Add service orchestration and web UI

2026-02-13 15:03:02 +00:00
parent 6f0509ff18
commit d5a27c776e
17 changed files with 3890 additions and 0 deletions
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -0,0 +1,130 @@
+// Package config loads and validates YAML configuration for odidere.
+package config
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"time"
+
+	"github.com/chimerical-llc/odidere/internal/llm"
+	"github.com/chimerical-llc/odidere/internal/stt"
+	"github.com/chimerical-llc/odidere/internal/tool"
+	"github.com/chimerical-llc/odidere/internal/tts"
+
+	"gopkg.in/yaml.v3"
+)
+
+// Config holds all application configuration sections.
+type Config struct {
+	// Address is the host:port to listen on.
+	Address string `yaml:"address"`
+
+	// Concurrency is the number of concurrent requests to allow.
+	// Defaults to 1.
+	Concurrency int `yaml:"concurrency"`
+	// ShutdownTimeout is the maximum time to wait for graceful shutdown.
+	// Defaults to "30s".
+	ShutdownTimeout string `yaml:"shutdown_timeout"`
+	// shutdownTimeout is the parsed duration, set during Load.
+	shutdownTimeout time.Duration `yaml:"-"`
+
+	// LLM configures the language model client.
+	LLM llm.Config `yaml:"llm"`
+	// STT configures the speech-to-text client.
+	STT stt.Config `yaml:"stt"`
+	// Tools defines external commands available to the LLM.
+	Tools []tool.Tool `yaml:"tools"`
+	// TTS configures the text-to-speech client.
+	TTS tts.Config `yaml:"tts"`
+}
+
+// ApplyDefaults sets default values for optional configuration fields.
+// Called automatically by Load before validation.
+func (cfg *Config) ApplyDefaults() {
+	if cfg.Concurrency == 0 {
+		cfg.Concurrency = 1
+	}
+	if cfg.ShutdownTimeout == "" {
+		cfg.ShutdownTimeout = "30s"
+	}
+	if cfg.Address == "" {
+		cfg.Address = ":8080"
+	}
+}
+
+// GetShutdownTimeout returns the parsed shutdown timeout duration.
+func (cfg *Config) GetShutdownTimeout() time.Duration {
+	return cfg.shutdownTimeout
+}
+
+// Validate checks that all required fields are present and valid.
+// Delegates to each subsection's Validate method.
+func (cfg *Config) Validate() error {
+	if cfg.Address == "" {
+		return fmt.Errorf("address required")
+	}
+
+	if err := cfg.LLM.Validate(); err != nil {
+		return fmt.Errorf("invalid llm config: %w", err)
+	}
+	if err := cfg.STT.Validate(); err != nil {
+		return fmt.Errorf("invalid stt config: %w", err)
+	}
+	if err := cfg.TTS.Validate(); err != nil {
+		return fmt.Errorf("invalid tts config: %w", err)
+	}
+	if _, err := time.ParseDuration(cfg.ShutdownTimeout); err != nil {
+		return fmt.Errorf(
+			"invalid shutdown_timeout %q: %w",
+			cfg.ShutdownTimeout, err,
+		)
+	}
+	for i, t := range cfg.Tools {
+		if err := t.Validate(); err != nil {
+			return fmt.Errorf("tools[%d] invalid: %w", i, err)
+		}
+	}
+
+	return nil
+}
+
+// Load reads a YAML configuration file, expands environment variables,
+// applies defaults, and validates the result. Returns an error if the
+// file cannot be read, parsed, or contains invalid configuration.
+func Load(path string) (*Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read file: %w", err)
+	}
+
+	// Expand environment variables.
+	// Unset variables are replaced with empty strings.
+	re := regexp.MustCompile(`\$\{([^}]+)\}`)
+	expanded := re.ReplaceAllStringFunc(
+		string(data),
+		func(match string) string {
+			// Extract variable name from ${VAR}.
+			v := match[2 : len(match)-1]
+			return os.Getenv(v)
+		},
+	)
+
+	var cfg Config
+	if err := yaml.Unmarshal([]byte(expanded), &cfg); err != nil {
+		return nil, fmt.Errorf("parse config: %w", err)
+	}
+	cfg.ApplyDefaults()
+
+	if err := cfg.Validate(); err != nil {
+		return nil, fmt.Errorf("invalid config: %v", err)
+	}
+
+	d, err := time.ParseDuration(cfg.ShutdownTimeout)
+	if err != nil {
+		return nil, fmt.Errorf("parse shutdown timeout: %v", err)
+	}
+	cfg.shutdownTimeout = d
+
+	return &cfg, nil
+}
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -0,0 +1,399 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// validConfig returns a minimal valid YAML configuration.
+func validConfig() string {
+	return `
+address: ":9090"
+concurrency: 2
+shutdown_timeout: "60s"
+
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`
+}
+
+func writeConfig(t *testing.T, content string) string {
+	t.Helper()
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.yaml")
+	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+		t.Fatalf("write config file: %v", err)
+	}
+	return path
+}
+
+func TestLoad(t *testing.T) {
+	tests := []struct {
+		name      string
+		config    string
+		setup     func(t *testing.T)
+		shouldErr bool
+		check     func(t *testing.T, cfg *Config)
+	}{
+		{
+			name:   "valid config",
+			config: validConfig(),
+			check: func(t *testing.T, cfg *Config) {
+				if cfg.Address != ":9090" {
+					t.Errorf(
+						"Address = %q, want %q",
+						cfg.Address, ":9090",
+					)
+				}
+				if cfg.Concurrency != 2 {
+					t.Errorf(
+						"Concurrency = %d, want 2",
+						cfg.Concurrency,
+					)
+				}
+				if cfg.ShutdownTimeout != "60s" {
+					t.Errorf(
+						"ShutdownTimeout = %q, want %q",
+						cfg.ShutdownTimeout, "60s",
+					)
+				}
+				if cfg.GetShutdownTimeout() != 60*time.Second {
+					t.Errorf(
+						"GetShutdownTimeout() = %v, want 60s",
+						cfg.GetShutdownTimeout(),
+					)
+				}
+			},
+		},
+		{
+			name: "defaults applied",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			check: func(t *testing.T, cfg *Config) {
+				if cfg.Address != ":8080" {
+					t.Errorf(
+						"Address = %q, want %q",
+						cfg.Address, ":8080",
+					)
+				}
+				if cfg.Concurrency != 1 {
+					t.Errorf(
+						"Concurrency = %d, want 1",
+						cfg.Concurrency,
+					)
+				}
+				if cfg.ShutdownTimeout != "30s" {
+					t.Errorf(
+						"ShutdownTimeout = %q, want %q",
+						cfg.ShutdownTimeout, "30s",
+					)
+				}
+				if cfg.GetShutdownTimeout() != 30*time.Second {
+					t.Errorf(
+						"GetShutdownTimeout() = %v, want 30s",
+						cfg.GetShutdownTimeout(),
+					)
+				}
+			},
+		},
+		{
+			name: "env expansion",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+  key: ${TEST_LLM_KEY}
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			setup: func(t *testing.T) {
+				t.Setenv("TEST_LLM_KEY", "secret-api-key")
+			},
+			check: func(t *testing.T, cfg *Config) {
+				if cfg.LLM.Key != "secret-api-key" {
+					t.Errorf(
+						"LLM.Key = %q, want %q",
+						cfg.LLM.Key, "secret-api-key",
+					)
+				}
+			},
+		},
+		{
+			name: "env expansion unset var becomes empty",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+  key: ${TEST_UNSET_VAR}
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			check: func(t *testing.T, cfg *Config) {
+				if cfg.LLM.Key != "" {
+					t.Errorf(
+						"LLM.Key = %q, want empty",
+						cfg.LLM.Key,
+					)
+				}
+			},
+		},
+		{
+			name:      "invalid yaml",
+			config:    `llm: [invalid yaml`,
+			shouldErr: true,
+		},
+		{
+			name: "invalid shutdown_timeout",
+			config: `
+shutdown_timeout: "not-a-duration"
+
