diff --git a/src/hypofuzz/dashboard/dashboard.py b/src/hypofuzz/dashboard/dashboard.py
index 8ed2acb9..55965b39 100644
--- a/src/hypofuzz/dashboard/dashboard.py
+++ b/src/hypofuzz/dashboard/dashboard.py
@@ -208,7 +208,8 @@ async def initial(self, tests: dict[str, Test]) -> None:
             }
             await self.send_event(report_event)
 
-        # then its observations.
+        # then its observations, sending the observations (without their repr)
+        # first, followed by the repr of each observation.
         for obs_type, observations in [
             ("rolling", test.rolling_observations),
             ("corpus", test.corpus_observations),
@@ -224,6 +225,26 @@ async def initial(self, tests: dict[str, Test]) -> None:
                 },
             )
 
+        for obs_type, observations in [
+            ("rolling", test.rolling_observations),
+            ("corpus", test.corpus_observations),
+        ]:
+            await self.send_event(
+                {
+                    "type": DashboardEventType.SET_OBSERVATION_REPRS,
+                    "nodeid": self.nodeid,
+                    "observation_type": obs_type,  # type: ignore
+                    "representations": [
+                        {
+                            # using run_start as the observation primary key
+                            "run_start": obs.run_start,
+                            "repr": obs.representation,
+                        }
+                        for obs in observations
+                    ],
+                },
+            )
+
     async def on_event(
         self, event_type: Literal["save", "delete"], key: DatabaseEventKey, value: Any
     ) -> None:
diff --git a/src/hypofuzz/dashboard/models.py b/src/hypofuzz/dashboard/models.py
index f759c809..54ced898 100644
--- a/src/hypofuzz/dashboard/models.py
+++ b/src/hypofuzz/dashboard/models.py
@@ -14,7 +14,7 @@ class DashboardObservation(TypedDict):
     type: str
     status: ObservationStatus
     status_reason: str
-    representation: str
+    representation: None
     arguments: dict[str, Any]
     how_generated: str
     features: dict[str, Any]
@@ -29,7 +29,8 @@ def dashboard_observation(observation: Observation) -> DashboardObservation:
         "type": observation.type,
         "status": observation.status,
         "status_reason": observation.status_reason,
-        "representation": observation.representation,
+        # explicitly dropping representation
+        "representation": None,
         "arguments": observation.arguments,
         "how_generated": observation.how_generated,
         "features": observation.features,
@@ -69,7 +70,8 @@ class DashboardEventType(IntEnum):
     ADD_TESTS = 1
     ADD_REPORTS = 2
     ADD_OBSERVATIONS = 3
-    SET_FAILURE = 4
+    SET_OBSERVATION_REPRS = 4
+    SET_FAILURE = 5
 
 
 ObservationType = Literal["rolling", "corpus"]
@@ -101,6 +103,15 @@ class AddObservationsEvent(TypedDict):
     observations: list[DashboardObservation]
 
 
+class SetObservationReprsEvent(TypedDict):
+    type: Literal[DashboardEventType.SET_OBSERVATION_REPRS]
+    nodeid: str
+    # TODO we might want to make this names shorter (obs_type / reprs) for json
+    # size
+    observation_type: ObservationType
+    representations: list[dict[str, Any]]
+
+
 class SetFailureEvent(TypedDict):
     type: Literal[DashboardEventType.SET_FAILURE]
     failure: DashboardObservation
@@ -110,5 +121,6 @@ class SetFailureEvent(TypedDict):
     AddTestsEvent,
     AddReportsEvent,
     AddObservationsEvent,
+    SetObservationReprsEvent,
     SetFailureEvent,
 ]
diff --git a/src/hypofuzz/frontend/src/context/DataProvider.tsx b/src/hypofuzz/frontend/src/context/DataProvider.tsx
index f324a52a..18e986b9 100644
--- a/src/hypofuzz/frontend/src/context/DataProvider.tsx
+++ b/src/hypofuzz/frontend/src/context/DataProvider.tsx
@@ -23,7 +23,8 @@ enum DashboardEventType {
   ADD_TESTS = 1,
   ADD_REPORTS = 2,
   ADD_OBSERVATIONS = 3,
-  SET_FAILURE = 4,
+  SET_OBSERVATION_REPRS = 4,
+  SET_FAILURE = 5,
 }
 
 type TestsAction =
@@ -48,6 +49,12 @@ type TestsAction =
       observation_type: "rolling" | "corpus"
       observations: Observation[]
     }
+  | {
+      type: DashboardEventType.SET_OBSERVATION_REPRS
+      nodeid: string
+      observation_type: "rolling" | "corpus"
+      representations: { run_start: number; representation: string }[]
+    }
 
 function testsReducer(
   state: Map<string, Test>,
@@ -110,6 +117,20 @@ function testsReducer(
       return newState
     }
 
+    case DashboardEventType.SET_OBSERVATION_REPRS: {
+      const { nodeid, observation_type, representations } = action
+      const test = getOrCreateTest(nodeid)
+      const observations =
+        observation_type === "rolling"
+          ? test.rolling_observations
+          : test.corpus_observations
+      for (const { run_start, representation } of representations) {
+        const observation = observations.find(o => o.run_start === run_start)!
+        observation.representation = representation
+      }
+      return newState
+    }
+
     default:
       throw new Error("non-exhaustive switch in testsReducer")
   }
@@ -250,6 +271,19 @@ export function DataProvider({ children }: DataProviderProps) {
           break
         }
 
+        case DashboardEventType.SET_OBSERVATION_REPRS: {
+          dispatch({
+            type: DashboardEventType.SET_OBSERVATION_REPRS,
+            nodeid: data.nodeid,
+            observation_type: data.observation_type,
+            representations: data.representations.map((r: any) => ({
+              run_start: Number(r.run_start),
+              representation: r.repr,
+            })),
+          })
+          break
+        }
+
         default:
           throw new Error(`Unknown event type: ${data.type}`)
       }
diff --git a/src/hypofuzz/frontend/src/tyche/Representation.tsx b/src/hypofuzz/frontend/src/tyche/Representation.tsx
index 80ebc581..daebb3b7 100644
--- a/src/hypofuzz/frontend/src/tyche/Representation.tsx
+++ b/src/hypofuzz/frontend/src/tyche/Representation.tsx
@@ -52,6 +52,9 @@ export function Representation({ observations, observationType }: Props) {
   const rawRepresentations = new Map<string, number>()
   observations.forEach(observation => {
     const repr = observation.representation
+    if (repr === null) {
+      return
+    }
     rawRepresentations.set(repr, (rawRepresentations.get(repr) || 0) + 1)
   })
 
diff --git a/src/hypofuzz/frontend/src/tyche/Samples.tsx b/src/hypofuzz/frontend/src/tyche/Samples.tsx
index 1fa36293..ce86befb 100644
--- a/src/hypofuzz/frontend/src/tyche/Samples.tsx
+++ b/src/hypofuzz/frontend/src/tyche/Samples.tsx
@@ -15,16 +15,25 @@ export function Samples({ observations }: { observations: Observation[] }) {
   // unique observation for that representation.
   const uniqueReprIndex = new Map<string, number>()
   for (const [index, observation] of observations.entries()) {
+    if (observation.representation === null) {
+      continue
+    }
     uniqueReprIndex.set(observation.representation, index)
   }
 
   function isUnique(observation: Observation) {
+    if (observation.representation === null) {
+      return false
+    }
     return (
       observations.indexOf(observation) ===
       uniqueReprIndex.get(observation.representation)
     )
   }
   function isDuplicate(observation: Observation) {
+    if (observation.representation === null) {
+      return false
+    }
     return (
       observations.indexOf(observation) !==
       uniqueReprIndex.get(observation.representation)
diff --git a/src/hypofuzz/frontend/src/types/dashboard.ts b/src/hypofuzz/frontend/src/types/dashboard.ts
index a3f07609..e3d6b3b6 100644
--- a/src/hypofuzz/frontend/src/types/dashboard.ts
+++ b/src/hypofuzz/frontend/src/types/dashboard.ts
@@ -162,7 +162,7 @@ export class Observation extends Dataclass<Observation> {
     public type: string,
     public status: ObservationStatus,
     public status_reason: string,
-    public representation: string,
+    public representation: string | null,
     // arguments is a reserved keyword in javascript
     public arguments_: Map<string, any>,
     public how_generated: string,
diff --git a/src/hypofuzz/hypofuzz.py b/src/hypofuzz/hypofuzz.py
index 3a5efce0..e41a8fb3 100644
--- a/src/hypofuzz/hypofuzz.py
+++ b/src/hypofuzz/hypofuzz.py
@@ -478,6 +478,8 @@ def callback(test_case: dict) -> None:
             # re-use per FuzzProcess. Overwrite with the current timestamp for use
             # in sorting observations. This is not perfectly reliable in a
             # distributed setting, but is good enough.
+            #
+            # We also re-use this as the primary key for this observation.
             test_case["run_start"] = time.time()
             # "arguments" duplicates part of the call repr in "representation".
             # We don't use this for anything, so drop it.