From 203e0ff553bd53c2e40030af035ce58099d41915 Mon Sep 17 00:00:00 2001
From: Cameron Chisholm <cam@camchis.com>
Date: Fri, 30 Oct 2026 19:36:28 +0000
Subject: [PATCH] perf(mobile): opening a file reads it alongside its metadata

On a remote host the file viewer waited for the metadata lookup before
asking for the contents, so every uncached text file paid two serial round
trips. Read both at once; a directory answers the read with a cheap
not-a-file error that its view never shows.
---
 .../features/files/ThreadFilesRouteScreen.tsx | 16 +++++++---------
 .../src/features/files/filePath.test.ts       |  9 +++++++++
 apps/mobile/src/features/files/filePath.ts    | 19 +++++++++++++++++++
 3 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx b/apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx
index 117dbc44ede58..4844063f5d16a 100644
--- a/apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx
+++ b/apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx
@@ -68,6 +68,7 @@ import {
   isMarkdownPreviewFile,
   isSvgImagePreviewFile,
   isVideoPreviewFile,
+  needsWorkspaceFileContents,
 } from "./filePath";
 import { useWorkspaceFileAssetUrlState } from "./workspaceFileAssetUrl";
 
@@ -707,15 +708,12 @@ export function ThreadFileScreen(props: ThreadFileRouteScreenProps) {
   const handleRetryPreview = () => {
     void assetPreview.refresh().finally(() => setPreviewRevision((current) => current + 1));
   };
-  const needsFileContents =
-    !metadataPending &&
-    directoryPath === null &&
-    relativePath !== null &&
-    !isVideoFile &&
-    !isAudioFile &&
-    (resolvedActiveMode === "source" ||
-      isMarkdownPreviewFile(relativePath) ||
-      filePreviewDelimiter({ name: relativePath }) !== null);
+  // Metadata is needed only to distinguish directories; file contents can load concurrently.
+  const needsFileContents = needsWorkspaceFileContents({
+    relativePath,
+    metadataKind: metadata.data?.kind,
+    activeMode: resolvedActiveMode,
+  });
   const fileQuery = useEnvironmentQuery(
     canReadFiles &&
       environmentId !== null &&
diff --git a/apps/mobile/src/features/files/filePath.test.ts b/apps/mobile/src/features/files/filePath.test.ts
index 0a5fd943e88f8..46b26d7e3bf3d 100644
--- a/apps/mobile/src/features/files/filePath.test.ts
+++ b/apps/mobile/src/features/files/filePath.test.ts
@@ -2,6 +2,7 @@ import { describe, expect, it } from "vite-plus/test";
 
 import {
   fileRoutePathSegments,
+  needsWorkspaceFileContents,
   resolveFileLinkPath,
   resolveWorkspaceRelativeFilePath,
 } from "./filePath";
@@ -49,3 +50,11 @@ describe("resolveWorkspaceRelativeFilePath", () => {
     expect(resolveWorkspaceRelativeFilePath(null, "/repo/main.ts")).toBeNull();
   });
 });
+
+describe("needsWorkspaceFileContents", () => {
+  it("reads a text file while its metadata is still pending, but not a directory", () => {
+    const input = { relativePath: "package.json", activeMode: "source" } as const;
+    expect(needsWorkspaceFileContents({ ...input, metadataKind: undefined })).toBe(true);
+    expect(needsWorkspaceFileContents({ ...input, metadataKind: "directory" })).toBe(false);
+  });
+});
diff --git a/apps/mobile/src/features/files/filePath.ts b/apps/mobile/src/features/files/filePath.ts
index d889e88825830..e38ff86fa6656 100644
--- a/apps/mobile/src/features/files/filePath.ts
+++ b/apps/mobile/src/features/files/filePath.ts
@@ -1,3 +1,5 @@
+import type { FilesystemEntryMetadata } from "@t3tools/contracts";
+import { filePreviewDelimiter } from "@t3tools/shared/delimitedPreview";
 import { joinPath, resolvePathLinkTarget } from "@t3tools/shared/fileLinks";
 import {
   isWorkspaceAudioPreviewPath,
@@ -109,6 +111,23 @@ export function isMarkdownPreviewFile(path: string): boolean {
   return /\.(?:md|mdx)$/i.test(path.split(/[?#]/, 1)[0] ?? "");
 }
 
+export function needsWorkspaceFileContents(input: {
+  readonly relativePath: string | null;
+  readonly metadataKind: FilesystemEntryMetadata["kind"] | undefined;
+  readonly activeMode: "preview" | "source";
+}): boolean {
+  const path = input.relativePath;
+  return (
+    input.metadataKind !== "directory" &&
+    path !== null &&
+    !isVideoPreviewFile(path) &&
+    !isAudioPreviewFile(path) &&
+    (input.activeMode === "source" ||
+      isMarkdownPreviewFile(path) ||
+      filePreviewDelimiter({ name: path }) !== null)
+  );
+}
+
 export function fileHeaderSubtitle(projectName: string, relativePath: string): string {
   const parentDir = relativePath.slice(
     0,