diff --git a/.github/aw/schemas/agentic-workflow.json b/.github/aw/schemas/agentic-workflow.json
index f8f6e5c73a..510479189b 100644
--- a/.github/aw/schemas/agentic-workflow.json
+++ b/.github/aw/schemas/agentic-workflow.json
@@ -273,7 +273,47 @@
                     "type": "string"
                   }
                 }
-              }
+              },
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ],
+              "allOf": [
+                {
+                  "oneOf": [
+                    {
+                      "required": ["paths"],
+                      "not": { "required": ["paths-ignore"] }
+                    },
+                    {
+                      "required": ["paths-ignore"],
+                      "not": { "required": ["paths"] }
+                    },
+                    {
+                      "not": {
+                        "anyOf": [
+                          { "required": ["paths"] },
+                          { "required": ["paths-ignore"] }
+                        ]
+                      }
+                    }
+                  ]
+                }
+              ]
             },
             "pull_request": {
               "description": "Pull request event trigger that runs the workflow when pull requests are created, updated, or closed",
@@ -379,10 +419,50 @@
                   ]
                 }
               },
-              "additionalProperties": false
+              "additionalProperties": false,
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ],
+              "allOf": [
+                {
+                  "oneOf": [
+                    {
+                      "required": ["paths"],
+                      "not": { "required": ["paths-ignore"] }
+                    },
+                    {
+                      "required": ["paths-ignore"],
+                      "not": { "required": ["paths"] }
+                    },
+                    {
+                      "not": {
+                        "anyOf": [
+                          { "required": ["paths"] },
+                          { "required": ["paths-ignore"] }
+                        ]
+                      }
+                    }
+                  ]
+                }
+              ]
             },
             "issues": {
-              "description": "Issues event trigger that runs the workflow when repository issues are created, updated, or managed",
+              "description": "Issues event trigger that runs when repository issues are created, updated, or managed",
               "type": "object",
               "additionalProperties": false,
               "properties": {
@@ -577,7 +657,25 @@
                     "type": "string"
                   }
                 }
-              }
+              },
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ]
             },
             "release": {
               "description": "Release event trigger",
@@ -886,7 +984,47 @@
                   ]
                 }
               },
-              "additionalProperties": false
+              "additionalProperties": false,
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ],
+              "allOf": [
+                {
+                  "oneOf": [
+                    {
+                      "required": ["paths"],
+                      "not": { "required": ["paths-ignore"] }
+                    },
+                    {
+                      "required": ["paths-ignore"],
+                      "not": { "required": ["paths"] }
+                    },
+                    {
+                      "not": {
+                        "anyOf": [
+                          { "required": ["paths"] },
+                          { "required": ["paths-ignore"] }
+                        ]
+                      }
+                    }
+                  ]
+                }
+              ]
             },
             "pull_request_review": {
               "description": "Pull request review event trigger that runs when a pull request review is submitted, edited, or dismissed",
@@ -4982,6 +5120,16 @@
                     }
                   },
                   "required": ["pull_request_review_comment"]
+                },
+                {
+                  "properties": {
+                    "label": {
+                      "not": {
+                        "type": "null"
+                      }
+                    }
+                  },
+                  "required": ["label"]
                 }
               ]
             }
diff --git a/pkg/parser/schema_oneof_test.go b/pkg/parser/schema_oneof_test.go
new file mode 100644
index 0000000000..8fcf36c45b
--- /dev/null
+++ b/pkg/parser/schema_oneof_test.go
@@ -0,0 +1,332 @@
+package parser
+
+import (
+	"strings"
+	"testing"
+)
+
+// TestValidateOneOfConstraints tests the oneOf constraints added to the schema
+// to prevent mutually exclusive fields from being specified together.
