feat(cycle): exclude disturbed temperatures from the symptothermal engine

A fever, illness, alcohol or a late/short-sleep reading can fake or mask
a temperature rise. Add a per-day `temperatureExcluded` flag on
CycleDayLog (migration 0156): when set, the engine drops the reading from
the cover-line baseline AND the shift evaluation, so a spike neither
fabricates nor masks a rise (Sensiplan: the cover line is drawn over the
last six unbracketed values).

Wired end to end — schema + Prisma, the engine's `detectTempShift`
filter, the Zod input/patch schemas, the day-log upsert (partial merge +
change detection), the read DTO, the calendar/insights/coach selects, the
backup round-trip, and the OpenAPI contract (a new boolean on the day-log
and calendar-day DTOs for the iOS client). The log-day sheet gains a
"mark reading as disturbed" toggle that appears once a temperature is
entered, translated across all six locales.

Citation: de.wikipedia "Symptothermale Methode"; myNFP "Temperaturkurve
auswerten" — Störfaktor bracketing.

docs/api/openapi.yaml

@@ -117,6 +117,8 @@ paths:
                   type: number
                   minimum: 30
                   maximum: 45
+                temperatureExcluded:
+                  type: boolean
                 ovulationTest:
                   type: string
                   enum:
@@ -252,6 +254,8 @@ paths:
                       minimum: 30
                       maximum: 45
                     - type: "null"
+                temperatureExcluded:
+                  type: boolean
                 ovulationTest:
                   anyOf:
                     - type: string
@@ -412,6 +416,8 @@ paths:
                         type: number
                         minimum: 30
                         maximum: 45
+                      temperatureExcluded:
+                        type: boolean
                       ovulationTest:
                         type: string
                         enum:
@@ -6240,6 +6246,8 @@ components:
           anyOf:
             - type: number
             - type: "null"
+        temperatureExcluded:
+          type: boolean
         ovulationTest:
           anyOf:
             - type: string
@@ -6333,6 +6341,7 @@ components:
         - flow
         - intermenstrualBleeding
         - basalBodyTempC
+        - temperatureExcluded
         - ovulationTest
         - cervicalMucus
         - sexualActivity
@@ -6647,6 +6656,8 @@ components:
                     anyOf:
                       - type: number
                       - type: "null"
+                  temperatureExcluded:
+                    type: boolean
                   ovulationTest:
                     anyOf:
                       - type: string
@@ -6677,6 +6688,7 @@ components:
                   - hasSymptoms
                   - confidence
                   - basalBodyTempC
+                  - temperatureExcluded
                   - ovulationTest
                   - cervicalMucus
                 additionalProperties: false

messages/de.json

@@ -5882,6 +5882,8 @@
       "symptoms": "Symptome",
       "temperature": "Basaltemperatur",
       "temperaturePlaceholder": "°C",
+      "temperatureDisturbed": "Messwert als gestört markieren",
+      "temperatureDisturbedHint": "Fieber, Krankheit, Alkohol oder eine späte Messung — wird von der Temperaturauswertung ausgeschlossen.",
       "ovulationTest": "Ovulationstest",
       "mucus": "Zervixschleim",
       "intercourse": "Geschlechtsverkehr",

messages/en.json

@@ -5882,6 +5882,8 @@
       "symptoms": "Symptoms",
       "temperature": "Basal body temperature",
       "temperaturePlaceholder": "°C",
+      "temperatureDisturbed": "Mark reading as disturbed",
+      "temperatureDisturbedHint": "Fever, illness, alcohol or a late measurement — excluded from the temperature evaluation.",
       "ovulationTest": "Ovulation test",
       "mucus": "Cervical mucus",
       "intercourse": "Intercourse",

messages/es.json

@@ -5882,6 +5882,8 @@
       "symptoms": "Síntomas",
       "temperature": "Temperatura basal",
       "temperaturePlaceholder": "°C",
+      "temperatureDisturbed": "Marcar la medición como alterada",
+      "temperatureDisturbedHint": "Fiebre, enfermedad, alcohol o una medición tardía: se excluye de la evaluación de temperatura.",
       "ovulationTest": "Test de ovulación",
       "mucus": "Moco cervical",
       "intercourse": "Relaciones",

