diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 62fad8c..a1010f4 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -33,8 +33,8 @@ android {
         targetSdk = 35
         // Bump both for every release installed on the phone — versionName for
         // humans, versionCode so dumpsys/install history can tell builds apart.
-        versionCode = 2
-        versionName = "0.2.0"
+        versionCode = 3
+        versionName = "0.3.0"
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
 
diff --git a/app/schemas/no.naiv.meddetsamme.data.MedDatabase/3.json b/app/schemas/no.naiv.meddetsamme.data.MedDatabase/3.json
new file mode 100644
index 0000000..a2db4ac
--- /dev/null
+++ b/app/schemas/no.naiv.meddetsamme.data.MedDatabase/3.json
@@ -0,0 +1,375 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 3,
+    "identityHash": "24354334e7b708174aa927342ae33d38",
+    "entities": [
+      {
+        "tableName": "inventory_item",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `name` TEXT NOT NULL, `strength` TEXT NOT NULL, `unit` TEXT NOT NULL, `form` TEXT NOT NULL, `atcCode` TEXT, `packageSize` REAL, `stockUnits` REAL NOT NULL, `lowStockLeadDays` INTEGER NOT NULL, `rxExpiryEpochDay` INTEGER, `refillsRemaining` INTEGER)",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "name",
+            "columnName": "name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "strength",
+            "columnName": "strength",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "unit",
+            "columnName": "unit",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "form",
+            "columnName": "form",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "atcCode",
+            "columnName": "atcCode",
+            "affinity": "TEXT"
+          },
+          {
+            "fieldPath": "packageSize",
+            "columnName": "packageSize",
+            "affinity": "REAL"
+          },
+          {
+            "fieldPath": "stockUnits",
+            "columnName": "stockUnits",
+            "affinity": "REAL",
+            "notNull": true
+          },
+          {
+            "fieldPath": "lowStockLeadDays",
+            "columnName": "lowStockLeadDays",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "rxExpiryEpochDay",
+            "columnName": "rxExpiryEpochDay",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "refillsRemaining",
+            "columnName": "refillsRemaining",
+            "affinity": "INTEGER"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        }
+      },
+      {
+        "tableName": "medication",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `itemId` INTEGER NOT NULL, `withFood` INTEGER NOT NULL, `notes` TEXT NOT NULL, `active` INTEGER NOT NULL, FOREIGN KEY(`itemId`) REFERENCES `inventory_item`(`id`) ON UPDATE NO ACTION ON DELETE RESTRICT )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "itemId",
+            "columnName": "itemId",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "withFood",
+            "columnName": "withFood",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "notes",
+            "columnName": "notes",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "active",
+            "columnName": "active",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_medication_itemId",
+            "unique": false,
+            "columnNames": [
+              "itemId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_medication_itemId` ON `${TABLE_NAME}` (`itemId`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "inventory_item",
+            "onDelete": "RESTRICT",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "itemId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "dose_time",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `medId` INTEGER NOT NULL, `minuteOfDay` INTEGER NOT NULL, `amount` REAL NOT NULL, `daysOfWeekMask` INTEGER NOT NULL, `intervalDays` INTEGER NOT NULL, `anchorEpochDay` INTEGER, `cycleActiveDays` INTEGER NOT NULL DEFAULT 0, `cycleLengthDays` INTEGER NOT NULL DEFAULT 0, `startEpochDay` INTEGER, `endEpochDay` INTEGER, FOREIGN KEY(`medId`) REFERENCES `medication`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "medId",
+            "columnName": "medId",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "minuteOfDay",
+            "columnName": "minuteOfDay",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "amount",
+            "columnName": "amount",
+            "affinity": "REAL",
+            "notNull": true
+          },
+          {
+            "fieldPath": "daysOfWeekMask",
+            "columnName": "daysOfWeekMask",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "intervalDays",
+            "columnName": "intervalDays",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "anchorEpochDay",
+            "columnName": "anchorEpochDay",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "cycleActiveDays",
+            "columnName": "cycleActiveDays",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "cycleLengthDays",
+            "columnName": "cycleLengthDays",
+            "affinity": "INTEGER",
+            "notNull": true,
+            "defaultValue": "0"
+          },
+          {
+            "fieldPath": "startEpochDay",
+            "columnName": "startEpochDay",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "endEpochDay",
+            "columnName": "endEpochDay",
+            "affinity": "INTEGER"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_dose_time_medId",
+            "unique": false,
+            "columnNames": [
+              "medId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_dose_time_medId` ON `${TABLE_NAME}` (`medId`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "medication",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "medId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "tableName": "dose_log",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `medId` INTEGER NOT NULL, `doseTimeId` INTEGER, `scheduledAtMillis` INTEGER NOT NULL, `amount` REAL NOT NULL, `status` TEXT NOT NULL, `actionedAtMillis` INTEGER, `nagCount` INTEGER NOT NULL, FOREIGN KEY(`medId`) REFERENCES `medication`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , FOREIGN KEY(`doseTimeId`) REFERENCES `dose_time`(`id`) ON UPDATE NO ACTION ON DELETE SET NULL )",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "medId",
+            "columnName": "medId",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "doseTimeId",
+            "columnName": "doseTimeId",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "scheduledAtMillis",
+            "columnName": "scheduledAtMillis",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "amount",
+            "columnName": "amount",
+            "affinity": "REAL",
+            "notNull": true
+          },
+          {
+            "fieldPath": "status",
+            "columnName": "status",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "actionedAtMillis",
+            "columnName": "actionedAtMillis",
+            "affinity": "INTEGER"
+          },
+          {
+            "fieldPath": "nagCount",
+            "columnName": "nagCount",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": true,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_dose_log_medId",
+            "unique": false,
+            "columnNames": [
+              "medId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_dose_log_medId` ON `${TABLE_NAME}` (`medId`)"
+          },
+          {
+            "name": "index_dose_log_doseTimeId",
+            "unique": false,
+            "columnNames": [
+              "doseTimeId"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_dose_log_doseTimeId` ON `${TABLE_NAME}` (`doseTimeId`)"
+          },
+          {
+            "name": "index_dose_log_doseTimeId_scheduledAtMillis",
+            "unique": false,
+            "columnNames": [
+              "doseTimeId",
+              "scheduledAtMillis"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_dose_log_doseTimeId_scheduledAtMillis` ON `${TABLE_NAME}` (`doseTimeId`, `scheduledAtMillis`)"
+          },
+          {
+            "name": "index_dose_log_status",
+            "unique": false,
+            "columnNames": [
+              "status"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_dose_log_status` ON `${TABLE_NAME}` (`status`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "medication",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "medId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          },
+          {
+            "table": "dose_time",
+            "onDelete": "SET NULL",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "doseTimeId"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      }
+    ],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, '24354334e7b708174aa927342ae33d38')"
+    ]
+  }
+}
\ No newline at end of file
diff --git a/app/src/androidTest/java/no/naiv/meddetsamme/data/MigrationTest.kt b/app/src/androidTest/java/no/naiv/meddetsamme/data/MigrationTest.kt
index eba6497..e57272e 100644
--- a/app/src/androidTest/java/no/naiv/meddetsamme/data/MigrationTest.kt
+++ b/app/src/androidTest/java/no/naiv/meddetsamme/data/MigrationTest.kt
@@ -77,6 +77,37 @@ class MigrationTest {
         }
     }
 
