build: /implement-feature user-preferences

2026-02-08 09:29:22 +00:00 · 2026-02-08 09:29:22 +00:00 · e3e19a3fa8
commit e3e19a3fa8
parent f18c076325
24 changed files with 1132 additions and 1342 deletions
--- a/.sdlc/features/user-preferences/manifest.yaml
+++ b/.sdlc/features/user-preferences/manifest.yaml
@ -1,20 +1,36 @@
 slug: user-preferences
 title: User Preferences API
 created: 2026-02-08T09:06:06.819418064Z
-phase: draft
+phase: implementation
 phase_history:
    - phase: draft
      entered: 2026-02-08T09:06:06.819418064Z
+      exited: 2026-02-08T09:20:31.709383944Z
+    - phase: specified
+      entered: 2026-02-08T09:20:31.709383944Z
+      exited: 2026-02-08T09:20:31.715778577Z
+    - phase: planned
+      entered: 2026-02-08T09:20:31.715778577Z
+      exited: 2026-02-08T09:20:31.721032282Z
+    - phase: ready
+      entered: 2026-02-08T09:20:31.721032282Z
+      exited: 2026-02-08T09:20:31.727173118Z
+    - phase: implementation
+      entered: 2026-02-08T09:20:31.727173118Z
 artifacts:
    audit:
        status: pending
        path: audit.md
    design:
-        status: draft
+        status: approved
        path: design.md
+        approved_by: user
+        approved_at: 2026-02-08T09:20:28.25927382Z
    qa_plan:
-        status: draft
+        status: approved
        path: qa-plan.md
+        approved_by: user
+        approved_at: 2026-02-08T09:20:28.26939164Z
    qa_results:
        status: pending
        path: qa-results.md
@ -22,34 +38,55 @@ artifacts:
        status: pending
        path: review.md
    spec:
-        status: draft
+        status: approved
        path: spec.md
+        approved_by: user
+        approved_at: 2026-02-08T09:20:28.254388769Z
    tasks:
-        status: draft
+        status: approved
        path: tasks.md
+        approved_by: user
+        approved_at: 2026-02-08T09:20:28.264355002Z
        total: 8
+        completed: 8
 tasks:
    - id: task-001
      title: Domain layer - preferences types, validation, defaults, and errors
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:20:36.310646192Z
+      done_at: 2026-02-08T09:21:30.037686457Z
    - id: task-002
      title: Port layer - PreferencesRepository interface
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:21:33.903171827Z
+      done_at: 2026-02-08T09:22:14.064726881Z
    - id: task-003
      title: Database migration - user_preferences table
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:21:33.907199366Z
+      done_at: 2026-02-08T09:22:14.069927938Z
    - id: task-004
      title: PostgreSQL adapter - PreferencesRepository implementation
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:22:18.985170366Z
+      done_at: 2026-02-08T09:23:28.657646091Z
    - id: task-005
      title: Service layer - PreferencesService with get/set logic and tests
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:22:18.990366915Z
+      done_at: 2026-02-08T09:23:28.663751019Z
    - id: task-006
      title: HTTP handlers - GET and PUT with auth, mapping, and tests
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:23:28.66873089Z
+      done_at: 2026-02-08T09:25:11.5724865Z
    - id: task-007
      title: Routes, OpenAPI spec, and main.go wiring
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:25:11.579240669Z
+      done_at: 2026-02-08T09:26:45.825892515Z
    - id: task-008
      title: Remove example scaffold code
-      status: pending
+      status: complete
+      started_at: 2026-02-08T09:26:45.832233337Z
+      done_at: 2026-02-08T09:28:59.532153587Z
--- a/.sdlc/state.yaml
+++ b/.sdlc/state.yaml
@ -4,10 +4,10 @@ project:
 active_work:
    features:
        - slug: user-preferences
-          phase: draft
+          phase: implementation
 blocked: []
-last_updated: 2026-02-08T09:06:06.8197296Z
-last_action: CREATE_FEATURE
+last_updated: 2026-02-08T09:28:59.532990472Z
+last_action: COMPLETE_TASK
 last_actor: cli
 history:
    - timestamp: 2026-02-08T09:06:06.819729169Z
@ -15,3 +15,83 @@ history:
      feature: user-preferences
      actor: cli
      result: success
+    - timestamp: 2026-02-08T09:20:28.254858111Z
+      action: APPROVE_ARTIFACT
+      feature: user-preferences
+      actor: user
+      result: success
+    - timestamp: 2026-02-08T09:20:28.259691267Z
+      action: APPROVE_ARTIFACT
+      feature: user-preferences
+      actor: user
+      result: success
+    - timestamp: 2026-02-08T09:20:28.264889368Z
+      action: APPROVE_ARTIFACT
+      feature: user-preferences
+      actor: user
+      result: success
+    - timestamp: 2026-02-08T09:20:28.270015674Z
+      action: APPROVE_ARTIFACT
+      feature: user-preferences
+      actor: user
+      result: success
+    - timestamp: 2026-02-08T09:20:31.709946893Z
+      action: TRANSITION
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:20:31.716562232Z
+      action: TRANSITION
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:20:31.722532105Z
+      action: TRANSITION
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:20:31.727808804Z
+      action: TRANSITION
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:21:30.038352049Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:22:14.06532107Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:22:14.070655487Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:23:28.658494578Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:23:28.664874463Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:25:11.573327772Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:26:45.827793942Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
+    - timestamp: 2026-02-08T09:28:59.532989701Z
+      action: COMPLETE_TASK
+      feature: user-preferences
+      actor: cli
+      result: success
--- a/services/preferences-api/cmd/server/main.go
+++ b/services/preferences-api/cmd/server/main.go
@ -2,15 +2,19 @@
 package main

 import (
+	"context"
 	"flag"
 	"fmt"
 	"os"

 	"git.threesix.ai/jordan/slack5-1770541397/pkg/app"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/config"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/database"
 	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/adapter/memory"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/adapter/postgres"
 	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/api"
 	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/service"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/migrations"
 )

 func main() {
@ -33,17 +37,37 @@ func main() {
 	// Create logger
 	logger := logging.Default()

+	// Connect to database
+	dbCfg := config.ReadDatabaseConfig()
+	pool, err := database.Connect(context.Background(), dbCfg.URL, database.Options{
+		MaxOpenConns:    dbCfg.MaxOpenConns,
+		MaxIdleConns:    dbCfg.MaxIdleConns,
+		ConnMaxLifetime: dbCfg.ConnMaxLifetime,
+	})
+	if err != nil {
+		logger.Error("failed to connect to database", "error", err)
+		os.Exit(1)
+	}
+
+	// Run migrations
+	database.MustRunMigrations(context.Background(), pool, migrations.FS, ".")
+
 	// Create adapters (repositories)
-	exampleRepo := memory.NewExampleRepository()
+	prefsRepo := postgres.NewPreferencesRepository(pool.DB, logger)

 	// Create services (business logic)
-	exampleService := service.NewExampleService(exampleRepo, logger)
+	preferencesService := service.NewPreferencesService(prefsRepo, logger)

 	// Create application
 	application := app.New("preferences-api", app.WithDefaultPort(8001))

+	// Register cleanup on shutdown
+	application.OnShutdown(func(ctx context.Context) error {
+		return pool.Close()
+	})
+
 	// Register routes with dependency injection
-	api.RegisterRoutes(application, exampleService)
+	api.RegisterRoutes(application, preferencesService)

