diff --git a/src/lib/ai/coach/glp1-snapshot.ts b/src/lib/ai/coach/glp1-snapshot.ts
index 810bb4512..3fb131689 100644
--- a/src/lib/ai/coach/glp1-snapshot.ts
+++ b/src/lib/ai/coach/glp1-snapshot.ts
@@ -70,7 +70,6 @@ function deriveDrugNames(raw: string): { display: string; generic: string } {
   return { display, generic };
 }
 
-const WEEKDAY_KEYS = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"] as const;
 
 function parseDaysOfWeek(raw: string | null): number[] {
   if (!raw) return [];
@@ -417,5 +416,4 @@ export const __testables = {
   parseTagList,
   parseDaysOfWeek,
   predictNextInjection,
-  WEEKDAY_KEYS,
 };
diff --git a/src/lib/medications/glp1-knowledge.ts b/src/lib/medications/glp1-knowledge.ts
index 3db2f9ded..70fb61a10 100644
--- a/src/lib/medications/glp1-knowledge.ts
+++ b/src/lib/medications/glp1-knowledge.ts
@@ -45,16 +45,16 @@ export type Glp1DrugId =
  * record AND a per-brand override map so a single drug-id can carry
  * mixed routes (semaglutide → Ozempic/Wegovy sc, Rybelsus oral).
  */
-export type Glp1Route = "subcutaneous" | "oral";
+type Glp1Route = "subcutaneous" | "oral";
 
 /**
  * Drug class descriptor — Tirzepatide is the only dual GIP/GLP-1
  * agonist among EMA-approved agents (2026-05); the rest are pure
  * GLP-1 receptor agonists.
  */
-export type Glp1DrugClass = "GIP-GLP1 dual agonist" | "GLP-1 receptor agonist";
+type Glp1DrugClass = "GIP-GLP1 dual agonist" | "GLP-1 receptor agonist";
 
-export type Glp1Pharmacology = {
+type Glp1Pharmacology = {
   /** Terminal elimination half-life. Days for the long-acting agents,
    *  hours for liraglutide / short-acting exenatide. */
   halfLifeDays: number;
@@ -83,7 +83,7 @@ export type Glp1Pharmacology = {
   compartmentModel: "one-compartment" | "two-compartment";
 };
 
-export type Glp1Storage = {
+type Glp1Storage = {
   /** Refrigerated stability — every GLP-1 product is shipped 2–8 °C
    *  per EMA. */
   unopened: {
@@ -97,7 +97,7 @@ export type Glp1Storage = {
   };
 };
 
-export type Glp1Pen = {
+type Glp1Pen = {
   /** Pen device name as printed on the carton. */
   type: string;
   /** Doses per pen / per cartridge — drives W19b inventory
@@ -105,7 +105,7 @@ export type Glp1Pen = {
   dosesPerPen: number | null;
 };
 
-export type Glp1AdverseReactions = {
+type Glp1AdverseReactions = {
   /** ≥ 1/10 frequency per EMA §4.8. */
   veryCommon: readonly string[];
   /** 1/100 to <1/10 per EMA §4.8. */
@@ -116,12 +116,12 @@ export type Glp1AdverseReactions = {
   rare: readonly string[];
 };
 
-export type Glp1Indications = {
+type Glp1Indications = {
   t2dm: { firstLine: boolean };
   weightManagement: { bmiThreshold: number | null };
 };
 
-export type Glp1SourceCitations = {
+type Glp1SourceCitations = {
   /** Direct link to the EMA EPAR product-information PDF. */
   sourceEMA: string;
   /** Peer-reviewed pharmacometric citation where one exists. */
@@ -548,7 +548,8 @@ export const GLP1_DRUGS: Readonly<Record<Glp1DrugId, Glp1DrugRecord>> = {
 
 /**
  * Resolve the route for a given drug + brand. Falls back to the
- * record default when no per-brand override is registered.
+ * record default when no per-brand override is registered. Read by
+ * the glp1-knowledge test suite.
  */
 export function routeForBrand(
   drugId: Glp1DrugId,
@@ -597,8 +598,9 @@ export function findDrugIdByBrand(brand: string): Glp1DrugId | null {
 }
 