messages/fr.json

@@ -5882,6 +5882,8 @@
       "symptoms": "Symptômes",
       "temperature": "Température basale",
       "temperaturePlaceholder": "°C",
+      "temperatureDisturbed": "Marquer la mesure comme perturbée",
+      "temperatureDisturbedHint": "Fièvre, maladie, alcool ou mesure tardive — exclue de l'évaluation de la température.",
       "ovulationTest": "Test d'ovulation",
       "mucus": "Glaire cervicale",
       "intercourse": "Rapports",

messages/it.json

@@ -5882,6 +5882,8 @@
       "symptoms": "Sintomi",
       "temperature": "Temperatura basale",
       "temperaturePlaceholder": "°C",
+      "temperatureDisturbed": "Segna la misurazione come disturbata",
+      "temperatureDisturbedHint": "Febbre, malattia, alcol o una misurazione tardiva: esclusa dalla valutazione della temperatura.",
       "ovulationTest": "Test di ovulazione",
       "mucus": "Muco cervicale",
       "intercourse": "Rapporti",

messages/pl.json

@@ -5882,6 +5882,8 @@
       "symptoms": "Objawy",
       "temperature": "Podstawowa temperatura ciała",
       "temperaturePlaceholder": "°C",
+      "temperatureDisturbed": "Oznacz pomiar jako zakłócony",
+      "temperatureDisturbedHint": "Gorączka, choroba, alkohol lub spóźniony pomiar — wykluczony z oceny temperatury.",
       "ovulationTest": "Test owulacyjny",
       "mucus": "Śluz szyjkowy",
       "intercourse": "Współżycie",

prisma/migrations/0156_v1170_cycle_temp_excluded/migration.sql

@@ -0,0 +1,10 @@
+-- v1.17.0 — disturbed-temperature exclusion for the symptothermal engine.
+--
+-- A fever / illness / alcohol / late or short-sleep BBT reading can fake or
+-- mask a temperature rise. `temperature_excluded = true` marks a day's basal
+-- body temperature as a disturbed value: the Sensiplan cover-line baseline and
+-- the shift evaluation both skip it, so a spike neither fabricates nor masks a
+-- rise (the cover line is drawn over the last six *unbracketed* values).
+-- Additive: every existing row backfills `false`.
+
+ALTER TABLE "cycle_day_logs" ADD COLUMN "temperature_excluded" BOOLEAN NOT NULL DEFAULT false;

prisma/schema.prisma

@@ -3749,6 +3749,13 @@ model CycleDayLog {
   /// symptothermal confirmation. BBT also lands in Measurement
   /// (BODY_TEMPERATURE) for charting; this column is the cycle-local copy.
   basalBodyTempC Float?         @map("basal_body_temp_c")
+  /// Whether this day's BBT is a disturbed/unreliable reading (fever,
+  /// illness, alcohol, a late or short-sleep measurement) the user marked
+  /// excluded. When true the symptothermal engine drops the reading from the
+  /// cover-line baseline AND the shift evaluation, so a spike neither
+  /// fabricates nor masks a temperature rise (Sensiplan: the cover line is
+  /// drawn over the last six *unbracketed* values).
+  temperatureExcluded Boolean @default(false) @map("temperature_excluded")
   /// Ovulation predictor-kit (OPK) reading.
   ovulationTest  OvulationTest? @map("ovulation_test")
   /// Cervical-mucus quality.

