diff --git a/apps/server/src/attachmentPaths.ts b/apps/server/src/attachmentPaths.ts
index c1680f6c082f360371fb4cdd35ce93574511c6d3..be404076bd6f7c0c8ec9096b2cd820afe918fc05 100644
--- a/apps/server/src/attachmentPaths.ts
+++ b/apps/server/src/attachmentPaths.ts
@@ -2,6 +2,14 @@ import path from "node:path";
 
 export const ATTACHMENTS_ROUTE_PREFIX = "/attachments";
 
+export function stripAttachmentRoutePrefix(pathname: string): string | null {
+  if (!pathname.startsWith(ATTACHMENTS_ROUTE_PREFIX)) {
+    return null;
+  }
+  const remainder = pathname.slice(ATTACHMENTS_ROUTE_PREFIX.length);
+  return remainder.startsWith("/") ? remainder.slice(1) : remainder;
+}
+
 export function normalizeAttachmentRelativePath(rawRelativePath: string): string | null {
   const normalized = path.normalize(rawRelativePath).replace(/^[/\\]+/, "");
   if (normalized.length === 0 || normalized.startsWith("..") || normalized.includes("\0")) {
diff --git a/apps/server/src/attachmentStore.ts b/apps/server/src/attachmentStore.ts
index 48be2df8a6cfcc053656de8de6835053241587a4..5fcebd64570fc9ce0ba391807e068c1fc602b39e 100644
--- a/apps/server/src/attachmentStore.ts
+++ b/apps/server/src/attachmentStore.ts
@@ -14,6 +14,7 @@ const ATTACHMENT_ID_THREAD_SEGMENT_MAX_CHARS = 80;
 const ATTACHMENT_ID_THREAD_SEGMENT_PATTERN = "[a-z0-9_]+(?:-[a-z0-9_]+)*";
 const ATTACHMENT_ID_UUID_PATTERN =
   "[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}";
+// Keep this regex strict so attachment IDs cannot be used as path traversal vectors.
 const ATTACHMENT_ID_PATTERN = new RegExp(
   `^(${ATTACHMENT_ID_THREAD_SEGMENT_PATTERN})-(${ATTACHMENT_ID_UUID_PATTERN})$`,
   "i",
diff --git a/apps/server/src/config.ts b/apps/server/src/config.ts
index ccbcea469d6feaf6d63876f91175f9ab6d9b6874..ce226dc7b01e4408975bdfc8473079c4238f8863 100644
--- a/apps/server/src/config.ts
+++ b/apps/server/src/config.ts
@@ -9,9 +9,12 @@
 import { Effect, FileSystem, Layer, Path, ServiceMap } from "effect";
 
 export const DEFAULT_PORT = 3773;
+export const KEYBINDINGS_CONFIG_FILENAME = "keybindings.json" as const;
 
 export type RuntimeMode = "web" | "desktop";
 
+export const isDesktopMode = (mode: RuntimeMode): mode is "desktop" => mode === "desktop";
+
 /**
  * ServerConfigShape - Process/runtime configuration required by the server.
  */
@@ -50,7 +53,7 @@ export class ServerConfig extends ServiceMap.Service<ServerConfig, ServerConfigS
           port: 0,
           host: undefined,
           authToken: undefined,
-          keybindingsConfigPath: path.join(statedir, "keybindings.json"),
+          keybindingsConfigPath: path.join(statedir, KEYBINDINGS_CONFIG_FILENAME),
           staticDir: undefined,
           devUrl: undefined,
           noBrowser: false,
diff --git a/apps/server/src/git/Errors.ts b/apps/server/src/git/Errors.ts
index 15bf482f7bfe073b9037e8eed68fe7ec2c33ef60..a51fc0e8a703e8a164b8642e8b603c08e8c28ec5 100644
--- a/apps/server/src/git/Errors.ts
+++ b/apps/server/src/git/Errors.ts
@@ -59,6 +59,8 @@ export class GitManagerError extends Schema.TaggedErrorClass<GitManagerError>()(
 
