feat: localchat, a Go + Templ + HTMX chat app for local Gemma models

Streams replies over SSE from any OpenAI-compatible server (oMLX,
llama.cpp, Ollama, ...). Single binary that can install itself as an
OS service; docker compose bundles llama.cpp + Gemma 4 E2B.

internal/llm/client_test.go

@@ -0,0 +1,107 @@
+package llm
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// fakeServer mimics an OpenAI-compatible server that streams the given chunks.
+func fakeServer(t *testing.T, chunks []string) *httptest.Server {
+	t.Helper()
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/v1/models":
+			fmt.Fprint(w, `{"data":[{"id":"tiny-model"},{"id":"other"}]}`)
+		case "/v1/chat/completions":
+			if got := r.Header.Get("Authorization"); got != "Bearer secret" {
+				http.Error(w, `{"error":"bad key"}`, http.StatusUnauthorized)
+				return
+			}
+			var req struct {
+				Model  string    `json:"model"`
+				Stream bool      `json:"stream"`
+				Msgs   []Message `json:"messages"`
+			}
+			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+				t.Errorf("decode request: %v", err)
+			}
+			if req.Model != "tiny-model" || !req.Stream || len(req.Msgs) != 1 {
+				t.Errorf("unexpected request: %+v", req)
+			}
+			w.Header().Set("Content-Type", "text/event-stream")
+			fmt.Fprint(w, ": keep-alive comment\n\n")
+			fmt.Fprint(w, `data: {"choices":[{"delta":{"role":"assistant"}}]}`+"\n\n")
+			for _, c := range chunks {
+				b, _ := json.Marshal(c)
+				fmt.Fprintf(w, `data: {"choices":[{"delta":{"content":%s}}]}`+"\n\n", b)
+			}
+			fmt.Fprint(w, "data: [DONE]\n\n")
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+}
+
+func TestStream(t *testing.T) {
+	srv := fakeServer(t, []string{"Hel", "lo", "\n", "world"})
+	defer srv.Close()
+
+	c := &Client{BaseURL: srv.URL + "/v1", APIKey: "secret"} // no model: auto-pick first
+	var got strings.Builder
+	err := c.Stream(context.Background(), []Message{{Role: "user", Content: "hi"}}, func(d string) error {
+		got.WriteString(d)
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got.String() != "Hello\nworld" {
+		t.Fatalf("got %q", got.String())
+	}
+}
+
+func TestStreamHTTPError(t *testing.T) {
+	srv := fakeServer(t, nil)
+	defer srv.Close()
+
+	c := &Client{BaseURL: srv.URL + "/v1", APIKey: "wrong", Model: "tiny-model"}
+	err := c.Stream(context.Background(), []Message{{Role: "user", Content: "hi"}}, func(string) error { return nil })
+	if err == nil || !strings.Contains(err.Error(), "401") {
+		t.Fatalf("want 401 error, got %v", err)
+	}
+}
+
+func TestStreamCallbackErrorStops(t *testing.T) {
+	srv := fakeServer(t, []string{"a", "b", "c"})
+	defer srv.Close()
+
+	c := &Client{BaseURL: srv.URL + "/v1", APIKey: "secret"}
+	stop := fmt.Errorf("stop")
+	n := 0
+	err := c.Stream(context.Background(), []Message{{Role: "user", Content: "hi"}}, func(string) error {
+		n++
+		return stop
+	})
+	if err != stop || n != 1 {
+		t.Fatalf("err=%v n=%d", err, n)
+	}
+}
+
+func TestResolveModel(t *testing.T) {
+	srv := fakeServer(t, nil)
+	defer srv.Close()
+
+	c := &Client{BaseURL: srv.URL + "/v1"}
+	if m, err := c.ResolveModel(context.Background()); err != nil || m != "tiny-model" {
+		t.Fatalf("auto: %q %v", m, err)
+	}
+	c.Model = "pinned"
+	if m, _ := c.ResolveModel(context.Background()); m != "pinned" {
+		t.Fatalf("pinned: %q", m)
+	}
+}