372 lines
11 KiB
Go
372 lines
11 KiB
Go
package mcp
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"net/http/httptest"
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"strings"
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"testing"
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)
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// stubMCP serves a minimal streamable-HTTP MCP server with one "echo" tool and
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// records the Authorization header of the last request.
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func stubMCP(t *testing.T, lastAuth *string) *httptest.Server {
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t.Helper()
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return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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*lastAuth = r.Header.Get("Authorization")
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var req struct {
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Method string `json:"method"`
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Params json.RawMessage `json:"params"`
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}
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if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
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t.Errorf("decode rpc: %v", err)
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return
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}
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var result any
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switch req.Method {
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case "tools/list":
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result = map[string]any{"tools": []map[string]any{{
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"name": "echo",
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"description": "Echo back its input text",
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"inputSchema": Object(Props{"text": String("the text to echo")}, []string{"text"}),
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}}}
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case "tools/call":
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var p struct {
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Name string `json:"name"`
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Args struct {
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Text string `json:"text"`
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} `json:"arguments"`
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}
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_ = json.Unmarshal(req.Params, &p)
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if p.Name != "echo" {
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http.Error(w, "unknown tool", http.StatusBadRequest)
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return
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}
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result = map[string]any{
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"content": []map[string]any{{"type": "text", "text": `{"echo":"` + p.Args.Text + `"}`}},
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}
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default:
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http.Error(w, "unknown method", http.StatusBadRequest)
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return
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}
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b, _ := json.Marshal(map[string]any{"jsonrpc": "2.0", "id": 1, "result": result})
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w.Header().Set("Content-Type", "application/json")
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_, _ = w.Write(b)
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}))
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}
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// stubUpstream serves an OpenAI-compatible /v1/chat/completions SSE stream.
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// On the first call it emits one echo tool call; afterwards it streams
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// "done " + the tool message content as the final answer.
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func stubUpstream(t *testing.T, calls *int, sawTools *[][]string) *httptest.Server {
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t.Helper()
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mux := http.NewServeMux()
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mux.HandleFunc("POST /v1/chat/completions", func(w http.ResponseWriter, r *http.Request) {
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var req ChatRequest
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if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
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t.Errorf("decode chat request: %v", err)
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return
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}
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if sawTools != nil {
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names := make([]string, 0, len(req.Tools))
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for _, tl := range req.Tools {
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names = append(names, tl.Function.Name)
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}
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*sawTools = append(*sawTools, names)
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}
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*calls++
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w.Header().Set("Content-Type", "text/event-stream")
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flusher := w.(http.Flusher)
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send := func(v any) {
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b, _ := json.Marshal(v)
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fmt.Fprintf(w, "data: %s\n\n", b)
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flusher.Flush()
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}
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if *calls == 1 {
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send(struct {
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Choices []struct {
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Delta struct {
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ToolCalls []ToolCall `json:"tool_calls"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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} `json:"choices"`
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}{Choices: []struct {
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Delta struct {
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ToolCalls []ToolCall `json:"tool_calls"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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}{{
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Delta: struct {
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ToolCalls []ToolCall `json:"tool_calls"`
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}{ToolCalls: []ToolCall{{
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ID: "call_1",
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Type: "function",
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Function: FunctionCall{Name: "echo", Arguments: `{"text":"hi"}`},
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}}},
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FinishReason: strPtr("tool_calls"),
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}}})
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} else {
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// Second round: the model should have seen the tool result message.
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toolMsg := ""
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for _, m := range req.Messages {
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if m.Role == "tool" && m.ToolCallID == "call_1" {
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toolMsg, _ = m.Content.(string)
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}
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}
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send(struct {
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Choices []struct {
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Delta struct {
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Content string `json:"content"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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} `json:"choices"`
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}{Choices: []struct {
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Delta struct {
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Content string `json:"content"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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}{{
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Delta: struct {
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Content string `json:"content"`
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}{Content: "saw:" + toolMsg},
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FinishReason: strPtr("stop"),
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}}})
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}
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fmt.Fprint(w, "data: [DONE]\n\n")
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flusher.Flush()
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})
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return httptest.NewServer(mux)
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}
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func strPtr(s string) *string { return &s }
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func TestAgentAgenticLoop(t *testing.T) {
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var lastAuth string
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mcpSrv := stubMCP(t, &lastAuth)
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defer mcpSrv.Close()
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var calls int
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var sawTools [][]string
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upSrv := stubUpstream(t, &calls, &sawTools)
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defer upSrv.Close()
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agent := NewAgent(AgentConfig{
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UpstreamURL: upSrv.URL,
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UpstreamAPIKey: "sk-test",
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MCPURL: mcpSrv.URL + "/mcp",
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MCPToken: "mcp-secret",
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SystemPrompt: "You are a test.",
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ProgressEvent: "cms_progress",
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})
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body := `{"model":"test-model","messages":[{"role":"user","content":"hi"}],"stream":true}`
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req := httptest.NewRequest(http.MethodPost, "/chat/completions", strings.NewReader(body))
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rec := httptest.NewRecorder()
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agent.Handler().ServeHTTP(rec, req)
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if rec.Code != http.StatusOK {
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t.Fatalf("status = %d, body = %s", rec.Code, rec.Body.String())
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}
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sse := rec.Body.String()
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// The model must have been offered the MCP tool (round 1)…
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if len(sawTools) < 2 || sawTools[0][0] != "echo" {
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t.Fatalf("model was not offered the echo tool: %v", sawTools)
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}
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// …and executed via tools/call with the bearer token appended.
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if lastAuth != "Bearer mcp-secret" {
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t.Errorf("MCP Authorization = %q, want Bearer mcp-secret", lastAuth)
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}
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// The final answer must reflect the tool result fed back to the model.
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if !strings.Contains(sse, `"saw:{\"echo\":\"hi\"}"`) {
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t.Errorf("final delta missing tool feedback; SSE:\n%s", sse)
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}
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// Wire contract: progress event, response event, [DONE].
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for _, want := range []string{"event: cms_progress", `"status":"calling"`, `"status":"done"`, "event: response", `"finish_reason":"stop"`, "data: [DONE]"} {
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if !strings.Contains(sse, want) {
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t.Errorf("SSE missing %q;\n%s", want, sse)
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}
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}
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if calls != 2 {
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t.Errorf("upstream calls = %d, want 2", calls)
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}
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}
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func TestAgentLocalTool(t *testing.T) {
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var lastAuth string
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mcpSrv := stubMCP(t, &lastAuth)
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defer mcpSrv.Close()
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// Upstream asks for the local tool; second round confirms the model saw
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// its in-process result.
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var calls int
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upSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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calls++
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w.Header().Set("Content-Type", "text/event-stream")
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flusher := w.(http.Flusher)
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send := func(v any) {
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b, _ := json.Marshal(v)
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fmt.Fprintf(w, "data: %s\n\n", b)
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flusher.Flush()
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}
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if calls == 1 {
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send(struct {
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Choices []struct {
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Delta struct {
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ToolCalls []ToolCall `json:"tool_calls"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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} `json:"choices"`
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}{Choices: []struct {
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Delta struct {
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ToolCalls []ToolCall `json:"tool_calls"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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}{{
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Delta: struct {
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ToolCalls []ToolCall `json:"tool_calls"`
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}{ToolCalls: []ToolCall{{
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ID: "loc_1",
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Type: "function",
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Function: FunctionCall{Name: "local_ping", Arguments: `{}`},
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}}},
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FinishReason: strPtr("tool_calls"),
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}}})
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} else {
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toolMsg := ""
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for _, m := range reqMessages(r) {
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if m.Role == "tool" && m.ToolCallID == "loc_1" {
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toolMsg, _ = m.Content.(string)
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}
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}
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send(struct {
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Choices []struct {
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Delta struct {
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Content string `json:"content"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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} `json:"choices"`
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}{Choices: []struct {
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Delta struct {
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Content string `json:"content"`
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} `json:"delta"`
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FinishReason *string `json:"finish_reason"`
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}{{
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Delta: struct {
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Content string `json:"content"`
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}{Content: toolMsg},
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FinishReason: strPtr("stop"),
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}}})
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}
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fmt.Fprint(w, "data: [DONE]\n\n")
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flusher.Flush()
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}))
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defer upSrv.Close()
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authBefore := lastAuth
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agent := NewAgent(AgentConfig{
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UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
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MCPURL: mcpSrv.URL + "/mcp",
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LocalTools: []Tool{{
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Name: "local_ping",
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Description: "In-process ping",
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InputSchema: Object(nil, nil),
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Invoke: func(ctx context.Context, args json.RawMessage) (any, error) {
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return map[string]any{"pong": true}, nil
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},
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}},
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})
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req := httptest.NewRequest(http.MethodPost, "/chat/completions",
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strings.NewReader(`{"messages":[{"role":"user","content":"ping"}],"stream":true}`))
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rec := httptest.NewRecorder()
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agent.Handler().ServeHTTP(rec, req)
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sse := rec.Body.String()
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if !strings.Contains(sse, `\"pong\":true`) {
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t.Errorf("local tool result not fed back to the model:\n%s", sse)
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}
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if lastAuth != authBefore {
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t.Errorf("local tool dispatch leaked to the MCP endpoint (auth header changed)")
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}
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}
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// reqMessages decodes the chat request body from a recorded upstream call.