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			shouldErr: true,
+		},
+		{
+			name: "missing llm model",
+			config: `
+llm:
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			shouldErr: true,
+		},
+		{
+			name: "missing llm url",
+			config: `
+llm:
+  model: test-model
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			shouldErr: true,
+		},
+		{
+			name: "missing stt url",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  timeout: "30s"
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+`,
+			shouldErr: true,
+		},
+		{
+			name: "missing tts url",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  voice: af_heart
+`,
+			shouldErr: true,
+		},
+		{
+			name: "missing tts voice",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+`,
+			shouldErr: true,
+		},
+		{
+			name: "config with tools",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+
+tools:
+  - name: echo
+    description: echoes input
+    command: echo
+    arguments:
+      - "{{.message}}"
+`,
+			check: func(t *testing.T, cfg *Config) {
+				if len(cfg.Tools) != 1 {
+					t.Errorf(
+						"len(Tools) = %d, want 1",
+						len(cfg.Tools),
+					)
+				}
+				if cfg.Tools[0].Name != "echo" {
+					t.Errorf(
+						"Tools[0].Name = %q, want %q",
+						cfg.Tools[0].Name, "echo",
+					)
+				}
+			},
+		},
+		{
+			name: "invalid tool",
+			config: `
+llm:
+  model: test-model
+  url: http://localhost:8080
+
+stt:
+  url: http://localhost:8178
+
+tts:
+  url: http://localhost:8880
+  voice: af_heart
+
+tools:
+  - name: ""
+    description: missing name
+    command: echo
+`,
+			shouldErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.setup != nil {
+				tt.setup(t)
+			}
+
+			path := writeConfig(t, tt.config)
+			cfg, err := Load(path)
+
+			if tt.shouldErr {
+				if err == nil {
+					t.Fatal("Load() expected error")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Fatalf("Load() error = %v", err)
+			}
+
+			if tt.check != nil {
+				tt.check(t, cfg)
+			}
+		})
+	}
+}
+
+func TestLoad_FileNotFound(t *testing.T) {
+	if _, err := Load("/nonexistent/path/config.yaml"); err == nil {
+		t.Fatal("Load() expected error for missing file")
+	}
+}
+
+func TestApplyDefaults(t *testing.T) {
+	cfg := &Config{}
+	cfg.ApplyDefaults()
+
+	if cfg.Address != ":8080" {
+		t.Errorf("Address = %q, want %q", cfg.Address, ":8080")
+	}
+	if cfg.Concurrency != 1 {
+		t.Errorf("Concurrency = %d, want 1", cfg.Concurrency)
+	}
+	if cfg.ShutdownTimeout != "30s" {
+		t.Errorf(
+			"ShutdownTimeout = %q, want %q",
+			cfg.ShutdownTimeout, "30s",
+		)
+	}
+}
+
+func TestApplyDefaults_NoOverwrite(t *testing.T) {
+	cfg := &Config{
+		Address:         ":9999",
+		Concurrency:     5,
+		ShutdownTimeout: "120s",
+	}
+	cfg.ApplyDefaults()
+
+	if cfg.Address != ":9999" {
+		t.Errorf("Address = %q, want %q", cfg.Address, ":9999")
+	}
+	if cfg.Concurrency != 5 {
+		t.Errorf("Concurrency = %d, want 5", cfg.Concurrency)
+	}
+	if cfg.ShutdownTimeout != "120s" {
+		t.Errorf(
+			"ShutdownTimeout = %q, want %q",
+			cfg.ShutdownTimeout, "120s",
+		)
+	}
+}
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -0,0 +1,856 @@
+// Package service orchestrates the odidere voice assistant server.
+// It coordinates the HTTP server, STT/LLM/TTS clients, and handles
+// graceful shutdown.
+package service
+
+import (
+	"context"
+	"embed"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"html/template"
+	"io/fs"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"runtime/debug"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/chimerical-llc/odidere/internal/config"
+	"github.com/chimerical-llc/odidere/internal/llm"
+	"github.com/chimerical-llc/odidere/internal/service/templates"
+	"github.com/chimerical-llc/odidere/internal/stt"
+	"github.com/chimerical-llc/odidere/internal/tool"
+	"github.com/chimerical-llc/odidere/internal/tts"
+
+	"github.com/google/uuid"
+	openai "github.com/sashabaranov/go-openai"
+	"golang.org/x/sync/semaphore"
+)
+
+//go:embed all:static/*
+var static embed.FS
+
+// Service is the main application coordinator.
+// It owns the HTTP server and all processing clients.
+type Service struct {
+	cfg    *config.Config
+	llm    *llm.Client
+	log    *slog.Logger
+	mux    *http.ServeMux
+	sem    *semaphore.Weighted
+	server *http.Server
+	stt    *stt.Client
+	tmpl   *template.Template
+	tools  *tool.Registry
+	tts    *tts.Client
+}
+
+// New creates a Service from the provided configuration.
+// It initializes all clients and the HTTP server.
+func New(cfg *config.Config, log *slog.Logger) (*Service, error) {
+	var svc = &Service{
+		cfg: cfg,
+		log: log,
+		mux: http.NewServeMux(),
+		sem: semaphore.NewWeighted(int64(cfg.Concurrency)),
+	}
+
+	// Setup tool registry.
+	registry, err := tool.NewRegistry(cfg.Tools)
+	if err != nil {
+		return nil, fmt.Errorf("load tools: %v", err)
+	}
+	svc.tools = registry
+
+	// Create STT client.
+	sttClient, err := stt.NewClient(cfg.STT, log)
+	if err != nil {
+		return nil, fmt.Errorf("create STT client: %v", err)
+	}
+	svc.stt = sttClient
+
+	// Create LLM client.
+	llmClient, err := llm.NewClient(cfg.LLM, registry, log)
+	if err != nil {
+		return nil, fmt.Errorf("create LLM client: %v", err)
+	}
+	svc.llm = llmClient
+
+	// Create TTS client.
+	ttsClient, err := tts.NewClient(cfg.TTS, log)
+	if err != nil {
+		return nil, fmt.Errorf("create TTS client: %v", err)
+	}
+	svc.tts = ttsClient
+
+	// Parse templates.
+	tmpl, err := templates.Parse()
+	if err != nil {
+		return nil, fmt.Errorf("parse templates: %v", err)
+	}
+	svc.tmpl = tmpl
+
+	// Setup static file server.
+	staticFS, err := fs.Sub(static, "static")
+	if err != nil {
+		return nil, fmt.Errorf("setup static fs: %v", err)
+	}
+
+	// Register routes.
+	svc.mux.HandleFunc("GET /", svc.home)
+	svc.mux.HandleFunc("GET /status", svc.status)
+	svc.mux.Handle(
+		"GET /static/",
+		http.StripPrefix(
+			"/static/", http.FileServer(http.FS(staticFS)),
+		),
+	)
+	svc.mux.HandleFunc("POST /v1/chat/voice", svc.voice)
+	svc.mux.HandleFunc("POST /v1/chat/voice/stream", svc.voiceStream)
+	svc.mux.HandleFunc("GET /v1/voices", svc.voices)
+	svc.mux.HandleFunc("GET /v1/models", svc.models)
+
+	svc.server = &http.Server{
+		Addr:    cfg.Address,
+		Handler: svc,
+	}
+
+	return svc, nil
+}
+
+// ServeHTTP implements http.Handler. It logs requests, assigns a UUID,
+// sets context values, handles panics, and delegates to the mux.
+func (svc *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	var (
+		start = time.Now()
+		id    = uuid.NewString()
+		ip    = func() string {
+			if ip := r.Header.Get("X-Forwarded-For"); ip != "" {
+				if idx := strings.Index(ip, ","); idx != -1 {
+					return strings.TrimSpace(ip[:idx])
+				}
+				return ip
+			}
+			return r.RemoteAddr
+		}()
+		log = svc.log.With(slog.Group(
+			"request",
+			slog.String("id", id),
+			slog.String("ip", ip),
+			slog.String("method", r.Method),
+			slog.String("path", r.URL.Path),
+		))
+	)
+
+	// Log completion time.
+	defer func() {
+		log.InfoContext(
+			r.Context(),
+			"completed",
+			slog.Duration("duration", time.Since(start)),
+		)
+	}()
+
+	// Panic recovery.