src/app/api/cycle/calendar/route.ts

@@ -99,6 +99,7 @@ export const GET = apiHandler(async (request: NextRequest) => {
         date: true,
         flow: true,
         basalBodyTempC: true,
+        temperatureExcluded: true,
         ovulationTest: true,
         cervicalMucus: true,
         _count: { select: { symptomLinks: true } },
@@ -125,6 +126,7 @@ export const GET = apiHandler(async (request: NextRequest) => {
     date: l.date,
     flow: l.flow,
     basalBodyTempC: l.basalBodyTempC,
+    temperatureExcluded: l.temperatureExcluded,
     ovulationTest: l.ovulationTest,
     cervicalMucus: l.cervicalMucus,
     hasSymptoms: l._count.symptomLinks > 0,

src/app/api/cycle/insights/route.ts

@@ -90,6 +90,7 @@ export const GET = apiHandler(async () => {
         date: true,
         flow: true,
         basalBodyTempC: true,
+        temperatureExcluded: true,
         ovulationTest: true,
         cervicalMucus: true,
         symptomLinks: { select: { symptom: { select: { key: true } } } },

src/components/cycle/__tests__/log-day-sheet.test.ts

@@ -11,6 +11,7 @@ function blank(): DayLogFormState {
     flow: null,
     intermenstrual: false,
     bbt: "",
+    bbtDisturbed: false,
     opk: null,
     mucus: null,
     intercourse: false,
@@ -90,4 +91,27 @@ describe("buildDayLogInput (new row → omit empties)", () => {
     expect(input.flow).toBe("LIGHT");
     expect(input.basalBodyTempC).toBe(36.5);
   });
+
+  it("carries the disturbed flag alongside a BBT reading", () => {
+    const input = buildDayLogInput(
+      { ...blank(), bbt: "36.5", bbtDisturbed: true },
+      "2026-06-06",
+    );
+    expect(input.basalBodyTempC).toBe(36.5);
+    expect(input.temperatureExcluded).toBe(true);
+    const patch = buildDayLogPatch({ ...blank(), bbt: "36.5", bbtDisturbed: true });
+    expect(patch.temperatureExcluded).toBe(true);
+  });
+
+  it("never marks an absent BBT reading disturbed", () => {
+    // A disturbed flag with no temperature is meaningless — it must reset.
+    const patch = buildDayLogPatch({ ...blank(), bbt: "", bbtDisturbed: true });
+    expect(patch.basalBodyTempC).toBeNull();
+    expect(patch.temperatureExcluded).toBe(false);
+    const input = buildDayLogInput(
+      { ...blank(), bbt: "", bbtDisturbed: true },
+      "2026-06-06",
+    );
+    expect("temperatureExcluded" in input).toBe(false);
+  });
 });

