diff --git a/ui/src/components/workspace/Terminal.tsx b/ui/src/components/workspace/Terminal.tsx
index acd1e735..7570924c 100644
--- a/ui/src/components/workspace/Terminal.tsx
+++ b/ui/src/components/workspace/Terminal.tsx
@@ -11,7 +11,8 @@ import {
   type ClientControlMessage,
 } from './protocol';
 import { attachWebglRenderer } from './renderer';
-import { darkTheme } from './theme';
+import { darkTheme, lightTheme } from './theme';
+import { useEffectiveTheme } from '../../theme/useEffectiveTheme';
 // Lazy-import so the demo subtree (transcripts, fixtures, handlers) is
 // dynamic-imported only when demo mode is actually on. With a static import,
 // Rollup is conservative about module side-effects (the transcript file
@@ -99,6 +100,19 @@ export function TerminalView(props: TerminalViewProps): ReactElement {
   const onSessionLostRef = useRef<TerminalViewProps['onSessionLost']>(props.onSessionLost);
   onSessionLostRef.current = props.onSessionLost;
 
+  // Terminal palette follows the app theme (auto resolves via the OS). Read the
+  // current value through a ref so the connect effect doesn't recreate the
+  // terminal on a theme flip — a separate effect re-skins the live instance.
+  const effectiveTheme = useEffectiveTheme();
+  const xtermTheme = effectiveTheme === 'light' ? lightTheme : darkTheme;
+  const themeRef = useRef(xtermTheme);
+  themeRef.current = xtermTheme;
+  const termRef = useRef<Xterm | null>(null);
+
+  useEffect(() => {
+    if (termRef.current) termRef.current.options.theme = xtermTheme;
+  }, [xtermTheme]);
+
   useEffect(() => {
     const container = containerRef.current;
     if (!container) return undefined;
@@ -110,7 +124,7 @@ export function TerminalView(props: TerminalViewProps): ReactElement {
     setChildExited(false);
 
     const term = new Xterm({
-      theme: darkTheme,
+      theme: themeRef.current,
       fontFamily:
         'ui-monospace, "SF Mono", Menlo, Monaco, "Cascadia Mono", "DejaVu Sans Mono", monospace',
       fontSize: 13,
@@ -121,6 +135,7 @@ export function TerminalView(props: TerminalViewProps): ReactElement {
       macOptionIsMeta: true,
       convertEol: false,
     });
+    termRef.current = term;
 
     const fit = new FitAddon();
     term.loadAddon(fit);
@@ -313,6 +328,7 @@ export function TerminalView(props: TerminalViewProps): ReactElement {
       }
       webgl?.dispose();
       term.dispose();
+      termRef.current = null;
     };
   }, [wsId, sessionId, wsUrl]);
 
diff --git a/ui/src/components/workspace/theme.ts b/ui/src/components/workspace/theme.ts
index 67892e48..6a4ae557 100644
--- a/ui/src/components/workspace/theme.ts
+++ b/ui/src/components/workspace/theme.ts
@@ -1,5 +1,36 @@
 import type { ITheme } from '@xterm/xterm';
 
+/**
+ * Light xterm palette (GitHub-light-ish, warmed to sit on Daybreak's cream).
+ * ANSI `white` maps to a mid-grey and `brightWhite` to near-black, the way
+ * every light terminal theme does, so CLI output that prints as bright-white
+ * on a dark terminal becomes dark + legible here instead of vanishing.
+ * Picked by the active theme in Terminal.tsx (`auto` resolves via the OS).
+ */
+export const lightTheme: ITheme = {
+  background: '#faf8f1',
+  foreground: '#1c2a41',
+  cursor: '#2f62b0',
+  cursorAccent: '#faf8f1',
+  selectionBackground: 'rgba(47, 98, 176, 0.22)',
+  black: '#1c2a41',
+  red: '#cf222e',
+  green: '#116329',
+  yellow: '#7a4d05',
+  blue: '#0969da',
+  magenta: '#8250df',
+  cyan: '#1b7c83',
+  white: '#6e7781',
+  brightBlack: '#57606a',
+  brightRed: '#a40e26',
+  brightGreen: '#1a7f37',
+  brightYellow: '#633c01',
+  brightBlue: '#218bff',
+  brightMagenta: '#a475f9',
+  brightCyan: '#3192aa',
+  brightWhite: '#24292f',
+};
+
 export const darkTheme: ITheme = {
   background: '#0b0d10',
   foreground: '#e6edf3',
diff --git a/ui/src/components/workspace/workspaces.css b/ui/src/components/workspace/workspaces.css
index d59b037f..4b8fec04 100644
--- a/ui/src/components/workspace/workspaces.css
+++ b/ui/src/components/workspace/workspaces.css
@@ -1,13 +1,18 @@
 .workspaces-root {
-  color-scheme: dark;
-  --bg: #0b0d10;
-  --panel: #11151a;
-  --sidebar: #0d1014;
-  --border: #21262d;
-  --fg-dim: #8b949e;
-  --fg: #e6edf3;
-  --accent: #79c0ff;
-  --danger: #ff7b72;
+  /* Alias the local palette to the global theme tokens so the whole
+     Workspaces surface (session view + sidebar) follows light / dark.
+     `color-scheme` is inherited from :root (per-theme), not pinned dark.
+     The terminal itself is themed separately (xterm ITheme in Terminal.tsx).
+     Remaining hardcoded semantic chips (agent badges, status pills) are
+     tracked in ANG-110. */
+  --bg: var(--color-bg);
+  --panel: var(--color-bg-secondary);
+  --sidebar: var(--color-bg-secondary);
+  --border: var(--color-border);
+  --fg-dim: var(--color-text-muted);
+  --fg: var(--color-text);
+  --accent: var(--color-accent);
+  --danger: var(--color-red);
 }
 