+	defer func() {
+		if err := recover(); err != nil {
+			log.ErrorContext(
+				r.Context(),
+				"panic recovered",
+				slog.Any("error", err),
+				slog.String("stack", string(debug.Stack())),
+			)
+			http.Error(
+				w,
+				http.StatusText(
+					http.StatusInternalServerError,
+				),
+				http.StatusInternalServerError,
+			)
+		}
+	}()
+
+	// Enrich context with request-scoped values.
+	ctx := r.Context()
+	ctx = context.WithValue(ctx, "log", log)
+	ctx = context.WithValue(ctx, "id", id)
+	ctx = context.WithValue(ctx, "ip", ip)
+	r = r.WithContext(ctx)
+
+	log.InfoContext(ctx, "handling")
+
+	// Pass the request on to the multiplexer.
+	svc.mux.ServeHTTP(w, r)
+}
+
+// Run starts the service and blocks until shutdown.
+// Shutdown is triggered by SIGINT or SIGTERM.
+func (svc *Service) Run(ctx context.Context) error {
+	svc.log.Info(
+		"starting odidere",
+		slog.Int("concurrency", svc.cfg.Concurrency),
+		slog.Group(
+			"llm",
+			slog.String("url", svc.cfg.LLM.URL),
+			slog.String("model", svc.cfg.LLM.Model),
+		),
+		slog.Group(
+			"server",
+			slog.String("address", svc.cfg.Address),
+		),
+		slog.Group(
+			"stt",
+			slog.String("url", svc.cfg.STT.URL),
+		),
+		slog.Group(
+			"tools",
+			slog.Int("count", len(svc.tools.List())),
+			slog.Any(
+				"names",
+				strings.Join(svc.tools.List(), ","),
+			),
+		),
+		slog.Group(
+			"tts",
+			slog.String("url", svc.cfg.TTS.URL),
+			slog.String("default_voice", svc.cfg.TTS.Voice),
+		),
+		slog.Any("shutdown_timeout", svc.cfg.GetShutdownTimeout()),
+	)
+
+	// Setup signal handling for graceful shutdown.
+	ctx, cancel := signal.NotifyContext(
+		ctx,
+		os.Interrupt, syscall.SIGTERM,
+	)
+	defer cancel()
+
+	// Start HTTP server in background.
+	var errs = make(chan error, 1)
+	go func() {
+		svc.log.Info(
+			"HTTP server listening",
+			slog.String("address", svc.cfg.Address),
+		)
+		if err := svc.server.ListenAndServe(); err != nil &&
+			err != http.ErrServerClosed {
+			errs <- err
+		}
+		close(errs)
+	}()
+
+	// Wait for shutdown signal or server error.
+	select {
+	case <-ctx.Done():
+		svc.log.Info("shutdown signal received")
+	case err := <-errs:
+		if err != nil {
+			return fmt.Errorf("server error: %w", err)
+		}
+	}
+
+	// Graceful shutdown with timeout.
+	shutdownCtx, shutdownCancel := context.WithTimeout(
+		context.Background(),
+		svc.cfg.GetShutdownTimeout(),
+	)
+	defer shutdownCancel()
+
+	svc.log.Info("shutting down HTTP server")
+	if err := svc.server.Shutdown(shutdownCtx); err != nil {
+		svc.log.Warn(
+			"shutdown timeout reached",
+			slog.Any("error", err),
+		)
+	}
+
+	svc.log.Info("terminating")
+	return nil
+}
+
+func (svc *Service) home(w http.ResponseWriter, r *http.Request) {
+	var (
+		ctx = r.Context()
+		log = ctx.Value("log").(*slog.Logger)
+	)
+
+	if r.URL.Path != "/" {
+		http.NotFound(w, r)
+		return
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if err := svc.tmpl.ExecuteTemplate(
+		w, "index.gohtml", nil,
+	); err != nil {
+		log.ErrorContext(
+			ctx, "template error", slog.Any("error", err),
+		)
+		http.Error(
+			w,
+			http.StatusText(http.StatusInternalServerError),
+			http.StatusInternalServerError,
+		)
+	}
+}
+
+// status returns server status.
+func (svc *Service) status(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+}
+
+// Request is the incoming request format for chat and voice endpoints.
+type Request struct {
+	// Audio is base64-encoded audio data (webm) for transcription.
+	Audio string `json:"audio,omitempty"`
+	// Messages is the conversation history.
+	Messages []openai.ChatCompletionMessage `json:"messages"`
+	// Model is the LLM model ID. If empty, the default model is used.
+	Model string `json:"model,omitempty"`
+	// Voice is the voice ID for TTS.
+	Voice string `json:"voice,omitempty"`
+}
+
+// Response is the response format for chat and voice endpoints.
+type Response struct {
+	// Audio is the base64-encoded WAV audio response.
+	Audio string `json:"audio,omitempty"`
+	// DetectedLanguage is the language detected in the input speech.
+	DetectedLanguage string `json:"detected_language,omitempty"`
+	// Messages is the full list of messages generated during the query,
+	// including tool calls and tool results.
+	Messages []openai.ChatCompletionMessage `json:"messages,omitempty"`
+	// Model is the LLM model used for the response.
+	Model string `json:"used_model,omitempty"`
+	// Transcription is the transcribed user speech from the input audio.
+	Transcription string `json:"transcription,omitempty"`
+	// Voice is the voice used for TTS synthesis.
+	Voice string `json:"used_voice,omitempty"`
+}
+
+// voice processes voice requests with audio input/output.
+func (svc *Service) voice(w http.ResponseWriter, r *http.Request) {
+	var (
+		ctx = r.Context()
+		log = ctx.Value("log").(*slog.Logger)
+	)
+
+	// Parse request.
+	r.Body = http.MaxBytesReader(w, r.Body, 32<<20)
+	var req Request
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to decode request",
+			slog.Any("error", err),
+		)
+		http.Error(w, "invalid request", http.StatusBadRequest)
+		return
+	}
+
+	// Validate messages.
+	if len(req.Messages) == 0 {
+		http.Error(w, "messages required", http.StatusBadRequest)
+		return
+	}
+	log.InfoContext(ctx, "messages",
+		slog.Any("data", req.Messages),
+	)
+
+	var (
+		messages      = req.Messages
+		transcription string
+		detectedLang  string
+	)
+
+	// If audio provided, transcribe and append to last message.
+	if req.Audio != "" {
+		last := &messages[len(messages)-1]
+		if last.Role != openai.ChatMessageRoleUser {
+			http.Error(
+				w,
+				"last message must be role=user when audio is provided",
+				http.StatusBadRequest,
+			)
+			return
+		}
+
+		data, err := base64.StdEncoding.DecodeString(req.Audio)
+		if err != nil {
+			log.ErrorContext(
+				ctx,
+				"failed to decode audio",
+				slog.Any("error", err),
+			)
+			http.Error(w, "invalid audio", http.StatusBadRequest)
+			return
+		}
+
+		output, err := svc.stt.Transcribe(ctx, data)
+		if err != nil {
+			log.ErrorContext(
+				ctx,
+				"STT failed",
+				slog.Any("error", err),
+			)
+			http.Error(
+				w,
+				"STT error",
+				http.StatusInternalServerError,
+			)
+			return
+		}
+
+		transcription = strings.TrimSpace(output.Text)
+		detectedLang = output.DetectedLanguage
+		if detectedLang == "" {
+			detectedLang = output.Language
+		}
+		log.InfoContext(
+			ctx,
+			"transcribed audio",
+			slog.String("text", transcription),
+			slog.String("language", detectedLang),
+		)
+
+		// Append transcription to last message's content.
+		switch {
+		// Already using MultiContent, append text part.
+		case len(last.MultiContent) > 0:
+			last.MultiContent = append(last.MultiContent,
+				openai.ChatMessagePart{
+					Type: openai.ChatMessagePartTypeText,
+					Text: transcription,
+				},
+			)
+			last.Content = ""
+
+		// Has string content, convert to MultiContent.
+		case last.Content != "":
+			last.MultiContent = []openai.ChatMessagePart{
+				{
+					Type: openai.ChatMessagePartTypeText,
+					Text: last.Content,
+				},
+				{
+					Type: openai.ChatMessagePartTypeText,
+					Text: transcription,
+				},
+			}
+			last.Content = ""
+		// Empty message, just set content.
+		// Clear MultiContent, as required by the API spec.
+		default:
+			last.Content = transcription
+			last.MultiContent = nil
+		}
+	}
+
+	// Get LLM response.
