diff --git a/common/web/types/src/kpj/keyman-developer-project.ts b/common/web/types/src/kpj/keyman-developer-project.ts
index 841111e00a..ce9f78cf59 100644
--- a/common/web/types/src/kpj/keyman-developer-project.ts
+++ b/common/web/types/src/kpj/keyman-developer-project.ts
@@ -127,51 +127,38 @@ export class KeymanDeveloperProjectOptions {
   }
 };
 
-export type KeymanDeveloperProjectFile = KeymanDeveloperProjectFile10 | KeymanDeveloperProjectFile20;
-
-export class KeymanDeveloperProjectFile10 {
-  readonly id: string;           // 1.0 only
-  readonly filename: string;
+export interface KeymanDeveloperProjectFile {
+  get filename(): string;
+  get fileType(): string;
   readonly filePath: string;
-  readonly fileVersion: string;  // 1.0 only
-  /**
-   * file extension of filename; warning: .model.ts is technically not the fileType because of 2 periods
-   * @deprecated use `getFileType()`
-   */
-  readonly fileType: KeymanFileTypes.Any; // 1.0 only
+};
+
+export class KeymanDeveloperProjectFile10 implements KeymanDeveloperProjectFile {
+  get filename(): string {
+    return this.callbacks.path.basename(this.filePath);
+  }
+  get fileType(): string {
+    return KeymanFileTypes.fromFilename(this.filename);
+  }
   details: KeymanDeveloperProjectFileDetail_Kmn & KeymanDeveloperProjectFileDetail_Kps; // 1.0 only
   childFiles: KeymanDeveloperProjectFile[]; // 1.0 only
-  constructor(id: string, filename: string, filePath: string, fileVersion:string, fileType: KeymanFileTypes.Any) {
+
+  constructor(public readonly id: string, public readonly filePath: string, public readonly fileVersion:string, private readonly callbacks: CompilerCallbacks) {
     this.details = {};
     this.childFiles = [];
-    this.id = id;
-    this.filename = filename;
-    this.filePath = filePath;
-    this.fileVersion = fileVersion;
-    this.fileType = fileType;
-  }
-  getFileType() {
-    return KeymanFileTypes.sourceTypeFromFilename(this.filename);
   }
 };
 
 export type KeymanDeveloperProjectFileType20 = KeymanFileTypes.Source;
 
-export class KeymanDeveloperProjectFile20 {
-  readonly filename: string;
-  readonly filePath: string;
-  /**
-   * file extension of filename, but .model.ts is technically not the ext because of 2 periods
-   * @deprecated TODO: remove this from 2.0 or make it private
-   */
-  readonly fileType: KeymanFileTypes.Source;
-  constructor(filePath: string, private callbacks: CompilerCallbacks) {
-    this.filename = this.callbacks.path.basename(filePath);
-    this.filePath = filePath;
-    this.fileType = KeymanFileTypes.sourceTypeFromFilename(this.filename);
+export class KeymanDeveloperProjectFile20 implements KeymanDeveloperProjectFile {
+  get filename(): string {
+    return this.callbacks.path.basename(this.filePath);
   }
-  getFileType() {
-    return this.fileType;
+  get fileType() {
+    return KeymanFileTypes.fromFilename(this.filename);
+  }
+  constructor(public readonly filePath: string, private readonly callbacks: CompilerCallbacks) {
   }
 };
 
diff --git a/common/web/types/src/kpj/kpj-file-reader.ts b/common/web/types/src/kpj/kpj-file-reader.ts
index 9e3b934c35..2c8589b5c1 100644
--- a/common/web/types/src/kpj/kpj-file-reader.ts
+++ b/common/web/types/src/kpj/kpj-file-reader.ts
@@ -88,10 +88,9 @@ export class KPJFileReader {
     for (let sourceFile of project.Files?.File) {
       let file: KeymanDeveloperProjectFile10 = new KeymanDeveloperProjectFile10(
         sourceFile.ID || '',
-        sourceFile.Filename || '',
         (sourceFile.Filepath || '').replace(/\\/g, '/'),
         sourceFile.FileVersion || '',
-        sourceFile.FileType || ''
+        this.callbacks
       );
       if (sourceFile.Details) {
         file.details.copyright = sourceFile.Details.Copyright;
diff --git a/common/web/types/src/util/file-types.ts b/common/web/types/src/util/file-types.ts
index 230792d9b7..ebad759638 100644
--- a/common/web/types/src/util/file-types.ts
+++ b/common/web/types/src/util/file-types.ts
@@ -68,6 +68,23 @@ export type All = Source | Binary;
  */
 export type Any = string;
 
