme.gd b/tests/unit/test_ui_theme.gd
new file mode 100644
index 0000000..6f45715
--- /dev/null
+++ b/tests/unit/test_ui_theme.gd
@@ -0,0 +1,140 @@
+extends GutTest
+## The control theme. A missing texture gives a null and a silently unstyled
+## control, which looks exactly like the theme never having been applied -- so
+## every path is checked rather than assumed.
+
+
+func test_every_declared_texture_loads() -> void:
+	for key in UiTheme.TEXTURES:
+		var tex := UiTheme.texture(key)
+		assert_not_null(tex, "%s (%s) did not load" % [key, UiTheme.TEXTURES[key]])
+		assert_gt(tex.get_width(), 0)
+		assert_gt(tex.get_height(), 0)
+
+
+func test_the_theme_styles_the_controls_the_game_actually_builds() -> void:
+	var t := UiTheme.get_theme()
+	for state in ["normal", "hover", "pressed", "disabled", "focus"]:
+		assert_true(t.has_stylebox(state, "Button"), "Button has no %s style" % state)
+	assert_true(t.has_stylebox("panel", "Panel"))
+	assert_true(t.has_stylebox("panel", "PanelContainer"))
+	assert_true(t.has_stylebox("normal", "LineEdit"))
+
+
+## The pack's surfaces are cream with a black outline, so text on them has to be
+## dark. Everything the game draws over the world stays light; only controls
+## sitting on this art flip.
+func test_text_on_the_packs_surfaces_is_dark() -> void:
+	var t := UiTheme.get_theme()
+	for key in ["font_color", "font_hover_color", "font_pressed_color"]:
+		var c: Color = t.get_color(key, "Button")
+		assert_lt(c.get_luminance(), 0.35, "%s is too light for cream art" % key)
+	assert_lt((t.get_color("font_color", "LineEdit") as Color).get_luminance(), 0.35)
+
+
+## Nine-patch margins are what stop a 1px border smearing across a stretched
+## button. Zero margins would render as a plain stretched texture.
+func test_button_styles_are_nine_patched() -> void:
+	var t := UiTheme.get_theme()
+	for state in ["normal", "hover", "pressed", "disabled"]:
+		var sb := t.get_stylebox(state, "Button") as StyleBoxTexture
+		assert_not_null(sb)
+		for side in [SIDE_LEFT, SIDE_TOP, SIDE_RIGHT, SIDE_BOTTOM]:
+			assert_gt(sb.get_texture_margin(side), 0.0,
+				"%s has no stretch margin on side %d" % [state, side])
+
+
+## The corner size cannot exceed half the sprite, or the two caps overlap and
+## the middle has negative width.
+func test_stretch_margins_fit_inside_their_sprites() -> void:
+	var t := UiTheme.get_theme()
+	for entry in [["normal", "Button"], ["panel", "Panel"], ["normal", "LineEdit"]]:
+		var sb := t.get_stylebox(entry[0], entry[1]) as StyleBoxTexture
+		var size := Vector2(sb.texture.get_size())
+		assert_lte(sb.get_texture_margin(SIDE_LEFT) + sb.get_texture_margin(SIDE_RIGHT),
+			size.x, "%s margins exceed its width" % entry[1])
+		assert_lte(sb.get_texture_margin(SIDE_TOP) + sb.get_texture_margin(SIDE_BOTTOM),
+			size.y, "%s margins exceed its height" % entry[1])
+
+
+## Built once and shared. Themes are read-only data, so a second instance would
+## be waste rather than isolation.
+func test_the_theme_is_built_once() -> void:
+	assert_eq(UiTheme.get_theme(), UiTheme.get_theme())
+
+
+## The four button states have to be four different pictures, or the interface
+## gives no feedback and the pack's state art is going unused.