+    @Test
+    fun migrate2To3_addsCyclicAndWindowColumnsKeepingRows() {
+        helper.createDatabase(TEST_DB, 2).use { db ->
+            db.execSQL(
+                "INSERT INTO inventory_item (id, name, strength, unit, form, stockUnits, " +
+                    "lowStockLeadDays) VALUES (1, 'Levaxin', '50 µg', 'tablett', 'TABLET', 42.0, 7)",
+            )
+            db.execSQL("INSERT INTO medication (id, itemId, withFood, notes, active) VALUES (1, 1, 0, '', 1)")
+            db.execSQL(
+                "INSERT INTO dose_time (id, medId, minuteOfDay, amount, daysOfWeekMask, " +
+                    "intervalDays, anchorEpochDay) VALUES (3, 1, 450, 1.5, 127, 0, NULL)",
+            )
+        }
+
+        // Validates the migrated schema against 3.json AND checks the new columns
+        // default to "no cycle / no window" while the existing row survives.
+        helper.runMigrationsAndValidate(TEST_DB, 3, true, MedDatabase.MIGRATION_2_3).use { db ->
+            db.query(
+                "SELECT amount, cycleActiveDays, cycleLengthDays, startEpochDay, endEpochDay " +
+                    "FROM dose_time WHERE id = 3",
+            ).use { c ->
+                assertTrue(c.moveToFirst())
+                assertEquals(1.5, c.getDouble(0), 0.0)
+                assertEquals(0, c.getInt(1)) // cycleActiveDays
+                assertEquals(0, c.getInt(2)) // cycleLengthDays
+                assertTrue("startEpochDay null", c.isNull(3))
+                assertTrue("endEpochDay null", c.isNull(4))
+            }
+        }
+    }
+
     private companion object {
         const val TEST_DB = "migration-test.db"
     }
diff --git a/app/src/main/java/no/naiv/meddetsamme/alarm/SupplyCheckReceiver.kt b/app/src/main/java/no/naiv/meddetsamme/alarm/SupplyCheckReceiver.kt
index b0ca4a9..27422af 100644
--- a/app/src/main/java/no/naiv/meddetsamme/alarm/SupplyCheckReceiver.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/alarm/SupplyCheckReceiver.kt
@@ -47,7 +47,7 @@ class SupplyCheckReceiver : BroadcastReceiver() {
         for ((_, meds) in byItem) {
             val item = meds.first().item
             var rate = 0.0
-            for (med in meds) rate += ScheduleEngine.dailyConsumption(db.doseTimeDao().getForMed(med.med.id))
+            for (med in meds) rate += ScheduleEngine.dailyConsumption(db.doseTimeDao().getForMed(med.med.id), today)
             if (ScheduleEngine.needsRefill(item.stockUnits, rate, item.lowStockLeadDays)) {
                 val days = ScheduleEngine.daysOfSupply(item.stockUnits, rate)
                 lowStock += "${item.name}: lager for ${no.naiv.meddetsamme.domain.ScheduleText.daysCount(days?.toInt() ?: 0)}"
diff --git a/app/src/main/java/no/naiv/meddetsamme/backup/BackupSerializer.kt b/app/src/main/java/no/naiv/meddetsamme/backup/BackupSerializer.kt
index 5192bd6..7b7f283 100644
--- a/app/src/main/java/no/naiv/meddetsamme/backup/BackupSerializer.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/backup/BackupSerializer.kt
@@ -157,6 +157,11 @@ data class DoseTimeDto(
     val daysOfWeekMask: Int,
     val intervalDays: Int,
     val anchorEpochDay: Long? = null,
+    // Added in schema v3; defaults keep older (v2) backup files parsing.
+    val cycleActiveDays: Int = 0,
+    val cycleLengthDays: Int = 0,
+    val startEpochDay: Long? = null,
+    val endEpochDay: Long? = null,
 )
 
 @Serializable
@@ -193,9 +198,15 @@ private fun MedicationDto.toEntity() = Medication(
     active = active,
 )
 
-private fun DoseTime.toDto() = DoseTimeDto(id, medId, minuteOfDay, amount, daysOfWeekMask, intervalDays, anchorEpochDay)
+private fun DoseTime.toDto() = DoseTimeDto(
+    id, medId, minuteOfDay, amount, daysOfWeekMask, intervalDays, anchorEpochDay,
+    cycleActiveDays, cycleLengthDays, startEpochDay, endEpochDay,
+)
 
