diff --git a/crates/khive-pack-kg/src/handlers/common.rs b/crates/khive-pack-kg/src/handlers/common.rs
index d6ecdb510..b4d78bbb5 100644
--- a/crates/khive-pack-kg/src/handlers/common.rs
+++ b/crates/khive-pack-kg/src/handlers/common.rs
@@ -1047,6 +1047,70 @@ pub(crate) fn render_query_result(result: QueryResult) -> Value {
     Value::Object(out)
 }
 
+/// Name a JSON value's type the way a caller's schema names it.
+fn json_type_name(value: &Value) -> &'static str {
+    match value {
+        Value::Null => "null",
+        Value::Bool(_) => "boolean",
+        Value::Number(_) => "number",
+        Value::String(_) => "string",
+        Value::Array(_) => "array",
+        Value::Object(_) => "object",
+    }
+}
+
+/// Refuse a value for a parameter this pack declares as an object.
+///
+/// `param_type` is a promise to the caller and nothing was checking it. It is
+/// rendered into the JSON schema handed to a model and then never compared
+/// against the argument that arrives, so `properties: "not-an-object"` was
+/// accepted and persisted, and every later reader found a string where the
+/// schema said map. For an agent that is worse than a refusal: a success
+/// return gives it nothing to correct on, so it proceeds believing the write
+/// landed in the shape it intended.
+///
+/// Absent and explicit null are not type errors. Null is how a caller clears
+/// the field on the update path, and absent means unchanged.
+pub(crate) fn require_object_param(value: Option<&Value>, param: &str) -> Result<(), RuntimeError> {
+    match value {
+        None | Some(Value::Null) | Some(Value::Object(_)) => Ok(()),
+        Some(other) => Err(RuntimeError::InvalidInput(format!(
+            "{param} must be an object; got {}",
+            json_type_name(other)
+        ))),
+    }
+}
+
+#[cfg(test)]
+mod param_contract_tests {
+    use super::*;
+
+    #[test]
+    fn an_object_parameter_refuses_every_non_object_and_names_what_it_got() {
+        // The shape that was accepted and persisted.
+        let err = require_object_param(Some(&json!("not-an-object")), "properties")
+            .expect_err("a string is not an object");
+        let message = err.to_string();
+        assert!(message.contains("properties"), "{message}");
+        assert!(message.contains("string"), "names what arrived: {message}");
+
+        // An array is the near miss a caller is most likely to send next, so it
+        // must be refused by type rather than by a map-specific probe.
+        assert!(require_object_param(Some(&json!([1, 2])), "properties").is_err());
+        assert!(require_object_param(Some(&json!(7)), "properties").is_err());
+        assert!(require_object_param(Some(&json!(true)), "properties").is_err());
+    }
+
+    #[test]
+    fn absent_and_explicit_null_are_not_type_errors() {
+        // Absent means unchanged and null is how the update path clears a field;
+        // an implementation that refuses anything that is not an object breaks both.
+        require_object_param(None, "properties").expect("absent is allowed");
+        require_object_param(Some(&Value::Null), "properties").expect("null is allowed");
+        require_object_param(Some(&json!({"a": 1})), "properties").expect("an object is allowed");
+    }
+}
+
 #[cfg(test)]
 mod note_projection_tests {
     use super::*;
diff --git a/crates/khive-pack-kg/src/handlers/create.rs b/crates/khive-pack-kg/src/handlers/create.rs
index 1d757e780..b490982e0 100644
--- a/crates/khive-pack-kg/src/handlers/create.rs
+++ b/crates/khive-pack-kg/src/handlers/create.rs
@@ -155,6 +155,10 @@ impl KgPack {
                 let mut specs: Vec<EntityCreateSpec> = Vec::with_capacity(attempted);
                 let mut entity_type_normalized: Vec<Value> = Vec::new();
                 for (idx, entry) in entries.into_iter().enumerate() {
+                    super::common::require_object_param(
+                        entry.properties.as_ref(),
+                        &format!("items[{idx}].properties"),
+                    )?;
                     // Resolve the item's own kind.
                     let item_kind_spec = resolve_kind_spec(&entry.kind, registry).map_err(|e| {
                         RuntimeError::InvalidInput(format!("items[{idx}].kind: {e}"))
@@ -378,6 +382,7 @@ impl KgPack {
         }
 