 /**
  * GitManagerServiceError - Errors emitted by stacked Git workflow orchestration.
+ *
+ * Keep this union centralized so callers can pattern-match once at API boundaries.
  */
 export type GitManagerServiceError =
   | GitManagerError
diff --git a/apps/server/src/git/Services/GitManager.ts b/apps/server/src/git/Services/GitManager.ts
index e3f90202dd92a047e9b466fb0a32c7b48900e8e8..d917d4c1e91855b303a7855d521b0c94bcc39a0b 100644
--- a/apps/server/src/git/Services/GitManager.ts
+++ b/apps/server/src/git/Services/GitManager.ts
@@ -38,6 +38,8 @@ export interface GitManagerShape {
 
 /**
  * GitManager - Service tag for stacked Git workflow orchestration.
+ *
+ * Single tag keeps orchestration wiring swappable in Layer-based tests.
  */
 export class GitManager extends ServiceMap.Service<GitManager, GitManagerShape>()(
   "t3/git/Services/GitManager",
diff --git a/apps/server/src/git/Services/TextGeneration.ts b/apps/server/src/git/Services/TextGeneration.ts
index daae27fe66d4e7b313c72a741a39ea2dbc14d3de..877d1904ece2c1510034972169ee7d0c6b2f5dac 100644
--- a/apps/server/src/git/Services/TextGeneration.ts
+++ b/apps/server/src/git/Services/TextGeneration.ts
@@ -62,6 +62,8 @@ export interface TextGenerationService {
 
 /**
  * TextGenerationShape - Service API for commit/PR text generation.
+ *
+ * Interface isolates provider-specific model behavior behind deterministic method contracts.
  */
 export interface TextGenerationShape {
   /**
diff --git a/apps/server/src/imageMime.ts b/apps/server/src/imageMime.ts
index 814abbb32c1c483b595a2a0c8e82e3d03718f0db..8131dcec3a2953db66e7b699569b604c4a9b2022 100644
--- a/apps/server/src/imageMime.ts
+++ b/apps/server/src/imageMime.ts
@@ -29,6 +29,28 @@ export const SAFE_IMAGE_FILE_EXTENSIONS = new Set([
   ".webp",
 ]);
 
+const normalizeImageExtension = (extension: string): string | null => {
+  const trimmed = extension.trim();
+  if (trimmed.length === 0) {
+    return null;
+  }
+
+  const lower = trimmed.toLowerCase();
+  return lower.startsWith(".") ? lower : `.${lower}`;
+};
+
+const coerceSafeImageExtension = (
+  extension: string | null | undefined,
+): string | null => {
+  if (!extension) return null;
+  const normalized = normalizeImageExtension(extension);
+  if (!normalized) return null;
+  return SAFE_IMAGE_FILE_EXTENSIONS.has(normalized) ? normalized : null;
+};
+
+export const isSafeImageExtension = (extension: string): boolean =>
+  coerceSafeImageExtension(extension) !== null;
+
 export function parseBase64DataUrl(
   dataUrl: string,
 ): { readonly mimeType: string; readonly base64: string } | null {
@@ -63,15 +85,15 @@ export function inferImageExtension(input: { mimeType: string; fileName?: string
     return fromMime;
   }
 
-  const fromMimeExtension = Mime.getExtension(input.mimeType);
-  if (fromMimeExtension && SAFE_IMAGE_FILE_EXTENSIONS.has(fromMimeExtension)) {
+  const fromMimeExtension = coerceSafeImageExtension(Mime.getExtension(input.mimeType));
+  if (fromMimeExtension) {
     return fromMimeExtension;
   }
 
   const fileName = input.fileName?.trim() ?? "";
   const extensionMatch = /\.([a-z0-9]{1,8})$/i.exec(fileName);
-  const fileNameExtension = extensionMatch ? `.${extensionMatch[1]!.toLowerCase()}` : "";
-  if (SAFE_IMAGE_FILE_EXTENSIONS.has(fileNameExtension)) {
+  const fileNameExtension = extensionMatch ? coerceSafeImageExtension(extensionMatch[1]) : null;
+  if (fileNameExtension) {
     return fileNameExtension;
   }
 
