diff --git a/src/db/repositories.ts b/src/db/repositories.ts
index 4c1f4d7831..16fcbbaaed 100644
--- a/src/db/repositories.ts
+++ b/src/db/repositories.ts
@@ -3606,6 +3606,13 @@ async function upsertProductUsageDailyRollup(env: Env, day: string, generatedAt:
   return record;
 }
 
+// Bounded enum dimensions (surface / outcome / eventName) are consumed by exact-name lookups
+// (e.g. the weekly value report's sumEvent over byEvent), so they must be stored complete:
+// frequency-truncating a bounded exact-lookup dimension silently zeroes any value below the
+// top-N cut on a high-diversity day. Only the genuinely-unbounded repo/command/tool/route
+// dimensions keep a display top-N.
+const FULL_DIMENSION_LIMIT = Number.MAX_SAFE_INTEGER;
+
 function buildProductUsageDailyRollupRecord(args: {
   day: string;
   generatedAt: string;
@@ -3633,9 +3640,9 @@ function buildProductUsageDailyRollupRecord(args: {
     maxEventCapacity: PRODUCT_USAGE_ROLLUP_EVENT_SCAN_LIMIT,
     firstEventAt: args.events[0]?.occurredAt ?? null,
     lastEventAt: args.events.at(-1)?.occurredAt ?? null,
-    bySurface: countProductUsageDimensions(args.events.map((event) => event.surface)).map(({ key, count }) => ({ surface: normalizeProductUsageSurface(key), count })),
-    byOutcome: countProductUsageDimensions(args.events.map((event) => event.outcome)).map(({ key, count }) => ({ outcome: normalizeProductUsageOutcome(key), count })),
-    byEvent: countProductUsageDimensions(args.events.map((event) => event.eventName)).map(({ key, count }) => ({ eventName: key, count })),
+    bySurface: countProductUsageDimensions(args.events.map((event) => event.surface), FULL_DIMENSION_LIMIT).map(({ key, count }) => ({ surface: normalizeProductUsageSurface(key), count })),
+    byOutcome: countProductUsageDimensions(args.events.map((event) => event.outcome), FULL_DIMENSION_LIMIT).map(({ key, count }) => ({ outcome: normalizeProductUsageOutcome(key), count })),
+    byEvent: countProductUsageDimensions(args.events.map((event) => event.eventName), FULL_DIMENSION_LIMIT).map(({ key, count }) => ({ eventName: key, count })),
     byRepo: countProductUsageDimensions(args.events.map((event) => event.repoFullName)),
     byCommand: countProductUsageDimensions(args.events.map((event) => productUsageMetadataString(event, "command"))),
     byTool: countProductUsageDimensions(args.events.map((event) => productUsageMetadataString(event, "toolName"))),
diff --git a/test/unit/product-usage.test.ts b/test/unit/product-usage.test.ts
index 55a9992df3..8e7e503d5d 100644
--- a/test/unit/product-usage.test.ts
+++ b/test/unit/product-usage.test.ts
@@ -472,6 +472,24 @@ describe("product usage events", () => {
     await expect(getProductUsageRollupStatus(env, { nowIso: "2026-05-31T00:40:00.000Z" })).resolves.toMatchObject({ status: "ready", warnings: [] });
   });
 
+  it("retains low-frequency bounded events in byEvent on a high-diversity day (no top-20 truncation)", async () => {
+    const env = createTestEnv();
+    const day = "2026-05-30";
+    // 20 distinct filler events, each recorded twice (count 2), occupy the highest-frequency slots.
+    for (let i = 0; i < 20; i++) {
+      const eventName = `filler_event_${String(i).padStart(2, "0")}`;
+      await recordProductUsageEvent(env, { surface: "control_panel", eventName, actor: "user", outcome: "success", occurredAt: `${day}T00:00:00.000Z` });
+      await recordProductUsageEvent(env, { surface: "control_panel", eventName, actor: "user", outcome: "success", occurredAt: `${day}T01:00:00.000Z` });
+    }
+    // A low-frequency flagship event the weekly report looks up by exact name (count 1, ranks 21st).
+    await recordProductUsageEvent(env, { surface: "control_panel", eventName: "agent_pr_packet_completed", actor: "user", outcome: "success", occurredAt: `${day}T05:00:00.000Z` });
+
+    const run = await rollupProductUsageDaily(env, { day, nowIso: "2026-05-31T00:10:00.000Z" });
+    // Without the fix, byEvent was frequency-truncated to the top 20 and dropped this event.
+    expect(run.rollups[0]?.byEvent).toEqual(expect.arrayContaining([{ eventName: "agent_pr_packet_completed", count: 1 }]));
+    expect((run.rollups[0]?.byEvent ?? []).length).toBe(21);
+  });
+
   it("builds empty role and retention rollups for days without product usage", async () => {
     const env = createTestEnv({ PRODUCT_USAGE_HASH_SALT: "fixed-test-salt" });
     const result = await rollupProductUsageDaily(env, { day: "2026-06-01", nowIso: "2026-06-02T00:00:00.000Z" });