 	// Start server
 	application.Run()
--- a/services/preferences-api/internal/adapter/memory/example.go
+++ b/services/preferences-api/internal/adapter/memory/example.go
@ -1,106 +0,0 @@
-// Package memory provides in-memory implementations of repository interfaces.
-// Useful for development, testing, and prototyping.
-package memory
-
-import (
-	"context"
-	"sync"
-
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
-)
-
-// Compile-time verification that ExampleRepository implements port.ExampleRepository.
-var _ port.ExampleRepository = (*ExampleRepository)(nil)
-
-// ExampleRepository is a thread-safe in-memory implementation of port.ExampleRepository.
-type ExampleRepository struct {
-	mu       sync.RWMutex
-	examples map[domain.ExampleID]*domain.Example
-}
-
-// NewExampleRepository creates a new in-memory example repository.
-func NewExampleRepository() *ExampleRepository {
-	return &ExampleRepository{
-		examples: make(map[domain.ExampleID]*domain.Example),
-	}
-}
-
-// List returns all examples.
-func (r *ExampleRepository) List(ctx context.Context) ([]domain.Example, error) {
-	r.mu.RLock()
-	defer r.mu.RUnlock()
-
-	result := make([]domain.Example, 0, len(r.examples))
-	for _, e := range r.examples {
-		result = append(result, *e)
-	}
-	return result, nil
-}
-
-// Get returns an example by ID.
-// Returns domain.ErrExampleNotFound if not found.
-func (r *ExampleRepository) Get(ctx context.Context, id domain.ExampleID) (*domain.Example, error) {
-	r.mu.RLock()
-	defer r.mu.RUnlock()
-
-	e, ok := r.examples[id]
-	if !ok {
-		return nil, domain.ErrExampleNotFound
-	}
-	// Return a copy to prevent external mutation
-	copy := *e
-	return &copy, nil
-}
-
-// Create stores a new example.
-func (r *ExampleRepository) Create(ctx context.Context, example *domain.Example) error {
-	r.mu.Lock()
-	defer r.mu.Unlock()
-
-	// Store a copy to prevent external mutation
-	copy := *example
-	r.examples[example.ID] = &copy
-	return nil
-}
-
-// Update modifies an existing example.
-// Returns domain.ErrExampleNotFound if not found.
-func (r *ExampleRepository) Update(ctx context.Context, example *domain.Example) error {
-	r.mu.Lock()
-	defer r.mu.Unlock()
-
-	if _, ok := r.examples[example.ID]; !ok {
-		return domain.ErrExampleNotFound
-	}
-	// Store a copy to prevent external mutation
-	copy := *example
-	r.examples[example.ID] = &copy
-	return nil
-}
-
-// Delete removes an example by ID.
-// Returns domain.ErrExampleNotFound if not found.
-func (r *ExampleRepository) Delete(ctx context.Context, id domain.ExampleID) error {
-	r.mu.Lock()
-	defer r.mu.Unlock()
-
-	if _, ok := r.examples[id]; !ok {
-		return domain.ErrExampleNotFound
-	}
-	delete(r.examples, id)
-	return nil
-}
-
-// ExistsByName checks if an example with the given name exists.
-func (r *ExampleRepository) ExistsByName(ctx context.Context, name string) (bool, error) {
-	r.mu.RLock()
-	defer r.mu.RUnlock()
-
-	for _, e := range r.examples {
-		if e.Name == name {
-			return true, nil
-		}
-	}
-	return false, nil
-}
--- a/services/preferences-api/internal/adapter/postgres/preferences.go
+++ b/services/preferences-api/internal/adapter/postgres/preferences.go
@ -0,0 +1,84 @@
+// Package postgres provides PostgreSQL implementations of port interfaces.
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"time"
+
+	"github.com/jmoiron/sqlx"
+
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
+)
+
+// preferencesRow represents a row in the user_preferences table.
+type preferencesRow struct {
+	UserID      string    `db:"user_id"`
+	Preferences []byte    `db:"preferences"`
+	UpdatedAt   time.Time `db:"updated_at"`
+}
+
+// PreferencesRepository implements port.PreferencesRepository using PostgreSQL.
+type PreferencesRepository struct {
+	db     *sqlx.DB
+	logger *logging.Logger
+}
+
+var _ port.PreferencesRepository = (*PreferencesRepository)(nil)
+
+// NewPreferencesRepository creates a new PostgreSQL preferences repository.
+func NewPreferencesRepository(db *sqlx.DB, logger *logging.Logger) *PreferencesRepository {
+	return &PreferencesRepository{
+		db:     db,
+		logger: logger.WithComponent("PreferencesRepository"),
+	}
+}
+
+// Get retrieves preferences for a user by ID.
+// Returns domain.ErrPreferencesNotFound if no row exists.
+func (r *PreferencesRepository) Get(ctx context.Context, userID domain.UserID) (*domain.UserPreferences, error) {
+	var row preferencesRow
+	err := r.db.GetContext(ctx, &row,
+		`SELECT user_id, preferences, updated_at FROM user_preferences WHERE user_id = $1`,
+		string(userID),
+	)
+	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, domain.ErrPreferencesNotFound
+		}
+		return nil, err
+	}
+
+	var prefs domain.Preferences
+	if err := json.Unmarshal(row.Preferences, &prefs); err != nil {
+		return nil, err
+	}
+
+	return &domain.UserPreferences{
+		UserID:      domain.UserID(row.UserID),
+		Preferences: prefs,
+		UpdatedAt:   row.UpdatedAt,
+	}, nil
+}
+
+// Upsert creates or replaces preferences for a user.
+func (r *PreferencesRepository) Upsert(ctx context.Context, prefs *domain.UserPreferences) error {
+	prefsJSON, err := json.Marshal(prefs.Preferences)
+	if err != nil {
+		return err
+	}
+
+	_, err = r.db.ExecContext(ctx, `
+		INSERT INTO user_preferences (user_id, preferences, updated_at)
+		VALUES ($1, $2, $3)
+		ON CONFLICT (user_id) DO UPDATE SET
+			preferences = $2,
+			updated_at = $3
+	`, string(prefs.UserID), prefsJSON, prefs.UpdatedAt)
+
+	return err
+}
--- a/services/preferences-api/internal/api/handlers/example.go
+++ b/services/preferences-api/internal/api/handlers/example.go
@ -1,170 +0,0 @@
-package handlers
-
-import (
-	"errors"
-	"net/http"
-
-	"github.com/go-chi/chi/v5"
-	"github.com/google/uuid"
-
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/app"
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/httperror"
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/httpresponse"
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/service"
-)
-
-// Example handles HTTP requests for example resources.
-type Example struct {
-	svc    *service.ExampleService
-	logger *logging.Logger
-}
-
-// NewExample creates a new Example handler with injected dependencies.
-func NewExample(svc *service.ExampleService, logger *logging.Logger) *Example {
-	return &Example{
-		svc:    svc,
-		logger: logger.WithComponent("ExampleHandler"),
-	}
-}
-
-// CreateRequest is the request body for creating an example.
-type CreateRequest struct {
-	Name        string `json:"name" validate:"required,min=1,max=100"`
-	Description string `json:"description" validate:"max=500"`
-}
-
-// UpdateRequest is the request body for updating an example.
-type UpdateRequest struct {
-	Name        string `json:"name" validate:"required,min=1,max=100"`
-	Description string `json:"description" validate:"max=500"`
-}
-
-// ExampleResponse is the response for an example resource.
-type ExampleResponse struct {
-	ID          string `json:"id"`
-	Name        string `json:"name"`
-	Description string `json:"description"`
-	CreatedAt   string `json:"created_at"`
-	UpdatedAt   string `json:"updated_at"`
-}
-
-// toResponse converts a domain example to an API response.
-func toResponse(e *domain.Example) ExampleResponse {
-	return ExampleResponse{
-		ID:          e.ID.String(),
-		Name:        e.Name,
-		Description: e.Description,
-		CreatedAt:   e.CreatedAt.Format("2006-01-02T15:04:05Z"),
-		UpdatedAt:   e.UpdatedAt.Format("2006-01-02T15:04:05Z"),
-	}
-}
-
-// List returns all examples.
-func (h *Example) List(w http.ResponseWriter, r *http.Request) error {
-	examples, err := h.svc.List(r.Context())
-	if err != nil {
-		return err
-	}
-
-	result := make([]ExampleResponse, len(examples))
-	for i, e := range examples {
-		result[i] = toResponse(&e)
-	}
-
-	httpresponse.OK(w, r, result)
-	return nil
-}
-
-// Get returns an example by ID.
-func (h *Example) Get(w http.ResponseWriter, r *http.Request) error {
-	id := chi.URLParam(r, "id")
-
-	// Validate UUID format
