diff --git a/controller/src/emit/asapquery_backend.rs b/controller/src/emit/asapquery_backend.rs
index 61d1d16ef..16eed5549 100644
--- a/controller/src/emit/asapquery_backend.rs
+++ b/controller/src/emit/asapquery_backend.rs
@@ -10,13 +10,18 @@
 //!     `processors: { ddsketch_merge: {...} }` + `service.pipelines`.
 //!   * `config::asapquery_backend` (this module) — ASAPQuery-backend
 //!     query engine, expects
-//!     `aggregations: [{ aggregationId, aggregationType, metric, labels,
-//!                       parameters, windowSize, windowType, spatialFilter }]`.
+//!     `aggregations: [{ aggregationType, metric, labels, parameters,
+//!                       windowSize, windowType, spatialFilter }]`.
 //!
 //! Both are generated from the same `CollectionPlan` fields but target
 //! different services. The replanner pushes the OTel YAML via OpAMP to
 //! backend-role collectors and pushes this one via HTTP to the
 //! ASAPQuery-backend's `/api/v1/streaming-config` endpoint.
+//!
+//! Phase 5 M2.2: this emitter no longer writes `aggregationId`. The
+//! backend's `AggregationConfig::from_yaml_data` derives one
+//! deterministically via `compute_agg_config_id` from the same set of
+//! fields we emit, so the explicit field is redundant.
 
 use std::time::Duration;
 
@@ -24,21 +29,6 @@ use anyhow::{Context, Result};
 
 use crate::types::{AgentCollectorConfig, CollectionPlan, SketchType};
 
-/// Stable aggregation ID used when the planner has no explicit id to
-/// assign. The ASAPQuery-backend uses `u64` agg IDs; we derive one
-/// deterministically from the metric name so the same metric always
-/// maps to the same id across successive pushes (otherwise the backend
-/// would grow unbounded as each replan introduces a new agg_id).
-pub fn deterministic_agg_id(metric: &str) -> u64 {
-    use std::collections::hash_map::DefaultHasher;
-    use std::hash::{Hash, Hasher};
-    let mut h = DefaultHasher::new();
-    metric.hash(&mut h);
-    // Bias away from 0 so the id space is [1, u64::MAX]; 0 is reserved
-    // in some of the backend's existing test fixtures as a sentinel.
-    h.finish().saturating_add(1)
-}
-
 /// Generate the `StreamingConfig` YAML for the ASAPQuery-backend from a
 /// single-metric `CollectionPlan`. Produces a one-element `aggregations`
 /// list — the backend's endpoint will merge this into its active config
@@ -73,10 +63,6 @@ pub fn generate_streaming_config_yaml(metric: &str, plan: &CollectionPlan) -> Re
     let agg_type_str = map_sketch_type_to_agg_type(&agg.sketch_type);
 
     let aggregation = serde_yaml::Mapping::from_iter([
-        (
-            serde_yaml::Value::from("aggregationId"),
-            serde_yaml::Value::from(deterministic_agg_id(metric)),
-        ),
         (
             serde_yaml::Value::from("aggregationType"),
             serde_yaml::Value::from(agg_type_str),
@@ -218,18 +204,15 @@ mod tests {
     }
 
     #[test]
-    fn deterministic_id_is_stable_across_calls() {
-        assert_eq!(
-            deterministic_agg_id("cpu_usage"),
-            deterministic_agg_id("cpu_usage")
-        );
-        assert_ne!(
-            deterministic_agg_id("cpu_usage"),
-            deterministic_agg_id("mem_usage")
+    fn emitted_yaml_omits_aggregation_id() {
+        let plan = dummy_plan(SketchType::DDSketch);
+        let yaml = generate_streaming_config_yaml("cpu_usage", &plan).expect("yaml ok");
+        let parsed: serde_yaml::Value = serde_yaml::from_str(&yaml).expect("re-parse ok");
+        let a = &parsed["aggregations"][0];
+        assert!(
+            a["aggregationId"].is_null(),
+            "controller must not emit aggregationId — backend derives it from content (M2.2)"
         );
-        // Id is biased away from 0 so test fixtures that use 0 as a
-        // sentinel don't accidentally collide.
-        assert_ne!(deterministic_agg_id("any"), 0);
     }
 
     #[test]
diff --git a/data_plane/src/query_engines/asap_query_engine/engine.rs b/data_plane/src/query_engines/asap_query_engine/engine.rs
index d255b1591..0b29f2d54 100644
--- a/data_plane/src/query_engines/asap_query_engine/engine.rs
+++ b/data_plane/src/query_engines/asap_query_engine/engine.rs
@@ -5003,9 +5003,12 @@ mod e2e_feedback_loop_tests {
         //    that covers the requested metric. This mirrors DC's
         //    replanner running and POSTing via its BackendClient.
         let mock = Arc::new(InProcessMockController::new(hot_reload.clone(), |req| {
-            // Use a deterministic agg_id derived from the metric
-            // name (same strategy as DC's
-            // asapquery_backend::deterministic_agg_id from PR #156).
+            // Mock controller mints an explicit id here just to keep
+            // the test self-contained. In production, the
+            // `controller::emit::asapquery_backend` emitter no longer
+            // writes `aggregationId` (M2.2) and the backend derives
+            // one via `compute_agg_config_id`; explicit ids in the
+            // YAML are still honored for backwards compatibility.
             let id: u64 = {
                 use std::collections::hash_map::DefaultHasher;
                 use std::hash::{Hash, Hasher};
@@ -5092,9 +5095,9 @@ mod e2e_feedback_loop_tests {
         assert_eq!(recorded[0].statistics, vec![Statistic::Sum]);
         assert_eq!(recorded[0].data_range_ms, Some(60_000));
 
-        // 9. And the aggregation_id is the deterministic hash the
-        //    planner produced — not a random value. This pins the
-        //    DC #156 deterministic_agg_id contract.
+        // 9. And the aggregation_id is the deterministic value the
+        //    mock controller produced — not a random one. Explicit
+        //    ids in YAML are still honored after M2.2.
         let new_ids: Vec<u64> = snap_after.aggregation_configs.keys().copied().collect();
         assert_eq!(new_ids.len(), 1);
         let id = new_ids[0];
@@ -5109,7 +5112,7 @@ mod e2e_feedback_loop_tests {
         };
         assert_eq!(
             id, expected_id,
-            "deterministic_agg_id contract: same metric → same id"
+            "explicit YAML aggregationId honored unchanged"
         );
     }