diff --git a/src/lib/ai/coach/conversation-summary.ts b/src/lib/ai/coach/conversation-summary.ts
index 083cb07fe..f94d5bc93 100644
--- a/src/lib/ai/coach/conversation-summary.ts
+++ b/src/lib/ai/coach/conversation-summary.ts
@@ -174,10 +174,20 @@ export async function refreshConversationSummary(
   const priorSummary = decryptPriorSummary(conversation.summaryEncrypted);
   const foldedTurns: SummaryFoldTurn[] = turns
     .slice(0, foldHighWater)
-    .map((m) => ({
-      role: m.role === "assistant" ? "assistant" : "user",
-      content: decryptFromBytes(m.encryptedContent),
-    }));
+    .flatMap((m) => {
+      let content: string;
+      try {
+        content = decryptFromBytes(m.encryptedContent);
+      } catch {
+        // Skip an undecryptable message (e.g. a row mid key-rotation) instead
+        // of throwing and permanently stalling this conversation's summary —
+        // fail-closed like every other decrypt in the Coach stack.
+        return [];
+      }
+      return [
+        { role: m.role === "assistant" ? "assistant" : "user", content },
+      ];
+    });
 
   // 5. Run the user's provider chain. Best-effort: non-ok leaves the old
   //    summary in place.
diff --git a/src/lib/analytics/source-rank-sql.ts b/src/lib/analytics/source-rank-sql.ts
index e2bcc4314..5aac2e1c4 100644
--- a/src/lib/analytics/source-rank-sql.ts
+++ b/src/lib/analytics/source-rank-sql.ts
@@ -14,7 +14,7 @@
  * single-round-trip `GROUP BY type` shape (no six-figure row transfer).
  *
  * Every spliced literal is a closed-enum value (`MeasurementType` /
- * `MeasurementSource`) asserted against `/^[A-Z_]+$/`, the same whitelist
+ * `MeasurementSource`) asserted against `/^[A-Z0-9_]+$/`, the same whitelist
  * convention the rollup writer uses for its date-trunc + type-list splices.
  * The user id is always passed as a bound parameter, never spliced.
  */
diff --git a/src/lib/analytics/summaries-slice.ts b/src/lib/analytics/summaries-slice.ts
index 33045b551..1c5f16dc6 100644
--- a/src/lib/analytics/summaries-slice.ts
+++ b/src/lib/analytics/summaries-slice.ts
@@ -415,7 +415,7 @@ async function computeFromRollups(userId: string): Promise<SummariesSlice> {
         FROM "measurement_rollups"
         WHERE "user_id" = $1
           AND "granularity" = 'DAY'
-        ORDER BY "type", "bucket_start", (${rankUnqualified}), "count" DESC, "source"
+        ORDER BY "type", "bucket_start", (${rankUnqualified}), "source"
       )
       SELECT
         "type"::text                                       AS type,
diff --git a/src/lib/rollups/__tests__/collapse-rollup-rows-by-source.test.ts b/src/lib/rollups/__tests__/collapse-rollup-rows-by-source.test.ts
index cd37fb4c0..3108cae1b 100644
--- a/src/lib/rollups/__tests__/collapse-rollup-rows-by-source.test.ts
+++ b/src/lib/rollups/__tests__/collapse-rollup-rows-by-source.test.ts
@@ -136,19 +136,21 @@ describe("collapseRollupRowsBySource", () => {
     expect(out[0].source).toBe("APPLE_HEALTH");
   });
 
-  it("falls back to max-count when no ladder source is present", () => {
-    // IMPORT is not on the restingHeartRate ladder; keep one row (most data).
+  it("falls back to the alphabetically-smallest source when none is on the ladder", () => {
+    // Neither IMPORT nor MANUAL is on the restingHeartRate ladder; keep one
+    // row deterministically by source name, matching the live-SQL paths'
+    // `ORDER BY … source` tiebreak (live/rollup parity).
     const out = collapseRollupRowsBySource(
       [
-        row(DAY1, "IMPORT", 60, 2),
         row(DAY1, "MANUAL", 58, 5),
+        row(DAY1, "IMPORT", 60, 2),
       ],
       "RESTING_HEART_RATE",
       null,
     );
     expect(out).toHaveLength(1);
-    expect(out[0].source).toBe("MANUAL");
-    expect(out[0].count).toBe(5);
+    // "IMPORT" < "MANUAL" alphabetically.
+    expect(out[0].source).toBe("IMPORT");
   });
 
   it("returns empty input untouched", () => {
diff --git a/src/lib/rollups/measurement-read.ts b/src/lib/rollups/measurement-read.ts
index 9db48f5ef..67d657470 100644
--- a/src/lib/rollups/measurement-read.ts
+++ b/src/lib/rollups/measurement-read.ts
@@ -114,13 +114,13 @@ export function collapseRollupRowsBySource<T extends SourcedBucketRow>(
       }
     }
     if (!picked) {
-      // No ladder match — keep one row deterministically (most data wins,
-      // tie-broken by source name) so the bucket neither doubles nor goes dark.
+      // No ladder match — keep one row deterministically by alphabetically
+      // smallest source name, so the bucket neither doubles nor goes dark AND
+      // the pick matches the live-SQL paths' `ORDER BY … source` tiebreak
+      // (live/rollup parity for a ranked type whose day carries only
+      // non-ladder sources).
       picked = bucketRows.reduce((best, r) =>
-        r.count > best.count ||
-        (r.count === best.count && r.source < best.source)
-          ? r
-          : best,
+        r.source < best.source ? r : best,
       );
     }
     out.push(picked);