+	var model = req.Model
+	if model == "" {
+		model = svc.llm.DefaultModel()
+	}
+	msgs, err := svc.llm.Query(ctx, messages, model)
+	if err != nil {
+		log.ErrorContext(
+			ctx,
+			"LLM request failed",
+			slog.Any("error", err),
+		)
+		http.Error(w, "LLM error", http.StatusInternalServerError)
+		return
+	}
+	if len(msgs) == 0 {
+		http.Error(
+			w,
+			"no response from LLM",
+			http.StatusInternalServerError,
+		)
+		return
+	}
+	final := msgs[len(msgs)-1]
+	log.InfoContext(
+		ctx,
+		"LLM response",
+		slog.String("text", final.Content),
+		slog.String("model", model),
+	)
+
+	// Determine voice to use.
+	var voice = req.Voice
+	if req.Voice == "" && detectedLang != "" {
+		if autoVoice := svc.tts.SelectVoice(
+			detectedLang,
+		); autoVoice != "" {
+			voice = autoVoice
+			log.InfoContext(ctx, "auto-selected voice",
+				slog.String("language", detectedLang),
+				slog.String("voice", voice),
+			)
+		}
+	} else if req.Voice == "" {
+		log.WarnContext(
+			ctx,
+			"auto-voice enabled but no language detected",
+		)
+	}
+
+	// Generate audio response with selected voice.
+	audio, err := svc.tts.Synthesize(ctx, final.Content, voice)
+	if err != nil {
+		log.ErrorContext(ctx, "TTS failed", slog.Any("error", err))
+		http.Error(w, "TTS error", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(Response{
+		Audio:            base64.StdEncoding.EncodeToString(audio),
+		DetectedLanguage: detectedLang,
+		Messages:         msgs,
+		Model:            model,
+		Transcription:    transcription,
+		Voice:            voice,
+	}); err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to json encode response",
+			slog.Any("error", err),
+		)
+	}
+}
+
+// StreamMessage is the SSE event payload for the streaming voice endpoint.
+type StreamMessage struct {
+	// Audio is the base64-encoded WAV audio response.
+	Audio string `json:"audio,omitempty"`
+	// DetectedLanguage is the language detected in the input speech.
+	DetectedLanguage string `json:"detected_language,omitempty"`
+	// Error is an error message, if any.
+	Error string `json:"error,omitempty"`
+	// Message is the chat completion message.
+	Message openai.ChatCompletionMessage `json:"message"`
+	// Model is the LLM model used for the response.
+	Model string `json:"model,omitempty"`
+	// Transcription is the transcribed user speech from the input audio.
+	Transcription string `json:"transcription,omitempty"`
+	// Voice is the voice used for TTS synthesis.
+	Voice string `json:"voice,omitempty"`
+}
+
+// voiceStream processes voice requests with streaming SSE output.
+func (svc *Service) voiceStream(w http.ResponseWriter, r *http.Request) {
+	var (
+		ctx = r.Context()
+		log = ctx.Value("log").(*slog.Logger)
+	)
+
+	// Check that the response writer supports flushing.
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		http.Error(
+			w,
+			"streaming not supported",
+			http.StatusInternalServerError,
+		)
+		return
+	}
+
+	// Parse request.
+	r.Body = http.MaxBytesReader(w, r.Body, 32<<20)
+	var req Request
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to decode request",
+			slog.Any("error", err),
+		)
+		http.Error(w, "invalid request", http.StatusBadRequest)
+		return
+	}
+
+	// Validate messages.
+	if len(req.Messages) == 0 {
+		http.Error(w, "messages required", http.StatusBadRequest)
+		return
+	}
+
+	// Acquire semaphore.
+	if err := svc.sem.Acquire(ctx, 1); err != nil {
+		http.Error(
+			w,
+			"service unavailable",
+			http.StatusServiceUnavailable,
+		)
+		return
+	}
+	defer svc.sem.Release(1)
+
+	var (
+		messages      = req.Messages
+		transcription string
+		detectedLang  string
+	)
+
+	// If audio provided, transcribe and append to last message.
+	if req.Audio != "" {
+		last := &messages[len(messages)-1]
+		if last.Role != openai.ChatMessageRoleUser {
+			http.Error(
+				w,
+				"last message must be role=user when audio is provided",
+				http.StatusBadRequest,
+			)
+			return
+		}
+
+		data, err := base64.StdEncoding.DecodeString(req.Audio)
+		if err != nil {
+			log.ErrorContext(
+				ctx,
+				"failed to decode audio",
+				slog.Any("error", err),
+			)
+			http.Error(w, "invalid audio", http.StatusBadRequest)
+			return
+		}
+
+		output, err := svc.stt.Transcribe(ctx, data)
+		if err != nil {
+			log.ErrorContext(
+				ctx,
+				"STT failed",
+				slog.Any("error", err),
+			)
+			http.Error(
+				w,
+				"STT error",
+				http.StatusInternalServerError,
+			)
+			return
+		}
+
+		transcription = strings.TrimSpace(output.Text)
+		detectedLang = output.DetectedLanguage
+		if detectedLang == "" {
+			detectedLang = output.Language
+		}
+		log.InfoContext(
+			ctx,
+			"transcribed audio",
+			slog.String("text", transcription),
+			slog.String("language", detectedLang),
+		)
+
+		// Append transcription to last message's content.
+		switch {
+		case len(last.MultiContent) > 0:
+			last.MultiContent = append(last.MultiContent,
+				openai.ChatMessagePart{
+					Type: openai.ChatMessagePartTypeText,
+					Text: transcription,
+				},
+			)
+			last.Content = ""
+		case last.Content != "":
+			last.MultiContent = []openai.ChatMessagePart{
+				{
+					Type: openai.ChatMessagePartTypeText,
+					Text: last.Content,
+				},
+				{
+					Type: openai.ChatMessagePartTypeText,
+					Text: transcription,
+				},
+			}
+			last.Content = ""
+		default:
+			last.Content = transcription
+			last.MultiContent = nil
+		}
+	}
+
+	// Set SSE headers.
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+	w.Header().Set("Content-Type", "text/event-stream")
+
+	// Helper to send an SSE event.
+	send := func(msg StreamMessage) {
+		data, err := json.Marshal(msg)
+		if err != nil {
+			log.ErrorContext(ctx, "failed to marshal SSE event",
+				slog.Any("error", err),
+			)
+			return
+		}
+		fmt.Fprintf(w, "event: message\ndata: %s\n\n", data)
+		flusher.Flush()
+	}
+
+	// If audio was transcribed, send user message with transcription.
+	if transcription != "" {
+		send(StreamMessage{
+			Message: openai.ChatCompletionMessage{
+				Role:    openai.ChatMessageRoleUser,
+				Content: transcription,
+			},
+			Transcription:    transcription,
+			DetectedLanguage: detectedLang,
+		})
+	}
+
+	// Get model.
+	var model = req.Model
+	if model == "" {
+		model = svc.llm.DefaultModel()
+	}
+
+	// Determine voice to use.
+	var voice = req.Voice
+	if req.Voice == "" && detectedLang != "" {
+		if autoVoice := svc.tts.SelectVoice(
+			detectedLang,
+		); autoVoice != "" {
+			voice = autoVoice
+			log.InfoContext(ctx, "auto-selected voice",
+				slog.String("language", detectedLang),
+				slog.String("voice", voice),
+			)
+		}
+	}
+
+	// Start streaming LLM query.
+	var (
+		events = make(chan llm.StreamEvent)
+		llmErr error
+	)
+	go func() {
+		llmErr = svc.llm.QueryStream(ctx, messages, model, events)
+	}()
+
+	// Consume events and send as SSE.
+	var last StreamMessage
+	for evt := range events {
+		msg := StreamMessage{Message: evt.Message}
+
+		// Track the last assistant message for TTS.
+		if evt.Message.Role == openai.ChatMessageRoleAssistant &&
+			len(evt.Message.ToolCalls) == 0 {
+			last = msg
+			continue
+		}
+
+		send(msg)
+	}
+	// Check for LLM errors.