+/**
+ * Gets the file type based on extension, dealing with multi-part file
+ * extensions. Does not sniff contents of file or assume file existence. Does
+ * transform upper-cased file extensions to lower-case.
+ * @param filename
+ * @returns file extension, or `""` if no extension. Note that this return value
+ *          differs from the other, more-specific fromFilename functions below,
+ *          which return `null` if a supported extension is not found.
+ */
+export function fromFilename(filename: string): Binary | Source | Any {
+  const result =
+    sourceOrBinaryTypeFromFilename(filename) ??
+    filename.match(/\.[^\.]+$/)?.[0] ??
+    "";
+  return result;
+}
+
 /**
  * Gets the file type based on extension, dealing with multi-part file
  * extensions. Does not sniff contents of file or assume file existence.
@@ -75,7 +92,7 @@ export type Any = string;
  * @param filename
  * @returns file type, or `null` if not found
  */
-export function fromFilename(filename: string): Binary | Source {
+export function sourceOrBinaryTypeFromFilename(filename: string): Binary | Source {
   filename = filename.toLowerCase();
   const result =
     ALL_SOURCE.find(type => filename.endsWith(type)) ??
diff --git a/developer/src/kmc/src/commands/buildClasses/BuildKeyboardInfo.ts b/developer/src/kmc/src/commands/buildClasses/BuildKeyboardInfo.ts
index decc5197e5..14670c99b4 100644
--- a/developer/src/kmc/src/commands/buildClasses/BuildKeyboardInfo.ts
+++ b/developer/src/kmc/src/commands/buildClasses/BuildKeyboardInfo.ts
@@ -81,7 +81,7 @@ export class BuildKeyboardInfo extends BuildActivity {
 }
 
 function findProjectFile(callbacks: CompilerCallbacks, project: KeymanDeveloperProject, ext: KeymanFileTypes.Source) {
-  const file = project.files.find(file => file.getFileType() == ext);
+  const file = project.files.find(file => file.fileType == ext);
   if(!file) {
     callbacks.reportMessage(InfrastructureMessages.Error_FileTypeNotFound({ext}));
   }
diff --git a/developer/src/kmc/src/commands/buildClasses/BuildModelInfo.ts b/developer/src/kmc/src/commands/buildClasses/BuildModelInfo.ts
index c20f038369..bfb167bdcc 100644
--- a/developer/src/kmc/src/commands/buildClasses/BuildModelInfo.ts
+++ b/developer/src/kmc/src/commands/buildClasses/BuildModelInfo.ts
@@ -35,19 +35,19 @@ export class BuildModelInfo extends BuildActivity {
       return false;
     }
 
-    const metadata = project.files.find(file => file.getFileType() == KeymanFileTypes.Source.ModelInfo);
+    const metadata = project.files.find(file => file.fileType == KeymanFileTypes.Source.ModelInfo);
     if(!metadata) {
       callbacks.reportMessage(InfrastructureMessages.Error_FileTypeNotFound({ext: KeymanFileTypes.Source.ModelInfo}));
       return false;
     }
 
-    const model = project.files.find(file => file.getFileType() == KeymanFileTypes.Source.Model);
+    const model = project.files.find(file => file.fileType == KeymanFileTypes.Source.Model);
     if(!model) {
       callbacks.reportMessage(InfrastructureMessages.Error_FileTypeNotFound({ext: KeymanFileTypes.Source.Model}));
       return false;
     }
 
-    const kps = project.files.find(file => file.getFileType() == KeymanFileTypes.Source.Package);
+    const kps = project.files.find(file => file.fileType == KeymanFileTypes.Source.Package);
     if(!kps) {
       callbacks.reportMessage(InfrastructureMessages.Error_FileTypeNotFound({ext: KeymanFileTypes.Source.Package}));
       return false;