Return assignees from list_issues

The list_issues GraphQL fragment never selected assignees, so the tool
could not report who an issue was assigned to. Its nearest field, user,
is the issue author, which callers conflate with the assignee. Answering
"is anything unassigned?" therefore cost one list_issues call plus one
issue_read per candidate, and a truncated sweep invites a fabricated
answer drawn from the author instead.

Add an assignees selection to IssueFragment, flatten it to logins in
fragmentToMinimalIssue, and add "assignees" to listIssuesItemFieldEnum so
it is selectable through fields. GitHub caps issue assignees at 10, so
first: 100 cannot truncate; it also matches the page size already used
for assignees in copilot.go.

Drop omitempty from MinimalIssue.Assignees and initialize the slice in
both converters so an unassigned issue serializes as [] rather than an
absent key, which is what lets a caller identify unassigned issues from
a single response. This also affects issue_read, the other MinimalIssue
consumer, which now reports "assignees": [] instead of omitting the key.

Author: tgockel

pkg/github/__toolsnaps__/list_issues.snap

@@ -50,6 +50,7 @@
             "state",
             "user",
             "labels",
+            "assignees",
             "comments",
             "created_at",
             "updated_at",

pkg/github/fields_filtering_test.go

@@ -274,7 +274,7 @@ func Test_SearchIssues_FieldsTelemetry(t *testing.T) {
 // getIssueQueryType; see Test_ListIssues for the canonical copies.
 const listIssuesFieldsFieldValuesSelection = "issueFieldValues(first: 25){nodes{__typename,... on IssueFieldDateValue{field{... on IssueFieldDate{name,fullDatabaseId},... on IssueFieldNumber{name,fullDatabaseId},... on IssueFieldSingleSelect{name,fullDatabaseId},... on IssueFieldText{name,fullDatabaseId}},value},... on IssueFieldNumberValue{field{... on IssueFieldDate{name,fullDatabaseId},... on IssueFieldNumber{name,fullDatabaseId},... on IssueFieldSingleSelect{name,fullDatabaseId},... on IssueFieldText{name,fullDatabaseId}},valueNumber: value},... on IssueFieldSingleSelectValue{field{... on IssueFieldDate{name,fullDatabaseId},... on IssueFieldNumber{name,fullDatabaseId},... on IssueFieldSingleSelect{name,fullDatabaseId},... on IssueFieldText{name,fullDatabaseId}},value},... on IssueFieldTextValue{field{... on IssueFieldDate{name,fullDatabaseId},... on IssueFieldNumber{name,fullDatabaseId},... on IssueFieldSingleSelect{name,fullDatabaseId},... on IssueFieldText{name,fullDatabaseId}},value}}}"
 
-const listIssuesFieldsQuery = "query($after:String$direction:OrderDirection!$first:Int!$issueFieldValues:[IssueFieldValueFilter!]!$orderBy:IssueOrderField!$owner:String!$repo:String!$states:[IssueState!]!){repository(owner: $owner, name: $repo){issues(first: $first, after: $after, states: $states, orderBy: {field: $orderBy, direction: $direction}, filterBy: {issueFieldValues: $issueFieldValues}){nodes{number,title,body,state,databaseId,author{login},createdAt,updatedAt,labels(first: 100){nodes{name,id,description}},comments{totalCount}," + listIssuesFieldsFieldValuesSelection + "},pageInfo{hasNextPage,hasPreviousPage,startCursor,endCursor},totalCount},isPrivate}}"
+const listIssuesFieldsQuery = "query($after:String$direction:OrderDirection!$first:Int!$issueFieldValues:[IssueFieldValueFilter!]!$orderBy:IssueOrderField!$owner:String!$repo:String!$states:[IssueState!]!){repository(owner: $owner, name: $repo){issues(first: $first, after: $after, states: $states, orderBy: {field: $orderBy, direction: $direction}, filterBy: {issueFieldValues: $issueFieldValues}){nodes{number,title,body,state,databaseId,author{login},createdAt,updatedAt,labels(first: 100){nodes{name,id,description}},assignees(first: 100){nodes{login}},comments{totalCount}," + listIssuesFieldsFieldValuesSelection + "},pageInfo{hasNextPage,hasPreviousPage,startCursor,endCursor},totalCount},isPrivate}}"
 
