fix(inbox): tiebreak priority sort by newest first

packages/core/src/inbox/reportFiltering.test.ts

@@ -99,12 +99,25 @@ describe("filterReportsBySearch", () => {
 
 describe("buildSignalReportListOrdering", () => {
   it.each([
-    ["total_weight", "desc", "status,-total_weight"],
-    ["created_at", "asc", "status,created_at"],
-    ["signal_count", "desc", "status,-signal_count"],
-  ] as const)("orders by status then %s (%s)", (field, direction, expected) => {
-    expect(buildSignalReportListOrdering(field, direction)).toBe(expected);
-  });
+    ["total_weight", "desc", "status,-total_weight,priority"],
+    ["created_at", "asc", "status,created_at,priority"],
+    ["signal_count", "desc", "status,-signal_count,priority"],
+  ] as const)(
+    "orders by status then %s (%s), tiebreaking by priority",
+    (field, direction, expected) => {
+      expect(buildSignalReportListOrdering(field, direction)).toBe(expected);
+    },
+  );
+
+  it.each([
+    ["priority", "asc", "status,priority,-created_at"],
+    ["priority", "desc", "status,-priority,-created_at"],
+  ] as const)(
+    "tiebreaks %s (%s) by newest first",
+    (field, direction, expected) => {
+      expect(buildSignalReportListOrdering(field, direction)).toBe(expected);
+    },
+  );
 
   it("does not float the current user's reports via ordering", () => {
     expect(buildSignalReportListOrdering("priority", "asc")).not.toContain(

packages/core/src/inbox/reportFiltering.ts

@@ -65,6 +65,11 @@ export function buildStatusFilterParam(statuses: SignalReportStatus[]): string {
  * Comma-separated `ordering` for the signal report list API:
  * 1. Status rank (ready first – semantic server-side rank, always applied)
  * 2. Toolbar-selected field (priority, total_weight, created_at, etc.)
+ * 3. A tiebreak so reports the primary field can't separate come back in a
+ *    sensible order. Sorting by priority (a coarse 5-bucket P0–P4 rank) tiebreaks
+ *    by `-created_at` so the newest report wins within a tier; every other field
+ *    tiebreaks by `priority` so the most urgent report wins. The server applies
+ *    the clauses in order (and falls back to `id`), so this only breaks ties.
  *
  * Reviewer scope is applied via the `suggested_reviewers` param, not ordering:
  * a `-is_suggested_reviewer` tiebreak would float the user's reports to the top
@@ -75,7 +80,8 @@ export function buildSignalReportListOrdering(
   direction: "asc" | "desc",
 ): string {
   const fieldKey = direction === "desc" ? `-${field}` : field;
-  return `status,${fieldKey}`;
+  const tiebreak = field === "priority" ? "-created_at" : "priority";
+  return ["status", fieldKey, tiebreak].join(",");
 }
 
 export function buildSuggestedReviewerFilterParam(