+func test_the_button_states_are_visually_distinct() -> void:
+	var seen := {}
+	for key in ["button", "button_hover", "button_pressed", "button_disabled"]:
+		seen[UiTheme.TEXTURES[key]] = true
+	assert_eq(seen.size(), 4, "two button states share a texture")
+
+
+## The inventory draws slots at exactly twice the source size. A non-integer
+## scale on pixel art with nearest filtering gives uneven pixel widths, which on
+## a 1px border reads as a wobble along every edge.
+func test_the_inventory_slot_is_drawn_at_a_whole_multiple() -> void:
+	var slot := UiTheme.texture("slot")
+	var scale := HUD_SLOT / float(slot.get_width())
+	assert_eq(scale, floorf(scale), "slot art is scaled by %f" % scale)
+	assert_eq(slot.get_width(), slot.get_height(), "the slot should be square")
+
+
+const HUD_SLOT := 64.0
+
+
+## A Control resolves its theme by walking up the parent chain, which is why
+## one assignment near the root covers screens that share no parent. Checked on
+## the mechanism rather than on a Window, so it runs headless.
+func test_the_theme_reaches_controls_through_their_ancestors() -> void:
+	var root: Control = autofree(Control.new())
+	root.theme = UiTheme.get_theme()
+	var middle := Control.new()
+	root.add_child(middle)
+	var button := Button.new()
+	middle.add_child(button)
+	assert_eq(button.get_theme_stylebox("normal", "Button"),
+		UiTheme.get_theme().get_stylebox("normal", "Button"),
+		"a button two levels down should still find the theme")
+	assert_eq(button.get_theme_color("font_color", "Button"), UiTheme.INK)
+
+
+func test_applying_to_nothing_is_harmless() -> void:
+	UiTheme.apply_to(null)
+	assert_true(true, "a null root must not be a crash")
+
+
+func test_a_themed_root_fills_its_parent_and_carries_the_theme() -> void:
+	var root: Control = autofree(UiTheme.themed_root())
+	assert_eq(root.theme, UiTheme.get_theme())
+	assert_eq(root.anchor_right, 1.0)
+	assert_eq(root.anchor_bottom, 1.0)
+
+
+## Every screen in the game is built in code and hangs off either a plain Node
+## or a CanvasLayer, and theme inheritance travels Control-to-Control ONLY --
+## the chain breaks at the first non-Control parent. Setting the theme once on
+## the Window therefore looked like it worked and styled nothing, which is a
+## mistake that is invisible until somebody looks at the screen. So: every
+## screen is instantiated here and asked what its buttons actually resolve.
+func test_every_screen_actually_gets_the_theme() -> void:
+	var screens := {
+		"HUD": "res://src/ui/hud.gd",
+		"GameMenu": "res://src/ui/game_menu.gd",
+		"CharacterSelect": "res://src/ui/character_select.gd",
+		"UpgradeScreen": "res://src/ui/upgrade_screen.gd",
+		"SettingsScreen": "res://src/ui/settings_screen.gd",
+		"CreditsScreen": "res://src/ui/credits_screen.gd",
+		"MainMenu": "res://src/ui/main_menu.gd",
+	}
+	var wanted := UiTheme.get_theme().get_stylebox("normal", "Button")
+	for name in screens:
+		var node: Node = (load(screens[name]) as Script).new()
+		add_child_autofree(node)
+		var buttons := node.find_children("*", "Button", true, false)
+		assert_gt(buttons.size(), 0, "%s has no button to check" % name)
+		for b: Button in buttons:
+			assert_eq(b.get_theme_stylebox("normal", "Button"), wanted,
+				"%s: '%s' is not themed" % [name, b.text])
diff --git a/tests/unit/test_ui_theme.gd.uid b/tests/unit/test_ui_theme.gd.uid
new file mode 100644
index 0000000..0d62a90
--- /dev/null
+++ b/tests/unit/test_ui_theme.gd.uid
@@ -0,0 +1 @@
+uid://ddwfq3jpwgfep
diff --git a/tools/screenshot.gd b/tools/screenshot.gd
new file mode 100644
index 0000000..b94b327
--- /dev/null
+++ b/tools/screenshot.gd
@@ -0,0 +1,86 @@
+extends Node
+## Boot the client windowed, capture a few screens, and quit.