src/components/cycle/log-day-sheet.tsx

@@ -154,6 +154,8 @@ export interface DayLogFormState {
   intermenstrual: boolean;
   /** Raw text from the BBT input; "" / non-finite resolves to null. */
   bbt: string;
+  /** Whether the BBT reading is marked disturbed (fever/late) — engine skips it. */
+  bbtDisturbed: boolean;
   opk: OvulationTest | null;
   mucus: CervicalMucus | null;
   intercourse: boolean;
@@ -189,6 +191,8 @@ export function buildDayLogPatch(s: DayLogFormState): CycleDayLogPatch {
     flow: s.flow ?? null,
     intermenstrualBleeding: s.intermenstrual,
     basalBodyTempC: resolveBbt(s.bbt),
+    // Only meaningful with a BBT present; a cleared reading resets the flag.
+    temperatureExcluded: resolveBbt(s.bbt) != null ? s.bbtDisturbed : false,
     ovulationTest: s.opk ?? null,
     cervicalMucus: s.mucus ?? null,
     sexualActivity: s.intercourse,
@@ -214,7 +218,9 @@ export function buildDayLogInput(
     source: "MANUAL",
     ...(s.flow ? { flow: s.flow } : {}),
     intermenstrualBleeding: s.intermenstrual,
-    ...(bbtVal != null ? { basalBodyTempC: bbtVal } : {}),
+    ...(bbtVal != null
+      ? { basalBodyTempC: bbtVal, temperatureExcluded: s.bbtDisturbed }
+      : {}),
     ...(s.opk ? { ovulationTest: s.opk } : {}),
     ...(s.mucus ? { cervicalMucus: s.mucus } : {}),
     sexualActivity: s.intercourse,
@@ -292,6 +298,7 @@ export function LogDaySheet({
     new Map(),
   );
   const [bbt, setBbt] = useState<string>("");
+  const [bbtDisturbed, setBbtDisturbed] = useState(false);
   const [opk, setOpk] = useState<OvulationTest | null>(null);
   const [mucus, setMucus] = useState<CervicalMucus | null>(null);
   const [intercourse, setIntercourse] = useState(false);
@@ -324,6 +331,7 @@ export function LogDaySheet({
     setIntermenstrual(dto?.intermenstrualBleeding ?? false);
     setSymptoms(new Map((dto?.symptoms ?? []).map((s) => [s.key, s.severity])));
     setBbt(dto?.basalBodyTempC != null ? String(dto.basalBodyTempC) : "");
+    setBbtDisturbed(dto?.temperatureExcluded ?? false);
     setOpk((dto?.ovulationTest ?? null) as OvulationTest | null);
     setMucus((dto?.cervicalMucus ?? null) as CervicalMucus | null);
     setIntercourse(dto?.sexualActivity ?? false);
@@ -359,6 +367,7 @@ export function LogDaySheet({
       flow,
       intermenstrual,
       bbt,
+      bbtDisturbed,
       opk,
       mucus,
       intercourse,
@@ -601,6 +610,23 @@ export function LogDaySheet({
           className="border-input bg-background focus-visible:ring-ring/50 w-32 rounded-md border px-3 py-2 text-sm focus-visible:ring-2 focus-visible:outline-none"
           aria-label={t("cycle.sheet.temperature")}
         />
+        {resolveBbt(bbt) != null && (
+          <div className="mt-3 flex items-start justify-between gap-3">
+            <div className="flex flex-col">
+              <span className="text-sm">
+                {t("cycle.sheet.temperatureDisturbed")}
+              </span>
+              <span className="text-muted-foreground text-xs">
+                {t("cycle.sheet.temperatureDisturbedHint")}
+              </span>
+            </div>
+            <Switch
+              checked={bbtDisturbed}
+              onCheckedChange={setBbtDisturbed}
+              aria-label={t("cycle.sheet.temperatureDisturbed")}
+            />
+          </div>
+        )}
       </Field>
 
       {/* Ovulation test */}

src/components/cycle/types.ts

@@ -138,6 +138,7 @@ export interface CycleDayLogInput {
   flow?: FlowLevel;
   intermenstrualBleeding?: boolean;
   basalBodyTempC?: number;
+  temperatureExcluded?: boolean;
   ovulationTest?: OvulationTest;
   cervicalMucus?: CervicalMucus;
   sexualActivity?: boolean;
@@ -159,6 +160,7 @@ export interface CycleDayLogDTO {
   flow: FlowLevel | null;
   intermenstrualBleeding: boolean;
   basalBodyTempC: number | null;
+  temperatureExcluded: boolean;
   ovulationTest: OvulationTest | null;
   cervicalMucus: CervicalMucus | null;
   sexualActivity: boolean;

src/components/cycle/use-cycle.ts

@@ -237,6 +237,7 @@ export interface CycleDayLogPatch {
   flow?: FlowLevel | null;
   intermenstrualBleeding?: boolean;
   basalBodyTempC?: number | null;
+  temperatureExcluded?: boolean;
   ovulationTest?: OvulationTest | null;
   cervicalMucus?: CervicalMucus | null;
   sexualActivity?: boolean;

src/lib/ai/coach/cycle-snapshot.ts

@@ -176,6 +176,7 @@ export async function buildCycleSnapshotBlock(
           date: true,
           flow: true,
           basalBodyTempC: true,
+          temperatureExcluded: true,
           ovulationTest: true,
           cervicalMucus: true,
         },