-private fun DoseTimeDto.toEntity() = DoseTime(id, medId, minuteOfDay, amount, daysOfWeekMask, intervalDays, anchorEpochDay)
+private fun DoseTimeDto.toEntity() = DoseTime(
+    id, medId, minuteOfDay, amount, daysOfWeekMask, intervalDays, anchorEpochDay,
+    cycleActiveDays, cycleLengthDays, startEpochDay, endEpochDay,
+)
 
 private fun DoseLog.toDto() = DoseLogDto(id, medId, doseTimeId, scheduledAtMillis, amount, status.name, actionedAtMillis, nagCount)
 
diff --git a/app/src/main/java/no/naiv/meddetsamme/data/DoseTime.kt b/app/src/main/java/no/naiv/meddetsamme/data/DoseTime.kt
index 18168e0..10a9797 100644
--- a/app/src/main/java/no/naiv/meddetsamme/data/DoseTime.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/data/DoseTime.kt
@@ -1,5 +1,6 @@
 package no.naiv.meddetsamme.data
 
+import androidx.room.ColumnInfo
 import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Index
@@ -7,14 +8,22 @@ import androidx.room.PrimaryKey
 
 /**
  * One scheduled time-of-day for a medication. Multiple rows per med give
- * different times on different days (e.g. weekend row + weekday row).
+ * different times on different days (e.g. weekend row + weekend row).
  *
  * Schedule semantics (enforced by the pure ScheduleEngine, not the DB):
  * - [intervalDays] > 1 → dose every N days counted from [anchorEpochDay];
  *   [daysOfWeekMask] is ignored.
  * - otherwise → weekly pattern from [daysOfWeekMask], bit 0 = Sunday … bit 6 =
- *   Saturday (matches java.time DayOfWeek.SUNDAY rotated; engine owns the mapping).
- *   0x7F = daily. Cyclic/taper schedules extend from the same two fields.
+ *   Saturday. 0x7F = daily.
+ *
+ * Two orthogonal filters layer on top (the brief's "cyclic/taper extend from
+ * the same model"):
+ * - **Cyclic** ([cycleLengthDays] > 0): the dose only occurs in the first
+ *   [cycleActiveDays] of each [cycleLengthDays]-day cycle counted from
+ *   [anchorEpochDay] — e.g. 21-on/7-off contraception is 21/28.
+ * - **Validity window** ([startEpochDay]/[endEpochDay], inclusive): the dose
+ *   only occurs within the date range. A taper is several rows with descending
+ *   [amount] and adjacent windows.
  */
 @Entity(
     tableName = "dose_time",
@@ -39,6 +48,16 @@ data class DoseTime(
     val daysOfWeekMask: Int = 0x7F,
     /** 0 or 1 = use the weekly mask; N > 1 = every N days from [anchorEpochDay]. */
     val intervalDays: Int = 0,
-    /** Day 0 of an every-N-days cycle (LocalDate.toEpochDay). Required if intervalDays > 1. */
+    /** Day 0 of an every-N-days OR cyclic schedule (LocalDate.toEpochDay). */
     val anchorEpochDay: Long? = null,
+    // defaultValue "0" makes the entity schema match the v2→v3 ADD COLUMN … DEFAULT 0,
+    // so Room's migration validation passes.
+    /** Days "on" at the start of each cycle. 0 = not cyclic. Needs [anchorEpochDay]. */
+    @ColumnInfo(defaultValue = "0") val cycleActiveDays: Int = 0,
+    /** Total cycle length. 0 = not cyclic. Cyclic requires this > [cycleActiveDays]. */
+    @ColumnInfo(defaultValue = "0") val cycleLengthDays: Int = 0,
+    /** Inclusive validity-window start (LocalDate.toEpochDay); null = no lower bound. */
+    val startEpochDay: Long? = null,
+    /** Inclusive validity-window end; null = no upper bound. Taper rows set this. */
+    val endEpochDay: Long? = null,
 )
diff --git a/app/src/main/java/no/naiv/meddetsamme/data/MedDatabase.kt b/app/src/main/java/no/naiv/meddetsamme/data/MedDatabase.kt
index 78725a6..d893a06 100644
--- a/app/src/main/java/no/naiv/meddetsamme/data/MedDatabase.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/data/MedDatabase.kt
@@ -17,7 +17,7 @@ import androidx.sqlite.db.SupportSQLiteDatabase
  */
 @Database(
     entities = [InventoryItem::class, Medication::class, DoseTime::class, DoseLog::class],
-    version = 2,
+    version = 3,
     exportSchema = true,
 )
 abstract class MedDatabase : RoomDatabase() {
@@ -78,13 +78,27 @@ abstract class MedDatabase : RoomDatabase() {
             }
         }
 
+        /**
+         * v2 → v3: cyclic + validity-window columns on dose_time. Pure additive
+         * ALTERs with defaults that mean "no cycle, no window" — existing rows
+         * keep behaving exactly as before.
+         */
+        val MIGRATION_2_3 = object : Migration(2, 3) {
+            override fun migrate(db: SupportSQLiteDatabase) {
+                db.execSQL("ALTER TABLE dose_time ADD COLUMN `cycleActiveDays` INTEGER NOT NULL DEFAULT 0")
+                db.execSQL("ALTER TABLE dose_time ADD COLUMN `cycleLengthDays` INTEGER NOT NULL DEFAULT 0")
+                db.execSQL("ALTER TABLE dose_time ADD COLUMN `startEpochDay` INTEGER")
+                db.execSQL("ALTER TABLE dose_time ADD COLUMN `endEpochDay` INTEGER")
+            }
+        }
+
         fun get(context: Context): MedDatabase =
             instance ?: synchronized(this) {
                 instance ?: Room.databaseBuilder(
                     context.applicationContext,
                     MedDatabase::class.java,
                     "med-det-samme.db",
-                ).addMigrations(MIGRATION_1_2).build().also { instance = it }
+                ).addMigrations(MIGRATION_1_2, MIGRATION_2_3).build().also { instance = it }
             }
     }
 }
diff --git a/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleEngine.kt b/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleEngine.kt
index f9bb601..f967cbd 100644
--- a/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleEngine.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleEngine.kt
@@ -20,54 +20,66 @@ import no.naiv.meddetsamme.data.DoseTime
  * - intervalDays > 1 → every N days counted from anchorEpochDay; mask ignored.
  * - otherwise → weekly daysOfWeekMask, bit 0 = Sunday … bit 6 = Saturday.
  *   Mask 0 selects nothing: no occurrences, never an error.
+ * - cyclic ([cycleLengthDays] > 0) and validity window ([startEpochDay]/
+ *   [endEpochDay]) further restrict the above — see [occursOn].
  */
 object ScheduleEngine {
 
