Clarify metric values for result events

src/analytics/metrics/types.ts

@@ -713,14 +713,42 @@ export type Events = {
     textLength: number
   }
   'translate:result': {
-    method: 'on-device' | 'fallback-alert'
+    success: boolean
     os: Platform['OS']
-    sourceSelection: 'automatic' | 'manual'
-    sourceLanguage: string | null
-    targetLanguage: string
-
-    /* Only relevant to posts */
-    postLanguages?: string[]
+    /**
+     * The languages the content might be in, such as the user-supplied
+     * language codes on posts. Currently only available on posts.
+     */
+    possibleSourceLanguages: string[] | undefined
+    /**
+     * The language we expected the content to be in. This could be based on
+     * user selection or on our confidence in the detected language. This is
+     * nullable because we may not always have an expected source language.
+     */
+    expectedSourceLanguage: string | null
+    /**
+     * This is the user's configured primary language, which is always defined.
+     */
+    expectedTargetLanguage: string
+    /**
+     * The language the translation result was actually in. This is nullable
+     * because the translation could have failed, in which case we won't have a
+     * result source language.
+     */
+    resultSourceLanguage: string | null
+    /**
+     * The language the translation result was translated into. This should be
+     * the same as `expectedTargetLanguage`, but we include it for completeness
+     * and in case there are any edge cases where they differ. This is nullable
+     * because if the translation failed, we won't have a result target
+     * language.
+     */
+    resultTargetLanguage: string | null
+    /**
+     * The length of the text being translated. We assume shorter texts are
+     * more likely to have inaccurate translations.
+     */
+    textLength: number
   }
   'translate:override': {
     os: Platform['OS']

src/components/Post/Translated/index.tsx

@@ -408,7 +408,6 @@ function TranslationLanguageSelect({
       text: postText,
       targetLangCode: langPrefs.primaryLanguage,
       sourceLangCode,
-      sourceSelection: 'manual',
     })
   }
 

src/lib/translation/index.tsx

@@ -212,13 +212,12 @@ export function Provider({children}: React.PropsWithChildren<unknown>) {
       key,
       text,
       targetLangCode,
-      sourceLangCode,
-      sourceSelection = 'automatic',
+      sourceLangCode: expectedSourceLanguage,
       postLangCodes,
       ...options
     }) => {
       if (options?.forceGoogleTranslate || !HAS_ON_DEVICE_TRANSLATION) {
-        await googleTranslate(text, targetLangCode, sourceLangCode)
+        await googleTranslate(text, targetLangCode, expectedSourceLanguage)
         return
       }
 
@@ -233,15 +232,17 @@ export function Provider({children}: React.PropsWithChildren<unknown>) {
         const result = await attemptTranslation(
           text,
           targetLangCode,
-          sourceLangCode,
+          expectedSourceLanguage,
         )
         ax.metric('translate:result', {
-          method: 'on-device',
+          success: true,
           os: Platform.OS,
-          sourceSelection,
-          sourceLanguage: result.sourceLanguage,
-          targetLanguage: result.targetLanguage,
-          postLanguages: postLangCodes,
+          possibleSourceLanguages: postLangCodes,
+          expectedSourceLanguage: expectedSourceLanguage ?? null,
+          expectedTargetLanguage: targetLangCode,
+          resultSourceLanguage: result.sourceLanguage,
+          resultTargetLanguage: result.targetLanguage,
+          textLength: text.length,
         })
         if (!IS_ANDROID) {
           LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut)
@@ -261,12 +262,14 @@ export function Provider({children}: React.PropsWithChildren<unknown>) {
         // On-device translation failed (language pack missing or user
         // dismissed the download prompt).
         ax.metric('translate:result', {
-          method: 'fallback-alert',
+          success: false,
           os: Platform.OS,
-          sourceSelection,
-          sourceLanguage: sourceLangCode ?? null,
-          targetLanguage: targetLangCode,
-          postLanguages: postLangCodes,
+          possibleSourceLanguages: postLangCodes,
+          expectedSourceLanguage: expectedSourceLanguage ?? null,
+          expectedTargetLanguage: targetLangCode,
+          resultSourceLanguage: null,
+          resultTargetLanguage: null,
+          textLength: text.length,
         })
         let errorMessage = l`Device failed to translate :(`
         if (!IS_ANDROID) {

src/lib/translation/types.ts

@@ -24,13 +24,12 @@ export type TranslationFunctionParams = {
    */
   targetLangCode: string
   /**
-   * The source language of the text. Will auto-detect if not provided.
+   * We auto-detect the source language by default, but the user has the option
+   * to specify a source language if they want to. If this value is present, it
+   * means the user selected a source language, or we were certain of the
+   * source language and want to specify it explicitly.
    */
   sourceLangCode?: string
-  /**
-   * Whether we auto-detected the language or it was selected manually. Defaults to 'automatic'.
-   */
-  sourceSelection?: 'automatic' | 'manual'
 }
 
 export type TranslationOptions = {