-	if _, err := uuid.Parse(id); err != nil {
-		return httperror.BadRequest("invalid id format")
-	}
-
-	example, err := h.svc.Get(r.Context(), domain.ExampleID(id))
-	if err != nil {
-		return mapDomainError(err)
-	}
-
-	httpresponse.OK(w, r, toResponse(example))
-	return nil
-}
-
-// Create creates a new example.
-func (h *Example) Create(w http.ResponseWriter, r *http.Request) error {
-	var req CreateRequest
-	if err := app.BindAndValidate(r, &req); err != nil {
-		return err
-	}
-
-	example, err := h.svc.Create(r.Context(), service.CreateInput{
-		Name:        req.Name,
-		Description: req.Description,
-	})
-	if err != nil {
-		return mapDomainError(err)
-	}
-
-	httpresponse.Created(w, r, toResponse(example))
-	return nil
-}
-
-// Update updates an existing example.
-func (h *Example) Update(w http.ResponseWriter, r *http.Request) error {
-	id := chi.URLParam(r, "id")
-
-	if _, err := uuid.Parse(id); err != nil {
-		return httperror.BadRequest("invalid id format")
-	}
-
-	var req UpdateRequest
-	if err := app.BindAndValidate(r, &req); err != nil {
-		return err
-	}
-
-	example, err := h.svc.Update(r.Context(), domain.ExampleID(id), service.UpdateInput{
-		Name:        req.Name,
-		Description: req.Description,
-	})
-	if err != nil {
-		return mapDomainError(err)
-	}
-
-	httpresponse.OK(w, r, toResponse(example))
-	return nil
-}
-
-// Delete removes an example by ID.
-func (h *Example) Delete(w http.ResponseWriter, r *http.Request) error {
-	id := chi.URLParam(r, "id")
-
-	if _, err := uuid.Parse(id); err != nil {
-		return httperror.BadRequest("invalid id format")
-	}
-
-	if err := h.svc.Delete(r.Context(), domain.ExampleID(id)); err != nil {
-		return mapDomainError(err)
-	}
-
-	httpresponse.NoContent(w)
-	return nil
-}
-
-// mapDomainError converts domain errors to HTTP errors.
-func mapDomainError(err error) error {
-	switch {
-	case errors.Is(err, domain.ErrExampleNotFound):
-		return httperror.NotFound("example not found")
-	case errors.Is(err, domain.ErrDuplicateExample):
-		return httperror.Conflict("example with this name already exists")
-	case errors.Is(err, domain.ErrInvalidExampleName):
-		return httperror.BadRequest("invalid example name")
-	default:
-		return err
-	}
-}
--- a/services/preferences-api/internal/api/handlers/example_test.go
+++ b/services/preferences-api/internal/api/handlers/example_test.go
@ -1,402 +0,0 @@
-package handlers
-
-import (
-	"bytes"
-	"context"
-	"encoding/json"
-	"net/http"
-	"net/http/httptest"
-	"sync"
-	"testing"
-
-	"github.com/go-chi/chi/v5"
-
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/service"
-)
-
-// mockExampleRepository implements port.ExampleRepository for testing.
-type mockExampleRepository struct {
-	mu       sync.RWMutex
-	examples map[domain.ExampleID]*domain.Example
-}
-
-var _ port.ExampleRepository = (*mockExampleRepository)(nil)
-
-func newMockExampleRepository() *mockExampleRepository {
-	return &mockExampleRepository{
-		examples: make(map[domain.ExampleID]*domain.Example),
-	}
-}
-
-func (m *mockExampleRepository) List(ctx context.Context) ([]domain.Example, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
-
-	result := make([]domain.Example, 0, len(m.examples))
-	for _, e := range m.examples {
-		result = append(result, *e)
-	}
-	return result, nil
-}
-
-func (m *mockExampleRepository) Get(ctx context.Context, id domain.ExampleID) (*domain.Example, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
-
-	e, ok := m.examples[id]
-	if !ok {
-		return nil, domain.ErrExampleNotFound
-	}
-	copy := *e
-	return &copy, nil
-}
-
-func (m *mockExampleRepository) Create(ctx context.Context, example *domain.Example) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-
-	copy := *example
-	m.examples[example.ID] = &copy
-	return nil
-}
-
-func (m *mockExampleRepository) Update(ctx context.Context, example *domain.Example) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-
-	if _, ok := m.examples[example.ID]; !ok {
-		return domain.ErrExampleNotFound
-	}
-	copy := *example
-	m.examples[example.ID] = &copy
-	return nil
-}
-
-func (m *mockExampleRepository) Delete(ctx context.Context, id domain.ExampleID) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-
-	if _, ok := m.examples[id]; !ok {
-		return domain.ErrExampleNotFound
-	}
-	delete(m.examples, id)
-	return nil
-}
-
-func (m *mockExampleRepository) ExistsByName(ctx context.Context, name string) (bool, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
-
-	for _, e := range m.examples {
-		if e.Name == name {
-			return true, nil
-		}
-	}
-	return false, nil
-}
-
-func newTestHandler() (*Example, *mockExampleRepository) {
-	repo := newMockExampleRepository()
-	svc := service.NewExampleService(repo, logging.Nop())
-	handler := NewExample(svc, logging.Nop())
-	return handler, repo
-}
-
-func TestExample_List(t *testing.T) {
-	handler, repo := newTestHandler()
-
-	// Seed data
-	ex, _ := domain.NewExample("test-id-1", "Test Example", "Description")
-	_ = repo.Create(context.Background(), ex)
-
-	r := chi.NewRouter()
-	r.Get("/api/v1/examples", func(w http.ResponseWriter, r *http.Request) {
-		if err := handler.List(w, r); err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-	})
-
-	req := httptest.NewRequest(http.MethodGet, "/api/v1/examples", nil)
-	w := httptest.NewRecorder()
-	r.ServeHTTP(w, req)
-
-	if w.Code != http.StatusOK {
-		t.Errorf("expected status 200, got %d", w.Code)
-	}
-
-	var resp map[string]any
-	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
-		t.Fatalf("failed to decode response: %v", err)
-	}
-
-	data, ok := resp["data"]
-	if !ok {
-		t.Fatal("expected 'data' field in response")
-	}
-
-	items, ok := data.([]any)
-	if !ok {
-		t.Fatal("expected 'data' to be an array")
-	}
-
-	if len(items) != 1 {
-		t.Errorf("expected 1 item, got %d", len(items))
-	}
-}
-
-func TestExample_Get(t *testing.T) {
-	handler, repo := newTestHandler()
-
-	// Seed data
-	ex, _ := domain.NewExample("550e8400-e29b-41d4-a716-446655440000", "Test Example", "Description")
-	_ = repo.Create(context.Background(), ex)
-
-	tests := []struct {
-		name       string
-		id         string
-		wantStatus int
-	}{
-		{
-			name:       "valid uuid - found",
-			id:         "550e8400-e29b-41d4-a716-446655440000",
-			wantStatus: http.StatusOK,
-		},
-		{
-			name:       "valid uuid - not found",
-			id:         "550e8400-e29b-41d4-a716-446655440001",
-			wantStatus: http.StatusNotFound,
-		},
-		{
-			name:       "invalid uuid",
-			id:         "not-a-uuid",
-			wantStatus: http.StatusBadRequest,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			r := chi.NewRouter()
-			r.Get("/api/v1/examples/{id}", func(w http.ResponseWriter, r *http.Request) {
-				if err := handler.Get(w, r); err != nil {
-					// Map error to status for testing
-					switch tt.wantStatus {
-					case http.StatusNotFound:
-						w.WriteHeader(http.StatusNotFound)
-					case http.StatusBadRequest:
-						w.WriteHeader(http.StatusBadRequest)
-					default:
-						w.WriteHeader(http.StatusInternalServerError)
-					}
-					return
-				}
-			})
-
-			req := httptest.NewRequest(http.MethodGet, "/api/v1/examples/"+tt.id, nil)
-			w := httptest.NewRecorder()
-			r.ServeHTTP(w, req)
-
-			if w.Code != tt.wantStatus {
-				t.Errorf("expected status %d, got %d", tt.wantStatus, w.Code)
-			}
-		})
-	}
-}
-
-func TestExample_Create(t *testing.T) {
-	handler, repo := newTestHandler()
-
-	// Seed existing data for duplicate test
-	ex, _ := domain.NewExample("existing-id", "Existing Name", "")
-	_ = repo.Create(context.Background(), ex)
-
-	tests := []struct {
-		name       string
-		body       any
-		wantStatus int
-	}{
-		{
-			name: "valid request",
-			body: CreateRequest{
-				Name:        "New Example",
-				Description: "A test description",
-			},
-			wantStatus: http.StatusCreated,
-		},
-		{
-			name:       "empty body",
-			body:       nil,
-			wantStatus: http.StatusBadRequest,
-		},
-		{
-			name: "duplicate name",
-			body: CreateRequest{
-				Name:        "Existing Name",