+    /** How far ahead [nextOccurrence] searches — covers any realistic cycle/window. */
+    private const val SEARCH_HORIZON_DAYS = 366
+
     /** Bit position for a day-of-week: Sunday=0 … Saturday=6 (brief's convention). */
     fun bitFor(day: DayOfWeek): Int = day.value % 7 // java.time: MON=1..SUN=7
 
-    /** Does this dose-time occur on [date]? */
-    fun occursOn(doseTime: DoseTime, date: LocalDate): Boolean {
-        return if (doseTime.intervalDays > 1) {
+    /** The base weekly/interval rule, before cyclic and window filters. */
+    private fun baseOccursOn(doseTime: DoseTime, date: LocalDate): Boolean =
+        if (doseTime.intervalDays > 1) {
             val anchor = doseTime.anchorEpochDay ?: return false
             val delta = date.toEpochDay() - anchor
             delta >= 0 && delta % doseTime.intervalDays == 0L
         } else {
             doseTime.daysOfWeekMask and (1 shl bitFor(date.dayOfWeek)) != 0
         }
+
+    /** Is [date] inside this dose-time's "on" window of its cycle? */
+    private fun inCycleWindow(doseTime: DoseTime, date: LocalDate): Boolean {
+        val length = doseTime.cycleLengthDays
+        val active = doseTime.cycleActiveDays
+        // Degenerate configs (no anchor, full or empty active span) = no cycle filter.
+        if (length <= 0 || active !in 1 until length) return true
+        val anchor = doseTime.anchorEpochDay ?: return true
+        val day = date.toEpochDay()
+        if (day < anchor) return false // a cycle can't run before it starts
+        return Math.floorMod(day - anchor, length.toLong()) < active
+    }
+
+    /** Does this dose-time occur on [date]? Base rule ∧ validity window ∧ cycle. */
+    fun occursOn(doseTime: DoseTime, date: LocalDate): Boolean {
+        val day = date.toEpochDay()
+        doseTime.startEpochDay?.let { if (day < it) return false }
+        doseTime.endEpochDay?.let { if (day > it) return false }
+        return baseOccursOn(doseTime, date) && inCycleWindow(doseTime, date)
     }
 
     /**
      * Earliest occurrence strictly after [after], or null if the schedule never
-     * fires (empty mask / missing anchor). Strict-after is load-bearing: the
-     * alarm receiver passes the occurrence it just fired, and must get the
-     * *next* one — never the same minute again.
+     * fires within the search horizon (empty mask / missing anchor / window
+     * elapsed). Strict-after is load-bearing: the alarm receiver passes the
+     * occurrence it just fired, and must get the *next* one — never the same
+     * minute again.
+     *
+     * A uniform day-by-day scan over [occursOn] so weekly, interval, cyclic and
+     * windowed schedules all fall out of one correct path.
      */
     fun nextOccurrence(doseTime: DoseTime, after: LocalDateTime): LocalDateTime? {
         val time = LocalTime.of(doseTime.minuteOfDay / 60, doseTime.minuteOfDay % 60)
         // First candidate day: today if the time is still ahead of us, else tomorrow.
         var date = if (time > after.toLocalTime()) after.toLocalDate() else after.toLocalDate().plusDays(1)
-
-        if (doseTime.intervalDays > 1) {
-            val anchor = doseTime.anchorEpochDay ?: return null
-            val interval = doseTime.intervalDays.toLong()
-            val delta = date.toEpochDay() - anchor
-            date = when {
-                delta <= 0 -> LocalDate.ofEpochDay(anchor) // cycle starts in the future
-                else -> {
-                    val intoCycle = delta % interval
-                    if (intoCycle == 0L) date else date.plusDays(interval - intoCycle)
-                }
-            }
-            return LocalDateTime.of(date, time)
-        }
-
-        if (doseTime.daysOfWeekMask and 0x7F == 0) return null
-        repeat(7) {
+        repeat(SEARCH_HORIZON_DAYS) {
             if (occursOn(doseTime, date)) return LocalDateTime.of(date, time)
             date = date.plusDays(1)
         }
-        return null // unreachable with a non-empty mask; defensive
+        return null
     }
 
     /** Earliest next occurrence across all of a med's dose-times (what to arm). */
@@ -84,18 +96,28 @@ object ScheduleEngine {
             .sortedBy { it.second }
 
