diff --git a/persistent-memory.md b/persistent-memory.md
index 2f9e74d..b52df56 100644
--- a/persistent-memory.md
+++ b/persistent-memory.md
@@ -32,9 +32,9 @@ separate dev team rather than an in-tree Worldtree tool.
 
 ## Current state / in-flight
 
-_As of 2026-05-24 (post-v0.6.2 neutral-dark palette):_
+_As of 2026-05-24 (post-v0.6.3 Australis restored, $background → black):_
 
-**Status: v0.6.2 shipped.** Nine core issues complete (`sse_client`
+**Status: v0.6.3 shipped.** Nine core issues complete (`sse_client`
 #1, `sessions` #2, `cli` #3, `tui` #4, `--end-user-id` #5, TUI
 startup error visibility #6, presenter contract semantics amendment
 #12, startup agent picker #8, §5 layout reshape + Tools pane #13)
@@ -51,7 +51,8 @@ Static in the footer (static "Tools" v1; dynamic when more tabs
 land). CLI mode (--send) unaffected by design — INV-018.
 
 Last commits on `main`:
-- v0.6.2 style(tui): neutralize Australis dark palette — bg no longer blue-tinted
+- v0.6.3 style(tui): restore Australis palette, only $background → pure black
+- `d845b20` style(tui): neutralize Australis dark palette — bg no longer blue-tinted (v0.6.2, reverted)
 - `8463eb2` style(tui): kill remaining blue + thinking-current into pane (v0.6.1)
 - `cfee89a` refactor(tui): streaming + turn headers + Thinking pane (v0.6.0)
 - `7106af5` style(tui): UI polish pass — terminal label colors, placeholders (v0.5.1)
diff --git a/pyproject.toml b/pyproject.toml
index 13ef027..eb97527 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.6.2"
+version = "0.6.3"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"
diff --git a/src/ratatoskr/tui.py b/src/ratatoskr/tui.py
index 2b995fd..8b99c62 100644
--- a/src/ratatoskr/tui.py
+++ b/src/ratatoskr/tui.py
@@ -61,31 +61,33 @@ from ratatoskr.sse_client import (
     stream_turn,
 )
 
-# ---- Australis-derived theme (https://github.com/lkraven/australis) ----------
+# ---- Australis theme (https://github.com/lkraven/australis) ------------------
 #
-# v0.6.2 deliberate deviation from spec: the Australis Dark theme's design
-# principle "all colors are cooler than neutral" bakes a blue cast into
-# every dark surface (Ice black #222531 = RGB 34/37/49 — blue dominant).
-# Operators reported the whole-app chrome reading as blue. Ratatoskr keeps
-# the Australis ACCENTS (Aurora blue/cyan/green, Dawn red/yellow) — those
-# are the brand signature — but **neutralizes the Ice/Sea dark palette to
-# true grays** so the chrome reads as neutral dark, not blue-leaning.
+# The Australis Dark color theme, inspired by the Southern Lights. 16 cool-tone
+# terminal colors with medium contrast. Preference order: blue > cyan > green
+# for primary surfaces; Dawn accents (red/yellow/magenta) used sparingly for
+# terminal-event labels (error/cancelled).
+#
+# **v0.6.3 single deviation from spec**: `$background` is `#000000` (pure
+# black), NOT Australis Ice black `#222531`. The Ice black is RGB(34,37,49)
+# — blue dominant — and at App-wide scale the cumulative cast reads as
+# "the whole app is blue" to operators (even though no single surface is
+# "blue" in the strict-color sense). Pure black for the App background
+# kills that perception. EVERY OTHER Australis value — Aurora accents,
+# Sea darks for chrome (surface/panel), Ice white foreground, Dawn
+# accents — stays verbatim per spec.
 #
 # Mapping to Textual's Theme semantic tokens:
-#   primary    = Aurora blue (#6388D8) — focus rings, active selection (KEEP).
-#   secondary  = Aurora cyan (#00b1a8) — secondary highlights (KEEP).
-#   accent     = Aurora bright cyan (#42dcd1) — bright accents (KEEP).
-#   success    = Aurora green (#16B866) — [done] label (KEEP).
-#   warning    = Dawn yellow (#e1c631) — [cancelled] label (KEEP).
-#   error      = Dawn red (#ff491a) — [error] label (KEEP).
-#   foreground = neutral light gray (#bdbdbd) — default text (was Ice white).
-#   background = neutral near-black (#1a1a1a) — App bg (was Ice black).
-#   surface    = neutral dark gray (#2a2a2a) — chrome (was Sea bright-black).
-#   panel      = neutral mid gray (#3a3a3a) — borders (was Sea dark-30).
-#
-# Dark contrast steps preserve Australis's LAB lightness levels but drop the
-# blue/green tint. Variables renamed mentally but kept under $au-* slugs so
-# downstream CSS doesn't change.
+#   primary    = Aurora blue (#6388D8) — focus rings, active selection.
+#   secondary  = Aurora cyan (#00b1a8) — secondary highlights.
+#   accent     = Aurora bright cyan (#42dcd1) — bright accents.
+#   success    = Aurora green (#16B866) — [done] label.
+#   warning    = Dawn yellow (#e1c631) — [cancelled] label.
+#   error      = Dawn red (#ff491a) — [error] label.
+#   foreground = Ice white (#a9bcc3) — default text.
+#   background = pure black (#000000) — App background (v0.6.3 deviation).
+#   surface    = Sea bright black (#373b46) — raised chrome.
+#   panel      = Sea dark 30 (#414751) — borders, separators.
 
