diff --git a/asap-query-engine/src/stores/sketch_db/simple_map_store/global.rs b/asap-query-engine/src/stores/sketch_db/simple_map_store/global.rs
index adabdf5a..ac551e00 100644
--- a/asap-query-engine/src/stores/sketch_db/simple_map_store/global.rs
+++ b/asap-query-engine/src/stores/sketch_db/simple_map_store/global.rs
@@ -695,4 +695,34 @@ impl Store for SimpleMapStoreGlobal {
         info!("SimpleMapStoreGlobal closed");
         Ok(())
     }
+
+    fn drop_agg_id(&self, agg_id: u64) -> StoreResult<usize> {
+        let mut data = self.lock.lock().unwrap();
+        // Count windows before eviction so callers get an accurate
+        // "records dropped" number, useful for audit logging.
+        let evicted = data
+            .stores
+            .get(&agg_id)
+            .map(|per_key| {
+                per_key.current_epoch.len()
+                    + per_key
+                        .sealed_epochs
+                        .values()
+                        .map(|e| e.entries.len())
+                        .sum::<usize>()
+            })
+            .unwrap_or(0);
+        data.stores.remove(&agg_id);
+        data.read_counts.remove(&agg_id);
+        data.earliest_timestamp_per_aggregation_id.remove(&agg_id);
+        // `metrics` and `items_inserted` are keyed by metric name,
+        // not agg_id, so we don't touch them — other agg_ids for the
+        // same metric (e.g. historical schemas) may still exist.
+        info!(
+            agg_id,
+            evicted_windows = evicted,
+            "SimpleMapStoreGlobal::drop_agg_id"
+        );
+        Ok(evicted)
+    }
 }
diff --git a/asap-query-engine/src/stores/sketch_db/simple_map_store/mod.rs b/asap-query-engine/src/stores/sketch_db/simple_map_store/mod.rs
index 5caab2cf..3319a991 100644
--- a/asap-query-engine/src/stores/sketch_db/simple_map_store/mod.rs
+++ b/asap-query-engine/src/stores/sketch_db/simple_map_store/mod.rs
@@ -161,4 +161,158 @@ impl Store for SimpleMapStore {
             SimpleMapStore::PerKey(store) => store.close(),
         }
     }
+
+    fn drop_agg_id(&self, agg_id: u64) -> StoreResult<usize> {
+        match self {
+            SimpleMapStore::Global(store) => store.drop_agg_id(agg_id),
+            SimpleMapStore::PerKey(store) => store.drop_agg_id(agg_id),
+        }
+    }
+}
+
+#[cfg(test)]
+mod drop_agg_id_tests {
+    use super::*;
+    use crate::data_model::AggregationType;
+    use crate::precompute_operators::SumAccumulator;
+    use asap_types::aggregation_config::AggregationConfig;
+    use asap_types::enums::WindowType;
+    use promql_utilities::data_model::key_by_label_names::KeyByLabelNames;
+
+    fn two_agg_streaming_config() -> Arc<StreamingConfig> {
+        let cfg = |id: u64| AggregationConfig {
+            aggregation_id: id,
+            aggregation_type: AggregationType::Sum,
+            aggregation_sub_type: String::new(),
+            parameters: HashMap::new(),
+            grouping_labels: KeyByLabelNames::empty(),
+            aggregated_labels: KeyByLabelNames::empty(),
+            rollup_labels: KeyByLabelNames::empty(),
+            original_yaml: String::new(),
+            window_size: 1,
+            slide_interval: 1,
+            window_type: WindowType::Tumbling,
+            spatial_filter: String::new(),
+            spatial_filter_normalized: String::new(),
+            metric: format!("metric_{id}"),
+            num_aggregates_to_retain: None,
+            read_count_threshold: None,
+            table_name: None,
+            value_column: None,
+        };
+        let mut map = HashMap::new();
+        map.insert(1u64, cfg(1));
+        map.insert(2u64, cfg(2));
+        Arc::new(StreamingConfig::new(map))
+    }
+