src/lib/cycle/__tests__/engine-adapter.test.ts

@@ -55,7 +55,7 @@ describe("buildCalendar", () => {
 
   it("labels logged-flow days and emits a forecast for ≥2 cycles", () => {
     const dayLogs: CalendarDayLogRow[] = [
-      { date: "2026-02-26", flow: "MEDIUM", basalBodyTempC: null, ovulationTest: null, cervicalMucus: null, hasSymptoms: true },
+      { date: "2026-02-26", flow: "MEDIUM", basalBodyTempC: null, temperatureExcluded: false, ovulationTest: null, cervicalMucus: null, hasSymptoms: true },
     ];
     const { prediction, days } = buildCalendar(
       profile(),

src/lib/cycle/__tests__/prediction.test.ts

@@ -389,6 +389,52 @@ describe("cycle/prediction — symptothermal confirmation (§4.2)", () => {
     expect(shift?.evaluationCompleteDate).toBe(addDays(start, 9));
   });
 
+  it("detectTempShift: an excluded (disturbed) baseline spike no longer masks a true rise", () => {
+    const start = "2024-01-01";
+    // 6 baseline days; the LAST (immediately before the rise) is a fever spike,
+    // so it sits in the cover-line window. Unexcluded it raises the cover line
+    // and contaminates detection; excluded it is dropped and the remaining lows
+    // form the real (lower) cover line.
+    const baseline = [36.4, 36.42, 36.38, 36.41, 36.4, 37.5];
+    const extraLow = 36.39; // a 6th valid low so exclusion still leaves 6
+    const rise = [36.55, 36.6, 36.62];
+    const build = (excludeFever: boolean): DayLogInput[] => {
+      const logs: DayLogInput[] = [];
+      logs.push(bbtDay(addDays(start, 0), extraLow));
+      baseline.forEach((t, i) => {
+        const day = bbtDay(addDays(start, 1 + i), t);
+        if (i === 5 && excludeFever) day.temperatureExcluded = true;
+        logs.push(day);
+      });
+      rise.forEach((t, i) => logs.push(bbtDay(addDays(start, 7 + i), t)));
+      return logs;
+    };
+    // Fever NOT excluded: the 37.5 spike contaminates detection — it does NOT
+    // yield the correct shift (ovulation = day before the real rise).
+    const corrupted = detectTempShift(build(false), 0.2);
+    expect(corrupted?.ovulationDate).not.toBe(addDays(start, 6));
+    // Fever excluded: cover line falls to the real baseline max and the genuine
+    // rise confirms with ovulation the day before it (2024-01-07).
+    const shift = detectTempShift(build(true), 0.2);
+    expect(shift?.rule).toBe(0);
+    expect(shift?.ovulationDate).toBe(addDays(start, 6));
+  });
+
+  it("detectTempShift: an excluded fever spike inside the rise no longer fabricates a shift", () => {
+    const start = "2024-01-01";
+    const logs: DayLogInput[] = [];
+    [36.4, 36.4, 36.4, 36.4, 36.4, 36.4].forEach((t, i) =>
+      logs.push(bbtDay(addDays(start, i), t)),
+    );
+    const fever = bbtDay(addDays(start, 6), 38.0);
+    fever.temperatureExcluded = true;
+    logs.push(fever);
+    logs.push(bbtDay(addDays(start, 7), 36.41));
+    logs.push(bbtDay(addDays(start, 8), 36.4));
+    // The excluded fever is dropped; the remaining readings show no rise.
+    expect(detectTempShift(logs, 0.2)).toBeNull();
+  });
+
   it("detectMucusPeak: confirms the last best-quality day followed by 3 drier days", () => {
     const m = (date: string, q: DayLogInput["cervicalMucus"]): DayLogInput => ({
       date,