     /**
-     * Scheduled (prospective) consumption in units/day. Weekly: amount × selected
-     * days ÷ 7; every-N-days: amount ÷ N. Prospective, not historical, because
-     * days-of-supply is a forward prediction.
+     * Scheduled (prospective) consumption in units/day on [today]. Weekly:
+     * amount × selected days ÷ 7; every-N-days: amount ÷ N; cyclic scales by
+     * activeDays ÷ cycleLength. Rows outside their validity window contribute 0
+     * — a finished taper step shouldn't inflate the rate forever. Prospective,
+     * not historical, because days-of-supply is a forward prediction.
      */
-    fun dailyConsumption(doseTimes: List<DoseTime>): Double =
-        doseTimes.sumOf { dt ->
-            if (dt.intervalDays > 1) {
+    fun dailyConsumption(doseTimes: List<DoseTime>, today: LocalDate): Double {
+        val day = today.toEpochDay()
+        return doseTimes.sumOf { dt ->
+            if (dt.startEpochDay != null && day < dt.startEpochDay) return@sumOf 0.0
+            if (dt.endEpochDay != null && day > dt.endEpochDay) return@sumOf 0.0
+            var rate = if (dt.intervalDays > 1) {
                 if (dt.anchorEpochDay == null) 0.0 else dt.amount / dt.intervalDays
             } else {
                 dt.amount * Integer.bitCount(dt.daysOfWeekMask and 0x7F) / 7.0
             }
+            if (dt.cycleLengthDays > 0 && dt.cycleActiveDays in 1 until dt.cycleLengthDays) {
+                rate *= dt.cycleActiveDays.toDouble() / dt.cycleLengthDays
+            }
+            rate
         }
+    }
 
     /** Days until stock runs out at the scheduled rate; null if nothing is consumed. */
     fun daysOfSupply(inventoryUnits: Double, dailyConsumption: Double): Double? =
diff --git a/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleText.kt b/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleText.kt
index fe738d3..029567d 100644
--- a/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleText.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/domain/ScheduleText.kt
@@ -1,5 +1,8 @@
 package no.naiv.meddetsamme.domain
 
+import java.time.LocalDate
+import java.time.format.DateTimeFormatter
+import java.util.Locale
 import no.naiv.meddetsamme.data.DoseTime
 
 /**
@@ -12,9 +15,30 @@ object ScheduleText {
     /** Mask bit order matches ScheduleEngine: bit 0 = Sunday. */
     private val DAY_ABBREV = listOf("søn", "man", "tir", "ons", "tor", "fre", "lør")
 
-    fun describe(doseTime: DoseTime): String {
-        val time = "%02d:%02d".format(doseTime.minuteOfDay / 60, doseTime.minuteOfDay % 60)
-        return "$time ${daysText(doseTime)}"
+    // Locale-pinned to nb so month names don't come out English on a foreign locale.
+    private val dateFmt = DateTimeFormatter.ofPattern("d. MMM", Locale.forLanguageTag("nb"))
+
+    fun describe(doseTime: DoseTime): String =
+        "${"%02d:%02d".format(doseTime.minuteOfDay / 60, doseTime.minuteOfDay % 60)} " +
+            "${daysText(doseTime)}${cycleText(doseTime)}${windowText(doseTime)}"
+
+    /** " · syklus 21/28" when cyclic, else "". */
+    fun cycleText(doseTime: DoseTime): String {
+        val length = doseTime.cycleLengthDays
+        val active = doseTime.cycleActiveDays
+        return if (length > 0 && active in 1 until length) " · syklus $active/$length" else ""
+    }
+
+    /** " · 1.–14. jun", " · f.o.m. 1. jun", " · t.o.m. 14. jun" for a validity window. */
+    fun windowText(doseTime: DoseTime): String {
+        val start = doseTime.startEpochDay?.let { LocalDate.ofEpochDay(it) }
+        val end = doseTime.endEpochDay?.let { LocalDate.ofEpochDay(it) }
+        return when {
+            start != null && end != null -> " · ${dateFmt.format(start)}–${dateFmt.format(end)}"
+            start != null -> " · f.o.m. ${dateFmt.format(start)}"
+            end != null -> " · t.o.m. ${dateFmt.format(end)}"
+            else -> ""
+        }
     }
 
     fun daysText(doseTime: DoseTime): String {
diff --git a/app/src/main/java/no/naiv/meddetsamme/pdf/DoctorSummaryPdf.kt b/app/src/main/java/no/naiv/meddetsamme/pdf/DoctorSummaryPdf.kt
index a1c74b4..ea5031a 100644
--- a/app/src/main/java/no/naiv/meddetsamme/pdf/DoctorSummaryPdf.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/pdf/DoctorSummaryPdf.kt
@@ -95,7 +95,7 @@ class DoctorSummaryPdf(private val context: Context) {
         for (med in meds) {
             val item = med.item
             val doseTimes = db.doseTimeDao().getForMed(med.med.id)
-            val rate = ScheduleEngine.dailyConsumption(doseTimes)
+            val rate = ScheduleEngine.dailyConsumption(doseTimes, today)
             val supplyDays = ScheduleEngine.daysOfSupply(item.stockUnits, rate)
             val logs = db.doseLogDao().getRange(windowStart, System.currentTimeMillis())
                 .filter { it.medId == med.med.id }
diff --git a/app/src/main/java/no/naiv/meddetsamme/ui/MedEditScreen.kt b/app/src/main/java/no/naiv/meddetsamme/ui/MedEditScreen.kt
index d6b4310..faffbf7 100644
--- a/app/src/main/java/no/naiv/meddetsamme/ui/MedEditScreen.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/ui/MedEditScreen.kt
@@ -21,6 +21,7 @@ import androidx.compose.material3.ExposedDropdownMenuAnchorType
 import androidx.compose.material3.ExposedDropdownMenuBox
 import androidx.compose.material3.ExposedDropdownMenuDefaults
 import androidx.compose.material3.FilterChip
+import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
@@ -294,6 +295,7 @@ private fun ScheduleSection(medId: Long, doseTimes: List<DoseTime>, onChanged: (
     val scope = rememberCoroutineScope()
     var editing by remember { mutableStateOf<DoseTime?>(null) }
     var showEditor by remember { mutableStateOf(false) }
+    var showTaper by remember { mutableStateOf(false) }
 
     Text("Doseringstider", style = MaterialTheme.typography.titleMedium)
 
