add set_vote tool

Sets a label vote with an optional message, riding the gated SetReview
call as a labels map -- value 0 clears an own vote. The label name is
required; range and label validation stay with Gerrit, whose rejection
(unknown label, value outside the permitted range, vote on a merged
change) is reported verbatim.

Refs: #17

Author: xobotyi

internal/tools/get-change_test.go

@@ -104,7 +104,7 @@ func Test_GetChange(t *testing.T) {
 
 		assert.ElementsMatch(t, []string{
 			"search_changes", "get_change", "list_change_files", "get_file_diff", "get_change_comments",
-			"post_comments",
+			"post_comments", "set_vote",
 		}, names)
 	})
 

internal/tools/set-vote.go

@@ -0,0 +1,58 @@
+package tools
+
+import (
+	"context"
+	"strings"
+
+	"dev.gaijin.team/go/golib/e"
+	gerrit "github.com/andygrunwald/go-gerrit"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"dev.gaijin.team/go/go-gerrit-mcp/internal/gerritclient"
+	"dev.gaijin.team/go/go-gerrit-mcp/internal/llmxml"
+)
+
+var errVoteNoLabel = e.New("vote label must not be empty")
+
+type setVoteInput struct {
+	Change  string `json:"change" jsonschema:"Change identifier: numeric ID, project~number, or Change-Id"`
+	Label   string `json:"label" jsonschema:"Label name, e.g. Code-Review or Verified"`
+	Value   int    `json:"value" jsonschema:"Numeric vote within the label's range; 0 clears an own vote"`
+	Message string `json:"message,omitempty" jsonschema:"Optional message accompanying the vote"`
+}
+
+func setVote(c *gerritclient.Client) Tool {
+	return Tool{
+		Name: NameSetVote,
+		Register: func(s *mcp.Server) {
+			mcp.AddTool(s, &mcp.Tool{
+				Name: NameSetVote,
+				Description: "Set a vote on a Gerrit change: label name plus numeric value, with an " +
+					"optional message. Value 0 clears an own vote. Gerrit validates the label and " +
+					"range; its refusal is reported verbatim. Refused on changes not owned by the " +
+					"authenticated account unless the operator disabled the own-changes restriction.",
+			}, func(ctx context.Context, _ *mcp.CallToolRequest, in setVoteInput,
+			) (*mcp.CallToolResult, any, error) {
+				label := strings.TrimSpace(in.Label)
+				if label == "" {
+					return nil, nil, errVoteNoLabel
+				}
+
+				input := &gerrit.ReviewInput{
+					Message: in.Message,
+					Labels:  map[string]int{label: in.Value},
+				}
+
+				if _, err := c.SetReview(ctx, in.Change, "", input); err != nil {
+					return nil, nil, err
+				}
+
+				return textResult(llmxml.NewElement("vote_set",
+					llmxml.Attr("change", in.Change),
+					llmxml.Attr("label", label),
+					llmxml.Attr("value", in.Value),
+				).String()), nil, nil
+			})
+		},
+	}
+}