 AUSTRALIS_THEME = Theme(
     name="australis",
@@ -95,22 +97,20 @@ AUSTRALIS_THEME = Theme(
     success="#16B866",
     warning="#e1c631",
     error="#ff491a",
-    foreground="#bdbdbd",
-    background="#1a1a1a",
-    surface="#2a2a2a",
-    panel="#3a3a3a",
+    foreground="#a9bcc3",
+    background="#000000",
+    surface="#373b46",
+    panel="#414751",
     dark=True,
     variables={
-        # Neutral dark contrast palette (LAB-matched to Australis Sea spec
-        # but with R=G=B, no cool cast). $au-dark-N accessible via TCSS.
-        "au-dark-30": "#3a3a3a",
-        "au-dark-40": "#4f4f4f",
-        "au-dark-50": "#6b6b6b",
-        "au-dark-60": "#878787",
-        "au-bright-70": "#9e9e9e",
-        "au-bright-80": "#bdbdbd",
-        "au-bright-white": "#e0e0e0",
-        # Accents — KEEP Australis Aurora brights for brand signature.
+        # Sea contrast palette — usable via $au-dark-50 etc. in TCSS.
+        "au-dark-30": "#414751",
+        "au-dark-40": "#565f69",
+        "au-dark-50": "#6e7882",
+        "au-dark-60": "#86929d",
+        "au-bright-70": "#9daeb6",
+        "au-bright-80": "#b3cbcf",
+        "au-bright-white": "#cce7ec",
         "au-bright-blue": "#a4c4ff",
         "au-bright-cyan": "#42dcd1",
         "au-bright-green": "#51e08a",
@@ -124,9 +124,9 @@ AUSTRALIS_THEME = Theme(
 _AU_SUCCESS = "#16B866"
 _AU_ERROR = "#ff491a"
 _AU_WARNING = "#e1c631"
-_AU_USER_ECHO = "#42dcd1"  # bright cyan — operator's voice
-_AU_DEMOTED = "#878787"  # neutral dark-60 — demoted telemetry
-_AU_DEMOTED_FAINT = "#6b6b6b"  # neutral dark-50 — empty-state placeholders
+_AU_USER_ECHO = "#42dcd1"  # Aurora bright cyan — operator's voice
+_AU_DEMOTED = "#86929d"  # Sea dark 60 — demoted telemetry
+_AU_DEMOTED_FAINT = "#6e7882"  # Sea dark 50 — empty-state placeholders
 
 
 # ---- Issue #12 presenter contract semantics amendment -------------------------
diff --git a/uv.lock b/uv.lock
index ea5122d..85a4816 100644
--- a/uv.lock
+++ b/uv.lock
@@ -968,7 +968,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.6.2"
+version = "0.6.3"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },