feat(tracking): ship the shell rebuild — k8s replicas 3 + REDIS_ONLY + HPA, partitioned ingest live

- deploy/k8s/25-tracking-orders.yaml: SHELL-REBUILD gating removed (LIVE) —
  replicas 3 + RollingUpdate, actor-pool=tracking label + POD_IP/NAMESPACE,
  REDIS_ONLY=1, TRACKING_PARTITIONS=16, HPA 3..12
- deploy/k8s/00-namespace-config.yaml: tracking PVC note → rebuild live (mount
  vestigial, kept for rollback)
- deploy/docker-compose.yml: TRACKING_PARTITIONS=16 on the reader producer +
  tracking consumer (partitioned ingest in the dev stack too)
- deploy/k8s/build-push.sh: gocartactor named context for the tracking image
- platform: rabbit.PublishEventTo (caller routing key) + event.PartitionOf /
  PartitionRoutingKey (shared §8 fnv1a hash) + tests
- docs: plan-tracking-shell-rebuild.md (config write half, pod-watcher
  assignment, real-AOF tape gate, R6 re-measure), status.md, CONTEXT,
  event-sourcing-stance, platform-architecture-review, read-model-projections;
  scripts/load-test-coordinator.sh
- submodules: slask-tracking ecbf894 (shell rebuild), slask-finder 84f7ff7
  (§8 partition-routed producer)

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

event/partition.go

@@ -0,0 +1,30 @@
+package event
+
+import (
+	"hash/fnv"
+	"strconv"
+)
+
+// PartitionOf maps a stable key (sessionId / listId / sendID, stringified) to a
+// partition index in [0, n) for the track.partition.{N} ingest scheme
+// (slask-tracking shell-rebuild §8). fnv1a-64 over the key bytes, so producers
+// (slask-finder's track.* publisher, slask-tracking's HTTP beacon edge) and
+// consumers agree on the routing without sharing app code. n <= 1 is a single
+// partition (index 0).
+func PartitionOf(key string, n int) int {
+	if n <= 1 {
+		return 0
+	}
+	h := fnv.New64a()
+	_, _ = h.Write([]byte(key))
+	return int(h.Sum64() % uint64(n))
+}
+
+// PartitionRoutingKey is the queue AND routing key for partition i: the queue
+// track.partition.{i} binds to the catalog exchange with the same key, so a
+// producer routing to track.partition.{i} lands on exactly that queue. This is
+// the shared name both the slask-finder producer and the slask-tracking
+// consumer use, so the partition→queue→consumer map is observable and stable.
+func PartitionRoutingKey(i int) string {
+	return "track.partition." + strconv.Itoa(i)
+}

event/partition_test.go

@@ -0,0 +1,36 @@
+package event
+
+import "testing"
+
+func TestPartitionOf_DeterministicInRange(t *testing.T) {
+	const n = 16
+	for _, key := range []string{"0", "1", "42", "9007199254740993", "sendA", "list-7"} {
+		first := PartitionOf(key, n)
+		if first < 0 || first >= n {
+			t.Fatalf("PartitionOf(%q, %d) = %d, out of range", key, n, first)
+		}
+		if again := PartitionOf(key, n); again != first {
+			t.Fatalf("PartitionOf(%q, %d) not deterministic: %d vs %d", key, n, first, again)
+		}
+	}
+}
+
+func TestPartitionOf_SameKeySamePartition(t *testing.T) {
+	// A session's sessionId must pin every beacon to one partition (per-session
+	// FIFO): the same key always hashes to the same partition across callers.
+	if PartitionOf("123456789", 32) != PartitionOf("123456789", 32) {
+		t.Fatal("same key mapped to different partitions")
+	}
+}
+
+func TestPartitionOf_SinglePartition(t *testing.T) {
+	if PartitionOf("anything", 1) != 0 || PartitionOf("anything", 0) != 0 {
+		t.Fatal("n <= 1 must collapse to partition 0")
+	}
+}
+
+func TestPartitionRoutingKey(t *testing.T) {
+	if got := PartitionRoutingKey(7); got != "track.partition.7" {
+		t.Fatalf("PartitionRoutingKey(7) = %q", got)
+	}
+}