 func listIssuesFieldsMockClient() *http.Client {
 	vars := map[string]any{
@@ -301,6 +301,7 @@ func listIssuesFieldsMockClient() *http.Client {
 						"updatedAt":        "2023-01-01T00:00:00Z",
 						"author":           map[string]any{"login": "user1"},
 						"labels":           map[string]any{"nodes": []map[string]any{}},
+						"assignees":        map[string]any{"nodes": []map[string]any{{"login": "octocat"}}},
 						"comments":         map[string]any{"totalCount": 1},
 						"issueFieldValues": map[string]any{"nodes": []map[string]any{}},
 					},
@@ -353,6 +354,57 @@ func Test_ListIssues_FieldFiltering(t *testing.T) {
 	assert.NotContains(t, textContent.Text, "\"body\"")
 }
 
+// Test_ListIssues_AssigneesField covers the assignees field end to end: it is
+// selectable via fields, it is dropped when not requested, and it is always
+// present in an unfiltered response so that "unassigned" reads as [] rather
+// than an absent key.
+func Test_ListIssues_AssigneesField(t *testing.T) {
+	serverTool := ListIssues(translations.NullTranslationHelper)
+
+	callWithFields := func(t *testing.T, fields []any) string {
+		t.Helper()
+		deps := BaseDeps{GQLClient: githubv4.NewClient(listIssuesFieldsMockClient())}
+		handler := serverTool.Handler(deps)
+
+		args := map[string]any{"owner": "owner", "repo": "repo"}
+		if fields != nil {
+			args["fields"] = fields
+		}
+		request := createMCPRequest(args)
+		result, err := handler(ContextWithDeps(context.Background(), deps), &request)
+		require.NoError(t, err)
+		require.False(t, result.IsError)
+		return getTextResult(t, result).Text
+	}
+
+	t.Run("selectable via fields", func(t *testing.T) {
+		var returned struct {
+			Issues []map[string]any `json:"issues"`
+		}
+		require.NoError(t, json.Unmarshal([]byte(callWithFields(t, []any{"number", "assignees"})), &returned))
+		require.Len(t, returned.Issues, 1)
+		require.Len(t, returned.Issues[0], 2, "only the two requested fields should be present")
+		assert.Equal(t, []any{"octocat"}, returned.Issues[0]["assignees"])
+	})
+
+	t.Run("omitted when not requested", func(t *testing.T) {
+		text := callWithFields(t, []any{"number", "title"})
+		assert.NotContains(t, text, "\"assignees\"")
+	})
+
+	t.Run("unassigned issues serialize as an empty array", func(t *testing.T) {
+		// The mock returns one assigned issue, so drive the empty case through
+		// the conversion directly: no assignees node must still yield [], never
+		// null and never an absent key.
+		issue := fragmentToMinimalIssue(IssueFragment{})
+		require.NotNil(t, issue.Assignees)
+
+		encoded, err := json.Marshal(issue)
+		require.NoError(t, err)
+		assert.Contains(t, string(encoded), "\"assignees\":[]")
+	})
+}
+
 func Test_ListIssues_FieldsTelemetry(t *testing.T) {
 	serverTool := ListIssues(translations.NullTranslationHelper)
 

pkg/github/issues.go

@@ -499,6 +499,12 @@ type IssueFragment struct {
 			Description githubv4.String
 		}
 	} `graphql:"labels(first: 100)"`
+	// GitHub caps issue assignees at 10, so first: 100 cannot truncate.
+	Assignees struct {
+		Nodes []struct {
+			Login githubv4.String
+		}
+	} `graphql:"assignees(first: 100)"`
 	Comments struct {
 		TotalCount githubv4.Int
 	} `graphql:"comments"`