diff --git a/bun.lock b/bun.lock
index 85a89615..5cba7b78 100644
--- a/bun.lock
+++ b/bun.lock
@@ -99,7 +99,7 @@
     },
     "packages/electron": {
       "name": "@openchamber/electron",
-      "version": "1.12.3",
+      "version": "1.12.4",
       "dependencies": {
         "@openchamber/web": "workspace:*",
         "electron-context-menu": "^4.1.2",
@@ -114,7 +114,7 @@
     },
     "packages/ui": {
       "name": "@openchamber/ui",
-      "version": "1.12.3",
+      "version": "1.12.4",
       "dependencies": {
         "@base-ui/react": "^1.4.0",
         "@codemirror/autocomplete": "^6.20.0",
@@ -146,7 +146,7 @@
         "@ibm/plex": "^6.4.1",
         "@lezer/highlight": "^1.2.3",
         "@opencode-ai/sdk": "^1.17.0",
-        "@pierre/diffs": "1.1.0-beta.13",
+        "@pierre/diffs": "1.3.0-beta.4",
         "@replit/codemirror-vim": "^6.3.0",
         "@simplewebauthn/browser": "13.3.0",
         "@tanstack/react-virtual": "^3.13.18",
@@ -216,7 +216,7 @@
     },
     "packages/vscode": {
       "name": "openchamber",
-      "version": "1.12.3",
+      "version": "1.12.4",
       "dependencies": {
         "@openchamber/ui": "workspace:*",
         "@opencode-ai/sdk": "^1.17.0",
@@ -239,7 +239,7 @@
     },
     "packages/web": {
       "name": "@openchamber/web",
-      "version": "1.12.3",
+      "version": "1.12.4",
       "bin": {
         "openchamber": "./bin/cli.js",
       },
@@ -969,7 +969,11 @@
 
     "@peculiar/x509": ["@peculiar/x509@1.14.3", "", { "dependencies": { "@peculiar/asn1-cms": "^2.6.0", "@peculiar/asn1-csr": "^2.6.0", "@peculiar/asn1-ecc": "^2.6.0", "@peculiar/asn1-pkcs9": "^2.6.0", "@peculiar/asn1-rsa": "^2.6.0", "@peculiar/asn1-schema": "^2.6.0", "@peculiar/asn1-x509": "^2.6.0", "pvtsutils": "^1.3.6", "reflect-metadata": "^0.2.2", "tslib": "^2.8.1", "tsyringe": "^4.10.0" } }, "sha512-C2Xj8FZ0uHWeCXXqX5B4/gVFQmtSkiuOolzAgutjTfseNOHT3pUjljDZsTSxXFGgio54bCzVFqmEOUrIVk8RDA=="],
 
-    "@pierre/diffs": ["@pierre/diffs@1.1.0-beta.13", "", { "dependencies": { "@shikijs/transformers": "^3.0.0", "diff": "8.0.3", "hast-util-to-html": "9.0.5", "lru_map": "0.4.1", "shiki": "^3.0.0" }, "peerDependencies": { "react": "^18.3.1 || ^19.0.0", "react-dom": "^18.3.1 || ^19.0.0" } }, "sha512-D35rxDu5V7XHX5aVGU6PF12GhscL+I+9QYgxK/i3h0d2XSirAxDdVNm49aYwlOhgmdvL0NbS1IHxPswVB5yJvw=="],
+    "@pierre/diffs": ["@pierre/diffs@1.3.0-beta.4", "", { "dependencies": { "@pierre/theme": "1.0.3", "@pierre/theming": "0.0.1", "@shikijs/transformers": "^3.0.0", "diff": "8.0.3", "hast-util-to-html": "9.0.5", "lru_map": "0.4.1", "shiki": "^3.0.0" }, "peerDependencies": { "react": "^18.3.1 || ^19.0.0", "react-dom": "^18.3.1 || ^19.0.0" } }, "sha512-poFcsvhcQt9lH/InzAPaGs47WYHMidnFCjuYGNU41HiVLJP4mkIQDSdvcnPIkBuh/cYbPOQg/YE3T1kSpr01GA=="],
+
+    "@pierre/theme": ["@pierre/theme@1.0.3", "", {}, "sha512-sWHv11TMoqKxKDgTIk5VbhQjdPhs8DCcBxbjh3mRlS3YOM/OcrWoGX6MM8eBGn9cUu3M46Py0JnxsG2nJaFTuA=="],
+
+    "@pierre/theming": ["@pierre/theming@0.0.1", "", { "peerDependencies": { "@pierre/theme": "^1.0.0", "@shikijs/themes": "^3.0.0 || ^4.0.0", "react": "^18.3.1 || ^19.0.0", "react-dom": "^18.3.1 || ^19.0.0", "shiki": "^3.0.0 || ^4.0.0" }, "optionalPeers": ["@pierre/theme", "@shikijs/themes", "react", "react-dom", "shiki"] }, "sha512-1thlEtJbqdyLzc1ZS2KQa1q7FzDGHT4dTEdKHoyQjOMeWWOmbVG5/ndEfOKfAb5Fzkz8cNJrOjFLiZoDH/A03A=="],
 