src/lib/cycle/backup.ts

@@ -40,6 +40,7 @@ export interface CycleBackupSection {
     flow: string | null;
     intermenstrualBleeding: boolean;
     basalBodyTempC: number | null;
+    temperatureExcluded: boolean;
     ovulationTest: string | null;
     cervicalMucus: string | null;
     sexualActivity: boolean;
@@ -108,6 +109,7 @@ export async function buildCycleBackupSection(
       flow: d.flow,
       intermenstrualBleeding: d.intermenstrualBleeding,
       basalBodyTempC: d.basalBodyTempC,
+      temperatureExcluded: d.temperatureExcluded,
       ovulationTest: d.ovulationTest,
       cervicalMucus: d.cervicalMucus,
       sexualActivity: d.sexualActivity,
@@ -289,6 +291,7 @@ export async function restoreCycleData(
         flow: enumOrNull(d.flow, FLOW_LEVELS) as never,
         intermenstrualBleeding: d.intermenstrualBleeding ?? false,
         basalBodyTempC: d.basalBodyTempC ?? null,
+        temperatureExcluded: d.temperatureExcluded ?? false,
         ovulationTest: enumOrNull(d.ovulationTest, OVULATION_TESTS) as never,
         cervicalMucus: enumOrNull(d.cervicalMucus, CERVICAL_MUCUS) as never,
         sexualActivity: d.sexualActivity ?? false,

src/lib/cycle/day-log-write.ts

@@ -140,6 +140,7 @@ type ExistingRow = {
   flow: string | null;
   intermenstrualBleeding: boolean;
   basalBodyTempC: number | null;
+  temperatureExcluded: boolean;
   ovulationTest: string | null;
   cervicalMucus: string | null;
   sexualActivity: boolean;
@@ -158,6 +159,7 @@ const EXISTING_SELECT = {
   flow: true,
   intermenstrualBleeding: true,
   basalBodyTempC: true,
+  temperatureExcluded: true,
   ovulationTest: true,
   cervicalMucus: true,
   sexualActivity: true,
@@ -309,6 +311,10 @@ async function writeDayLog(args: WriteArgs): Promise<DayLogWriteResult> {
     entry.basalBodyTempC !== undefined
       ? (entry.basalBodyTempC ?? null)
       : (existing?.basalBodyTempC ?? null);
+  const temperatureExcluded =
+    entry.temperatureExcluded !== undefined
+      ? entry.temperatureExcluded
+      : (existing?.temperatureExcluded ?? false);
   const ovulationTest =
     entry.ovulationTest !== undefined
       ? (entry.ovulationTest ?? null)
@@ -338,6 +344,7 @@ async function writeDayLog(args: WriteArgs): Promise<DayLogWriteResult> {
     flow: flow as never,
     intermenstrualBleeding,
     basalBodyTempC,
+    temperatureExcluded,
     ovulationTest: ovulationTest as never,
     cervicalMucus: cervicalMucus as never,
     sexualActivity: sensitivePlaintext.sexualActivity,
@@ -357,6 +364,7 @@ async function writeDayLog(args: WriteArgs): Promise<DayLogWriteResult> {
       (existing.flow ?? null) !== flow ||
       existing.intermenstrualBleeding !== intermenstrualBleeding ||
       (existing.basalBodyTempC ?? null) !== basalBodyTempC ||
+      existing.temperatureExcluded !== temperatureExcluded ||
       (existing.ovulationTest ?? null) !== ovulationTest ||
       (existing.cervicalMucus ?? null) !== cervicalMucus ||
       storedSensitive.sexualActivity !== resolvedSensitive.sexualActivity ||
@@ -395,6 +403,7 @@ async function writeDayLog(args: WriteArgs): Promise<DayLogWriteResult> {
         flow: baseData.flow as never,
         intermenstrualBleeding: baseData.intermenstrualBleeding as never,
         basalBodyTempC: baseData.basalBodyTempC as never,
+        temperatureExcluded: baseData.temperatureExcluded as never,
         ovulationTest: baseData.ovulationTest as never,
         cervicalMucus: baseData.cervicalMucus as never,
         sexualActivity: sensitivePlaintext.sexualActivity,

