From c11d71671d94cf258fa98e2359bdef3a47634998 Mon Sep 17 00:00:00 2001
From: Vishal Punjabi <10079537+vshalpnjabi@users.noreply.github.com>
Date: Mon, 2 Nov 2026 22:36:50 +0000
Subject: [PATCH] Reject list_label perPage=0 instead of defaulting to 100

---
 pkg/github/labels.go      | 10 +++++++---
 pkg/github/labels_test.go | 18 ++++++++++++++++++
 pkg/github/params.go      |  4 ++--
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/pkg/github/labels.go b/pkg/github/labels.go
index c9479e5062..9689d982a1 100644
--- a/pkg/github/labels.go
+++ b/pkg/github/labels.go
@@ -177,9 +177,13 @@ func listLabelsLegacy(t translations.TranslationHelperFunc) inventory.ServerTool
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
 
-			perPage, err := OptionalIntParamWithDefault(args, "perPage", listLabelsDefaultPerPage)
-			if err != nil {
-				return utils.NewToolResultError(err.Error()), nil, nil
+			// Distinguish omitted perPage (default 100) from an explicit 0, which is out of range.
+			perPage := listLabelsDefaultPerPage
+			if _, present := args["perPage"]; present {
+				perPage, err = OptionalIntParam(args, "perPage")
+				if err != nil {
+					return utils.NewToolResultError(err.Error()), nil, nil
+				}
 			}
 			after, err := OptionalParam[string](args, "after")
 			if err != nil {
diff --git a/pkg/github/labels_test.go b/pkg/github/labels_test.go
index 43075659bc..9e2aabc872 100644
--- a/pkg/github/labels_test.go
+++ b/pkg/github/labels_test.go
@@ -217,6 +217,24 @@ func TestListLabels(t *testing.T) {
 			expectToolError:    true,
 			expectedToolErrMsg: "perPage value 101 exceeds maximum of 100",
 		},
+		{
+			// Explicit 0 must not be treated as "omitted" and replaced by the default of 100.
+			// The mock matches first=100 so a silent default would succeed and fail this case.
+			name: "rejects a page size of 0",
+			requestArgs: map[string]any{
+				"owner":   "owner",
+				"repo":    "repo",
+				"perPage": float64(0),
+			},
+			mockedClient: githubv4mock.NewMockedHTTPClient(listLabelsMatcher(100, (*githubv4.String)(nil), map[string]any{
+				"hasNextPage":     githubv4.Boolean(false),
+				"hasPreviousPage": githubv4.Boolean(false),
+				"startCursor":     githubv4.String("c1"),
+				"endCursor":       githubv4.String("c2"),
+			})),
+			expectToolError:    true,
+			expectedToolErrMsg: "perPage value 0 is below minimum of 1",
+		},
 	}
 
 	for _, tc := range tests {
diff --git a/pkg/github/params.go b/pkg/github/params.go
index 416020abb7..0583c02ecb 100644
--- a/pkg/github/params.go
+++ b/pkg/github/params.go
@@ -476,8 +476,8 @@ func (p CursorPaginationParams) ToGraphQLParams() (*GraphQLPaginationParams, err
 	if p.PerPage > 100 {
 		return nil, fmt.Errorf("perPage value %d exceeds maximum of 100", p.PerPage)
 	}
-	if p.PerPage < 0 {
-		return nil, fmt.Errorf("perPage value %d cannot be negative", p.PerPage)
+	if p.PerPage < 1 {
+		return nil, fmt.Errorf("perPage value %d is below minimum of 1", p.PerPage)
 	}
 	first := int32(p.PerPage)