diff --git a/apps/server/src/index.ts b/apps/server/src/index.ts
index 6eb26602cab91bb1954d6f8b933ef4342877c0ca..8cdd090ec94e5683976847a294730f4813645449 100644
--- a/apps/server/src/index.ts
+++ b/apps/server/src/index.ts
@@ -10,6 +10,7 @@ import { version } from "../package.json" with { type: "json" };
 import { ServerLive } from "./wsServer";
 import { NetService } from "@t3tools/shared/Net";
 
+// Compose all required services once so every CLI invocation shares the same runtime.
 const RuntimeLayer = Layer.empty.pipe(
   Layer.provideMerge(CliConfig.layer),
   Layer.provideMerge(ServerLive),
diff --git a/apps/server/src/main.ts b/apps/server/src/main.ts
index 4f36e7ea1291bb7ca890a0ba507eb6b35a023fe3..2ea89cb609b1d64045007f723896a085ea62fc15 100644
--- a/apps/server/src/main.ts
+++ b/apps/server/src/main.ts
@@ -12,8 +12,10 @@ import { NetService } from "@t3tools/shared/Net";
 
 import {
   DEFAULT_PORT,
+  KEYBINDINGS_CONFIG_FILENAME,
   resolveStaticDir,
   ServerConfig,
+  isDesktopMode,
   type RuntimeMode,
   type ServerConfigShape,
 } from "./config";
@@ -133,6 +135,8 @@ const ServerConfigLive = (input: CliInput) =>
       );
 
       const mode = Option.getOrElse(input.mode, () => env.mode);
+      const isDesktop = isDesktopMode(mode);
+      const isWeb = !isDesktop;
 
       const port = yield* Option.match(input.port, {
         onSome: (value) => Effect.succeed(value),
@@ -140,7 +144,7 @@ const ServerConfigLive = (input: CliInput) =>
           if (env.port) {
             return Effect.succeed(env.port);
           }
-          if (mode === "desktop") {
+          if (isDesktop) {
             return Effect.succeed(DEFAULT_PORT);
           }
           return findAvailablePort(DEFAULT_PORT);
@@ -153,15 +157,15 @@ const ServerConfigLive = (input: CliInput) =>
       const noBrowser = Option.match(input.noBrowser, {
         // effect/cli boolean flags parse to `false` when absent; in that case
         // we still want env/mode fallbacks to apply.
-        onSome: (value) => (value ? true : (env.noBrowser ?? mode === "desktop")),
-        onNone: () => env.noBrowser ?? mode === "desktop",
+        onSome: (value) => (value ? true : (env.noBrowser ?? isDesktop)),
+        onNone: () => env.noBrowser ?? isDesktop,
       });
       const authToken = Option.getOrUndefined(input.authToken) ?? env.authToken;
       const autoBootstrapProjectFromCwd = Option.match(input.autoBootstrapProjectFromCwd, {
         // effect/cli boolean flags parse to `false` when absent; in that case
         // we still want env/mode fallbacks to apply.
-        onSome: (value) => (value ? true : (env.autoBootstrapProjectFromCwd ?? mode === "web")),
-        onNone: () => env.autoBootstrapProjectFromCwd ?? mode === "web",
+        onSome: (value) => (value ? true : (env.autoBootstrapProjectFromCwd ?? isWeb)),
+        onNone: () => env.autoBootstrapProjectFromCwd ?? isWeb,
       });
       const logWebSocketEvents = Option.match(input.logWebSocketEvents, {
         // effect/cli boolean flags parse to `false` when absent; in that case
@@ -171,11 +175,11 @@ const ServerConfigLive = (input: CliInput) =>
       });
       const staticDir = devUrl ? undefined : yield* cliConfig.resolveStaticDir;
       const { join } = yield* Path.Path;
-      const keybindingsConfigPath = join(stateDir, "keybindings.json");
+      const keybindingsConfigPath = join(stateDir, KEYBINDINGS_CONFIG_FILENAME);
       const host =
         Option.getOrUndefined(input.host) ??
         env.host ??
-        (mode === "desktop" ? "127.0.0.1" : undefined);
+        (isDesktop ? "127.0.0.1" : undefined);
 