-				Description: "Conflict",
-			},
-			wantStatus: http.StatusConflict,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			r := chi.NewRouter()
-			r.Post("/api/v1/examples", func(w http.ResponseWriter, r *http.Request) {
-				if err := handler.Create(w, r); err != nil {
-					switch tt.wantStatus {
-					case http.StatusBadRequest:
-						w.WriteHeader(http.StatusBadRequest)
-					case http.StatusConflict:
-						w.WriteHeader(http.StatusConflict)
-					default:
-						w.WriteHeader(http.StatusInternalServerError)
-					}
-					return
-				}
-			})
-
-			var body []byte
-			if tt.body != nil {
-				var err error
-				body, err = json.Marshal(tt.body)
-				if err != nil {
-					t.Fatalf("failed to marshal body: %v", err)
-				}
-			}
-
-			req := httptest.NewRequest(http.MethodPost, "/api/v1/examples", bytes.NewReader(body))
-			req.Header.Set("Content-Type", "application/json")
-			w := httptest.NewRecorder()
-			r.ServeHTTP(w, req)
-
-			if w.Code != tt.wantStatus {
-				t.Errorf("expected status %d, got %d", tt.wantStatus, w.Code)
-			}
-		})
-	}
-}
-
-func TestExample_Delete(t *testing.T) {
-	handler, repo := newTestHandler()
-
-	// Seed data
-	ex, _ := domain.NewExample("550e8400-e29b-41d4-a716-446655440000", "To Delete", "")
-	_ = repo.Create(context.Background(), ex)
-
-	tests := []struct {
-		name       string
-		id         string
-		wantStatus int
-	}{
-		{
-			name:       "existing example",
-			id:         "550e8400-e29b-41d4-a716-446655440000",
-			wantStatus: http.StatusNoContent,
-		},
-		{
-			name:       "non-existent example",
-			id:         "550e8400-e29b-41d4-a716-446655440001",
-			wantStatus: http.StatusNotFound,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			r := chi.NewRouter()
-			r.Delete("/api/v1/examples/{id}", func(w http.ResponseWriter, r *http.Request) {
-				if err := handler.Delete(w, r); err != nil {
-					if tt.wantStatus == http.StatusNotFound {
-						w.WriteHeader(http.StatusNotFound)
-					} else {
-						w.WriteHeader(http.StatusBadRequest)
-					}
-					return
-				}
-			})
-
-			req := httptest.NewRequest(http.MethodDelete, "/api/v1/examples/"+tt.id, nil)
-			w := httptest.NewRecorder()
-			r.ServeHTTP(w, req)
-
-			if w.Code != tt.wantStatus {
-				t.Errorf("expected status %d, got %d", tt.wantStatus, w.Code)
-			}
-		})
-	}
-}
-
-func TestExample_Update(t *testing.T) {
-	handler, repo := newTestHandler()
-
-	// Seed data
-	ex1, _ := domain.NewExample("550e8400-e29b-41d4-a716-446655440000", "Example 1", "")
-	_ = repo.Create(context.Background(), ex1)
-	ex2, _ := domain.NewExample("550e8400-e29b-41d4-a716-446655440001", "Example 2", "")
-	_ = repo.Create(context.Background(), ex2)
-
-	tests := []struct {
-		name       string
-		id         string
-		body       UpdateRequest
-		wantStatus int
-	}{
-		{
-			name: "valid update",
-			id:   "550e8400-e29b-41d4-a716-446655440000",
-			body: UpdateRequest{
-				Name:        "Updated Name",
-				Description: "Updated",
-			},
-			wantStatus: http.StatusOK,
-		},
-		{
-			name: "name conflict",
-			id:   "550e8400-e29b-41d4-a716-446655440000",
-			body: UpdateRequest{
-				Name:        "Example 2",
-				Description: "Conflict",
-			},
-			wantStatus: http.StatusConflict,
-		},
-		{
-			name: "not found",
-			id:   "550e8400-e29b-41d4-a716-446655440099",
-			body: UpdateRequest{
-				Name:        "Whatever",
-				Description: "",
-			},
-			wantStatus: http.StatusNotFound,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			r := chi.NewRouter()
-			r.Put("/api/v1/examples/{id}", func(w http.ResponseWriter, r *http.Request) {
-				if err := handler.Update(w, r); err != nil {
-					switch tt.wantStatus {
-					case http.StatusNotFound:
-						w.WriteHeader(http.StatusNotFound)
-					case http.StatusConflict:
-						w.WriteHeader(http.StatusConflict)
-					default:
-						w.WriteHeader(http.StatusBadRequest)
-					}
-					return
-				}
-			})
-
-			body, _ := json.Marshal(tt.body)
-			req := httptest.NewRequest(http.MethodPut, "/api/v1/examples/"+tt.id, bytes.NewReader(body))
-			req.Header.Set("Content-Type", "application/json")
-			w := httptest.NewRecorder()
-			r.ServeHTTP(w, req)
-
-			if w.Code != tt.wantStatus {
-				t.Errorf("expected status %d, got %d", tt.wantStatus, w.Code)
-			}
-		})
-	}
-}
--- a/services/preferences-api/internal/api/handlers/preferences.go
+++ b/services/preferences-api/internal/api/handlers/preferences.go
@ -0,0 +1,144 @@
+package handlers
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/app"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/auth"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/httperror"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/httpresponse"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/service"
+)
+
+// Preferences handles HTTP requests for user preferences.
+type Preferences struct {
+	svc    *service.PreferencesService
+	logger *logging.Logger
+}
+
+// NewPreferences creates a new Preferences handler with injected dependencies.
+func NewPreferences(svc *service.PreferencesService, logger *logging.Logger) *Preferences {
+	return &Preferences{
+		svc:    svc,
+		logger: logger.WithComponent("PreferencesHandler"),
+	}
+}
+
+// PutPreferencesRequest is the request body for setting preferences.
+type PutPreferencesRequest struct {
+	Preferences PreferencesPayload `json:"preferences" validate:"required"`
+}
+
+// PreferencesPayload represents the preferences JSON structure in requests/responses.
+type PreferencesPayload struct {
+	Theme         string                          `json:"theme,omitempty"`
+	Language      string                          `json:"language,omitempty"`
+	Notifications *NotificationPreferencesPayload `json:"notifications,omitempty"`
+}
+
+// NotificationPreferencesPayload represents notification settings in requests/responses.
+type NotificationPreferencesPayload struct {
+	Email bool `json:"email"`
+	Push  bool `json:"push"`
+	SMS   bool `json:"sms"`
+}
+
+// PreferencesResponse is the response for a user's preferences.
+type PreferencesResponse struct {
+	UserID      string             `json:"user_id"`
+	Preferences PreferencesPayload `json:"preferences"`
+	UpdatedAt   string             `json:"updated_at"`
+}
+
+// toPreferencesResponse converts a domain UserPreferences to an API response.
+func toPreferencesResponse(up *domain.UserPreferences) PreferencesResponse {
+	return PreferencesResponse{
+		UserID: up.UserID.String(),
+		Preferences: PreferencesPayload{
+			Theme:    up.Preferences.Theme,
+			Language: up.Preferences.Language,
+			Notifications: &NotificationPreferencesPayload{
+				Email: up.Preferences.Notifications.Email,
+				Push:  up.Preferences.Notifications.Push,
+				SMS:   up.Preferences.Notifications.SMS,
+			},
+		},
+		UpdatedAt: up.UpdatedAt.Format("2006-01-02T15:04:05Z"),
+	}
+}
+
+// toDomainPreferences converts an API payload to a domain Preferences.
+func toDomainPreferences(p PreferencesPayload) domain.Preferences {
+	prefs := domain.Preferences{
+		Theme:    p.Theme,
+		Language: p.Language,
+	}
+	if p.Notifications != nil {
+		prefs.Notifications = domain.NotificationPreferences{
+			Email: p.Notifications.Email,
+			Push:  p.Notifications.Push,
+			SMS:   p.Notifications.SMS,
+		}
+	}
+	return prefs
+}
+
+// Get returns the preferences for a user.
+func (h *Preferences) Get(w http.ResponseWriter, r *http.Request) error {
+	userID := chi.URLParam(r, "user_id")
+
+	// Authorization: authenticated user must match path user_id
+	authUser := auth.GetUser(r.Context())
+	if authUser == nil || authUser.ID != userID {
+		return httperror.Forbidden("access denied: can only access own preferences")
+	}
+
+	prefs, err := h.svc.GetPreferences(r.Context(), domain.UserID(userID))
+	if err != nil {
+		return mapPreferencesDomainError(err)
+	}
+
+	httpresponse.OK(w, r, toPreferencesResponse(prefs))
+	return nil
+}
+
+// Put creates or replaces preferences for a user.
+func (h *Preferences) Put(w http.ResponseWriter, r *http.Request) error {