         let p: CreateParams = deser(params.clone())?;
+        super::common::require_object_param(p.properties.as_ref(), "properties")?;
         if p.kind != "note" && (p.key.is_some() || p.embed.is_some() || p.fence.is_some()) {
             return Err(RuntimeError::InvalidInput(
                 "key, embed and fence apply only to notes".into(),
diff --git a/crates/khive-pack-kg/src/handlers/search.rs b/crates/khive-pack-kg/src/handlers/search.rs
index 44c4d0652..1c3a7e1f4 100644
--- a/crates/khive-pack-kg/src/handlers/search.rs
+++ b/crates/khive-pack-kg/src/handlers/search.rs
@@ -59,6 +59,7 @@ impl ValidatedSearchRequest {
     /// Parse and validate the canonical KG search wire contract.
     pub fn from_value(params: Value, registry: &VerbRegistry) -> Result<Self, RuntimeError> {
         let p: SearchParams = deser(params)?;
+        super::common::require_object_param(p.properties.as_ref(), "properties")?;
         let kind_raw = p
             .kind
             .as_deref()
@@ -74,7 +75,20 @@ impl ValidatedSearchRequest {
         };
         let tags = p.tags.unwrap_or_default();
         let limit = p.limit.unwrap_or(10).min(100);
-        let min_score = p.min_score.unwrap_or(0.0).max(0.0);
+        // The declared range is 0.0 to 1.0 and neither end was enforced. A floor
+        // above 1.0 was honoured and returned an empty result, which a caller cannot
+        // tell from no such record; a negative floor was silently clamped to 0.0, so
+        // the value the caller passed was not the value that ran. Refuse both and
+        // name the range, the way the other input refusals on this surface do.
+        let min_score = match p.min_score {
+            None => 0.0,
+            Some(value) if value.is_finite() && (0.0..=1.0).contains(&value) => value,
+            Some(value) => {
+                return Err(RuntimeError::InvalidInput(format!(
+                    "min_score must be between 0.0 and 1.0; got {value}"
+                )))
+            }
+        };
         let source = match p.source.as_deref() {
             None => None,
             Some("text") => Some(SearchSource::Text),
diff --git a/crates/khive-pack-kg/src/handlers/update.rs b/crates/khive-pack-kg/src/handlers/update.rs
index b2f3a08b7..12ac2ebd0 100644
--- a/crates/khive-pack-kg/src/handlers/update.rs
+++ b/crates/khive-pack-kg/src/handlers/update.rs
@@ -182,6 +182,7 @@ impl KgPack {
         registry: &VerbRegistry,
     ) -> Result<Value, RuntimeError> {
         let p: UpdateParams = deser(params.clone())?;
+        super::common::require_object_param(p.properties.as_ref(), "properties")?;
         if p.entity_kind.is_some() {
             return Err(RuntimeError::InvalidInput(
                 "entity_kind is immutable; to change kind, delete then re-create the entity, or use merge() if this is a deduplication correction".into(),
@@ -300,6 +301,7 @@ impl KgPack {
                     .prepare_note_update_hook(&self.runtime, token, &note, &mut params)
                     .await?;
                 let p: UpdateParams = deser(params)?;
+                super::common::require_object_param(p.properties.as_ref(), "properties")?;
                 let patch = NotePatch::new(
                     optional_string_patch(p.name, "name")?,
                     p.content,
diff --git a/crates/khive-pack-kg/tests/integration.rs b/crates/khive-pack-kg/tests/integration.rs
index 4e811ccee..8624b8581 100644
--- a/crates/khive-pack-kg/tests/integration.rs
+++ b/crates/khive-pack-kg/tests/integration.rs
@@ -14933,3 +14933,117 @@ async fn update_empty_string_property_survives_agent_echo_and_readback() {
         "Agent readback must retain the same empty-string value: {agent_readback}"
     );
 }
+
+/// A parameter this pack declares as an object must refuse a scalar rather than
+/// store it. The declared type is rendered into the schema a caller is handed and
+/// was never compared against the argument that arrived, so a string persisted and
+/// every later reader found a string where the schema promised a map. The success
+/// return is the harm: an agent has nothing to correct on.
+#[tokio::test]
+async fn create_refuses_a_scalar_where_properties_declares_an_object() {
+    let pack = pack();
+
+    let error = pack
+        .dispatch(
+            "create",
+            json!({
+                "kind": "entity",
+                "entity_kind": "concept",
+                "name": "ObjectParamScalar",
+                "properties": "not-an-object"
+            }),
+        )
+        .await
+        .expect_err("a string properties must be refused, not stored");
+    assert!(
+        is_invalid_input(&error),
+        "must be an input refusal, got {error:?}"
+    );
+    let message = error.to_string();
+    assert!(
+        message.contains("properties") && message.contains("object"),
+        "the refusal must name the parameter and the expected shape: {message}"
+    );
+
+    // Control in the same test: the identical call with a real object succeeds, so
+    // the refusal is about the shape and not about the field being present at all.
+    pack.dispatch(
+        "create",
+        json!({
+            "kind": "entity",
+            "entity_kind": "concept",
+            "name": "ObjectParamControl",
+            "properties": {"domain": "inference"}
+        }),
+    )
+    .await
+    .expect("an object properties must still be accepted");
+
+    // A batch names the offending item rather than the batch, since one error is
+    // returned for N records.
+    let error = pack
+        .dispatch(
+            "create",
+            json!({"items": [
+                {"kind": "entity", "entity_kind": "concept", "name": "BatchOk",
+                 "properties": {"domain": "inference"}},
+                {"kind": "entity", "entity_kind": "concept", "name": "BatchBad",
+                 "properties": "not-an-object"}
+            ]}),
+        )
+        .await
+        .expect_err("a scalar properties inside a batch must be refused");
+    assert!(
+        error.to_string().contains("items[1]"),
+        "the refusal must name which item: {error}"
+    );
+}
+
+/// `min_score` is documented as a 0.0-1.0 floor and neither end was enforced: a
+/// floor above the range was honoured and returned an empty result a caller
+/// cannot tell from "no such record", and a negative floor was silently clamped,
+/// so the value passed was not the value that ran.
+#[tokio::test]
+async fn search_refuses_a_score_floor_outside_the_declared_range() {
+    let pack = pack();
+    for name in ["ScoreFloorOne", "ScoreFloorTwo"] {
+        pack.dispatch(
+            "create",
+            json!({"kind": "entity", "entity_kind": "concept", "name": name}),
+        )
+        .await
+        .unwrap();
+    }
+
+    // Load-bearing control: the rows ARE findable at a sane floor. Without this the
+    // empty result at an out-of-range floor could be an empty corpus.
+    let hits = pack
+        .dispatch(
+            "search",
+            json!({"kind": "entity", "query": "ScoreFloor", "min_score": 0.0, "limit": 10}),
+        )
+        .await
+        .expect("a floor inside the range must be accepted");
+    assert!(
+        !hits.as_array().expect("array").is_empty(),
+        "control: the rows must be findable at a sane floor"
+    );
+
+    for floor in [json!(7), json!(-3), json!(1.5)] {
+        let error = pack
+            .dispatch(
+                "search",
+                json!({"kind": "entity", "query": "ScoreFloor", "min_score": floor, "limit": 10}),
+            )
+            .await
+            .expect_err("a floor outside 0.0-1.0 must be refused, not honoured");
+        assert!(
+            is_invalid_input(&error),
+            "must be an input refusal, got {error:?}"
+        );
+        assert!(
+            error.to_string().contains("min_score"),
+            "the refusal must name the parameter: {error}"
+        );
+    }
+}
diff --git a/tests/khive-contract/tests/test_coordinator_fanout.py b/tests/khive-contract/tests/test_coordinator_fanout.py
index 1c9078766..3ef2f2769 100644
--- a/tests/khive-contract/tests/test_coordinator_fanout.py
+++ b/tests/khive-contract/tests/test_coordinator_fanout.py
@@ -321,16 +321,21 @@ def test_search_min_score_filters_all_below_threshold(
     khive_session: KhiveMcpSession,
     temp_namespace: str,
 ) -> None:
-    """search(kind="entity", min_score=2.0) returns empty results for any real entity.
+    """search(kind="entity", min_score=1.0) returns empty results for any real entity.
 