       return {
         mode,
diff --git a/apps/server/src/os-jank.ts b/apps/server/src/os-jank.ts
index 3f5e2129da06fae068f70415a18331c03dbc8312..978b2414e6ada7dce6313e0eecca8090d3c1c4e8 100644
--- a/apps/server/src/os-jank.ts
+++ b/apps/server/src/os-jank.ts
@@ -3,6 +3,7 @@ import { Effect, Path } from "effect";
 import { execFileSync } from "node:child_process";
 
 export function fixPath(): void {
+  // Only macOS shells need PATH hydration from interactive startup files.
   if (process.platform !== "darwin") return;
 
   try {
diff --git a/apps/server/src/wsServer.ts b/apps/server/src/wsServer.ts
index 50af3b8b10ef5fd0b168047e61bd45269e7e4581..310bf756288df8fa34c254a33e788c9a6dcb8ae6 100644
--- a/apps/server/src/wsServer.ts
+++ b/apps/server/src/wsServer.ts
@@ -60,9 +60,9 @@ import { ServerConfig } from "./config";
 import { GitCore } from "./git/Services/GitCore.ts";
 import { tryHandleProjectFaviconRequest } from "./projectFaviconRoute";
 import {
-  ATTACHMENTS_ROUTE_PREFIX,
   normalizeAttachmentRelativePath,
   resolveAttachmentRelativePath,
+  stripAttachmentRoutePrefix,
 } from "./attachmentPaths";
 import {
   createAttachmentId,
@@ -350,9 +350,9 @@ export const createServer = Effect.fn(function* (): Effect.fn.Return<
           return;
         }
 
-        if (url.pathname.startsWith(ATTACHMENTS_ROUTE_PREFIX)) {
-          const rawRelativePath = url.pathname.slice(ATTACHMENTS_ROUTE_PREFIX.length);
-          const normalizedRelativePath = normalizeAttachmentRelativePath(rawRelativePath);
+        const routeRelativePath = stripAttachmentRoutePrefix(url.pathname);
+        if (routeRelativePath !== null) {
+          const normalizedRelativePath = normalizeAttachmentRelativePath(routeRelativePath);
           if (!normalizedRelativePath) {
             respond(400, { "Content-Type": "text/plain" }, "Invalid attachment path");
             return;
diff --git a/apps/web/src/components/ChatView.tsx b/apps/web/src/components/ChatView.tsx
index 2b3601bc3f0221b09d5f2684d905273fde15e761..1998ad84aed9798583fb61f13b7899c4187dfb6e 100644
--- a/apps/web/src/components/ChatView.tsx
+++ b/apps/web/src/components/ChatView.tsx
@@ -340,6 +340,7 @@ const VscodeEntryIcon = memo(function VscodeEntryIcon(props: {
   pathValue: string;
   kind: "file" | "directory";
   theme: "light" | "dark";
+  className?: string;
 }) {
   const [failedIconUrl, setFailedIconUrl] = useState<string | null>(null);
   const iconUrl = useMemo(
@@ -350,9 +351,9 @@ const VscodeEntryIcon = memo(function VscodeEntryIcon(props: {
 
   if (failed) {
     return props.kind === "directory" ? (
-      <FolderIcon className="size-4 text-muted-foreground/80" />
+      <FolderIcon className={cn("size-4 text-muted-foreground/80", props.className)} />
     ) : (
-      <FileIcon className="size-4 text-muted-foreground/80" />
+      <FileIcon className={cn("size-4 text-muted-foreground/80", props.className)} />
     );
   }
 