+func TestValidateOneOfConstraints(t *testing.T) {
+	tests := []struct {
+		name        string
+		frontmatter map[string]any
+		wantErr     bool
+		errContains string
+	}{
+		// branches vs branches-ignore in push event
+		{
+			name: "invalid: both branches and branches-ignore in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"branches":        []string{"main"},
+						"branches-ignore": []string{"dev"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+		{
+			name: "valid: only branches in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"branches": []string{"main"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid: only branches-ignore in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"branches-ignore": []string{"dev"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid: neither branches nor branches-ignore in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"tags": []string{"v*"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// paths vs paths-ignore in push event
+		{
+			name: "invalid: both paths and paths-ignore in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"paths":        []string{"src/**"},
+						"paths-ignore": []string{"docs/**"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+		{
+			name: "valid: only paths in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"paths": []string{"src/**"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid: only paths-ignore in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"paths-ignore": []string{"docs/**"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// branches vs branches-ignore in pull_request event
+		{
+			name: "invalid: both branches and branches-ignore in pull_request",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request": map[string]any{
+						"branches":        []string{"main"},
+						"branches-ignore": []string{"dev"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+		{
+			name: "valid: only branches in pull_request",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request": map[string]any{
+						"branches": []string{"main"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid: only branches-ignore in pull_request",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request": map[string]any{
+						"branches-ignore": []string{"dev"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// paths vs paths-ignore in pull_request event
+		{
+			name: "invalid: both paths and paths-ignore in pull_request",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request": map[string]any{
+						"paths":        []string{"src/**"},
+						"paths-ignore": []string{"docs/**"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+		{
+			name: "valid: only paths in pull_request",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request": map[string]any{
+						"paths": []string{"src/**"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// branches vs branches-ignore in pull_request_target event
+		{
+			name: "invalid: both branches and branches-ignore in pull_request_target",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request_target": map[string]any{
+						"branches":        []string{"main"},
+						"branches-ignore": []string{"dev"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+		{
+			name: "valid: only branches in pull_request_target",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request_target": map[string]any{
+						"branches": []string{"main"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// paths vs paths-ignore in pull_request_target event
+		{
+			name: "invalid: both paths and paths-ignore in pull_request_target",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"pull_request_target": map[string]any{
+						"paths":        []string{"src/**"},
+						"paths-ignore": []string{"docs/**"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+
+		// branches vs branches-ignore in workflow_run event
+		{
+			name: "invalid: both branches and branches-ignore in workflow_run",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"workflow_run": map[string]any{
+						"workflows":       []string{"CI"},
+						"branches":        []string{"main"},
+						"branches-ignore": []string{"dev"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "oneOf",
+		},
+		{
+			name: "valid: only branches in workflow_run",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"workflow_run": map[string]any{
+						"workflows": []string{"CI"},
+						"branches":  []string{"main"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// slash_command vs label events
+		{
+			name: "invalid: slash_command with label event",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"slash_command": "mybot",
+					"label": map[string]any{
+						"types": []string{"created"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "not",
+		},
+		{
+			name: "valid: slash_command without label event",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"slash_command": "mybot",
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid: label event without slash_command",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"label": map[string]any{
+						"types": []string{"created"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		// command vs label events (deprecated command field)
+		{
+			name: "invalid: command with label event",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"command": "mybot",
+					"label": map[string]any{
+						"types": []string{"created"},
+					},
+				},
+			},
+			wantErr:     true,
+			errContains: "not",
+		},
+
+		// Valid combinations of branches and paths
+		{
+			name: "valid: branches and paths in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"branches": []string{"main"},
+						"paths":    []string{"src/**"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid: branches-ignore and paths-ignore in push",
+			frontmatter: map[string]any{