+	userID := chi.URLParam(r, "user_id")
+
+	// Authorization: authenticated user must match path user_id
+	authUser := auth.GetUser(r.Context())
+	if authUser == nil || authUser.ID != userID {
+		return httperror.Forbidden("access denied: can only modify own preferences")
+	}
+
+	var req PutPreferencesRequest
+	if err := app.BindAndValidate(r, &req); err != nil {
+		return err
+	}
+
+	prefs, err := h.svc.SetPreferences(r.Context(), domain.UserID(userID), toDomainPreferences(req.Preferences))
+	if err != nil {
+		return mapPreferencesDomainError(err)
+	}
+
+	httpresponse.OK(w, r, toPreferencesResponse(prefs))
+	return nil
+}
+
+// mapPreferencesDomainError converts domain errors to HTTP errors.
+func mapPreferencesDomainError(err error) error {
+	switch {
+	case errors.Is(err, domain.ErrInvalidTheme):
+		return httperror.BadRequest("invalid theme: must be one of light, dark, system")
+	case errors.Is(err, domain.ErrInvalidLanguage):
+		return httperror.BadRequest("invalid language: must be at most 10 characters")
+	default:
+		return err
+	}
+}
--- a/services/preferences-api/internal/api/handlers/preferences_test.go
+++ b/services/preferences-api/internal/api/handlers/preferences_test.go
@ -0,0 +1,263 @@
+package handlers
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/auth"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/httperror"
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/service"
+)
+
+// mockPreferencesRepository implements port.PreferencesRepository for handler tests.
+type mockPreferencesRepository struct {
+	mu    sync.RWMutex
+	store map[domain.UserID]*domain.UserPreferences
+}
+
+var _ port.PreferencesRepository = (*mockPreferencesRepository)(nil)
+
+func newMockPreferencesRepository() *mockPreferencesRepository {
+	return &mockPreferencesRepository{
+		store: make(map[domain.UserID]*domain.UserPreferences),
+	}
+}
+
+func (m *mockPreferencesRepository) Get(ctx context.Context, userID domain.UserID) (*domain.UserPreferences, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	prefs, ok := m.store[userID]
+	if !ok {
+		return nil, domain.ErrPreferencesNotFound
+	}
+	copy := *prefs
+	return &copy, nil
+}
+
+func (m *mockPreferencesRepository) Upsert(ctx context.Context, prefs *domain.UserPreferences) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	copy := *prefs
+	m.store[prefs.UserID] = &copy
+	return nil
+}
+
+func newTestPreferencesHandler() (*Preferences, *mockPreferencesRepository) {
+	repo := newMockPreferencesRepository()
+	svc := service.NewPreferencesService(repo, logging.Nop())
+	handler := NewPreferences(svc, logging.Nop())
+	return handler, repo
+}
+
+// withAuthUser creates an HTTP handler that injects an auth user into the context.
+func withAuthUser(userID string, next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ctx := auth.SetUser(r.Context(), &auth.User{ID: userID})
+		next.ServeHTTP(w, r.WithContext(ctx))
+	}
+}
+
+func TestPreferences_Get(t *testing.T) {
+	handler, repo := newTestPreferencesHandler()
+
+	// Seed stored preferences for user-456
+	repo.store["user-456"] = &domain.UserPreferences{
+		UserID: "user-456",
+		Preferences: domain.Preferences{
+			Theme:    "dark",
+			Language: "fr",
+			Notifications: domain.NotificationPreferences{
+				Email: false,
+				Push:  true,
+				SMS:   true,
+			},
+		},
+	}
+
+	tests := []struct {
+		name       string
+		pathUserID string
+		authUserID string
+		wantStatus int
+		wantTheme  string
+	}{
+		{
+			name:       "returns defaults for new user",
+			pathUserID: "user-123",
+			authUserID: "user-123",
+			wantStatus: http.StatusOK,
+			wantTheme:  "system",
+		},
+		{
+			name:       "returns stored preferences",
+			pathUserID: "user-456",
+			authUserID: "user-456",
+			wantStatus: http.StatusOK,
+			wantTheme:  "dark",
+		},
+		{
+			name:       "returns forbidden for different user",
+			pathUserID: "user-456",
+			authUserID: "user-other",
+			wantStatus: http.StatusForbidden,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := chi.NewRouter()
+			r.Get("/api/preferences-api/preferences/{user_id}", withAuthUser(tt.authUserID, func(w http.ResponseWriter, r *http.Request) {
+				if err := handler.Get(w, r); err != nil {
+					writeErrorStatus(w, err)
+					return
+				}
+			}))
+
+			req := httptest.NewRequest(http.MethodGet, "/api/preferences-api/preferences/"+tt.pathUserID, nil)
+			w := httptest.NewRecorder()
+			r.ServeHTTP(w, req)
+
+			if w.Code != tt.wantStatus {
+				t.Errorf("expected status %d, got %d", tt.wantStatus, w.Code)
+			}
+
+			if tt.wantStatus == http.StatusOK && tt.wantTheme != "" {
+				var resp map[string]any
+				if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+					t.Fatalf("failed to decode response: %v", err)
+				}
+				data, ok := resp["data"].(map[string]any)
+				if !ok {
+					t.Fatal("expected 'data' field in response")
+				}
+				prefs, ok := data["preferences"].(map[string]any)
+				if !ok {
+					t.Fatal("expected 'preferences' field in data")
+				}
+				if prefs["theme"] != tt.wantTheme {
+					t.Errorf("expected theme '%s', got '%v'", tt.wantTheme, prefs["theme"])
+				}
+			}
+		})
+	}
+}
+
+func TestPreferences_Put(t *testing.T) {
+	handler, _ := newTestPreferencesHandler()
+
+	tests := []struct {
+		name       string
+		pathUserID string
+		authUserID string
+		body       any
+		wantStatus int
+	}{
+		{
+			name:       "sets preferences successfully",
+			pathUserID: "user-123",
+			authUserID: "user-123",
+			body: PutPreferencesRequest{
+				Preferences: PreferencesPayload{
+					Theme:    "dark",
+					Language: "en",
+					Notifications: &NotificationPreferencesPayload{
+						Email: true,
+						Push:  false,
+						SMS:   false,
+					},
+				},
+			},
+			wantStatus: http.StatusOK,
+		},
+		{
+			name:       "returns forbidden for different user",
+			pathUserID: "user-123",
+			authUserID: "user-other",
+			body: PutPreferencesRequest{
+				Preferences: PreferencesPayload{
+					Theme:    "dark",
+					Language: "en",
+				},
+			},
+			wantStatus: http.StatusForbidden,
+		},
+		{
+			name:       "rejects invalid theme",
+			pathUserID: "user-123",
+			authUserID: "user-123",
+			body: PutPreferencesRequest{
+				Preferences: PreferencesPayload{
+					Theme:    "neon",
+					Language: "en",
+				},
+			},
+			wantStatus: http.StatusBadRequest,
+		},
+		{
+			name:       "rejects language too long",
+			pathUserID: "user-123",
+			authUserID: "user-123",
+			body: PutPreferencesRequest{
+				Preferences: PreferencesPayload{
+					Theme:    "dark",
+					Language: "abcdefghijk",
+				},
+			},
+			wantStatus: http.StatusBadRequest,
+		},
+		{
+			name:       "rejects empty body",
+			pathUserID: "user-123",
+			authUserID: "user-123",
+			body:       nil,
+			wantStatus: http.StatusBadRequest,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := chi.NewRouter()
+			r.Put("/api/preferences-api/preferences/{user_id}", withAuthUser(tt.authUserID, func(w http.ResponseWriter, r *http.Request) {
+				if err := handler.Put(w, r); err != nil {
+					writeErrorStatus(w, err)
+					return
+				}
+			}))
+
+			var body []byte
+			if tt.body != nil {
+				var err error
+				body, err = json.Marshal(tt.body)
+				if err != nil {
+					t.Fatalf("failed to marshal body: %v", err)
+				}
+			}
+
+			req := httptest.NewRequest(http.MethodPut, "/api/preferences-api/preferences/"+tt.pathUserID, bytes.NewReader(body))
+			req.Header.Set("Content-Type", "application/json")
+			w := httptest.NewRecorder()
+			r.ServeHTTP(w, req)
+
+			if w.Code != tt.wantStatus {
+				t.Errorf("expected status %d, got %d (body: %s)", tt.wantStatus, w.Code, w.Body.String())
+			}
+		})
+	}
+}
+
+// writeErrorStatus writes an HTTP error status based on the error type.
+func writeErrorStatus(w http.ResponseWriter, err error) {
+	w.WriteHeader(httperror.StatusCode(err))
+}
--- a/services/preferences-api/internal/api/routes.go
+++ b/services/preferences-api/internal/api/routes.go
@ -11,32 +11,24 @@ import (