@@ -361,7 +362,7 @@ const VscodeEntryIcon = memo(function VscodeEntryIcon(props: {
       src={iconUrl}
       alt=""
       aria-hidden="true"
-      className="size-4 shrink-0"
+      className={cn("size-4 shrink-0", props.className)}
       loading="lazy"
       onError={() => setFailedIconUrl(iconUrl)}
     />
@@ -2554,6 +2555,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
           isRevertingCheckpoint={isRevertingCheckpoint}
           onImageExpand={onExpandTimelineImage}
           markdownCwd={gitCwd ?? undefined}
+          resolvedTheme={resolvedTheme}
         />
       </div>
 
@@ -3154,14 +3156,23 @@ const DiffStatLabel = memo(function DiffStatLabel(props: {
   );
 });
 
-function buildInitiallyExpandedDirectoryState(
-  nodes: ReadonlyArray<TurnDiffTreeNode>,
+function collectDirectoryPaths(nodes: ReadonlyArray<TurnDiffTreeNode>): string[] {
+  const paths: string[] = [];
+  for (const node of nodes) {
+    if (node.kind !== "directory") continue;
+    paths.push(node.path);
+    paths.push(...collectDirectoryPaths(node.children));
+  }
+  return paths;
+}
+
+function buildDirectoryExpansionState(
+  directoryPaths: ReadonlyArray<string>,
+  expanded: boolean,
 ): Record<string, boolean> {
   const expandedState: Record<string, boolean> = {};
-  for (const node of nodes) {
-    if (node.kind === "directory") {
-      expandedState[node.path] = true;
-    }
+  for (const directoryPath of directoryPaths) {
+    expandedState[directoryPath] = expanded;
   }
   return expandedState;
 }
@@ -3169,13 +3180,27 @@ function buildInitiallyExpandedDirectoryState(
 const ChangedFilesTree = memo(function ChangedFilesTree(props: {
   turnId: TurnId;
   files: ReadonlyArray<TurnDiffFileChange>;
+  allDirectoriesExpanded: boolean;
+  resolvedTheme: "light" | "dark";
   onOpenTurnDiff: (turnId: TurnId, filePath?: string) => void;
 }) {
-  const { files, onOpenTurnDiff, turnId } = props;
+  const { files, allDirectoriesExpanded, onOpenTurnDiff, resolvedTheme, turnId } = props;
   const treeNodes = useMemo(() => buildTurnDiffTree(files), [files]);
+  const directoryPathsKey = useMemo(() => collectDirectoryPaths(treeNodes).join("\u0000"), [treeNodes]);
+  const allDirectoryExpansionState = useMemo(
+    () =>
+      buildDirectoryExpansionState(
+        directoryPathsKey ? directoryPathsKey.split("\u0000") : [],
+        allDirectoriesExpanded,
+      ),
+    [allDirectoriesExpanded, directoryPathsKey],
+  );
   const [expandedDirectories, setExpandedDirectories] = useState<Record<string, boolean>>(
-    () => buildInitiallyExpandedDirectoryState(treeNodes),
+    () => buildDirectoryExpansionState((directoryPathsKey ? directoryPathsKey.split("\u0000") : []), true),
   );
+  useEffect(() => {
+    setExpandedDirectories(allDirectoryExpansionState);
+  }, [allDirectoryExpansionState]);
 
   const toggleDirectory = useCallback((pathValue: string) => {
     setExpandedDirectories((current) => ({
@@ -3233,7 +3258,12 @@ const ChangedFilesTree = memo(function ChangedFilesTree(props: {
         onClick={() => onOpenTurnDiff(turnId, node.path)}
       >
         <span aria-hidden="true" className="size-3.5 shrink-0" />
-        <FileIcon className="size-3.5 shrink-0 text-muted-foreground/70" />
+        <VscodeEntryIcon
+          pathValue={node.path}
+          kind="file"
+          theme={resolvedTheme}
+          className="size-3.5 text-muted-foreground/70"
+        />
         <span className="truncate font-mono text-[11px] text-muted-foreground/80 group-hover:text-foreground/90">
           {node.name}
         </span>
@@ -3272,6 +3302,7 @@ interface MessagesTimelineProps {
   isRevertingCheckpoint: boolean;
   onImageExpand: (preview: ExpandedImagePreview) => void;
   markdownCwd: string | undefined;
+  resolvedTheme: "light" | "dark";
 }
 