src/lib/cycle/dto.ts

@@ -29,6 +29,8 @@ export interface CycleDayLogDTO {
   flow: string | null;
   intermenstrualBleeding: boolean;
   basalBodyTempC: number | null;
+  /** Whether the day's BBT is marked disturbed (excluded from the engine). */
+  temperatureExcluded: boolean;
   ovulationTest: string | null;
   cervicalMucus: string | null;
   sexualActivity: boolean;
@@ -107,6 +109,7 @@ export function toCycleDayLogDTO(row: DayLogWithLinks): CycleDayLogDTO {
     flow: row.flow,
     intermenstrualBleeding: row.intermenstrualBleeding,
     basalBodyTempC: row.basalBodyTempC,
+    temperatureExcluded: row.temperatureExcluded,
     ovulationTest: row.ovulationTest,
     cervicalMucus: row.cervicalMucus,
     sexualActivity: hasEnvelope

src/lib/cycle/engine-adapter.ts

@@ -37,6 +37,8 @@ export interface CalendarDayDTO {
   confidence: number;
   /** Logged basal body temperature (°C), or null. Feeds the web BBT chart. */
   basalBodyTempC: number | null;
+  /** Whether the day's BBT is marked disturbed (excluded from the engine). */
+  temperatureExcluded: boolean;
   /** Logged ovulation-test result, or null. */
   ovulationTest: string | null;
   /** Logged cervical-mucus quality, or null. */
@@ -46,7 +48,12 @@ export interface CalendarDayDTO {
 /** Rows the calendar needs from each day-log. */
 export type CalendarDayLogRow = Pick<
   CycleDayLog,
-  "date" | "flow" | "basalBodyTempC" | "ovulationTest" | "cervicalMucus"
+  | "date"
+  | "flow"
+  | "basalBodyTempC"
+  | "temperatureExcluded"
+  | "ovulationTest"
+  | "cervicalMucus"
 > & { hasSymptoms: boolean };
 
 /** Map MenstrualCycle rows (oldest→newest) to engine `CycleInput`. */
@@ -73,13 +80,19 @@ export function toCycleInputs(
 export function toDayLogInputs(
   logs: readonly Pick<
     CycleDayLog,
-    "date" | "flow" | "basalBodyTempC" | "ovulationTest" | "cervicalMucus"
+    | "date"
+    | "flow"
+    | "basalBodyTempC"
+    | "temperatureExcluded"
+    | "ovulationTest"
+    | "cervicalMucus"
   >[],
 ): DayLogInput[] {
   return logs.map((l) => ({
     date: l.date,
     flow: l.flow,
     basalBodyTempC: l.basalBodyTempC,
+    temperatureExcluded: l.temperatureExcluded,
     ovulationTest: l.ovulationTest,
     cervicalMucus: l.cervicalMucus,
   }));
@@ -337,6 +350,7 @@ export function buildCalendar(
       hasSymptoms: log?.hasSymptoms ?? false,
       confidence: prediction?.confidence ?? 0,
       basalBodyTempC: log?.basalBodyTempC ?? null,
+      temperatureExcluded: log?.temperatureExcluded ?? false,
       ovulationTest: log?.ovulationTest ?? null,
       cervicalMucus: log?.cervicalMucus ?? null,
     });

src/lib/cycle/prediction.ts

@@ -272,8 +272,11 @@ interface TempShiftResult {
  * published Ausnahmeregeln (exception rules).
  *
  * Cover line (Hüllkurve) = the highest of the 6 measured low values immediately
- * preceding the rise. Ovulation = the last low day before the rise (the day
- * BEFORE the first elevated reading).
+ * preceding the rise. Excluded (disturbed) readings are dropped before the cover
+ * line and the rise are evaluated, so a fever / late reading neither raises the
+ * cover line nor masks a true shift (Sensiplan: the line is drawn over the last
+ * six *unbracketed* values). Ovulation = the last low day before the rise (the
+ * day BEFORE the first elevated reading).
  *
  * Rules (Arbeitsgruppe NFP / Raith-Paula & Frank-Herrmann; myNFP "Temperatur­kurve
  * auswerten"; Generation-Pille "Die wichtigsten NFP-Regeln"):
@@ -291,7 +294,7 @@ export function detectTempShift(
   thresholdC: number,
 ): TempShiftResult | null {
   const temps = dayLogs
-    .filter((l) => l.basalBodyTempC != null)
+    .filter((l) => l.basalBodyTempC != null && l.temperatureExcluded !== true)
     .map((l) => ({ date: l.date, t: l.basalBodyTempC as number }))
     .sort((a, b) => dayDiff(a.date, b.date));
 