+	if llmErr != nil {
+		log.ErrorContext(
+			ctx,
+			"LLM stream failed",
+			slog.Any("error", llmErr),
+		)
+		send(StreamMessage{
+			Message: openai.ChatCompletionMessage{
+				Role: openai.ChatMessageRoleAssistant,
+			},
+			Error: fmt.Sprintf("LLM error: %v", llmErr),
+		})
+		return
+	}
+
+	// Synthesize TTS for the final assistant message.
+	if last.Message.Content != "" {
+		audio, err := svc.tts.Synthesize(
+			ctx, last.Message.Content, voice,
+		)
+		if err != nil {
+			log.ErrorContext(
+				ctx, "TTS failed", slog.Any("error", err),
+			)
+			last.Error = fmt.Sprintf("TTS error: %v", err)
+		} else {
+			last.Audio = base64.StdEncoding.EncodeToString(audio)
+		}
+	}
+	last.Model = model
+	last.Voice = voice
+	send(last)
+}
+
+// models returns available LLM models.
+func (svc *Service) models(w http.ResponseWriter, r *http.Request) {
+	var (
+		ctx = r.Context()
+		log = ctx.Value("log").(*slog.Logger)
+	)
+
+	models, err := svc.llm.ListModels(ctx)
+	if err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to list models",
+			slog.Any("error", err),
+		)
+		http.Error(
+			w,
+			"failed to list models",
+			http.StatusInternalServerError,
+		)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(struct {
+		Models       []openai.Model `json:"models"`
+		DefaultModel string         `json:"default_model"`
+	}{
+		Models:       models,
+		DefaultModel: svc.llm.DefaultModel(),
+	}); err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to encode models response",
+			slog.Any("error", err),
+		)
+	}
+}
+
+// voices returns available TTS voices.
+func (svc *Service) voices(w http.ResponseWriter, r *http.Request) {
+	var (
+		ctx = r.Context()
+		log = ctx.Value("log").(*slog.Logger)
+	)
+
+	voices, err := svc.tts.ListVoices(ctx)
+	if err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to list voices",
+			slog.Any("error", err),
+		)
+		http.Error(
+			w,
+			"failed to list voices",
+			http.StatusInternalServerError,
+		)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	if err := json.NewEncoder(w).Encode(map[string][]string{
+		"voices": voices,
+	}); err != nil {
+		log.ErrorContext(
+			ctx,
+			"failed to encode voices response",
+			slog.Any("error", err),
+		)
+	}
+}
--- a/internal/service/service_test.go
+++ b/internal/service/service_test.go
@@ -0,0 +1,24 @@
+package service
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestStatusHandler(t *testing.T) {
+	svc := &Service{}
+
+	req := httptest.NewRequest(http.MethodGet, "/status", nil)
+	w := httptest.NewRecorder()
+
+	svc.status(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Errorf(
+			"status handler returned %d, want %d",
+			w.Code,
+			http.StatusOK,
+		)
+	}
+}
--- a/internal/service/static/icons.svg
+++ b/internal/service/static/icons.svg
@@ -0,0 +1,93 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+  <symbol id="user" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <circle cx="12" cy="8" r="4"/>
+    <path d="M20 21a8 8 0 1 0-16 0"/>
+  </symbol>
+
+  <symbol id="assistant" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M9.937 15.5A2 2 0 0 0 8.5 14.063l-6.135-1.582a.5.5 0 0 1 0-.962L8.5 9.936A2 2 0 0 0 9.937 8.5l1.582-6.135a.5.5 0 0 1 .963 0L14.063 8.5A2 2 0 0 0 15.5 9.937l6.135 1.581a.5.5 0 0 1 0 .964L15.5 14.063a2 2 0 0 0-1.437 1.437l-1.582 6.135a.5.5 0 0 1-.963 0z"/>
+    <path d="M20 3v4"/>
+    <path d="M22 5h-4"/>
+    <path d="M4 17v2"/>
+    <path d="M5 18H3"/>
+  </symbol>
+
+  <symbol id="copy" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <rect width="14" height="14" x="8" y="8" rx="2" ry="2"/>
+    <path d="M4 16c-1.1 0-2-.9-2-2V4c0-1.1.9-2 2-2h10c1.1 0 2 .9 2 2"/>
+  </symbol>
+
+  <symbol id="check" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M20 6 9 17l-5-5"/>
+  </symbol>
+
+  <symbol id="inspect" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <circle cx="11" cy="11" r="8"/>
+    <path d="m21 21-4.3-4.3"/>
+  </symbol>
+
+  <symbol id="tool" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M14.7 6.3a1 1 0 0 0 0 1.4l1.6 1.6a1 1 0 0 0 1.4 0l3.77-3.77a6 6 0 0 1-7.94 7.94l-6.91 6.91a2.12 2.12 0 0 1-3-3l6.91-6.91a6 6 0 0 1 7.94-7.94l-3.76 3.76z"/>
+  </symbol>
+
+  <symbol id="reasoning" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M12 5a3 3 0 1 0-5.997.125 4 4 0 0 0-2.526 5.77 4 4 0 0 0 .556 6.588A4 4 0 1 0 12 18Z"/>
+    <path d="M12 5a3 3 0 1 1 5.997.125 4 4 0 0 1 2.526 5.77 4 4 0 0 1-.556 6.588A4 4 0 1 1 12 18Z"/>
+    <path d="M15 13a4.5 4.5 0 0 1-3-4 4.5 4.5 0 0 1-3 4"/>
+    <path d="M17.599 6.5a3 3 0 0 0 .399-1.375"/>
+    <path d="M6.003 5.125A3 3 0 0 0 6.401 6.5"/>
+    <path d="M3.477 10.896a4 4 0 0 1 .585-.396"/>
+    <path d="M19.938 10.5a4 4 0 0 1 .585.396"/>
+    <path d="M6 18a4 4 0 0 1-1.967-.516"/>
+    <path d="M19.967 17.484A4 4 0 0 1 18 18"/>
+  </symbol>
+
+  <symbol id="reset" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M3 12a9 9 0 1 0 9-9 9.75 9.75 0 0 0-6.74 2.74L3 8"/>
+    <path d="M3 3v5h5"/>
+  </symbol>
+
+  <symbol id="attach" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="m21.44 11.05-9.19 9.19a6 6 0 0 1-8.49-8.49l8.57-8.57A4 4 0 1 1 18 8.84l-8.59 8.57a2 2 0 0 1-2.83-2.83l8.49-8.48"/>
+  </symbol>
+
+  <symbol id="mic" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M12 2a3 3 0 0 0-3 3v7a3 3 0 0 0 6 0V5a3 3 0 0 0-3-3Z"/>
+    <path d="M19 10v2a7 7 0 0 1-14 0v-2"/>
+    <line x1="12" x2="12" y1="19" y2="22"/>
+  </symbol>
+
+  <symbol id="send" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M14.536 21.686a.5.5 0 0 0 .937-.024l6.5-19a.496.496 0 0 0-.635-.635l-19 6.5a.5.5 0 0 0-.024.937l7.93 3.18a2 2 0 0 1 1.112 1.11z"/>
+    <path d="m21.854 2.147-10.94 10.939"/>
+  </symbol>
+
+  <symbol id="menu" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <line x1="4" x2="20" y1="12" y2="12"/>
+    <line x1="4" x2="20" y1="6" y2="6"/>
+    <line x1="4" x2="20" y1="18" y2="18"/>
+  </symbol>
+
+  <symbol id="close" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M18 6 6 18"/>
+    <path d="m6 6 12 12"/>
+  </symbol>
+
+  <symbol id="volume" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M11 4.702a.705.705 0 0 0-1.203-.498L6.413 7.587A1.4 1.4 0 0 1 5.416 8H3a1 1 0 0 0-1 1v6a1 1 0 0 0 1 1h2.416a1.4 1.4 0 0 1 .997.413l3.383 3.384A.705.705 0 0 0 11 19.298z"/>
+    <path d="M16 9a5 5 0 0 1 0 6"/>
+    <path d="M19.364 18.364a9 9 0 0 0 0-12.728"/>
+  </symbol>
+
+  <symbol id="volume-off" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M11 4.702a.705.705 0 0 0-1.203-.498L6.413 7.587A1.4 1.4 0 0 1 5.416 8H3a1 1 0 0 0-1 1v6a1 1 0 0 0 1 1h2.416a1.4 1.4 0 0 1 .997.413l3.383 3.384A.705.705 0 0 0 11 19.298z"/>
+    <line x1="22" x2="16" y1="9" y2="15"/>
+    <line x1="16" x2="22" y1="9" y2="15"/>
+  </symbol>
+
+  <symbol id="x-circle" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <circle cx="12" cy="12" r="10"/>
+    <path d="m15 9-6 6"/>
+    <path d="m9 9 6 6"/>
+  </symbol>
+</svg>
--- a/internal/service/static/main.css
+++ b/internal/service/static/main.css
@@ -0,0 +1,692 @@
+:root {
+  --base-font-size: calc(1rem + 0.1618vw);