+##
+##   SHOT_DIR=/tmp/shots godot --path . res://tools/screenshot.tscn
+##
+## This exists because UI is the one part of the game the rest of the tooling
+## cannot check. `check.sh` proves it parses, the suite proves the theme
+## resolves, the smoke test proves nothing errors -- and all three passed
+## while the entire interface rendered unstyled, because Godot's theme
+## inheritance breaks at the first non-Control parent and nothing had ever
+## looked at the screen.
+##
+## Needs a real display, so it is not part of any automated gate. Run it after
+## touching anything under src/ui/ and open the files.
+
+const GAME := preload("res://src/game.tscn")
+## Frame numbers, not seconds: the point is a deterministic sequence, and a
+## windowed client at 60fps gets there in about four seconds.
+const AT_MENU := 30
+const ENTER_GAME := 34
+const AT_GAME := 200
+const OPEN_MENU := 210
+const AT_INGAME_MENU := 240
+const OPEN_SETTINGS := 250
+const AT_SETTINGS := 280
+const OPEN_CREDITS := 290
+const AT_CREDITS := 320
+const DONE := 330
+
+var _frame: int = 0
+var _game: Node = null
+var _menu: Control = null
+var _dir: String = "user://"
+
+
+func _ready() -> void:
+	GameOpts.parse()
+	Engine.physics_ticks_per_second = SimConfig.TICK_RATE
+	Settings.load_and_apply()
+	var from_env := OS.get_environment("SHOT_DIR")
+	if not from_env.is_empty():
+		_dir = from_env
+	get_window().size = Vector2i(1280, 720)
+	_menu = preload("res://src/ui/main_menu.gd").new()
+	add_child(_menu)
+
+
+func _process(_delta: float) -> void:
+	_frame += 1
+	match _frame:
+		AT_MENU:
+			_grab("menu")
+		ENTER_GAME:
+			_menu.queue_free()
+			Net.host(27455)
+			Net.start_local_client()
+			_game = GAME.instantiate()
+			add_child(_game)
+		AT_GAME:
+			_grab("game")
+		OPEN_MENU:
+			_game.get_node("GameMenu").open()
+		AT_INGAME_MENU:
+			_grab("menu_ingame")
+		OPEN_SETTINGS:
+			_game.get_node("GameMenu").close()
+			_game.get_node("SettingsScreen").open()
+		AT_SETTINGS:
+			_grab("settings")
+		OPEN_CREDITS:
+			_game.get_node("SettingsScreen").visible = false
+			_game.get_node("CreditsScreen").open()
+		AT_CREDITS:
+			_grab("credits")
+		DONE:
+			Net.shutdown()
+			get_tree().quit(0)
+
+
+func _grab(shot_name: String) -> void:
+	var path := "%s/shot_%s.png" % [_dir, shot_name]
+	var err := get_viewport().get_texture().get_image().save_png(path)
+	if err != OK:
+		printerr("could not write %s (error %d)" % [path, err])
+		return
+	print("saved ", path)
diff --git a/tools/screenshot.gd.uid b/tools/screenshot.gd.uid
new file mode 100644
index 0000000..f95bcdb
--- /dev/null
+++ b/tools/screenshot.gd.uid
@@ -0,0 +1 @@
+uid://bnuqy4w5whjce
diff --git a/tools/screenshot.tscn b/tools/screenshot.tscn
new file mode 100644
index 0000000..64bd4f0
--- /dev/null
+++ b/tools/screenshot.tscn
@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://tools/screenshot.gd" id="1"]
+
+[node name="Screenshot" type="Node"]
+script = ExtResource("1")