@@ -321,6 +323,9 @@ private fun ScheduleSection(medId: Long, doseTimes: List<DoseTime>, onChanged: (
     OutlinedButton(onClick = { editing = null; showEditor = true }, modifier = Modifier.fillMaxWidth()) {
         Text("Legg til doseringstid")
     }
+    OutlinedButton(onClick = { showTaper = true }, modifier = Modifier.fillMaxWidth()) {
+        Text("Lag nedtrapping …")
+    }
 
     if (showEditor) {
         DoseTimeEditorDialog(
@@ -330,6 +335,98 @@ private fun ScheduleSection(medId: Long, doseTimes: List<DoseTime>, onChanged: (
             onSaved = { showEditor = false; onChanged() },
         )
     }
+    if (showTaper) {
+        TaperDialog(
+            medId = medId,
+            onDismiss = { showTaper = false },
+            onSaved = { showTaper = false; onChanged() },
+        )
+    }
+}
+
+/**
+ * Generates a tapering schedule: one daily dose-time row per step, each with a
+ * descending amount and an adjacent validity window. Far less tedious than
+ * hand-entering N windowed rows. Decreasing prednisolone is the canonical case.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun TaperDialog(medId: Long, onDismiss: () -> Unit, onSaved: () -> Unit) {
+    val context = LocalContext.current
+    val db = remember { MedDatabase.get(context) }
+    val scope = rememberCoroutineScope()
+
+    val timeState = androidx.compose.material3.rememberTimePickerState(initialHour = 8, initialMinute = 0, is24Hour = true)
+    var startAmount by remember { mutableStateOf("4") }
+    var stepDown by remember { mutableStateOf("1") }
+    var daysPerStep by remember { mutableStateOf("3") }
+    var steps by remember { mutableStateOf("4") }
+    var error by remember { mutableStateOf<String?>(null) }
+
+    AlertDialog(
+        onDismissRequest = onDismiss,
+        title = { Text("Lag nedtrapping") },
+        text = {
+            Column(
+                modifier = Modifier.verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(10.dp),
+            ) {
+                androidx.compose.material3.TimePicker(state = timeState)
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    OutlinedTextField(
+                        value = startAmount, onValueChange = { startAmount = it },
+                        label = { Text("Startdose") }, singleLine = true, modifier = Modifier.weight(1f),
+                    )
+                    OutlinedTextField(
+                        value = stepDown, onValueChange = { stepDown = it },
+                        label = { Text("Ned per trinn") }, singleLine = true, modifier = Modifier.weight(1f),
+                    )
+                }
+                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                    OutlinedTextField(
+                        value = daysPerStep, onValueChange = { daysPerStep = it },
+                        label = { Text("Dager per trinn") }, singleLine = true, modifier = Modifier.weight(1f),
+                    )
+                    OutlinedTextField(
+                        value = steps, onValueChange = { steps = it },
+                        label = { Text("Antall trinn") }, singleLine = true, modifier = Modifier.weight(1f),
+                    )
+                }
+                error?.let { Text(it, color = MaterialTheme.colorScheme.error) }
+            }
+        },
+        confirmButton = {
+            TextButton(onClick = {
+                val start = parseAmount(startAmount)
+                val step = parseAmount(stepDown)
+                val perStep = daysPerStep.toIntOrNull()
+                val n = steps.toIntOrNull()
+                if (start == null || step == null || perStep == null || n == null || start <= 0 || perStep < 1 || n < 1) {
+                    error = "Fyll inn gyldige tall"
+                    return@TextButton
+                }
+                val minute = timeState.hour * 60 + timeState.minute
+                val today = LocalDate.now().toEpochDay()
+                val rows = (0 until n).mapNotNull { k ->
+                    val amt = start - k * step
+                    if (amt <= 0) return@mapNotNull null // stop once the dose would hit zero
+                    DoseTime(
+                        medId = medId,
+                        minuteOfDay = minute,
+                        amount = amt,
+                        daysOfWeekMask = 0x7F,
+                        startEpochDay = today + k.toLong() * perStep,
+                        endEpochDay = today + (k + 1).toLong() * perStep - 1,
+                    )
+                }
+                scope.launch {
+                    rows.forEach { db.doseTimeDao().insert(it) }
+                    onSaved()
+                }
+            }) { Text("Opprett ${steps.toIntOrNull() ?: 0} trinn") }
+        },
+        dismissButton = { TextButton(onClick = onDismiss) { Text("Avbryt") } },
+    )
 }
 
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalLayoutApi::class)
@@ -353,12 +450,23 @@ private fun DoseTimeEditorDialog(
     var intervalMode by remember { mutableStateOf((existing?.intervalDays ?: 0) > 1) }
     var mask by remember { mutableStateOf(existing?.daysOfWeekMask ?: 0x7F) }
     var intervalDays by remember { mutableStateOf((existing?.intervalDays ?: 2).coerceAtLeast(2).toString()) }
+    val existingCyclic = (existing?.cycleLengthDays ?: 0) > 0
+    var cyclic by remember { mutableStateOf(existingCyclic) }
+    var onDays by remember { mutableStateOf((if (existingCyclic) existing!!.cycleActiveDays else 21).toString()) }
+    var offDays by remember {
+        mutableStateOf((if (existingCyclic) existing!!.cycleLengthDays - existing.cycleActiveDays else 7).toString())
+    }
 