 // RegisterRoutes registers all HTTP routes for the service.
 // Routes are mounted under /api/preferences-api to match the ingress path routing.
-// This allows the monorepo to expose multiple services under a single domain:
-//   - https://domain/api/preferences-api/health
-//   - https://domain/api/preferences-api/examples
-func RegisterRoutes(application *app.App, exampleService *service.ExampleService) {
+func RegisterRoutes(application *app.App, preferencesService *service.PreferencesService) {
 	logger := application.Logger()
 	cfg := config.Load()

 	// Initialize handlers with injected services
 	healthHandler := handlers.NewHealth(logger)
-	exampleHandler := handlers.NewExample(exampleService, logger)
+	prefsHandler := handlers.NewPreferences(preferencesService, logger)

 	// Build and mount OpenAPI spec
 	spec := NewServiceSpec()
 	application.EnableDocs(spec)

 	// Register API routes under /api/{service-name} to match ingress path routing.
-	// The ingress routes /api/preferences-api/* to this service.
 	application.Route("/api/preferences-api", func(r app.Router) {
 		r.Get("/health", healthHandler.Check)

-		// Public routes (no auth required)
-		r.Get("/examples", app.Wrap(exampleHandler.List))
-		r.Get("/examples/{id}", app.Wrap(exampleHandler.Get))
-
-		// Protected routes (auth required when enabled)
-		r.Group(func(r app.Router) {
+		// Protected routes — auth required for all preference endpoints
+		r.Route("/preferences", func(r app.Router) {
 			if cfg.AuthEnabled {
 				r.Use(auth.Middleware(auth.MiddlewareConfig{
 					Validator: auth.NewJWTValidator(auth.JWTConfig{
@ -46,9 +38,8 @@ func RegisterRoutes(application *app.App, exampleService *service.ExampleService
 				}))
 			}

-			r.Post("/examples", app.Wrap(exampleHandler.Create))
-			r.Put("/examples/{id}", app.Wrap(exampleHandler.Update))
-			r.Delete("/examples/{id}", app.Wrap(exampleHandler.Delete))
+			r.Get("/{user_id}", app.Wrap(prefsHandler.Get))
+			r.Put("/{user_id}", app.Wrap(prefsHandler.Put))
 		})
 	})
 }
--- a/services/preferences-api/internal/api/spec.go
+++ b/services/preferences-api/internal/api/spec.go
@ -5,30 +5,37 @@ import "git.threesix.ai/jordan/slack5-1770541397/pkg/openapi"
 // NewServiceSpec builds the OpenAPI specification for the preferences-api service.
 func NewServiceSpec() *openapi.OpenAPISpec {
 	spec := openapi.NewOpenAPISpec("preferences-api API", "1.0.0").
-		WithDescription("REST API for the preferences-api service").
+		WithDescription("REST API for managing user preferences").
 		WithBearerSecurity("bearer", "JWT authentication token").
 		WithTag("Health", "Service health endpoints").
-		WithTag("Examples", "Example CRUD endpoints")
+		WithTag("Preferences", "User preferences endpoints")

 	// Define reusable schemas
-	spec.WithSchema("Example", openapi.Object(map[string]openapi.Schema{
-		"id":          openapi.UUID().WithDescription("Unique identifier"),
-		"name":        openapi.String().WithDescription("Name of the example").WithExample("My Example"),
-		"description": openapi.String().WithDescription("Optional description").WithExample("A description"),
-		"created_at":  openapi.DateTime().WithDescription("Creation timestamp"),
-		"updated_at":  openapi.DateTime().WithDescription("Last update timestamp"),
-	}, "id", "name"))
-
-	spec.WithSchema("CreateExampleRequest", openapi.Object(map[string]openapi.Schema{
-		"name":        openapi.StringWithMinMax(1, 100).WithDescription("Name of the example"),
-		"description": openapi.StringWithMinMax(0, 500).WithDescription("Optional description"),
-	}, "name"))
-
-	spec.WithSchema("UpdateExampleRequest", openapi.Object(map[string]openapi.Schema{
-		"name":        openapi.StringWithMinMax(1, 100).WithDescription("Updated name"),
-		"description": openapi.StringWithMinMax(0, 500).WithDescription("Updated description"),
+	spec.WithSchema("NotificationPreferences", openapi.Object(map[string]openapi.Schema{
+		"email": openapi.Bool().WithDescription("Email notifications enabled"),
+		"push":  openapi.Bool().WithDescription("Push notifications enabled"),
+		"sms":   openapi.Bool().WithDescription("SMS notifications enabled"),
 	}))

+	spec.WithSchema("Preferences", openapi.Object(map[string]openapi.Schema{
+		"theme":         openapi.StringEnum("light", "dark", "system").WithDescription("UI theme preference"),
+		"language":      openapi.StringWithMinMax(0, 10).WithDescription("BCP-47 language tag").WithExample("en"),
+		"notifications": openapi.Ref("NotificationPreferences").WithDescription("Notification settings"),
+	}))
+
+	spec.WithSchema("UserPreferencesResponse", openapi.Object(map[string]openapi.Schema{
+		"user_id":     openapi.String().WithDescription("User identifier"),
+		"preferences": openapi.Ref("Preferences").WithDescription("User preferences"),
+		"updated_at":  openapi.DateTime().WithDescription("Last update timestamp"),
+	}, "user_id", "preferences", "updated_at"))
+
+	spec.WithSchema("PutPreferencesRequest", openapi.Object(map[string]openapi.Schema{
+		"preferences": openapi.Ref("Preferences").WithDescription("Preferences to save"),
+	}, "preferences"))
+
+	// user_id path parameter
+	userIDParam := openapi.PathParam("user_id", "User identifier")
+
 	// Health
 	spec.AddPath("/api/preferences-api/health", "get", map[string]any{
 		"summary": "Health check",
@ -41,70 +48,33 @@ func NewServiceSpec() *openapi.OpenAPISpec {
 		},
 	})

-	// List examples
-	spec.AddPath("/api/preferences-api/examples", "get", map[string]any{
-		"summary":     "List examples",
-		"description": "Returns a paginated list of examples.",
-		"tags":        []string{"Examples"},
-		"parameters":  []any{openapi.PageParam(), openapi.PerPageParam()},
-		"responses": map[string]any{
-			"200": openapi.OpResponse("Success", openapi.ResponseSchema(openapi.RefArray("Example"))),
-		},
-	})
-
-	// Get example
-	spec.AddPath("/api/preferences-api/examples/{id}", "get", map[string]any{
-		"summary":    "Get example by ID",
-		"tags":       []string{"Examples"},
-		"parameters": []any{openapi.IDParam()},
-		"responses": map[string]any{
-			"200": openapi.OpResponse("Success", openapi.ResponseSchema(openapi.Ref("Example"))),
-			"404": openapi.OpResponse("Not found", openapi.ErrorResponseSchema()),
-		},
-	})
-
-	// Create example
-	spec.AddPath("/api/preferences-api/examples", "post", map[string]any{
-		"summary":     "Create example",
-		"description": "Creates a new example. Requires authentication.",
-		"tags":        []string{"Examples"},
+	// Get preferences
+	spec.AddPath("/api/preferences-api/preferences/{user_id}", "get", map[string]any{
+		"summary":     "Get user preferences",
+		"description": "Returns the user's preferences. Returns defaults if none have been saved. Requires authentication.",
+		"tags":        []string{"Preferences"},
 		"security":    []map[string][]string{{"bearer": {}}},
-		"requestBody": openapi.RequestBody(openapi.Ref("CreateExampleRequest"), true),
+		"parameters":  []any{userIDParam},
 		"responses": map[string]any{
-			"201": openapi.OpResponse("Created", openapi.ResponseSchema(openapi.Ref("Example"))),
+			"200": openapi.OpResponse("Success", openapi.ResponseSchema(openapi.Ref("UserPreferencesResponse"))),
+			"401": openapi.OpResponse("Unauthorized", openapi.ErrorResponseSchema()),
+			"403": openapi.OpResponse("Forbidden", openapi.ErrorResponseSchema()),
+		},
+	})
+
+	// Put preferences
+	spec.AddPath("/api/preferences-api/preferences/{user_id}", "put", map[string]any{
+		"summary":     "Set user preferences",
+		"description": "Creates or replaces the user's preferences. Requires authentication.",
+		"tags":        []string{"Preferences"},
+		"security":    []map[string][]string{{"bearer": {}}},
+		"parameters":  []any{userIDParam},
+		"requestBody": openapi.RequestBody(openapi.Ref("PutPreferencesRequest"), true),
+		"responses": map[string]any{
+			"200": openapi.OpResponse("Success", openapi.ResponseSchema(openapi.Ref("UserPreferencesResponse"))),
 			"400": openapi.OpResponse("Bad request", openapi.ErrorResponseSchema()),
 			"401": openapi.OpResponse("Unauthorized", openapi.ErrorResponseSchema()),
-			"422": openapi.OpResponse("Validation error", openapi.ErrorResponseSchema()),
-		},
-	})
-
-	// Update example
-	spec.AddPath("/api/preferences-api/examples/{id}", "put", map[string]any{
-		"summary":     "Update example",
-		"description": "Updates an existing example. Requires authentication.",
-		"tags":        []string{"Examples"},
-		"security":    []map[string][]string{{"bearer": {}}},
-		"parameters":  []any{openapi.IDParam()},
-		"requestBody": openapi.RequestBody(openapi.Ref("UpdateExampleRequest"), true),
-		"responses": map[string]any{
-			"200": openapi.OpResponse("Updated", openapi.ResponseSchema(openapi.Ref("Example"))),
-			"400": openapi.OpResponse("Bad request", openapi.ErrorResponseSchema()),
-			"401": openapi.OpResponse("Unauthorized", openapi.ErrorResponseSchema()),
-			"404": openapi.OpResponse("Not found", openapi.ErrorResponseSchema()),
-		},
-	})
-
-	// Delete example
-	spec.AddPath("/api/preferences-api/examples/{id}", "delete", map[string]any{
-		"summary":     "Delete example",
-		"description": "Deletes an example by ID. Requires authentication.",
-		"tags":        []string{"Examples"},
-		"security":    []map[string][]string{{"bearer": {}}},
-		"parameters":  []any{openapi.IDParam()},
-		"responses": map[string]any{
-			"204": openapi.OpResponseNoContent(),
-			"401": openapi.OpResponse("Unauthorized", openapi.ErrorResponseSchema()),
-			"404": openapi.OpResponse("Not found", openapi.ErrorResponseSchema()),
+			"403": openapi.OpResponse("Forbidden", openapi.ErrorResponseSchema()),
 		},
 	})