+  --ratio: 1.618;
+  --s-2: calc(var(--s-1) / var(--ratio));
+  --s-1: calc(var(--s0) / var(--ratio));
+  --s0: var(--base-font-size);
+  --s1: calc(var(--s0) * var(--ratio));
+  --s2: calc(var(--s1) * var(--ratio));
+  --s3: calc(var(--s2) * var(--ratio));
+
+  --font-sans: system-ui, -apple-system, sans-serif;
+  --font-mono: ui-monospace, monospace;
+
+  --color-black: #1d1f21;
+  --color-blue: #4271ae;
+  --color-brown: #a3685a;
+  --color-cyan: #3e999f;
+  --color-gray0: #efefef;
+  --color-gray1: #e0e0e0;
+  --color-gray2: #d6d6d6;
+  --color-gray3: #8e908c;
+  --color-gray4: #969896;
+  --color-gray5: #4d4d4c;
+  --color-gray6: #282a2e;
+  --color-green: #718c00;
+  --color-orange: #f5871f;
+  --color-purple: #8959a8;
+  --color-red: #c82829;
+  --color-yellow: #eab700;
+
+  --color-bg: var(--color-gray0);
+  --color-surface: white;
+  --color-text: var(--color-black);
+  --color-text-muted: var(--color-gray3);
+  --color-border: var(--color-black);
+  --color-border-light: var(--color-gray2);
+  --color-primary: var(--color-blue);
+  --color-primary-hover: var(--color-cyan);
+  --color-recording: var(--color-red);
+  --color-error: var(--color-yellow);
+
+  --measure: 80ch;
+  --radius: 0.375rem;
+  --icon-size: 1.25rem;
+  --action-icon-size: 0.875rem;
+  --border-width: 2px;
+  --textarea-line-height: 1.5rem;
+}
+
+/* ==================== */
+/* Reset                */
+/* ==================== */
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+  margin: 0;
+}
+
+/* ==================== */
+/* Base                 */
+/* ==================== */
+
+html {
+  font-size: 100%;
+  font-family: var(--font-sans);
+  line-height: 1.5;
+  color: var(--color-text);
+  background: var(--color-bg);
+}
+
+body {
+  overflow: hidden;
+  min-height: 100dvh;
+}
+
+/* ==================== */
+/* Layout               */
+/* ==================== */
+
+.container {
+  display: flex;
+  flex-direction: column;
+  min-height: 100dvh;
+  height: 100dvh;
+  max-width: calc(var(--measure) + var(--s3) * 2);
+  margin-inline: auto;
+  padding: var(--s0);
+  padding-bottom: 0;
+}
+
+/* ==================== */
+/* Chat                 */
+/* ==================== */
+
+.chat {
+  flex: 1 1 0;
+  min-height: 0;
+  overflow-y: auto;
+  padding: var(--s1);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius);
+}
+
+.chat > * + * {
+  margin-top: var(--s0);
+}
+
+/* ==================== */
+/* Collapsible          */
+/* ==================== */
+
+.collapsible {
+  border: 1px dashed var(--color-border-light);
+  border-radius: var(--radius);
+}
+
+.collapsible[open] .collapsible__summary::before {
+  transform: rotate(90deg);
+}
+
+.collapsible:last-of-type:has(~ .message__actions:empty) {
+  border-bottom: none;
+}
+
+.collapsible__content {
+  padding: var(--s-2) var(--s-1);
+  border-top: 1px dashed var(--color-border-light);
+}
+
+.collapsible__content > pre {
+  margin: 0;
+  font-family: var(--font-mono);
+  font-size: var(--s-1);
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+
+.collapsible__label {
+  font-size: var(--s-1);
+  color: var(--color-text-muted);
+}
+
+.collapsible__pre {
+  margin: 0;
+  padding: var(--s-2);
+  font-family: var(--font-mono);
+  font-size: var(--s-1);
+  background: var(--color-bg);
+  border-radius: var(--radius);
+  overflow-x: auto;
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+
+.collapsible__section {
+  margin-bottom: var(--s-2);
+}
+
+.collapsible__section:last-child {
+  margin-bottom: 0;
+}
+
+.collapsible__section-label {
+  font-size: var(--s-2);
+  font-weight: 500;
+  color: var(--color-text-muted);
+  margin-bottom: 0.25rem;
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+}
+
+.collapsible__summary {
+  display: flex;
+  align-items: center;
+  gap: var(--s-2);
+  padding: var(--s-2) var(--s-1);
+  cursor: pointer;
+  user-select: none;
+  list-style: none;
+}
+
+.collapsible__summary::-webkit-details-marker {
+  display: none;
+}
+
+.collapsible__summary::before {
+  content: "▶";
+  font-size: 0.625em;
+  color: var(--color-text-muted);
+  transition: transform 0.15s ease;
+}
+
+.collapsible__summary .icon {
+  width: var(--icon-size);
+  height: var(--icon-size);
+  color: var(--color-text-muted);
+}
+
+.collapsible--reasoning .collapsible__summary .icon {
+  color: var(--color-purple);
+}
+
+.collapsible--reasoning:has(+ .collapsible--tool) {
+  margin-bottom: 0;
+  border-bottom-left-radius: 0;
+  border-bottom-right-radius: 0;
+}
+
+.collapsible--reasoning + .collapsible--tool {
+  margin-top: 0;
+  border-top: none;
+  border-top-left-radius: 0;
+  border-top-right-radius: 0;
+}
+
+.collapsible--tool .collapsible__summary .icon {
+  color: var(--color-orange);
+}
+
+/* ==================== */
+/* Compose              */
+/* ==================== */
+
+.compose {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius);
+  overflow: hidden;
+  margin-bottom: var(--s0);
+}
+
+.compose__action-btn {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0.25rem;
+  background: transparent;
+  border: none;
+  border-radius: 0.25rem;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  transition:
+    color 0.15s ease,
+    background-color 0.15s ease;
+}
+
+@media (hover: hover) {
+  .compose__action-btn:hover {
+    color: var(--color-text);
+  }
+}
+
+.compose__action-btn:focus-visible {
+  outline: 2px solid var(--color-primary);
+  outline-offset: 1px;
+}
+
+.compose__action-btn:disabled {
+  opacity: 0.4;
+  cursor: not-allowed;
+}
+
+.compose__action-btn .icon {
+  width: var(--action-icon-size);
+  height: var(--action-icon-size);
+}
+
+.compose__action-btn--record.recording {
+  color: white;
+  background: var(--color-recording);
+  animation: pulse 1s ease-in-out infinite;
+}
+
+.compose__action-btn--send.loading {
+  position: relative;
+  color: transparent;
+  pointer-events: none;
+}
+
+.compose__action-btn--send.loading::after {
+  content: "";
+  position: absolute;
+  width: 0.75rem;
+  height: 0.75rem;
+  border: 2px solid var(--color-gray2);
+  border-top-color: var(--color-primary);
+  border-radius: 50%;
+  animation: spin 0.8s linear infinite;
+}
+
+.compose__actions {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 0.125rem var(--s-2);
+  border-top: 1px dotted var(--color-border-light);
+}
+
+.compose__actions-right {
+  display: flex;
+  align-items: center;
+  gap: 0.125rem;
+}
+
+.compose__attachment {
+  display: flex;
+  align-items: center;
+  gap: 0.25rem;
+  padding: 0.125rem 0.375rem;
+  font-size: var(--s-1);
+  background: var(--color-gray1);
+  border-radius: var(--radius);
+  color: var(--color-text);
+}
+
+.compose__attachment-name {
+  max-width: 120px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.compose__attachment-remove {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0;
+  background: none;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  transition: color 0.15s ease;
+}
+
+@media (hover: hover) {
+  .compose__attachment-remove:hover {
+    color: var(--color-red);
+  }
+}
+