     AlertDialog(
         onDismissRequest = onDismiss,
         title = { Text(if (existing == null) "Ny doseringstid" else "Rediger doseringstid") },
         text = {
-            Column(verticalArrangement = Arrangement.spacedBy(10.dp)) {
+            // Scrollable: the dialog now has time + amount + mode + cycle and would
+            // otherwise overflow on small screens.
+            Column(
+                modifier = Modifier.verticalScroll(rememberScrollState()),
+                verticalArrangement = Arrangement.spacedBy(10.dp),
+            ) {
                 TimePicker(state = timeState)
                 OutlinedTextField(
                     value = amount, onValueChange = { amount = it },
@@ -399,12 +507,43 @@ private fun DoseTimeEditorDialog(
                             }
                     }
                 }
+
+                HorizontalDivider()
+                Row(
+                    verticalAlignment = Alignment.CenterVertically,
+                    modifier = Modifier.clickable { cyclic = !cyclic },
+                ) {
+                    Checkbox(checked = cyclic, onCheckedChange = { cyclic = it })
+                    Text("Syklisk (på/av-perioder)")
+                }
+                if (cyclic) {
+                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        OutlinedTextField(
+                            value = onDays, onValueChange = { onDays = it },
+                            label = { Text("Dager på") }, singleLine = true, modifier = Modifier.weight(1f),
+                        )
+                        OutlinedTextField(
+                            value = offDays, onValueChange = { offDays = it },
+                            label = { Text("Dager av") }, singleLine = true, modifier = Modifier.weight(1f),
+                        )
+                    }
+                    Text(
+                        "F.eks. 21 på / 7 av. Syklusen starter i dag.",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
             }
         },
         confirmButton = {
             TextButton(onClick = {
                 val amt = parseAmount(amount) ?: return@TextButton
                 val interval = if (intervalMode) (intervalDays.toIntOrNull() ?: 2).coerceIn(2, 365) else 0
+                val on = onDays.toIntOrNull()?.coerceAtLeast(1) ?: 0
+                val off = offDays.toIntOrNull()?.coerceAtLeast(0) ?: 0
+                val cycleActive = if (cyclic && on > 0 && off > 0) on else 0
+                val cycleLength = if (cycleActive > 0) on + off else 0
+                val needsAnchor = intervalMode || cycleActive > 0
                 val dt = DoseTime(
                     id = existing?.id ?: 0,
                     medId = medId,
@@ -412,9 +551,13 @@ private fun DoseTimeEditorDialog(
                     amount = amt,
                     daysOfWeekMask = if (intervalMode) 0 else mask,
                     intervalDays = interval,
-                    anchorEpochDay = if (intervalMode) {
+                    anchorEpochDay = if (needsAnchor) {
                         existing?.anchorEpochDay ?: LocalDate.now().toEpochDay()
                     } else null,
+                    cycleActiveDays = cycleActive,
+                    cycleLengthDays = cycleLength,
+                    startEpochDay = existing?.startEpochDay,
+                    endEpochDay = existing?.endEpochDay,
                 )
                 scope.launch {
                     if (existing == null) db.doseTimeDao().insert(dt) else db.doseTimeDao().update(dt)
diff --git a/app/src/main/java/no/naiv/meddetsamme/ui/TodayScreen.kt b/app/src/main/java/no/naiv/meddetsamme/ui/TodayScreen.kt
index 5870c36..a1265e6 100644
--- a/app/src/main/java/no/naiv/meddetsamme/ui/TodayScreen.kt
+++ b/app/src/main/java/no/naiv/meddetsamme/ui/TodayScreen.kt
@@ -109,7 +109,7 @@ fun TodayScreen(nav: Nav) {
                     val atMillis = at.atZone(zone).toInstant().toEpochMilli()
                     rows += TodayDose(med, dt, at, logs.find { it.doseTimeId == dt.id && it.scheduledAtMillis == atMillis })
                 }
-                ratePerItem.merge(med.item.id, ScheduleEngine.dailyConsumption(doseTimes), Double::plus)
+                ratePerItem.merge(med.item.id, ScheduleEngine.dailyConsumption(doseTimes, today), Double::plus)
             }
             for (item in meds.map { it.item }.distinctBy { it.id }) {
                 val rate = ratePerItem[item.id] ?: 0.0
diff --git a/app/src/test/java/no/naiv/meddetsamme/domain/ScheduleEngineTest.kt b/app/src/test/java/no/naiv/meddetsamme/domain/ScheduleEngineTest.kt
index 430f498..4988276 100644
--- a/app/src/test/java/no/naiv/meddetsamme/domain/ScheduleEngineTest.kt
+++ b/app/src/test/java/no/naiv/meddetsamme/domain/ScheduleEngineTest.kt
@@ -28,6 +28,10 @@ class ScheduleEngineTest {
         mask: Int = 0x7F,
         intervalDays: Int = 0,
         anchorEpochDay: Long? = null,
+        cycleActiveDays: Int = 0,
+        cycleLengthDays: Int = 0,
+        startEpochDay: Long? = null,
+        endEpochDay: Long? = null,
         id: Long = 1,
     ) = DoseTime(
         id = id,
@@ -37,6 +41,10 @@ class ScheduleEngineTest {
         daysOfWeekMask = mask,
         intervalDays = intervalDays,
         anchorEpochDay = anchorEpochDay,
+        cycleActiveDays = cycleActiveDays,
+        cycleLengthDays = cycleLengthDays,
+        startEpochDay = startEpochDay,
+        endEpochDay = endEpochDay,
     )
 
     private fun at(date: LocalDate, hour: Int, minute: Int = 0): LocalDateTime =
@@ -142,6 +150,78 @@ class ScheduleEngineTest {
         assertFalse(ScheduleEngine.occursOn(dt, wednesday.minusDays(2))) // before anchor
     }
 