+    fn write_one(store: &SimpleMapStore, agg_id: u64, value: f64, ts: u64) {
+        let acc = SumAccumulator::with_sum(value);
+        let output = PrecomputedOutput::new(ts, ts + 1000, None, agg_id);
+        store
+            .insert_precomputed_output(output, Box::new(acc))
+            .expect("insert ok");
+    }
+
+    fn total_buckets(store: &SimpleMapStore, metric: &str, agg_id: u64) -> usize {
+        let map = store
+            .query_precomputed_output(metric, agg_id, 0, u64::MAX / 2)
+            .expect("query ok");
+        map.values().map(|v| v.len()).sum()
+    }
+
+    fn make_store(strategy: LockStrategy) -> SimpleMapStore {
+        SimpleMapStore::new_with_strategy(
+            two_agg_streaming_config(),
+            CleanupPolicy::NoCleanup,
+            strategy,
+        )
+    }
+
+    #[test]
+    fn global_drop_removes_only_target_agg() {
+        let store = make_store(LockStrategy::Global);
+        write_one(&store, 1, 10.0, 0);
+        write_one(&store, 1, 20.0, 1_000);
+        write_one(&store, 1, 30.0, 2_000);
+        write_one(&store, 2, 99.0, 5_000);
+
+        assert_eq!(total_buckets(&store, "metric_1", 1), 3);
+        assert_eq!(total_buckets(&store, "metric_2", 2), 1);
+
+        let evicted = store.drop_agg_id(1).expect("drop ok");
+        assert_eq!(evicted, 3);
+
+        assert_eq!(total_buckets(&store, "metric_1", 1), 0);
+        assert_eq!(total_buckets(&store, "metric_2", 2), 1);
+    }
+
+    #[test]
+    fn global_drop_unknown_agg_is_noop_returns_zero() {
+        let store = make_store(LockStrategy::Global);
+        let evicted = store.drop_agg_id(999).expect("drop ok");
+        assert_eq!(evicted, 0);
+    }
+
+    #[test]
+    fn global_drop_clears_earliest_timestamp_index() {
+        let store = make_store(LockStrategy::Global);
+        write_one(&store, 1, 10.0, 100);
+        let before = store.get_earliest_timestamp_per_aggregation_id().unwrap();
+        assert!(before.contains_key(&1));
+
+        store.drop_agg_id(1).unwrap();
+
+        let after = store.get_earliest_timestamp_per_aggregation_id().unwrap();
+        assert!(!after.contains_key(&1));
+    }
+
+    #[test]
+    fn per_key_drop_removes_only_target_agg() {
+        let store = make_store(LockStrategy::PerKey);
+        write_one(&store, 1, 10.0, 0);
+        write_one(&store, 1, 20.0, 1_000);
+        write_one(&store, 2, 99.0, 5_000);
+
+        assert_eq!(total_buckets(&store, "metric_1", 1), 2);
+        assert_eq!(total_buckets(&store, "metric_2", 2), 1);
+
+        let evicted = store.drop_agg_id(1).expect("drop ok");
+        assert_eq!(evicted, 2);
+
+        assert_eq!(total_buckets(&store, "metric_1", 1), 0);
+        assert_eq!(total_buckets(&store, "metric_2", 2), 1);
+    }
+
+    #[test]
+    fn per_key_drop_unknown_agg_is_noop() {
+        let store = make_store(LockStrategy::PerKey);
+        let evicted = store.drop_agg_id(999).expect("drop ok");
+        assert_eq!(evicted, 0);
+    }
+
+    #[test]
+    fn per_key_drop_clears_earliest_timestamp_index() {
+        let store = make_store(LockStrategy::PerKey);
+        write_one(&store, 1, 10.0, 100);
+        let before = store.get_earliest_timestamp_per_aggregation_id().unwrap();
+        assert!(before.contains_key(&1));
+
+        store.drop_agg_id(1).unwrap();
+
+        let after = store.get_earliest_timestamp_per_aggregation_id().unwrap();
+        assert!(!after.contains_key(&1));
+    }
+
+    #[test]
+    fn drop_then_reinsert_behaves_as_fresh_agg() {
+        let store = make_store(LockStrategy::Global);
+        write_one(&store, 1, 10.0, 100);
+        store.drop_agg_id(1).unwrap();
+
+        write_one(&store, 1, 42.0, 500);
+        assert_eq!(total_buckets(&store, "metric_1", 1), 1);