     "@pkgjs/parseargs": ["@pkgjs/parseargs@0.11.0", "", {}, "sha512-+1VkjdD0QBLPodGrJUeqarH8VAIvQODIbwh9XpP5Syisf7YoQgsJKPNFoqqLQlu+VQ/tVSshMR6loPMn8U+dPg=="],
 
diff --git a/packages/ui/package.json b/packages/ui/package.json
index 2b28daf3..bec5fa1d 100644
--- a/packages/ui/package.json
+++ b/packages/ui/package.json
@@ -41,7 +41,7 @@
     "@ibm/plex": "^6.4.1",
     "@lezer/highlight": "^1.2.3",
     "@opencode-ai/sdk": "^1.17.0",
-    "@pierre/diffs": "1.1.0-beta.13",
+    "@pierre/diffs": "1.3.0-beta.4",
     "@replit/codemirror-vim": "^6.3.0",
     "@simplewebauthn/browser": "13.3.0",
     "@tanstack/react-virtual": "^3.13.18",
diff --git a/packages/ui/src/components/chat/message/ToolOutputDialog.tsx b/packages/ui/src/components/chat/message/ToolOutputDialog.tsx
index d322cca5..6c2278f7 100644
--- a/packages/ui/src/components/chat/message/ToolOutputDialog.tsx
+++ b/packages/ui/src/components/chat/message/ToolOutputDialog.tsx
@@ -119,7 +119,7 @@ const TOOL_DIFF_METRICS = {
     lineHeight: 24,
     diffHeaderHeight: 44,
     hunkSeparatorHeight: 24,
-    fileGap: 0,
+    spacing: 0,
 };
 
 const usePierreThemeConfig = (): PierreThemeConfig => {
diff --git a/packages/ui/src/components/chat/message/parts/ToolPart.tsx b/packages/ui/src/components/chat/message/parts/ToolPart.tsx
index 9fcc5808..d44eefcc 100644
--- a/packages/ui/src/components/chat/message/parts/ToolPart.tsx
+++ b/packages/ui/src/components/chat/message/parts/ToolPart.tsx
@@ -1388,7 +1388,7 @@ const TOOL_DIFF_METRICS = {
     lineHeight: 24,
     diffHeaderHeight: 44,
     hunkSeparatorHeight: 24,
-    fileGap: 0,
+    spacing: 0,
 };
 
 const TOOL_COLLAPSED_CUSTOM_STYLE: React.CSSProperties = {
diff --git a/packages/ui/src/components/views/DiffView.tsx b/packages/ui/src/components/views/DiffView.tsx
index 41b25dcc..c1887fa7 100644
--- a/packages/ui/src/components/views/DiffView.tsx
+++ b/packages/ui/src/components/views/DiffView.tsx
@@ -599,15 +599,15 @@ const MultiFileDiffEntry = React.memo<MultiFileDiffEntryProps>(({
 
     return (
         <div ref={setSectionRef} className="scroll-mt-9 border-b border-[var(--interactive-border)]/40 last:border-b-0">
-            <div className="sticky top-0 z-10 bg-[var(--surface-muted)]">
+            <div className="sticky top-0 z-10 border-b border-[var(--interactive-border)]/35 bg-[var(--surface-elevated)]/90 backdrop-blur-md supports-[backdrop-filter]:bg-[var(--surface-elevated)]/80">
                 <button
                     type="button"
                     onClick={handleToggle}
                     className={cn(
-                        'group/header relative flex w-full items-center gap-2 px-3 py-1.5 overflow-hidden',
+                        'group/header relative flex min-h-9 w-full items-center gap-2 overflow-hidden px-3 py-2',
                         'bg-transparent',
                         'text-muted-foreground hover:text-foreground',
-                        isSelected ? 'bg-[var(--interactive-selection)]/40' : null
+                        isSelected ? 'bg-[var(--interactive-selection)]/35' : null
                     )}
                 >
                     <div className="absolute inset-0 pointer-events-none group-hover/header:bg-[var(--interactive-hover)]/50" />
diff --git a/packages/ui/src/components/views/PierreDiffViewer.tsx b/packages/ui/src/components/views/PierreDiffViewer.tsx
index 1b935023..20dbb172 100644
--- a/packages/ui/src/components/views/PierreDiffViewer.tsx
+++ b/packages/ui/src/components/views/PierreDiffViewer.tsx
@@ -91,6 +91,104 @@ const WEBKIT_SCROLL_FIX_CSS = `
       height: 24px !important;
     }
   }
+
+  [data-separator="line-info-basic"] {
+    height: 24px !important;
+    background: var(--diffs-bg) !important;
+    position: relative;
+  }
+
+  [data-diff-type="single"] [data-gutter],
+  [data-diff-type="split"] [data-deletions] [data-gutter] {
+    [data-separator-wrapper] {
+      position: absolute;
+      left: 100%;
+      display: flex;
+      align-items: center;
+      gap: unset;
+      width: max-content;
+      background: transparent;
+      color: var(--diffs-fg-number);
+      font-family: var(--diffs-header-font-family, var(--font-sans));
+      font-size: 0.75rem;
+      line-height: 1;
+      margin-left: calc(-2ch - 2px);
+    }
+
+    [data-separator-wrapper][data-separator-multi-button] {
+      margin-left: calc(-3ch - 2px);
+    }
+
+    [data-expand-button],
+    [data-separator-content] {
+      display: block;
+      align-self: unset;
+      min-width: unset;
+      min-height: unset;
+      padding: 0;
+      flex-shrink: 0;
+      grid-column: unset;
+      border: none;
+      width: auto;
+      height: auto;
+      background-color: transparent;
+      color: inherit;
+      font: inherit;
+    }
+
+    [data-expand-button]:not([data-expand-all-button]) {
+      &[data-expand-down]::before {
+        content: '\\2191';
+      }
+
+      &[data-expand-up]::before {
+        content: '\\2193';
+      }
+
+      &[data-expand-both]::before {
+        content: '\\2195';
+      }
+
+      svg {
+        display: none;
+      }
+    }
+
+    [data-separator-content] {
+      background: transparent;
+      margin-left: calc(2px + 1ch);
+    }
+
+    [data-expand-all-button] {
+      position: relative;
+      margin-left: 14px;
+      text-transform: lowercase;
+    }
+
+    [data-expand-all-button]::before {
+      content: '';
+      display: block;
+      position: absolute;
+      top: 50%;
+      left: -8px;
+      margin-top: -1px;
+      width: 3px;
+      height: 3px;
+      border-radius: 2px;
+      background-color: var(--diffs-fg-number);
+      pointer-events: none;
+    }
+
+    [data-separator-content]:hover,
+    [data-expand-button]:hover,
+    [data-expand-all-button]:hover {
+      color: var(--diffs-fg);
+    }
+
+    [data-expand-all-button]:hover {
+      text-decoration: underline;
+    }
+  }
   `;
 
