diff --git a/tools/generators/files_and_groups/src/ElementCreator/CreateFileElement.swift b/tools/generators/files_and_groups/src/ElementCreator/CreateFileElement.swift
index 6f74eee377..32a6875a3e 100644
--- a/tools/generators/files_and_groups/src/ElementCreator/CreateFileElement.swift
+++ b/tools/generators/files_and_groups/src/ElementCreator/CreateFileElement.swift
@@ -93,7 +93,8 @@ extension ElementCreator.CreateFileElement {
         let content = """
 {isa = PBXFileReference; \
 \(calculateFileTypeType(basename: name, extension: impliedExt)) = \(
-    impliedExt.flatMap(Xcode.pbxProjEscapedFileType) ?? "file"
+    impliedExt.flatMap(Xcode.pbxProjEscapedFileType) ??
+        Xcode.unknownFileType
 ); \
 \(nameAttribute)\
 path = \(attributes.elementAttributes.path.pbxProjEscaped); \
diff --git a/tools/generators/files_and_groups/src/ElementCreator/CreateLocalizedFileElement.swift b/tools/generators/files_and_groups/src/ElementCreator/CreateLocalizedFileElement.swift
index 3fca4fe06c..17fc71b9b5 100644
--- a/tools/generators/files_and_groups/src/ElementCreator/CreateLocalizedFileElement.swift
+++ b/tools/generators/files_and_groups/src/ElementCreator/CreateLocalizedFileElement.swift
@@ -66,7 +66,7 @@ extension ElementCreator.CreateLocalizedFileElement {
             fileTypeType = "lastKnownFileType"
             fileType = ext
                 .flatMap { Xcode.pbxProjEscapedFileType(extension: $0) } ??
-                "file"
+                Xcode.unknownFileType
         }
 
         let content = """
diff --git a/tools/generators/files_and_groups/src/Xcode.swift b/tools/generators/files_and_groups/src/Xcode.swift
index fe4e182892..5c10d38f04 100644
--- a/tools/generators/files_and_groups/src/Xcode.swift
+++ b/tools/generators/files_and_groups/src/Xcode.swift
@@ -273,6 +273,17 @@ enum Xcode {
         "Podfile": "rb",
     ]
 
+    /// The `lastKnownFileType` used for files whose extension isn't in
+    /// `pbxProjEscapedFileTypes`.
+    ///
+    /// Xcode determines the type of such files by sniffing their contents,
+    /// and writes `text` for text files (e.g. `.graphql`, `LICENSE`) and
+    /// `file` for binary ones. We only see paths (and the files might not
+    /// exist yet, e.g. generated files), so we use `text`, as unknown files in
+    /// source trees are overwhelmingly text. Matching Xcode prevents it from
+    /// rewriting the `project.pbxproj` when it next saves the project.
+    public static let unknownFileType = "text"
+
     /// Returns the Xcode file type for any given extension.
     ///
     /// - Parameters:
diff --git a/tools/generators/files_and_groups/test/ElementCreator/CreateFileElementTests.swift b/tools/generators/files_and_groups/test/ElementCreator/CreateFileElementTests.swift
index 77e21b1d18..669287bf44 100644
--- a/tools/generators/files_and_groups/test/ElementCreator/CreateFileElementTests.swift
+++ b/tools/generators/files_and_groups/test/ElementCreator/CreateFileElementTests.swift
@@ -125,7 +125,7 @@ final class CreateFileElementTests: XCTestCase {
         )
 
         let expectedContent = #"""
-{isa = PBXFileReference; lastKnownFileType = file; path = "a path"; sourceTree = SOURCE_ROOT; }
+{isa = PBXFileReference; lastKnownFileType = text; path = "a path"; sourceTree = SOURCE_ROOT; }
 """#
 
         // Act
@@ -160,7 +160,7 @@ final class CreateFileElementTests: XCTestCase {
         )
 
         let expectedContent = #"""
-{isa = PBXFileReference; lastKnownFileType = file; path = a_path; sourceTree = "<group>"; }
+{isa = PBXFileReference; lastKnownFileType = text; path = a_path; sourceTree = "<group>"; }
 """#
 
         // Act
@@ -428,7 +428,7 @@ final class CreateFileElementTests: XCTestCase {
         )
 
         let expectedContent = #"""
-{isa = PBXFileReference; lastKnownFileType = file; name = "a name"; path = a_path; sourceTree = "<group>"; }
+{isa = PBXFileReference; lastKnownFileType = text; name = "a name"; path = a_path; sourceTree = "<group>"; }
 """#
 
         // Act