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func reqMessages(r *http.Request) []Message {
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var req ChatRequest
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_ = json.NewDecoder(r.Body).Decode(&req)
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return req.Messages
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}
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func TestAgentFrontendToolCallPassthrough(t *testing.T) {
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var lastAuth string
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mcpSrv := stubMCP(t, &lastAuth)
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defer mcpSrv.Close()
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calls := 0
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// Upstream immediately requests an unknown (frontend) tool.
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upSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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calls++
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w.Header().Set("Content-Type", "text/event-stream")
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fmt.Fprintf(w, `data: {"choices":[{"delta":{"tool_calls":[{"index":0,"id":"fe_1","type":"function","function":{"name":"browser_exec","arguments":"{\"x\":1}"}}]},"finish_reason":"tool_calls"}]}`+"\n\n")
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fmt.Fprint(w, "data: [DONE]\n\n")
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}))
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defer upSrv.Close()
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agent := NewAgent(AgentConfig{
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UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
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MCPURL: mcpSrv.URL + "/mcp",
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})
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req := httptest.NewRequest(http.MethodPost, "/chat/completions",
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strings.NewReader(`{"messages":[{"role":"user","content":"go"}],"stream":true}`))
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rec := httptest.NewRecorder()
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agent.Handler().ServeHTTP(rec, req)
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if !strings.Contains(rec.Body.String(), `"name":"browser_exec"`) ||
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!strings.Contains(rec.Body.String(), `"id":"fe_1"`) {
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t.Errorf("frontend tool call not passed through:\n%s", rec.Body.String())
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}
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if calls != 1 {
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t.Errorf("upstream calls = %d, want 1 (loop must stop for frontend calls)", calls)
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}
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}
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func TestAgentNonStreaming(t *testing.T) {
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var lastAuth string
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mcpSrv := stubMCP(t, &lastAuth)
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defer mcpSrv.Close()
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var calls int
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upSrv := stubUpstream(t, &calls, nil)
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defer upSrv.Close()
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agent := NewAgent(AgentConfig{
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UpstreamURL: upSrv.URL, UpstreamAPIKey: "k",
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MCPURL: mcpSrv.URL + "/mcp",
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Model: "default-model",
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})
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req := httptest.NewRequest(http.MethodPost, "/chat/completions",
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strings.NewReader(`{"messages":[{"role":"user","content":"hi"}]}`))
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rec := httptest.NewRecorder()
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agent.Handler().ServeHTTP(rec, req)
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var resp ChatResponse
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if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
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t.Fatalf("decode response: %v\n%s", err, rec.Body.String())
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}
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if len(resp.Choices) != 1 || resp.Choices[0].FinishReason != "stop" {
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t.Fatalf("unexpected response: %+v", resp)
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}
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if !strings.Contains(resp.Choices[0].Message.Content.(string), `saw:{"echo":"hi"}`) {
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t.Errorf("content = %q", resp.Choices[0].Message.Content)
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}
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if resp.Model != "default-model" {
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t.Errorf("model default not applied: %q", resp.Model)
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}
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}
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