[verified] fix: preserve tracker precision eligibility

.scratch/routing-compatibility-regression/prd.json

@@ -0,0 +1,29 @@
+{
+  "name": "Legacy routing compatibility regression",
+  "description": "Restore compat-policy routing for legacy node registrations that omit quantization without weakening validation for invalid declared values.",
+  "branchName": "ralph/routing-compatibility-regression",
+  "userStories": [
+    {
+      "id": "RCR-001",
+      "title": "Legacy registration precision fallback",
+      "description": "As an operator upgrading a mixed fleet, I need nodes that predate the quantization registration field to serve default-precision requests under compat, so otherwise healthy legacy nodes do not become dark.",
+      "acceptanceCriteria": [
+        "A legacy registration without quantization is eligible for a bfloat16 request when capability policy is compat.",
+        "The same registration is excluded under capability policy enforce because its capability report is absent.",
+        "A node that explicitly declares null, an invalid, or an unsupported quantization remains excluded from routing, assignment, and coverage calculations, including after managed shard assignment/rebalancing.",
+        "Raft-applied registrations preserve both singular quantization and plural quantizations so follower routing matches leader routing.",
+        "Automatic proxy routing, pinned routes, manual benchmarks, billing proxy paths, and route-latency sampling retain their existing behavior for legacy registrations.",
+        "Tests cover the legacy/no-field case and explicit-invalid-field case at the tracker HTTP seam.",
+        "Targeted routing, billing, benchmark, pricing, validation, and latency tests pass.",
+        "python -m pytest -q is run and unrelated failures are recorded exactly."
+      ],
+      "priority": 1,
+      "passes": true,
+      "dependsOn": [],
+      "completionNotes": "Completed by agent"
+    }
+  ],
+  "metadata": {
+    "updatedAt": "2026-07-13T07:25:08.460Z"
+  }
+}