 type TimelineEntry = ReturnType<typeof deriveTimelineEntries>[number];
@@ -3312,6 +3343,7 @@ const MessagesTimeline = memo(function MessagesTimeline({
   isRevertingCheckpoint,
   onImageExpand,
   markdownCwd,
+  resolvedTheme,
 }: MessagesTimelineProps) {
   const timelineRootRef = useRef<HTMLDivElement | null>(null);
   const [timelineWidthPx, setTimelineWidthPx] = useState<number | null>(null);
@@ -3484,6 +3516,15 @@ const MessagesTimeline = memo(function MessagesTimeline({
 
   const virtualRows = rowVirtualizer.getVirtualItems();
   const nonVirtualizedRows = rows.slice(virtualizedRowCount);
+  const [allDirectoriesExpandedByTurnId, setAllDirectoriesExpandedByTurnId] = useState<
+    Record<string, boolean>
+  >({});
+  const onToggleAllDirectories = useCallback((turnId: TurnId) => {
+    setAllDirectoriesExpandedByTurnId((current) => ({
+      ...current,
+      [turnId]: !(current[turnId] ?? true),
+    }));
+  }, []);
 
   const renderRowContent = (row: TimelineRow) => (
     <div
@@ -3659,6 +3700,8 @@ const MessagesTimeline = memo(function MessagesTimeline({
                   if (checkpointFiles.length === 0) return null;
                   const summaryStat = summarizeTurnDiffStats(checkpointFiles);
                   const changedFileCountLabel = String(checkpointFiles.length);
+                  const allDirectoriesExpanded =
+                    allDirectoriesExpandedByTurnId[turnSummary.turnId] ?? true;
                   return (
                     <div className="mt-2 rounded-lg border border-border/80 bg-card/45 p-2.5">
                       <div className="mb-1.5 flex items-center justify-between gap-2">
@@ -3674,21 +3717,33 @@ const MessagesTimeline = memo(function MessagesTimeline({
                             </>
                           )}
                         </p>
-                        <Button
-                          type="button"
-                          size="xs"
-                          variant="outline"
-                          onClick={() =>
-                            onOpenTurnDiff(turnSummary.turnId, checkpointFiles[0]?.path)
-                          }
-                        >
-                          View diff
-                        </Button>
+                        <div className="flex items-center gap-1.5">
+                          <Button
+                            type="button"
+                            size="xs"
+                            variant="outline"
+                            onClick={() => onToggleAllDirectories(turnSummary.turnId)}
+                          >
+                            {allDirectoriesExpanded ? "Collapse all" : "Expand all"}
+                          </Button>
+                          <Button
+                            type="button"
+                            size="xs"
+                            variant="outline"
+                            onClick={() =>
+                              onOpenTurnDiff(turnSummary.turnId, checkpointFiles[0]?.path)
+                            }
+                          >
+                            View diff
+                          </Button>
+                        </div>
                       </div>
                       <ChangedFilesTree
                         key={`changed-files-tree:${turnSummary.turnId}`}
                         turnId={turnSummary.turnId}
                         files={checkpointFiles}
+                        allDirectoriesExpanded={allDirectoriesExpanded}
+                        resolvedTheme={resolvedTheme}
                         onOpenTurnDiff={onOpenTurnDiff}
                       />
                     </div>
diff --git a/apps/web/src/lib/turnDiffTree.test.ts b/apps/web/src/lib/turnDiffTree.test.ts
index f852e40c61f8fea829f06ab337d8cee0466c6f5f..35b74bc9ad8e56c9b6b9db9ebdfb308f16f4e01c 100644
--- a/apps/web/src/lib/turnDiffTree.test.ts
+++ b/apps/web/src/lib/turnDiffTree.test.ts
@@ -96,32 +96,54 @@ describe("buildTurnDiffTree", () => {
     expect(tree).toEqual([
       {
         kind: "directory",
-        name: "apps",
-        path: "apps",
+        name: "apps/web/src",
+        path: "apps/web/src",
         stat: { additions: 2, deletions: 1 },
+        children: [
+          {
+            kind: "file",
+            name: "index.ts",
+            path: "apps/web/src/index.ts",
+            stat: { additions: 2, deletions: 1 },
+          },
+        ],
+      },
+    ]);
+  });
+
+  it("compacts only single-directory chains and stops at branch points", () => {
+    const tree = buildTurnDiffTree([
+      { path: "apps/server/src/index.ts", additions: 2, deletions: 1 },
+      { path: "apps/server/main.ts", additions: 4, deletions: 0 },
+    ]);
+
+    expect(tree).toEqual([
+      {
+        kind: "directory",
+        name: "apps/server",
+        path: "apps/server",
+        stat: { additions: 6, deletions: 1 },
         children: [
           {
             kind: "directory",
-            name: "web",
-            path: "apps/web",
+            name: "src",
+            path: "apps/server/src",
             stat: { additions: 2, deletions: 1 },
             children: [
               {
-                kind: "directory",
-                name: "src",
-                path: "apps/web/src",
+                kind: "file",
+                name: "index.ts",
+                path: "apps/server/src/index.ts",
                 stat: { additions: 2, deletions: 1 },
-                children: [
-                  {
-                    kind: "file",
-                    name: "index.ts",
-                    path: "apps/web/src/index.ts",
-                    stat: { additions: 2, deletions: 1 },
-                  },
-                ],
               },
             ],
           },
+          {
+            kind: "file",
+            name: "main.ts",
+            path: "apps/server/main.ts",
+            stat: { additions: 4, deletions: 0 },
+          },
         ],
       },
     ]);
diff --git a/apps/web/src/lib/turnDiffTree.ts b/apps/web/src/lib/turnDiffTree.ts
index 126f96783af4aa8214617e6120b4c83109782c78..5a5ad00924f5dfba45af10ad76206c21f598863e 100644
--- a/apps/web/src/lib/turnDiffTree.ts
+++ b/apps/web/src/lib/turnDiffTree.ts
@@ -54,10 +54,34 @@ function readStat(file: TurnDiffFileChange): TurnDiffStat | null {
   };
 }
 