+.compose__attachment-remove .icon {
+  width: 0.875rem;
+  height: 0.875rem;
+}
+
+.compose__attachments {
+  display: flex;
+  flex-wrap: wrap;
+  gap: var(--s-2);
+  padding: var(--s-2) var(--s-1);
+  border-top: 1px dotted var(--color-border-light);
+}
+
+.compose__attachments:empty {
+  display: none;
+}
+
+.compose__textarea {
+  display: block;
+  width: 100%;
+  height: auto;
+  min-height: calc(var(--textarea-line-height) + var(--s-1) * 2);
+  max-height: calc(var(--textarea-line-height) * 5 + var(--s-1) * 2);
+  padding: var(--s-1);
+  font-family: inherit;
+  font-size: var(--s0);
+  line-height: var(--textarea-line-height);
+  color: var(--color-text);
+  background: var(--color-surface);
+  border: none;
+  resize: none;
+  overflow-y: auto;
+  field-sizing: content;
+}
+
+.compose__textarea:focus {
+  outline: none;
+}
+
+.compose__textarea::placeholder {
+  color: var(--color-text-muted);
+}
+
+/* ==================== */
+/* Footer               */
+/* ==================== */
+
+.footer {
+  margin-top: var(--s0);
+  background: var(--color-bg);
+}
+
+.footer__select {
+  height: 2rem;
+  padding: 0 var(--s-1);
+  font-family: inherit;
+  font-size: var(--s-1);
+  line-height: 2rem;
+  color: var(--color-text);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius);
+  cursor: pointer;
+  max-width: 150px;
+}
+
+.footer__select:focus-visible {
+  outline: 2px solid var(--color-primary);
+  outline-offset: 2px;
+}
+
+.footer__toolbar {
+  border-inline: none;
+  border-bottom: none;
+  display: flex;
+  align-items: center;
+  gap: var(--s-2);
+  padding: var(--s-2);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius);
+}
+
+.footer__toolbar-btn {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  height: 2rem;
+  width: 2rem;
+  padding: 0;
+  background: transparent;
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius);
+  color: var(--color-text-muted);
+  cursor: pointer;
+  transition: all 0.15s ease;
+}
+
+@media (hover: hover) {
+  .footer__toolbar-btn:hover {
+    color: var(--color-text);
+    border-color: var(--color-text-muted);
+  }
+}
+
+.footer__toolbar-btn:focus-visible {
+  outline: 2px solid var(--color-primary);
+  outline-offset: 2px;
+}
+
+.footer__toolbar-btn .icon {
+  width: 1rem;
+  height: 1rem;
+}
+
+.footer__toolbar-btn--muted {
+  color: var(--color-red);
+  border-color: var(--color-red);
+}
+
+@media (hover: hover) {
+  .footer__toolbar-btn--muted:hover {
+    color: var(--color-red);
+    border-color: var(--color-red);
+  }
+}
+
+.footer__toolbar-spacer {
+  flex: 1;
+}
+
+/* ==================== */
+/* Message              */
+/* ==================== */
+
+.message {
+  display: flex;
+  max-width: 100%;
+  border: var(--border-width) solid var(--color-border);
+  border-radius: var(--radius);
+  overflow: hidden;
+}
+
+.message--assistant .message__icon {
+  color: var(--color-primary);
+}
+
+.message--debug-open .message__debug {
+  display: block;
+}
+
+.message--error {
+  border-color: var(--color-error);
+}
+
+.message--error .message__icon {
+  border-color: var(--color-error);
+}
+
+.message--user .message__icon {
+  color: var(--color-green);
+}
+
+.message__action-btn {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0.125rem;
+  background: transparent;
+  border: none;
+  border-radius: 0.125rem;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  transition: color 0.15s ease;
+}
+
+@media (hover: hover) {
+  .message__action-btn:hover {
+    color: var(--color-text);
+  }
+}
+
+.message__action-btn:focus-visible {
+  outline: 2px solid var(--color-primary);
+  outline-offset: 1px;
+}
+
+.message__action-btn svg {
+  width: var(--action-icon-size);
+  height: var(--action-icon-size);
+}
+
+.message__action-btn--success {
+  color: var(--color-primary);
+}
+
+.message__actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 0.125rem;
+  padding: 0.125rem 0.25rem;
+  border-top: 1px dotted var(--color-border-light);
+  background: var(--color-surface);
+}
+
+.message__actions:empty {
+  display: none;
+}
+
+.message__body {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+}
+
+.message__content {
+  padding: var(--s-2) var(--s-1);
+  white-space: pre-wrap;
+  word-wrap: break-word;
+  overflow-wrap: break-word;
+}
+
+.message__content img {
+  display: block;
+  max-width: 100%;
+  height: auto;
+  margin-block: var(--s-1);
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius);
+}
+
+.message__debug {
+  display: none;
+  padding: var(--s-2) var(--s-1);
+  border-top: 1px dotted var(--color-border-light);
+  background: var(--color-surface);
+}
+
+.message__debug-list {
+  display: grid;
+  grid-template-columns: auto 1fr;
+  gap: 0.125rem 1rem;
+  margin: 0;
+  font-size: var(--s-1);
+}
+
+.message__debug-list dt,
+.message__debug-list dd {
+  margin: 0;
+  text-align: left;
+  color: var(--color-text);
+}
+
+.message__debug-list dt {
+  white-space: nowrap;
+}
+
+.message__icon {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: var(--s-2);
+  border-right: var(--border-width) solid var(--color-border);
+  background: var(--color-bg);
+  color: var(--color-text-muted);
+}
+
+.message__icon svg {
+  width: var(--icon-size);
+  height: var(--icon-size);
+}
+
+/* ==================== */
+/* Animations           */
+/* ==================== */
+
+@keyframes pulse {
+  0%,
+  100% {
+    opacity: 1;
+  }
+  50% {
+    opacity: 0.7;
+  }
+}
+
+@keyframes spin {
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+/* ==================== */
+/* Media: Mobile        */
+/* ==================== */
+
+@media (max-width: 639px) {
+  .container {
+    padding: 0;
+    padding-top: var(--s-1);
+  }
+
+  .chat {
+    border-radius: 0;
+    border-inline: none;
+  }
+
+  .footer {
+    margin-top: var(--s-1);
+    padding-bottom: 0;
+  }
+
+  .compose {
+    border-radius: 0;
+    border-inline: none;
+    margin-bottom: var(--s-1);
+  }
+
+  .compose__action-btn {
+    min-width: 44px;
+    min-height: 44px;
+    padding: var(--s-1);
+  }
+
+  .compose__action-btn .icon {
+    width: var(--icon-size);
+    height: var(--icon-size);
+  }
+
+  .footer__toolbar {
+    border-inline: none;
+    border-bottom: none;
+    border-radius: 0;
+    margin-top: 0;
+  }
+
+  .footer__toolbar-btn {
+    height: 1.75rem;
+    width: 1.75rem;
+  }
+
+  .footer__select {
+    height: 1.75rem;
+    line-height: 1.75rem;
+    max-width: 128px;
+    font-size: var(--s-1);
+  }
+}
--- a/internal/service/static/main.js
+++ b/internal/service/static/main.js
--- a/internal/service/templates/static/body.gohtml
+++ b/internal/service/templates/static/body.gohtml
@@ -0,0 +1,6 @@
+{{ define "body" }}
+  <body>
+    {{ template "main" . }}
+    {{ template "templates" . }}
+  </body>
+{{ end }}
--- a/internal/service/templates/static/footer/compose.gohtml
+++ b/internal/service/templates/static/footer/compose.gohtml
@@ -0,0 +1,41 @@
+{{ define "footer/compose" }}
+  <div class="compose">
+    <textarea
+      class="compose__textarea"
+      id="text-input"
+      placeholder="Type a message..."