+				"on": map[string]any{
+					"push": map[string]any{
+						"branches-ignore": []string{"dev"},
+						"paths-ignore":    []string{"docs/**"},
+					},
+				},
+			},
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidateMainWorkflowFrontmatterWithSchema(tt.frontmatter)
+
+			if tt.wantErr && err == nil {
+				t.Errorf("ValidateMainWorkflowFrontmatterWithSchema() expected error, got nil")
+				return
+			}
+
+			if !tt.wantErr && err != nil {
+				t.Errorf("ValidateMainWorkflowFrontmatterWithSchema() error = %v", err)
+				return
+			}
+
+			if err != nil && tt.errContains != "" {
+				if !strings.Contains(err.Error(), tt.errContains) {
+					t.Errorf("ValidateMainWorkflowFrontmatterWithSchema() error = %v, expected to contain %q", err.Error(), tt.errContains)
+				}
+			}
+		})
+	}
+}
diff --git a/pkg/parser/schemas/main_workflow_schema.json b/pkg/parser/schemas/main_workflow_schema.json
index f8f6e5c73a..510479189b 100644
--- a/pkg/parser/schemas/main_workflow_schema.json
+++ b/pkg/parser/schemas/main_workflow_schema.json
@@ -273,7 +273,47 @@
                     "type": "string"
                   }
                 }
-              }
+              },
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ],
+              "allOf": [
+                {
+                  "oneOf": [
+                    {
+                      "required": ["paths"],
+                      "not": { "required": ["paths-ignore"] }
+                    },
+                    {
+                      "required": ["paths-ignore"],
+                      "not": { "required": ["paths"] }
+                    },
+                    {
+                      "not": {
+                        "anyOf": [
+                          { "required": ["paths"] },
+                          { "required": ["paths-ignore"] }
+                        ]
+                      }
+                    }
+                  ]
+                }
+              ]
             },
             "pull_request": {
               "description": "Pull request event trigger that runs the workflow when pull requests are created, updated, or closed",
@@ -379,10 +419,50 @@
                   ]
                 }
               },
-              "additionalProperties": false
+              "additionalProperties": false,
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ],
+              "allOf": [
+                {
+                  "oneOf": [
+                    {
+                      "required": ["paths"],
+                      "not": { "required": ["paths-ignore"] }
+                    },
+                    {
+                      "required": ["paths-ignore"],
+                      "not": { "required": ["paths"] }
+                    },
+                    {
+                      "not": {
+                        "anyOf": [
+                          { "required": ["paths"] },
+                          { "required": ["paths-ignore"] }
+                        ]
+                      }
+                    }
+                  ]
+                }
+              ]
             },
             "issues": {
-              "description": "Issues event trigger that runs the workflow when repository issues are created, updated, or managed",
+              "description": "Issues event trigger that runs when repository issues are created, updated, or managed",
               "type": "object",
               "additionalProperties": false,
               "properties": {
@@ -577,7 +657,25 @@
                     "type": "string"
                   }
                 }
-              }
+              },
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ]
             },
             "release": {
               "description": "Release event trigger",
@@ -886,7 +984,47 @@
                   ]
                 }
               },
-              "additionalProperties": false
+              "additionalProperties": false,
+              "oneOf": [
+                {
+                  "required": ["branches"],
+                  "not": { "required": ["branches-ignore"] }
+                },
+                {
+                  "required": ["branches-ignore"],
+                  "not": { "required": ["branches"] }
+                },
+                {
+                  "not": {
+                    "anyOf": [
+                      { "required": ["branches"] },
+                      { "required": ["branches-ignore"] }
+                    ]
+                  }
+                }
+              ],
+              "allOf": [
+                {
+                  "oneOf": [
+                    {
+                      "required": ["paths"],
+                      "not": { "required": ["paths-ignore"] }
+                    },
+                    {
+                      "required": ["paths-ignore"],
+                      "not": { "required": ["paths"] }
+                    },
+                    {
+                      "not": {
+                        "anyOf": [
+                          { "required": ["paths"] },
+                          { "required": ["paths-ignore"] }
+                        ]
+                      }
+                    }
+                  ]
+                }
+              ]
             },
             "pull_request_review": {
               "description": "Pull request review event trigger that runs when a pull request review is submitted, edited, or dismissed",
@@ -4982,6 +5120,16 @@
                     }
                   },
                   "required": ["pull_request_review_comment"]
+                },
+                {
+                  "properties": {
+                    "label": {
+                      "not": {
+                        "type": "null"
+                      }
+                    }
+                  },
+                  "required": ["label"]
                 }
               ]
             }