+function compactDirectoryNode(node: TurnDiffTreeDirectoryNode): TurnDiffTreeDirectoryNode {
+  const compactedChildren = node.children.map((child) =>
+    child.kind === "directory" ? compactDirectoryNode(child) : child,
+  );
+
+  let compactedNode: TurnDiffTreeDirectoryNode = {
+    ...node,
+    children: compactedChildren,
+  };
+
+  while (compactedNode.children.length === 1 && compactedNode.children[0]?.kind === "directory") {
+    const onlyChild = compactedNode.children[0];
+    compactedNode = {
+      kind: "directory",
+      name: `${compactedNode.name}/${onlyChild.name}`,
+      path: onlyChild.path,
+      stat: onlyChild.stat,
+      children: onlyChild.children,
+    };
+  }
+
+  return compactedNode;
+}
+
 function toTreeNodes(directory: MutableDirectoryNode): TurnDiffTreeNode[] {
   const subdirectories: TurnDiffTreeDirectoryNode[] = Array.from(directory.directories.values())
     .toSorted(compareByName)
-    .map((subdirectory) => ({
+    .map<TurnDiffTreeDirectoryNode>((subdirectory) => ({
       kind: "directory",
       name: subdirectory.name,
       path: subdirectory.path,
@@ -66,7 +90,8 @@ function toTreeNodes(directory: MutableDirectoryNode): TurnDiffTreeNode[] {
         deletions: subdirectory.stat.deletions,
       },
       children: toTreeNodes(subdirectory),
-    }));
+    }))
+    .map((subdirectory) => compactDirectoryNode(subdirectory));
 
   const files = directory.files.toSorted(compareByName);
   return [...subdirectories, ...files];