--- a/services/preferences-api/internal/domain/errors.go
+++ b/services/preferences-api/internal/domain/errors.go
@ -10,12 +10,15 @@ var (
 	// ErrNotFound indicates a requested resource does not exist.
 	ErrNotFound = errors.New("not found")

-	// ErrExampleNotFound indicates the requested example does not exist.
-	ErrExampleNotFound = errors.New("example not found")
+	// ErrPreferencesNotFound indicates no preferences exist for the user.
+	ErrPreferencesNotFound = errors.New("preferences not found")

-	// ErrDuplicateExample indicates an example with the same name already exists.
-	ErrDuplicateExample = errors.New("example with this name already exists")
+	// ErrInvalidTheme indicates the theme value is not one of light, dark, system.
+	ErrInvalidTheme = errors.New("invalid theme: must be one of light, dark, system")

-	// ErrInvalidExampleName indicates the example name is invalid.
-	ErrInvalidExampleName = errors.New("invalid example name")
+	// ErrInvalidLanguage indicates the language value exceeds 10 characters.
+	ErrInvalidLanguage = errors.New("invalid language: must be at most 10 characters")
+
+	// ErrForbidden indicates the user is not authorized for this operation.
+	ErrForbidden = errors.New("forbidden")
 )
--- a/services/preferences-api/internal/domain/example.go
+++ b/services/preferences-api/internal/domain/example.go
@ -1,89 +0,0 @@
-package domain
-
-import (
-	"time"
-	"unicode/utf8"
-)
-
-// ExampleID is a strongly-typed identifier for examples.
-type ExampleID string
-
-// String returns the string representation of the ID.
-func (id ExampleID) String() string {
-	return string(id)
-}
-
-// IsZero returns true if the ID is empty.
-func (id ExampleID) IsZero() bool {
-	return id == ""
-}
-
-// Example name constraints.
-const (
-	MinExampleNameLen = 1
-	MaxExampleNameLen = 100
-	MaxDescriptionLen = 500
-)
-
-// Example represents an example domain entity.
-// This is a pure domain model with no external dependencies.
-type Example struct {
-	ID          ExampleID
-	Name        string
-	Description string
-	CreatedAt   time.Time
-	UpdatedAt   time.Time
-}
-
-// NewExample creates a new Example with validation.
-// Returns ErrInvalidExampleName if the name is invalid.
-func NewExample(id ExampleID, name, description string) (*Example, error) {
-	if err := validateExampleName(name); err != nil {
-		return nil, err
-	}
-	if err := validateDescription(description); err != nil {
-		return nil, err
-	}
-
-	now := time.Now().UTC()
-	return &Example{
-		ID:          id,
-		Name:        name,
-		Description: description,
-		CreatedAt:   now,
-		UpdatedAt:   now,
-	}, nil
-}
-
-// Update modifies the example's mutable fields with validation.
-// Returns ErrInvalidExampleName if the name is invalid.
-func (e *Example) Update(name, description string) error {
-	if err := validateExampleName(name); err != nil {
-		return err
-	}
-	if err := validateDescription(description); err != nil {
-		return err
-	}
-
-	e.Name = name
-	e.Description = description
-	e.UpdatedAt = time.Now().UTC()
-	return nil
-}
-
-// validateExampleName validates an example name.
-func validateExampleName(name string) error {
-	length := utf8.RuneCountInString(name)
-	if length < MinExampleNameLen || length > MaxExampleNameLen {
-		return ErrInvalidExampleName
-	}
-	return nil
-}
-
-// validateDescription validates a description.
-func validateDescription(desc string) error {
-	if utf8.RuneCountInString(desc) > MaxDescriptionLen {
-		return ErrInvalidExampleName
-	}
-	return nil
-}
--- a/services/preferences-api/internal/domain/preferences.go
+++ b/services/preferences-api/internal/domain/preferences.go
@ -0,0 +1,143 @@
+package domain
+
+import (
+	"encoding/json"
+	"time"
+	"unicode/utf8"
+)
+
+// UserID is a strongly-typed identifier for users.
+type UserID string
+
+// String returns the string representation of the ID.
+func (id UserID) String() string {
+	return string(id)
+}
+
+// ValidThemes lists the allowed theme values.
+var ValidThemes = []string{"light", "dark", "system"}
+
+// NotificationPreferences controls notification delivery channels.
+type NotificationPreferences struct {
+	Email bool `json:"email"`
+	Push  bool `json:"push"`
+	SMS   bool `json:"sms"`
+}
+
+// Preferences holds a user's preference settings.
+// Known fields are typed; unknown keys are preserved in Extra for extensibility.
+type Preferences struct {
+	Theme         string                  `json:"theme"`
+	Language      string                  `json:"language"`
+	Notifications NotificationPreferences `json:"notifications"`
+	Extra         map[string]any          `json:"-"`
+}
+
+// MarshalJSON merges known fields and Extra into a single JSON object.
+func (p Preferences) MarshalJSON() ([]byte, error) {
+	// Build a map with known fields
+	m := make(map[string]any)
+
+	// Copy extra fields first (so known fields override if there's overlap)
+	for k, v := range p.Extra {
+		m[k] = v
+	}
+
+	m["theme"] = p.Theme
+	m["language"] = p.Language
+	m["notifications"] = p.Notifications
+
+	return json.Marshal(m)
+}
+
+// UnmarshalJSON decodes known fields into struct fields and captures unknown keys in Extra.
+func (p *Preferences) UnmarshalJSON(data []byte) error {
+	// Decode known fields via an alias to avoid recursion
+	type Alias Preferences
+	var alias Alias
+	if err := json.Unmarshal(data, &alias); err != nil {
+		return err
+	}
+
+	// Decode all fields into a map to find unknown keys
+	var raw map[string]json.RawMessage
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return err
+	}
+
+	// Copy known fields
+	p.Theme = alias.Theme
+	p.Language = alias.Language
+	p.Notifications = alias.Notifications
+
+	// Capture unknown keys
+	knownKeys := map[string]bool{
+		"theme":         true,
+		"language":      true,
+		"notifications": true,
+	}
+
+	p.Extra = nil
+	for k, v := range raw {
+		if knownKeys[k] {
+			continue
+		}
+		if p.Extra == nil {
+			p.Extra = make(map[string]any)
+		}
+		var val any
+		if err := json.Unmarshal(v, &val); err != nil {
+			return err
+		}
+		p.Extra[k] = val
+	}
+
+	return nil
+}
+
+// MaxLanguageLen is the maximum rune length for a language tag.
+const MaxLanguageLen = 10
+
+// Validate checks the known preference fields.
+// Returns ErrInvalidTheme if theme is not a valid value.
+// Returns ErrInvalidLanguage if language exceeds MaxLanguageLen runes.
+func (p *Preferences) Validate() error {
+	if p.Theme != "" {
+		valid := false
+		for _, t := range ValidThemes {
+			if p.Theme == t {
+				valid = true
+				break
+			}
+		}
+		if !valid {
+			return ErrInvalidTheme
+		}
+	}
+
+	if utf8.RuneCountInString(p.Language) > MaxLanguageLen {
+		return ErrInvalidLanguage
+	}
+
+	return nil
+}
+
+// DefaultPreferences returns the default preference values.
+func DefaultPreferences() Preferences {
+	return Preferences{
+		Theme:    "system",
+		Language: "en",
+		Notifications: NotificationPreferences{
+			Email: true,
+			Push:  true,
+			SMS:   false,
+		},
+	}
+}
+
+// UserPreferences is the aggregate associating preferences with a user.
+type UserPreferences struct {
+	UserID      UserID
+	Preferences Preferences
+	UpdatedAt   time.Time
+}
--- a/services/preferences-api/internal/port/example.go
+++ b/services/preferences-api/internal/port/example.go
@ -1,37 +0,0 @@
-// Package port defines interfaces (ports) for external dependencies.
-// These interfaces define the contracts between the application core and
-// infrastructure adapters, enabling testability and flexibility.
-package port
-
-import (
-	"context"
-
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
-)
-
-// ExampleRepository defines the interface for example persistence operations.
-// Implementations may use databases, in-memory storage, or external services.
-type ExampleRepository interface {