 // Fast cache key - use length + samples instead of full hash
@@ -267,7 +365,7 @@ const virtualizerCache = new WeakMap<Document | HTMLElement, VirtualizerEntry>()
 const VIRTUAL_METRICS: Partial<VirtualFileMetrics> = {
   lineHeight: 24,
   hunkSeparatorHeight: 24,
-  fileGap: 0,
+  spacing: 0,
 };
 
 function resolveVirtualizerTarget(container: HTMLElement): VirtualizerTarget {
@@ -324,7 +422,7 @@ function acquireSharedVirtualizer(container: HTMLElement): SharedVirtualizer | n
 }
 
 const wakeVirtualizer = (
-  instance: PierreFileDiff<unknown>,
+  instance: PierreFileDiff<PierreAnnotationData>,
   sharedVirtualizer: SharedVirtualizer | null,
   forceUpdate: () => void,
 ): (() => void) => {
@@ -545,11 +643,11 @@ export const PierreDiffViewer: React.FC<PierreDiffViewerProps> = ({
 
   const diffRootRef = useRef<HTMLDivElement | null>(null);
   const diffContainerRef = useRef<HTMLDivElement | null>(null);
-  const diffInstanceRef = useRef<PierreFileDiff<unknown> | null>(null);
+  const diffInstanceRef = useRef<PierreFileDiff<PierreAnnotationData> | null>(null);
   const sharedVirtualizerRef = useRef<SharedVirtualizer | null>(null);
   const instanceVirtualizerRef = useRef<Virtualizer | null>(null);
   const instanceWorkerPoolRef = useRef<unknown>(null);
-  const instanceVirtualHunkSeparatorsRef = useRef<FileDiffOptions<unknown>['hunkSeparators'] | undefined>(undefined);
+  const instanceVirtualHunkSeparatorsRef = useRef<FileDiffOptions<PierreAnnotationData>['hunkSeparators'] | undefined>(undefined);
   const instanceFileDiffRef = useRef<FileDiffMetadata | undefined>(undefined);
   const instanceOldFileRef = useRef<FileContents | undefined>(undefined);
   const instanceNewFileRef = useRef<FileContents | undefined>(undefined);
@@ -755,17 +853,17 @@ export const PierreDiffViewer: React.FC<PierreDiffViewerProps> = ({
       : false;
     if (!instance) {
       instance = sharedVirtualizer
-        ? new VirtualizedFileDiff(
-            options as unknown as FileDiffOptions<unknown>,
+        ? new VirtualizedFileDiff<PierreAnnotationData>(
+            options as FileDiffOptions<PierreAnnotationData>,
             sharedVirtualizer.virtualizer,
             VIRTUAL_METRICS,
             workerPool,
           )
-        : new PierreFileDiff(options as unknown as FileDiffOptions<unknown>, workerPool);
+        : new PierreFileDiff(options as FileDiffOptions<PierreAnnotationData>, workerPool);
       diffInstanceRef.current = instance;
       lastAppliedSelectionRef.current = null;
     } else {
-      instance.setOptions(options as unknown as FileDiffOptions<unknown>);
+      instance.setOptions(options as FileDiffOptions<PierreAnnotationData>);
     }
 
     instanceVirtualizerRef.current = virtualizer;