+    // ---- cyclic (N on / M off) -------------------------------------------
+
+    @Test
+    fun `cyclic 21 of 28 is on during the active window and off after`() {
+        // Daily, anchored on Wednesday, 21 active days of a 28-day cycle.
+        val dt = doseTime(anchorEpochDay = wednesday.toEpochDay(), cycleActiveDays = 21, cycleLengthDays = 28)
+        assertTrue(ScheduleEngine.occursOn(dt, wednesday)) // day 0
+        assertTrue(ScheduleEngine.occursOn(dt, wednesday.plusDays(20))) // last active day
+        assertFalse(ScheduleEngine.occursOn(dt, wednesday.plusDays(21))) // first off day
+        assertFalse(ScheduleEngine.occursOn(dt, wednesday.plusDays(27))) // last off day
+        assertTrue(ScheduleEngine.occursOn(dt, wednesday.plusDays(28))) // next cycle, day 0
+    }
+
+    @Test
+    fun `cyclic does not fire before its anchor`() {
+        val dt = doseTime(anchorEpochDay = wednesday.toEpochDay(), cycleActiveDays = 21, cycleLengthDays = 28)
+        assertFalse(ScheduleEngine.occursOn(dt, wednesday.minusDays(1)))
+    }
+
+    @Test
+    fun `nextOccurrence jumps across the cyclic off window`() {
+        // From the last active day, the next dose is at the start of the next cycle.
+        val dt = doseTime(anchorEpochDay = wednesday.toEpochDay(), cycleActiveDays = 21, cycleLengthDays = 28)
+        val next = ScheduleEngine.nextOccurrence(dt, at(wednesday.plusDays(20), 12, 0))
+        assertEquals(at(wednesday.plusDays(28), 8), next) // 7-day gap skipped
+    }
+
+    @Test
+    fun `full active span means no cycle filtering`() {
+        // active >= length is degenerate → behaves as a plain daily dose.
+        val dt = doseTime(anchorEpochDay = wednesday.toEpochDay(), cycleActiveDays = 28, cycleLengthDays = 28)
+        assertTrue(ScheduleEngine.occursOn(dt, wednesday.plusDays(25)))
+    }
+
+    // ---- validity window (taper rows) ------------------------------------
+
+    @Test
+    fun `validity window bounds occurrences inclusively`() {
+        val dt = doseTime(
+            startEpochDay = wednesday.toEpochDay(),
+            endEpochDay = wednesday.plusDays(2).toEpochDay(),
+        )
+        assertFalse(ScheduleEngine.occursOn(dt, wednesday.minusDays(1)))
+        assertTrue(ScheduleEngine.occursOn(dt, wednesday)) // start, inclusive
+        assertTrue(ScheduleEngine.occursOn(dt, wednesday.plusDays(2))) // end, inclusive
+        assertFalse(ScheduleEngine.occursOn(dt, wednesday.plusDays(3)))
+    }
+
+    @Test
+    fun `nextOccurrence is null once the window has elapsed`() {
+        val dt = doseTime(endEpochDay = wednesday.minusDays(1).toEpochDay())
+        assertNull(ScheduleEngine.nextOccurrence(dt, at(wednesday, 6, 0)))
+    }
+
+    @Test
+    fun `nextOccurrence waits for a future window start`() {
+        val dt = doseTime(startEpochDay = saturday.toEpochDay())
+        val next = ScheduleEngine.nextOccurrence(dt, at(wednesday, 6, 0))
+        assertEquals(at(saturday, 8), next)
+    }
+
+    @Test
+    fun `taper as adjacent windowed rows yields the right amount each day`() {
+        // 4 mg for 3 days, then 2 mg for 3 days — two rows, descending, adjacent.
+        val step1 = doseTime(amount = 4.0, startEpochDay = wednesday.toEpochDay(), endEpochDay = wednesday.plusDays(2).toEpochDay(), id = 1)
+        val step2 = doseTime(amount = 2.0, startEpochDay = wednesday.plusDays(3).toEpochDay(), endEpochDay = wednesday.plusDays(5).toEpochDay(), id = 2)
+        val rows = listOf(step1, step2)
+        assertEquals(4.0, ScheduleEngine.occurrencesOn(rows, wednesday).single().first.amount, 0.0)
+        assertEquals(2.0, ScheduleEngine.occurrencesOn(rows, wednesday.plusDays(4)).single().first.amount, 0.0)
+        assertTrue(ScheduleEngine.occurrencesOn(rows, wednesday.plusDays(6)).isEmpty())
+    }
+
     // ---- multiple dose-times --------------------------------------------
 
     @Test
@@ -167,13 +247,26 @@ class ScheduleEngineTest {
     fun `daily consumption sums weekly rows`() {
         // 1.0 every day + 0.5 Mon/Wed/Fri (bits 1,3,5 = 0x2A)
         val rows = listOf(doseTime(amount = 1.0), doseTime(amount = 0.5, mask = 0x2A, id = 2))
-        assertEquals(1.0 + 0.5 * 3 / 7.0, ScheduleEngine.dailyConsumption(rows), 1e-9)
+        assertEquals(1.0 + 0.5 * 3 / 7.0, ScheduleEngine.dailyConsumption(rows, wednesday), 1e-9)
     }
 
     @Test
     fun `daily consumption for every-N-days divides by N`() {
         val rows = listOf(doseTime(amount = 1.5, intervalDays = 3, anchorEpochDay = 0))
-        assertEquals(0.5, ScheduleEngine.dailyConsumption(rows), 1e-9)
+        assertEquals(0.5, ScheduleEngine.dailyConsumption(rows, wednesday), 1e-9)
+    }
+
+    @Test
+    fun `daily consumption scales by cycle and ignores rows outside window`() {
+        // Daily 1.0 but 21/28 cyclic → 1.0 × 21/28 = 0.75
+        val cyclic = doseTime(amount = 1.0, anchorEpochDay = 0, cycleActiveDays = 21, cycleLengthDays = 28)
+        assertEquals(0.75, ScheduleEngine.dailyConsumption(listOf(cyclic), wednesday), 1e-9)
+        // A taper row whose window has elapsed contributes nothing.
+        val expired = doseTime(amount = 4.0, endEpochDay = wednesday.toEpochDay() - 1)
+        assertEquals(0.0, ScheduleEngine.dailyConsumption(listOf(expired), wednesday), 1e-9)
+        // …and one not yet started likewise.
+        val future = doseTime(amount = 4.0, startEpochDay = wednesday.toEpochDay() + 1)
+        assertEquals(0.0, ScheduleEngine.dailyConsumption(listOf(future), wednesday), 1e-9)
     }
 
     @Test