 /**
- * The catalog's drug-ids in stable order. Useful for iteration in
- * tests and UI surfaces that need a deterministic display order.
+ * The catalog's drug-ids in stable order. Read by the GLP-1 PK +
+ * ladder test suites so a future drug addition flows through the
+ * verification matrix without a hand-rolled list.
  */
 export const GLP1_DRUG_IDS: readonly Glp1DrugId[] = [
   "tirzepatide",
@@ -607,3 +609,4 @@ export const GLP1_DRUG_IDS: readonly Glp1DrugId[] = [
   "dulaglutide",
   "exenatide",
 ] as const;
+
diff --git a/src/lib/medications/scheduling/cadence.ts b/src/lib/medications/scheduling/cadence.ts
index a9f71a0bb..332b59ed6 100644
--- a/src/lib/medications/scheduling/cadence.ts
+++ b/src/lib/medications/scheduling/cadence.ts
@@ -45,7 +45,7 @@ export interface IntakeEventLike {
 }
 
 /** One slot the schedule expected the user to dose. */
-export interface ExpectedDose {
+interface ExpectedDose {
   /** Midnight of the local day this dose was expected. */
   day: Date;
   /** Start of the dose window for this day (Date with HH:mm applied). */
@@ -308,16 +308,18 @@ export function pairDoses(
   now: Date,
 ): PairedDose[] {
   const claimed = new Set<number>();
-  const result: PairedDose[] = [];
 
-  // Sort slots by window centre so the earlier slot picks its match
-  // first; same shape as the reminder-worker's "process schedules in
-  // window order" loop.
+  // v1.4.27 B7 / simp-M6 — sort once by `windowStart` for the match
+  // pass and return the result in the same order. Slots that touch
+  // pairDoses are always strictly chronologically separable (the
+  // window radius is far smaller than the day grid step), so sorting
+  // by `windowStart` and sorting by the centre `(start+end)/2`
+  // produce the same order. Dropping the second `.sort()` at the
+  // end keeps the contract intact and removes the O(n log n) tail.
   const sorted = [...slots].sort(
-    (a, b) =>
-      (a.windowStart.getTime() + a.windowEnd.getTime()) / 2 -
-      (b.windowStart.getTime() + b.windowEnd.getTime()) / 2,
+    (a, b) => a.windowStart.getTime() - b.windowStart.getTime(),
   );
+  const result: PairedDose[] = [];
 
   for (const slot of sorted) {
     const centre = (slot.windowStart.getTime() + slot.windowEnd.getTime()) / 2;
@@ -352,8 +354,7 @@ export function pairDoses(
     result.push({ ...slot, match, status });
   }
 
-  // Restore the chronological order callers expect.
-  return result.sort((a, b) => a.windowStart.getTime() - b.windowStart.getTime());
+  return result;
 }
 
 /**
diff --git a/src/lib/medications/titration/ladder.ts b/src/lib/medications/titration/ladder.ts
index 8114ec246..c007541ce 100644
--- a/src/lib/medications/titration/ladder.ts
+++ b/src/lib/medications/titration/ladder.ts
@@ -183,7 +183,19 @@ export function weeksOnCurrentStep(
 
 /**
  * Display flag — true when the EMA-reference minimum dwell time has
- * elapsed AND a next step exists.
+ * elapsed AND a next ladder step exists.
+ *
+ * Parameters:
+ *   - `drugIdForCeiling`: identifies which ladder to walk so the
+ *     "next step exists" guard knows when the user has hit the
+ *     ceiling. The dwell-time check itself reads `typicalWeeks`
+ *     straight off `currentStep`; the drug id is only needed to
+ *     answer "is there a step above this one?".
+ *   - `currentStep`: the step the user is sitting on today. Null
+ *     when titration is paused or the user is at the bottom of the
+ *     ladder with no recorded dose history.
+ *   - `weeksOnStep`: how many complete weeks have elapsed since the
+ *     user landed on `currentStep`. Computed by `weeksOnCurrentStep`.
  *
  * IMPORTANT: this is a *reference* signal, not advice. The UI copy
  * tied to this boolean is strictly observational ("ladder typically
@@ -191,11 +203,11 @@ export function weeksOnCurrentStep(
  * the W19c safety ground-rules.
  */
 export function escalationDue(
-  drugId: Glp1DrugId,
+  drugIdForCeiling: Glp1DrugId,
   currentStep: TitrationStep | null,
   weeksOnStep: number,
 ): boolean {
   if (!currentStep) return false;
-  if (!nextStep(drugId, currentStep)) return false;
+  if (!nextStep(drugIdForCeiling, currentStep)) return false;
   return weeksOnStep >= currentStep.typicalWeeks;
 }