diff --git a/docs/openapi/monitoring-api.json b/docs/openapi/monitoring-api.json
index 3cde442..9e73bdb 100644
--- a/docs/openapi/monitoring-api.json
+++ b/docs/openapi/monitoring-api.json
@@ -22744,9 +22744,9 @@
             "format": "int32",
             "nullable": true
           },
-          "collapsed": {
+          "defaultOpen": {
             "type": "boolean",
-            "description": "Whether the group is collapsed by default (default: true)",
+            "description": "Initial expand/collapse state when a visitor first loads the page; renderer may auto-expand on active incidents (default: true)",
             "nullable": true
           }
         }
@@ -22816,7 +22816,7 @@
           },
           "startDate": {
             "type": "string",
-            "description": "Date from which to start showing uptime data",
+            "description": "Date from which to start showing uptime; defaults to component creation. Set earlier to backdate (e.g. launch day); clamped at the monitor's createdAt for MONITOR-type components",
             "format": "date",
             "nullable": true
           }
@@ -29659,7 +29659,7 @@
           "updatedAt",
           "displayOrder",
           "pageOrder",
-          "collapsed"
+          "defaultOpen"
         ],
         "type": "object",
         "properties": {
@@ -29686,7 +29686,7 @@
             "type": "integer",
             "format": "int32"
           },
-          "collapsed": {
+          "defaultOpen": {
             "type": "boolean"
           },
           "components": {
@@ -32405,9 +32405,9 @@
             "format": "int32",
             "nullable": true
           },
-          "collapsed": {
+          "defaultOpen": {
             "type": "boolean",
-            "description": "Whether the group is collapsed by default; null preserves current",
+            "description": "Initial expand/collapse state on first page load; null preserves current. Renderer may auto-expand on active incidents",
             "nullable": true
           }
         }
@@ -32458,7 +32458,7 @@
           },
           "startDate": {
             "type": "string",
-            "description": "Date from which to start showing uptime data; null preserves current",
+            "description": "Date from which to start showing uptime; null preserves current. Bars never extend earlier than the underlying monitor's createdAt regardless of value",
             "format": "date",
             "nullable": true
           }
diff --git a/src/devhelm/_generated.py b/src/devhelm/_generated.py
index 40171d6..8969c84 100644
--- a/src/devhelm/_generated.py
+++ b/src/devhelm/_generated.py
@@ -1,6 +1,6 @@
 # generated by datamodel-codegen:
 #   filename:  .openapi-preprocessed.json
-#   timestamp: 2026-04-22T07:20:30+00:00
+#   timestamp: 2026-04-22T14:03:54+00:00
 
 from __future__ import annotations
 from typing import Annotated, Any, Literal
@@ -1023,9 +1023,12 @@ class CreateStatusPageComponentGroupRequest(BaseModel):
         int | None,
         Field(alias="displayOrder", description="Position in the group list"),
     ] = None
-    collapsed: Annotated[
+    default_open: Annotated[
         bool | None,
-        Field(description="Whether the group is collapsed by default (default: true)"),
+        Field(
+            alias="defaultOpen",
+            description="Initial expand/collapse state when a visitor first loads the page; renderer may auto-expand on active incidents (default: true)",
+        ),
     ] = None
 
 
@@ -1088,7 +1091,7 @@ class CreateStatusPageComponentRequest(BaseModel):
         date_aliased | None,
         Field(
             alias="startDate",
-            description="Date from which to start showing uptime data",
+            description="Date from which to start showing uptime; defaults to component creation. Set earlier to backdate (e.g. launch day); clamped at the monitor's createdAt for MONITOR-type components",
         ),
     ] = None
 
@@ -4730,7 +4733,7 @@ class StatusPageComponentGroupDto(BaseModel):
     description: str | None = None
     display_order: Annotated[int, Field(alias="displayOrder")]
     page_order: Annotated[int, Field(alias="pageOrder")]
-    collapsed: bool
+    default_open: Annotated[bool, Field(alias="defaultOpen")]
     components: list[StatusPageComponentDto] | None = None
     created_at: Annotated[AwareDatetime, Field(alias="createdAt")]
     updated_at: Annotated[AwareDatetime, Field(alias="updatedAt")]
@@ -5760,10 +5763,11 @@ class UpdateStatusPageComponentGroupRequest(BaseModel):
             description="New position in the group list; null preserves current",
         ),
     ] = None
-    collapsed: Annotated[
+    default_open: Annotated[
         bool | None,
         Field(
-            description="Whether the group is collapsed by default; null preserves current"
+            alias="defaultOpen",
+            description="Initial expand/collapse state on first page load; null preserves current. Renderer may auto-expand on active incidents",
         ),
     ] = None
 
@@ -5825,7 +5829,7 @@ class UpdateStatusPageComponentRequest(BaseModel):
         date_aliased | None,
         Field(
             alias="startDate",
-            description="Date from which to start showing uptime data; null preserves current",
+            description="Date from which to start showing uptime; null preserves current. Bars never extend earlier than the underlying monitor's createdAt regardless of value",
         ),
     ] = None
 
diff --git a/tests/test_negative_validation.py b/tests/test_negative_validation.py
index 5c4b71b..8fd6ba1 100644
--- a/tests/test_negative_validation.py
+++ b/tests/test_negative_validation.py
@@ -299,7 +299,7 @@ def _sp_group(**kw: object) -> dict[str, Any]:
         "name": "Infra",
         "displayOrder": 0,
         "pageOrder": 0,
-        "collapsed": True,
+        "defaultOpen": True,
         "createdAt": NOW,
         "updatedAt": NOW,
     }
@@ -1874,9 +1874,9 @@ def test_missing_display_order(self) -> None:
                 _del(_sp_group(), "displayOrder")
             )
 
-    def test_missing_collapsed(self) -> None:
-        with pytest.raises(ValidationError, match="collapsed"):
-            StatusPageComponentGroupDto.model_validate(_del(_sp_group(), "collapsed"))
+    def test_missing_default_open(self) -> None:
+        with pytest.raises(ValidationError, match="defaultOpen"):
+            StatusPageComponentGroupDto.model_validate(_del(_sp_group(), "defaultOpen"))
 
     def test_empty_dict(self) -> None:
         with pytest.raises(ValidationError):
@@ -1924,9 +1924,9 @@ def test_description_too_long(self) -> None:
                 {"description": "x" * 501}
             )
 
-    def test_wrong_collapsed_type(self) -> None:
+    def test_wrong_default_open_type(self) -> None:
         with pytest.raises(ValidationError):
-            UpdateStatusPageComponentGroupRequest.model_validate({"collapsed": [1]})
+            UpdateStatusPageComponentGroupRequest.model_validate({"defaultOpen": [1]})
 
 
 # ===================================================================
diff --git a/uv.lock b/uv.lock
index 88df424..b27703c 100644
--- a/uv.lock
+++ b/uv.lock
@@ -331,7 +331,7 @@ wheels = [
 
 [[package]]
 name = "devhelm"
-version = "0.2.0"
+version = "0.2.1"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },