diff --git a/frontend/src/shared/state/agentsSlice.ts b/frontend/src/shared/state/agentsSlice.ts
index 24574591..a0620436 100644
--- a/frontend/src/shared/state/agentsSlice.ts
+++ b/frontend/src/shared/state/agentsSlice.ts
@@ -231,6 +231,7 @@ export const launchAgent = createAsyncThunk('agents/launchAgent', async (config:
     headers: { 'Content-Type': 'application/json' },
     body: JSON.stringify(config),
   });
+  if (!res.ok) throw new Error(`Launch failed: ${res.status}`);
   const data = await res.json();
   return data.session as AgentSession;
 });
diff --git a/frontend/src/shared/state/modesSlice.ts b/frontend/src/shared/state/modesSlice.ts
index 3679eb2a..f52aba9a 100644
--- a/frontend/src/shared/state/modesSlice.ts
+++ b/frontend/src/shared/state/modesSlice.ts
@@ -44,6 +44,7 @@ export const createMode = createAsyncThunk(
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify(body),
     });
+    if (!res.ok) throw new Error(`Create mode failed: ${res.status}`);
     const data = await res.json();
     return data.mode as Mode;
   }
@@ -57,6 +58,7 @@ export const updateMode = createAsyncThunk(
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify(updates),
     });
+    if (!res.ok) throw new Error(`Update mode failed: ${res.status}`);
     const data = await res.json();
     return data.mode as Mode;
   }
@@ -66,6 +68,7 @@ export const resetMode = createAsyncThunk(
   'modes/reset',
   async (id: string) => {
     const res = await fetch(`${MODES_API}/${id}/reset`, { method: 'POST' });
+    if (!res.ok) throw new Error(`Reset mode failed: ${res.status}`);
     const data = await res.json();
     return data.mode as Mode;
   }
diff --git a/frontend/src/shared/state/skillsSlice.ts b/frontend/src/shared/state/skillsSlice.ts
index 22759c76..8e38ae3b 100644
--- a/frontend/src/shared/state/skillsSlice.ts
+++ b/frontend/src/shared/state/skillsSlice.ts
@@ -51,6 +51,7 @@ export const createSkill = createAsyncThunk(
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify(body),
     });
+    if (!res.ok) throw new Error(`Create skill failed: ${res.status}`);
     const data = await res.json();
     return data.skill as Skill;
   }
@@ -64,6 +65,7 @@ export const updateSkill = createAsyncThunk(
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify(updates),
     });
+    if (!res.ok) throw new Error(`Update skill failed: ${res.status}`);
     const data = await res.json();
     return data.skill as Skill;
   }
diff --git a/frontend/src/shared/state/toolsSlice.ts b/frontend/src/shared/state/toolsSlice.ts
index a61ac51e..a564620a 100644
--- a/frontend/src/shared/state/toolsSlice.ts
+++ b/frontend/src/shared/state/toolsSlice.ts
@@ -66,6 +66,7 @@ export const createTool = createAsyncThunk(
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify(body),
     });
+    if (!res.ok) throw new Error(`Create tool failed: ${res.status}`);
     const data = await res.json();
     return data.tool as ToolDefinition;
   }