     Source: crates/kkernel/src/coordinator/tests.rs
       t7c_multi_backend_search_min_score_applied
 
-    RRF scores for any real hit are always <= 1/(60+1) ~= 0.016.  A min_score
-    of 2.0 is above any achievable RRF score.  If the coordinator or handler
-    ignores min_score, the seeded entity would be returned and this test fails.
-    An empty result proves min_score is applied (search.rs line 138,
-    score_floor = p.min_score.unwrap_or(0.0).max(0.0)).
+    RRF scores for any real hit are always <= 1/(60+1) ~= 0.016, so a floor of
+    1.0 is above any achievable score.  If the coordinator or handler ignores
+    min_score, the seeded entity would be returned and this test fails; an empty
+    result proves the floor is applied.
+
+    This port previously used 2.0, which is outside the documented 0.0-1.0 range
+    and was only accepted because the range was unenforced.  Its own Rust source
+    uses 1.0.  The intent, a floor above every achievable score, is expressible
+    inside the contract, so the out-of-range value bought nothing and hid the
+    fact that the range was a promise with nothing behind it.
     """
     ns = temp_namespace
 
@@ -355,13 +360,13 @@ def test_search_min_score_filters_all_below_threshold(
     hits = khive_session.verb("search", {
         "kind": "entity",
         "query": "cft7c_minscore_probe",
-        "min_score": 2.0,
+        "min_score": 1.0,
         "namespace": ns,
     })
 
     assert isinstance(hits, list), f"search must return a list; got {type(hits)}"
     assert hits == [], (
-        "min_score=2.0 must exclude all results (no real RRF score can reach 2.0); "
+        "min_score=1.0 must exclude all results (no real RRF score can reach 1.0); "
         f"got {len(hits)} hit(s): {hits}"
     )