Bug 1968074 - Fix truncated inferred interests ping r=thecount,home-newtab-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D250825

browser/components/newtab/metrics.yaml

@@ -1918,7 +1918,7 @@ newtab_content:
       - newtab-content
 
   inferred_interests:
-    type: string
+    type: object
     description: >
       Differentially private high-level inferred interests (e.g. Entertainment or News), encoded in a JSON string.
       Key is the feature, and the value is a unary encoded string that must be decoded based on known differential
@@ -1935,6 +1935,16 @@ newtab_content:
     lifetime: application
     send_in_pings:
       - newtab-content
+    structure:
+      type: object
+      properties:
+        values:
+          type: array
+          items:
+            type: string
+        model_id:
+          type: string
+
 
   coarse_os:
     type: string

browser/extensions/newtab/lib/InferredModel/FeatureModel.sys.mjs

@@ -395,6 +395,7 @@ export class FeatureModel {
     dataForIntervals,
     indexSchema,
     model_id = "unknown",
+    condensePrivateValues = true,
   }) {
     const result = {};
     let inferredInterests;
@@ -429,10 +430,17 @@ export class FeatureModel {
         applyDifferentialPrivacy: true,
       });
       if (coarsePrivateInferredInterests) {
-        result.coarsePrivateInferredInterests = {
-          ...coarsePrivateInferredInterests,
-          model_id,
-        };
+        if (condensePrivateValues) {
+          result.coarsePrivateInferredInterests = {
+            values: Object.values(coarsePrivateInferredInterests), // Key order presrved in Gecko
+            model_id,
+          };
+        } else {
+          result.coarsePrivateInferredInterests = {
+            ...coarsePrivateInferredInterests,
+            model_id,
+          };
+        }
       }
     }
     return result;

browser/extensions/newtab/lib/TelemetryFeed.sys.mjs

@@ -1037,9 +1037,7 @@ export class TelemetryFeed {
     const inferredInterests =
       this.privatePingInferredInterestsEnabled && this.inferredInterests;
     if (inferredInterests) {
-      Glean.newtabContent.inferredInterests.set(
-        JSON.stringify(inferredInterests)
-      );
+      Glean.newtabContent.inferredInterests.set(inferredInterests);
     }
 
     // When we have a coarse interest vector we want to make sure there isn't

browser/extensions/newtab/test/xpcshell/test_InferredFeatureModel.js

@@ -369,6 +369,7 @@ add_task(function test_computeMultipleVectors() {
     dataForIntervals: SQL_RESULT_DATA,
     indexSchema: SCHEMA,
     model_id: "test",
+    condensePrivateValues: false,
   });
   Assert.equal(
     result.coarsePrivateInferredInterests.parenting,
@@ -385,12 +386,48 @@ add_task(function test_computeMultipleVectors() {
   );
 });
 
+add_task(function test_computeMultipleVectorsCondensed() {
+  const modelData = { ...jsonModelData, rescale: true };
+  const model = FeatureModel.fromJSON(modelData);
+  const result = model.computeInterestVectors({
+    dataForIntervals: SQL_RESULT_DATA,
+    indexSchema: SCHEMA,
+    model_id: "test",
+  });
+  Assert.equal(
+    result.coarsePrivateInferredInterests.values.length,
+    3,
+    "Items in an array"
+  );
+  Assert.equal(
+    result.coarsePrivateInferredInterests.values[0].length,
+    3,
+    "One value in string per possible result"
+  );
+  Assert.ok(
+    result.coarsePrivateInferredInterests.values[0]
+      .split("")
+      .every(a => a === "1" || a === "0"),
+    "Combined coarse values are 1 and 0"
+  );
+  Assert.equal(
+    result.coarsePrivateInferredInterests.model_id,
+    "test",
+    "Model id returned"
+  );
+  Assert.ok(
+    result.inferredInterests.parenting > 0,
+    "Original inferred interest is returned"
+  );
+});
+
 add_task(function test_computeMultipleVectorsNoPrivate() {
   const model = FeatureModel.fromJSON(jsonModelDataNoCoarseSupport);
   const result = model.computeInterestVectors({
     dataForIntervals: SQL_RESULT_DATA,
     indexSchema: SCHEMA,
     model_id: "test",
+    condensePrivateValues: false,
   });
   Assert.ok(
     !result.coarsePrivateInferredInterests,