src/lib/cycle/types.ts

@@ -192,6 +192,15 @@ export interface DayLogInput {
   flow: FlowLevel | null;
   /** Basal body temperature in °C, already rounded to 2 dp before input. */
   basalBodyTempC: number | null;
+  /**
+   * Whether this day's BBT is a disturbed/unreliable reading (fever, illness,
+   * alcohol, a late or short-sleep measurement) the user marked excluded. When
+   * true the engine drops the reading from the cover-line baseline AND the shift
+   * evaluation, so a spike neither fabricates nor masks a temperature rise
+   * (Sensiplan: the cover line is drawn over the last six *unbracketed* values).
+   * Optional for back-compat; treated as `false` when absent.
+   */
+  temperatureExcluded?: boolean | null;
   ovulationTest: OvulationTest | null;
   cervicalMucus: CervicalMucus | null;
 }

src/lib/openapi/routes/cycle.ts

@@ -101,6 +101,7 @@ const cycleDayLogDto = z
     flow: flowLevelEnum.nullable(),
     intermenstrualBleeding: z.boolean(),
     basalBodyTempC: z.number().nullable(),
+    temperatureExcluded: z.boolean(),
     ovulationTest: ovulationTestEnum.nullable(),
     cervicalMucus: cervicalMucusEnum.nullable(),
     sexualActivity: z.boolean(),
@@ -175,6 +176,7 @@ const cycleCalendarDayDto = z.object({
   // so the web BBT chart renders from the calendar read (the values are already
   // loaded server-side for the symptothermal layer; no extra query).
   basalBodyTempC: z.number().nullable(),
+  temperatureExcluded: z.boolean(),
   ovulationTest: ovulationTestEnum.nullable(),
   cervicalMucus: cervicalMucusEnum.nullable(),
 });

src/lib/validations/backup.ts

@@ -141,6 +141,7 @@ const cycleDayLogSchema = z
     flow: z.string().nullable().optional(),
     intermenstrualBleeding: z.boolean().optional(),
     basalBodyTempC: z.number().nullable().optional(),
+    temperatureExcluded: z.boolean().optional(),
     ovulationTest: z.string().nullable().optional(),
     cervicalMucus: z.string().nullable().optional(),
     sexualActivity: z.boolean().optional(),

src/lib/validations/cycle.ts

@@ -103,6 +103,9 @@ export const cycleDayLogInputSchema = z.object({
   flow: flowLevelEnum.optional(),
   intermenstrualBleeding: z.boolean().optional(),
   basalBodyTempC: z.number().min(30).max(45).optional(),
+  // Marks the day's BBT as disturbed (fever / illness / late reading): the
+  // symptothermal engine drops it from the cover line + shift evaluation.
+  temperatureExcluded: z.boolean().optional(),
   ovulationTest: ovulationTestEnum.optional(),
   cervicalMucus: cervicalMucusEnum.optional(),
   sexualActivity: z.boolean().optional(),
@@ -132,6 +135,7 @@ export const cycleDayLogPatchSchema = z.object({
   flow: flowLevelEnum.nullable().optional(),
   intermenstrualBleeding: z.boolean().optional(),
   basalBodyTempC: z.number().min(30).max(45).nullable().optional(),
+  temperatureExcluded: z.boolean().optional(),
   ovulationTest: ovulationTestEnum.nullable().optional(),
   cervicalMucus: cervicalMucusEnum.nullable().optional(),
   sexualActivity: z.boolean().optional(),