internal/tools/set-vote_test.go

@@ -0,0 +1,167 @@
+package tools_test
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const foreignChangeJSON = ")]}'\n" + `{"_number":123,"project":"core","branch":"main",` +
+	`"owner":{"_account_id":7,"username":"alice"}}`
+
+// voteSession wires a fake Gerrit for the vote flow: self-check, change
+// resolve (owned by self), and a recording review POST.
+func voteSession(t *testing.T) (cs *mcp.ClientSession, body *map[string]any) {
+	t.Helper()
+
+	body = &map[string]any{}
+
+	cs = session(t, func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case r.URL.Path == "/a/accounts/self":
+			_, _ = w.Write([]byte(selfJSON))
+
+		case r.Method == http.MethodPost && strings.HasSuffix(r.URL.Path, "/review"):
+			raw, err := io.ReadAll(r.Body)
+			if err != nil {
+				t.Errorf("read review body: %v", err)
+
+				return
+			}
+
+			if err := json.Unmarshal(raw, body); err != nil {
+				t.Errorf("unmarshal review body: %v", err)
+
+				return
+			}
+
+			_, _ = w.Write([]byte(")]}'\n{}"))
+
+		default:
+			_, _ = w.Write([]byte(ownChangeJSON))
+		}
+	})
+
+	return cs, body
+}
+
+func Test_SetVote(t *testing.T) {
+	t.Parallel()
+
+	t.Run("posts label, value, and message as a review", func(t *testing.T) {
+		t.Parallel()
+
+		cs, body := voteSession(t)
+
+		out := callTool(t, cs, "set_vote", map[string]any{
+			"change":  "123",
+			"label":   "Code-Review",
+			"value":   2,
+			"message": "lgtm",
+		})
+
+		assert.Contains(t, out, `<vote_set change="123" label="Code-Review" value="2"/>`)
+
+		assert.Equal(t, "lgtm", (*body)["message"])
+		assert.Equal(t, map[string]any{"Code-Review": float64(2)}, (*body)["labels"])
+	})
+
+	t.Run("zero value stays on the wire to clear a vote", func(t *testing.T) {
+		t.Parallel()
+
+		cs, body := voteSession(t)
+
+		callTool(t, cs, "set_vote", map[string]any{
+			"change": "123",
+			"label":  "Code-Review",
+			"value":  0,
+		})
+
+		assert.Equal(t, map[string]any{"Code-Review": float64(0)}, (*body)["labels"])
+	})
+
+	t.Run("empty label refused", func(t *testing.T) {
+		t.Parallel()
+
+		cs, body := voteSession(t)
+
+		res, err := cs.CallTool(t.Context(), &mcp.CallToolParams{
+			Name:      "set_vote",
+			Arguments: map[string]any{"change": "123", "label": " ", "value": 1},
+		})
+		require.NoError(t, err)
+		require.True(t, res.IsError)
+
+		assert.Empty(t, *body, "no review may be posted")
+	})
+
+	t.Run("gerrit label rejection surfaced verbatim", func(t *testing.T) {
+		t.Parallel()
+
+		cs := session(t, func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/a/accounts/self":
+				_, _ = w.Write([]byte(selfJSON))
+
+			case r.Method == http.MethodPost:
+				w.WriteHeader(http.StatusBadRequest)
+
+				_, _ = w.Write([]byte(`label "Bogus" is not a configured label`))
+
+			default:
+				_, _ = w.Write([]byte(ownChangeJSON))
+			}
+		})
+
+		res, err := cs.CallTool(t.Context(), &mcp.CallToolParams{
+			Name:      "set_vote",
+			Arguments: map[string]any{"change": "123", "label": "Bogus", "value": 1},
+		})
+		require.NoError(t, err)
+		require.True(t, res.IsError)
+
+		text, ok := res.Content[0].(*mcp.TextContent)
+		require.True(t, ok)
+		assert.Contains(t, text.Text, `label "Bogus" is not a configured label`)
+	})
+
+	t.Run("foreign change refused by own-changes restriction", func(t *testing.T) {
+		t.Parallel()
+
+		posted := false
+
+		cs := session(t, func(w http.ResponseWriter, r *http.Request) {
+			switch {
+			case r.URL.Path == "/a/accounts/self":
+				_, _ = w.Write([]byte(selfJSON))
+
+			case r.Method == http.MethodPost:
+				posted = true
+
+				_, _ = w.Write([]byte(")]}'\n{}"))
+
+			default:
+				_, _ = w.Write([]byte(foreignChangeJSON))
+			}
+		})
+
+		res, err := cs.CallTool(t.Context(), &mcp.CallToolParams{
+			Name:      "set_vote",
+			Arguments: map[string]any{"change": "123", "label": "Code-Review", "value": -1},
+		})
+		require.NoError(t, err)
+		require.True(t, res.IsError)
+
+		text, ok := res.Content[0].(*mcp.TextContent)
+		require.True(t, ok)
+		assert.Contains(t, text.Text, "own-changes")
+
+		assert.False(t, posted, "no mutating request may leave the process")
+	})
+}

internal/tools/tools.go

@@ -17,6 +17,7 @@ const (
 	NameGetFileDiff       = "get_file_diff"
 	NameGetChangeComments = "get_change_comments"
 	NamePostComments      = "post_comments"
+	NameSetVote           = "set_vote"
 )
 
 // Tool binds a tool name to its MCP registration.
@@ -35,6 +36,7 @@ func All(c *gerritclient.Client) []Tool {
 		getFileDiff(c),
 		getChangeComments(c),
 		postComments(c),
+		setVote(c),
 	}
 }