 .app {
@@ -247,7 +252,7 @@
   transition: background 0.12s, color 0.12s, border-color 0.12s;
 }
 .sidebar-overview-btn:hover {
-  background: rgba(255, 255, 255, 0.04);
+  background: var(--color-overlay);
   color: var(--fg);
 }
 .sidebar-overview-btn.is-active {
@@ -290,7 +295,7 @@
   font: inherit;
 }
 .sidebar-row-main:hover {
-  background: rgba(255, 255, 255, 0.04);
+  background: var(--color-overlay);
 }
 
 .sidebar-status-dot {
@@ -370,7 +375,7 @@
   transition: background 80ms;
 }
 .sidebar-session:hover {
-  background: rgba(255, 255, 255, 0.03);
+  background: var(--color-overlay);
 }
 .sidebar-session.is-active {
   background: rgba(121, 192, 255, 0.10);
@@ -610,7 +615,7 @@
   transition: background 80ms;
 }
 .sidebar-headless-item:hover {
-  background: rgba(255, 255, 255, 0.03);
+  background: var(--color-overlay);
 }
 .sidebar-headless-item .sidebar-status-dot {
   width: 5px;
@@ -700,7 +705,7 @@
   margin: 0 0 14px;
   border: 1px solid var(--border);
   border-radius: 6px;
-  background: rgba(255, 255, 255, 0.02);
+  background: var(--color-overlay);
 }
 .resume-tui-meta-strong {
   font-weight: 600;
@@ -712,7 +717,7 @@
 .resume-tui-prompt {
   display: flex;
   gap: 10px;
-  background: rgba(255, 255, 255, 0.04);
+  background: var(--color-overlay);
   padding: 8px 14px;
   margin: 6px 0;
   border-radius: 4px;
@@ -995,7 +1000,7 @@
 }
 .workspace-cta-hint kbd {
   font-family: ui-monospace, "SF Mono", Menlo, monospace;
-  background: rgba(255, 255, 255, 0.06);
+  background: var(--color-overlay-strong);
   border: 1px solid var(--border);
   border-radius: 3px;
   padding: 0 4px;
@@ -1149,7 +1154,7 @@
   align-items: center;
   gap: 8px;
   padding: 8px 12px;
-  background: linear-gradient(180deg, #161b22, #11151a);
+  background: linear-gradient(180deg, var(--color-bg-tertiary), var(--color-bg-secondary));
   border-bottom: 1px solid var(--border);
   font-size: 11px;
   color: var(--fg-dim);
@@ -1179,7 +1184,7 @@
   transition: background 0.12s, color 0.12s;
 }
 .panel-collapse:hover {
-  background: rgba(255, 255, 255, 0.06);
+  background: var(--color-overlay-strong);
   color: var(--fg);
 }
 
@@ -1326,7 +1331,7 @@
   align-items: baseline;
 }
 .git-log-row:hover {
-  background: rgba(255, 255, 255, 0.03);
+  background: var(--color-overlay);
 }
 
 .git-log-hash {
@@ -1396,7 +1401,7 @@
 }
 .files-row.files-dir:hover,
 .files-row.files-symlink:hover {
-  background: rgba(255, 255, 255, 0.03);
+  background: var(--color-overlay);
 }
 
 .files-icon {
@@ -1439,7 +1444,7 @@
   align-items: center;
   gap: 10px;
   padding: 8px 12px;
-  background: linear-gradient(180deg, #161b22, #11151a);
+  background: linear-gradient(180deg, var(--color-bg-tertiary), var(--color-bg-secondary));
   border-bottom: 1px solid var(--border);
   font-size: 12px;
   color: var(--fg-dim);
diff --git a/ui/src/theme/useEffectiveTheme.ts b/ui/src/theme/useEffectiveTheme.ts
new file mode 100644
index 00000000..0ad744f1
--- /dev/null
+++ b/ui/src/theme/useEffectiveTheme.ts
@@ -0,0 +1,29 @@
+import { useSyncExternalStore } from 'react'
+
+import { useThemeStore } from './store'
+
+const mq = window.matchMedia('(prefers-color-scheme: dark)')
+
+function subscribeSystem(cb: () => void): () => void {
+  mq.addEventListener('change', cb)
+  return () => mq.removeEventListener('change', cb)
+}
+
+/**
+ * Resolve the preference (`light | dark | auto`) to a concrete `'light' | 'dark'`
+ * — `auto` follows the OS. Use this for the rare surfaces that need the actual
+ * value in JS rather than via CSS: notably the xterm terminal, whose palette is
+ * a JS object, not a CSS variable. CSS-driven surfaces should just read the
+ * `--color-*` tokens (which already resolve `data-theme` + prefers-color-scheme).
+ */
+export function useEffectiveTheme(): 'light' | 'dark' {
+  const theme = useThemeStore((s) => s.theme)
+  const systemDark = useSyncExternalStore(
+    subscribeSystem,
+    () => mq.matches,
+    () => true,
+  )
+  if (theme === 'light') return 'light'
+  if (theme === 'dark') return 'dark'
+  return systemDark ? 'dark' : 'light'
+}