+        let ts_map = store.get_earliest_timestamp_per_aggregation_id().unwrap();
+        assert_eq!(ts_map.get(&1).copied(), Some(500));
+    }
 }
diff --git a/asap-query-engine/src/stores/sketch_db/simple_map_store/per_key.rs b/asap-query-engine/src/stores/sketch_db/simple_map_store/per_key.rs
index 6e618811..dde41d7e 100644
--- a/asap-query-engine/src/stores/sketch_db/simple_map_store/per_key.rs
+++ b/asap-query-engine/src/stores/sketch_db/simple_map_store/per_key.rs
@@ -1008,6 +1008,40 @@ impl Store for SimpleMapStorePerKey {
         info!("SimpleMapStorePerKey closed");
         Ok(())
     }
+
+    fn drop_agg_id(&self, agg_id: u64) -> StoreResult<usize> {
+        // Count windows before eviction for the return value. Grab
+        // the shard's read lock to snapshot the count, then upgrade
+        // to a removal. DashMap::remove is atomic on the key — no
+        // global lock needed, so a concurrent insert for a
+        // different agg_id keeps running unblocked.
+        let evicted = match self.inner.store.get(&agg_id) {
+            Some(entry) => {
+                let data = entry.value().read().unwrap();
+                let count = data.current_epoch.len()
+                    + data
+                        .sealed_epochs
+                        .values()
+                        .map(|e| e.entries.len())
+                        .sum::<usize>();
+                drop(data);
+                drop(entry);
+                count
+            }
+            None => 0,
+        };
+        self.inner.store.remove(&agg_id);
+        self.inner.earliest_timestamps.remove(&agg_id);
+        // `metrics` and `items_inserted` are keyed by metric name,
+        // not agg_id, so we don't touch them — other agg_ids under
+        // the same metric stay live.
+        info!(
+            agg_id,
+            evicted_windows = evicted,
+            "SimpleMapStorePerKey::drop_agg_id"
+        );
+        Ok(evicted)
+    }
 }
 
 // =================================================================
diff --git a/asap-query-engine/src/stores/traits.rs b/asap-query-engine/src/stores/traits.rs
index 679568c3..dbd1de2e 100644
--- a/asap-query-engine/src/stores/traits.rs
+++ b/asap-query-engine/src/stores/traits.rs
@@ -57,6 +57,33 @@ pub trait Store: Send + Sync {
 
     /// Close the store and clean up resources
     fn close(&self) -> Result<(), Box<dyn std::error::Error + Send + Sync>>;
+
+    /// Drop every precompute record whose `aggregation_id` equals
+    /// `agg_id`, regardless of window or subpopulation key. Used by
+    /// the §6-driven `SchemaEvictionService` to reclaim space when
+    /// a retired schema passes its `expires_at_ms`.
+    ///
+    /// Returns the number of records removed (best-effort — a store
+    /// that can't easily count still returns 0 and logs, never
+    /// fails).
+    ///
+    /// Contract:
+    /// * Must be idempotent — calling on an unknown `agg_id` is a
+    ///   no-op that returns `Ok(0)`.
+    /// * Must be atomic AT LEAST with respect to concurrent reads
+    ///   for the same agg_id: a reader either sees all of the
+    ///   pre-drop records or none, not a half-dropped state. Stores
+    ///   backed by a single RwLock get this for free; stores with
+    ///   finer-grained locking may need to grab a global lock
+    ///   briefly.
+    /// * Does NOT touch any registry (backfill, schema); the caller
+    ///   is responsible for post-drop cleanup of those.
+    ///
+    /// Default impl returns `Ok(0)` so existing stores stay
+    /// compiling — the impl must override to actually delete.
+    fn drop_agg_id(&self, _agg_id: u64) -> Result<usize, Box<dyn std::error::Error + Send + Sync>> {
+        Ok(0)
+    }
 }
 
 /// Result type for store operations