+      aria-label="Message input"
+      rows="1"
+    ></textarea>
+    <div class="compose__attachments" id="attachments"></div>
+    <div class="compose__actions">
+      <button
+        type="button"
+        class="compose__action-btn"
+        id="attach"
+        aria-label="Attach files"
+      >
+        <svg class="icon"><use href="/static/icons.svg#attach"></use></svg>
+      </button>
+      <input type="file" id="file-input" multiple hidden />
+      <div class="compose__actions-right">
+        <button
+          type="button"
+          class="compose__action-btn compose__action-btn--record"
+          id="ptt"
+          aria-label="Push to talk"
+        >
+          <svg class="icon"><use href="/static/icons.svg#mic"></use></svg>
+        </button>
+        <button
+          type="button"
+          class="compose__action-btn compose__action-btn--send"
+          id="send"
+          aria-label="Send message"
+        >
+          <svg class="icon"><use href="/static/icons.svg#send"></use></svg>
+        </button>
+      </div>
+    </div>
+  </div>
+{{ end }}
--- a/internal/service/templates/static/footer/footer.gohtml
+++ b/internal/service/templates/static/footer/footer.gohtml
@@ -0,0 +1,6 @@
+{{ define "footer" }}
+  <footer class="footer">
+    {{ template "footer/compose" . }}
+    {{ template "footer/toolbar" . }}
+  </footer>
+{{ end }}
--- a/internal/service/templates/static/footer/toolbar.gohtml
+++ b/internal/service/templates/static/footer/toolbar.gohtml
@@ -0,0 +1,31 @@
+{{ define "footer/toolbar" }}
+  <div class="footer__toolbar">
+    <button
+      type="button"
+      class="footer__toolbar-btn"
+      id="reset"
+      aria-label="Reset conversation"
+    >
+      <svg class="icon"><use href="/static/icons.svg#reset"></use></svg>
+    </button>
+    <div class="footer__toolbar-spacer"></div>
+    <select id="model" class="footer__select" aria-label="Model">
+      <option value="" disabled selected>
+        Loading...
+      </option>
+    </select>
+    <select id="voice" class="footer__select" aria-label="Voice">
+      <option value="" disabled selected>
+        Loading...
+      </option>
+    </select>
+    <button
+      type="button"
+      class="footer__toolbar-btn"
+      id="mute"
+      aria-label="Mute"
+    >
+      <svg class="icon"><use href="/static/icons.svg#volume"></use></svg>
+    </button>
+  </div>
+{{ end }}
--- a/internal/service/templates/static/head.gohtml
+++ b/internal/service/templates/static/head.gohtml
@@ -0,0 +1,11 @@
+{{ define "head" }}
+  <head>
+    <meta name="author" content="Chimerical LLC">
+    <meta charset="utf-8">
+    <meta name="viewport"
+          content="width=device-width, initial-scale=1.0, shrink-to-fit= no, interactive-widget=resizes-content">
+    <title>Odidere</title>
+    <link rel="stylesheet" href="/static/main.css">
+    <script defer src="/static/main.js"></script>
+  </head>
+{{ end }}
--- a/internal/service/templates/static/index.gohtml
+++ b/internal/service/templates/static/index.gohtml
@@ -0,0 +1,5 @@
+<!doctype html>
+<html lang="en">
+  {{ template "head" . }}
+  {{ template "body" . }}
+</html>
--- a/internal/service/templates/static/main.gohtml
+++ b/internal/service/templates/static/main.gohtml
@@ -0,0 +1,7 @@
+{{ define "main" }}
+  <main class="container">
+    <section class="chat" id="chat" aria-live="polite">
+    </section>
+    {{ template "footer" . }}
+  </main>
+{{ end }}
--- a/internal/service/templates/static/templates.gohtml
+++ b/internal/service/templates/static/templates.gohtml
@@ -0,0 +1,126 @@
+{{ define "templates" }}
+  <template id="tpl-user-message">
+    <div class="message message--user">
+      <div class="message__icon" aria-hidden="true">
+        <svg class="icon"><use href="/static/icons.svg#user"></use></svg>
+      </div>
+      <div class="message__body">
+        <div class="message__content"></div>
+        <div class="message__actions">
+          <button
+            type="button"
+            class="message__action-btn"
+            data-action="inspect"
+            aria-label="Show details"
+            aria-expanded="false"
+          >
+            <svg class="icon"><use href="/static/icons.svg#inspect"></use></svg>
+          </button>
+          <button
+            type="button"
+            class="message__action-btn"
+            data-action="copy"
+            aria-label="Copy to clipboard"
+          >
+            <svg class="icon"><use href="/static/icons.svg#copy"></use></svg>
+          </button>
+        </div>
+        <div class="message__debug">
+          <dl class="message__debug-list"></dl>
+        </div>
+      </div>
+    </div>
+  </template>
+
+  <template id="tpl-assistant-message">
+    <div class="message message--assistant">
+      <div class="message__icon" aria-hidden="true">
+        <svg class="icon"><use href="/static/icons.svg#assistant"></use></svg>
+      </div>
+      <div class="message__body">
+        <div class="message__content"></div>
+        <div class="message__actions">
+          <button
+            type="button"
+            class="message__action-btn"
+            data-action="inspect"
+            aria-label="Show details"
+            aria-expanded="false"
+          >
+            <svg class="icon"><use href="/static/icons.svg#inspect"></use></svg>
+          </button>
+          <button
+            type="button"
+            class="message__action-btn"
+            data-action="copy"
+            aria-label="Copy to clipboard"
+          >
+            <svg class="icon"><use href="/static/icons.svg#copy"></use></svg>
+          </button>
+        </div>
+        <div class="message__debug">
+          <dl class="message__debug-list"></dl>
+        </div>
+      </div>
+    </div>
+  </template>
+
+  <template id="tpl-error-message">
+    <div class="message message--error message--assistant">
+      <div class="message__icon" aria-hidden="true">
+        <svg class="icon"><use href="/static/icons.svg#assistant"></use></svg>
+      </div>
+      <div class="message__body">
+        <div class="message__content"></div>
+      </div>
+    </div>
+  </template>
+
+  <template id="tpl-collapsible">
+    <details class="collapsible">
+      <summary class="collapsible__summary">
+        <span class="collapsible__label"></span>
+      </summary>
+      <div class="collapsible__content">
+        <pre></pre>
+      </div>
+    </details>
+  </template>
+
+  <template id="tpl-tool-call">
+    <details class="collapsible collapsible--tool">
+      <summary class="collapsible__summary">
+        <svg class="icon"><use href="/static/icons.svg#tool"></use></svg>
+        <span class="collapsible__label"></span>
+      </summary>
+      <div class="collapsible__content">
+        <div class="collapsible__section">
+          <div class="collapsible__section-label">Arguments</div>
+          <pre class="collapsible__pre" data-args></pre>
+        </div>
+        <div class="collapsible__section collapsible__section--output" hidden>
+          <div class="collapsible__section-label">Output</div>
+          <pre class="collapsible__pre" data-output></pre>
+        </div>
+      </div>
+    </details>
+  </template>
+
+  <template id="tpl-attachment-chip">
+    <div class="compose__attachment">
+      <span class="compose__attachment-name"></span>
+      <button
+        type="button"
+        class="compose__attachment-remove"
+        aria-label="Remove attachment"
+      >
+        <svg class="icon"><use href="/static/icons.svg#x-circle"></use></svg>
+      </button>
+    </div>
+  </template>
+
+  <template id="tpl-debug-row">
+    <dt></dt>
+    <dd></dd>
+  </template>
+{{ end }}
--- a/internal/service/templates/templates.go
+++ b/internal/service/templates/templates.go
@@ -0,0 +1,43 @@
+package templates
+
+import (
+	"embed"
+	"fmt"
+	"html/template"
+	"io/fs"
+	"strings"
+)
+
+//go:embed static/*
+var static embed.FS
+
+const fileType = ".gohtml"
+
+// Parse walks the embedded static directory and parses all .gohtml templates.
+func Parse() (*template.Template, error) {
+	tmpl := template.New("")
+
+	parseFS := func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+		if strings.Contains(path, fileType) {
+			if _, err := tmpl.ParseFS(static, path); err != nil {
+				return fmt.Errorf(
+					"failed to parse template %s: %w",
+					path, err,
+				)
+			}
+		}
+		return nil
+	}
+
+	if err := fs.WalkDir(static, ".", parseFS); err != nil {
+		return nil, fmt.Errorf("failed to parse templates: %w", err)
+	}
+
+	return tmpl, nil
+}