-	// List returns all examples.
-	List(ctx context.Context) ([]domain.Example, error)
-
-	// Get returns an example by ID.
-	// Returns domain.ErrExampleNotFound if not found.
-	Get(ctx context.Context, id domain.ExampleID) (*domain.Example, error)
-
-	// Create stores a new example.
-	// The example must have a valid ID set.
-	Create(ctx context.Context, example *domain.Example) error
-
-	// Update modifies an existing example.
-	// Returns domain.ErrExampleNotFound if not found.
-	Update(ctx context.Context, example *domain.Example) error
-
-	// Delete removes an example by ID.
-	// Returns domain.ErrExampleNotFound if not found.
-	Delete(ctx context.Context, id domain.ExampleID) error
-
-	// ExistsByName checks if an example with the given name exists.
-	// Used for duplicate detection.
-	ExistsByName(ctx context.Context, name string) (bool, error)
-}
--- a/services/preferences-api/internal/port/preferences.go
+++ b/services/preferences-api/internal/port/preferences.go
@ -0,0 +1,18 @@
+package port
+
+import (
+	"context"
+
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
+)
+
+// PreferencesRepository defines the interface for user preferences persistence.
+// Implementations may use databases or in-memory storage.
+type PreferencesRepository interface {
+	// Get returns the preferences for a user.
+	// Returns domain.ErrPreferencesNotFound if no preferences exist.
+	Get(ctx context.Context, userID domain.UserID) (*domain.UserPreferences, error)
+
+	// Upsert creates or replaces the preferences for a user.
+	Upsert(ctx context.Context, prefs *domain.UserPreferences) error
+}
--- a/services/preferences-api/internal/service/example.go
+++ b/services/preferences-api/internal/service/example.go
@ -1,137 +0,0 @@
-// Package service provides business logic / use cases for the application.
-// Services orchestrate domain operations using port interfaces.
-package service
-
-import (
-	"context"
-	"errors"
-
-	"github.com/google/uuid"
-
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
-)
-
-// ExampleService handles example-related business logic.
-type ExampleService struct {
-	repo   port.ExampleRepository
-	logger *logging.Logger
-}
-
-// NewExampleService creates a new example service.
-func NewExampleService(repo port.ExampleRepository, logger *logging.Logger) *ExampleService {
-	return &ExampleService{
-		repo:   repo,
-		logger: logger.WithService("ExampleService"),
-	}
-}
-
-// List returns all examples.
-func (s *ExampleService) List(ctx context.Context) ([]domain.Example, error) {
-	return s.repo.List(ctx)
-}
-
-// Get returns an example by ID.
-// Returns domain.ErrExampleNotFound if not found.
-func (s *ExampleService) Get(ctx context.Context, id domain.ExampleID) (*domain.Example, error) {
-	return s.repo.Get(ctx, id)
-}
-
-// CreateInput contains the data needed to create an example.
-type CreateInput struct {
-	Name        string
-	Description string
-}
-
-// Create creates a new example with duplicate detection.
-// Returns domain.ErrDuplicateExample if name already exists.
-// Returns domain.ErrInvalidExampleName if name is invalid.
-func (s *ExampleService) Create(ctx context.Context, input CreateInput) (*domain.Example, error) {
-	// Check for duplicates
-	exists, err := s.repo.ExistsByName(ctx, input.Name)
-	if err != nil {
-		return nil, err
-	}
-	if exists {
-		return nil, domain.ErrDuplicateExample
-	}
-
-	// Generate new ID
-	id := domain.ExampleID(uuid.New().String())
-
-	// Create domain entity (validates name)
-	example, err := domain.NewExample(id, input.Name, input.Description)
-	if err != nil {
-		return nil, err
-	}
-
-	// Persist
-	if err := s.repo.Create(ctx, example); err != nil {
-		return nil, err
-	}
-
-	s.logger.Info("example created", "id", id, "name", input.Name)
-	return example, nil
-}
-
-// UpdateInput contains the data needed to update an example.
-type UpdateInput struct {
-	Name        string
-	Description string
-}
-
-// Update modifies an existing example.
-// Returns domain.ErrExampleNotFound if not found.
-// Returns domain.ErrDuplicateExample if new name conflicts with another example.
-// Returns domain.ErrInvalidExampleName if name is invalid.
-func (s *ExampleService) Update(ctx context.Context, id domain.ExampleID, input UpdateInput) (*domain.Example, error) {
-	// Fetch existing
-	example, err := s.repo.Get(ctx, id)
-	if err != nil {
-		return nil, err
-	}
-
-	// Check for name conflicts (only if name changed)
-	if example.Name != input.Name {
-		exists, err := s.repo.ExistsByName(ctx, input.Name)
-		if err != nil {
-			return nil, err
-		}
-		if exists {
-			return nil, domain.ErrDuplicateExample
-		}
-	}
-
-	// Update domain entity (validates name)
-	if err := example.Update(input.Name, input.Description); err != nil {
-		return nil, err
-	}
-
-	// Persist
-	if err := s.repo.Update(ctx, example); err != nil {
-		return nil, err
-	}
-
-	s.logger.Info("example updated", "id", id, "name", input.Name)
-	return example, nil
-}
-
-// Delete removes an example by ID.
-// Returns domain.ErrExampleNotFound if not found.
-func (s *ExampleService) Delete(ctx context.Context, id domain.ExampleID) error {
-	// Verify exists before delete
-	if _, err := s.repo.Get(ctx, id); err != nil {
-		if errors.Is(err, domain.ErrExampleNotFound) {
-			return domain.ErrExampleNotFound
-		}
-		return err
-	}
-
-	if err := s.repo.Delete(ctx, id); err != nil {
-		return err
-	}
-
-	s.logger.Info("example deleted", "id", id)
-	return nil
-}
--- a/services/preferences-api/internal/service/example_test.go
+++ b/services/preferences-api/internal/service/example_test.go
@ -1,282 +0,0 @@
-package service
-
-import (
-	"context"
-	"sync"
-	"testing"
-
-	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
-	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
-)
-
-// mockExampleRepository implements port.ExampleRepository for testing.
-type mockExampleRepository struct {
-	mu       sync.RWMutex
-	examples map[domain.ExampleID]*domain.Example
-}
-
-var _ port.ExampleRepository = (*mockExampleRepository)(nil)
-
-func newMockExampleRepository() *mockExampleRepository {
-	return &mockExampleRepository{
-		examples: make(map[domain.ExampleID]*domain.Example),
-	}
-}
-
-func (m *mockExampleRepository) List(ctx context.Context) ([]domain.Example, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
-
-	result := make([]domain.Example, 0, len(m.examples))
-	for _, e := range m.examples {
-		result = append(result, *e)
-	}
-	return result, nil
-}
-
-func (m *mockExampleRepository) Get(ctx context.Context, id domain.ExampleID) (*domain.Example, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
-
-	e, ok := m.examples[id]
-	if !ok {
-		return nil, domain.ErrExampleNotFound
-	}
-	// Return a copy to avoid mutation
-	copy := *e
-	return &copy, nil
-}
-
-func (m *mockExampleRepository) Create(ctx context.Context, example *domain.Example) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-
-	// Store a copy
-	copy := *example
-	m.examples[example.ID] = &copy
-	return nil
-}
-
-func (m *mockExampleRepository) Update(ctx context.Context, example *domain.Example) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-
-	if _, ok := m.examples[example.ID]; !ok {
-		return domain.ErrExampleNotFound
-	}
-	// Store a copy
-	copy := *example
-	m.examples[example.ID] = &copy
-	return nil
-}
-
-func (m *mockExampleRepository) Delete(ctx context.Context, id domain.ExampleID) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-
-	if _, ok := m.examples[id]; !ok {
-		return domain.ErrExampleNotFound
-	}
-	delete(m.examples, id)
-	return nil
-}
-
-func (m *mockExampleRepository) ExistsByName(ctx context.Context, name string) (bool, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
-
-	for _, e := range m.examples {
-		if e.Name == name {
-			return true, nil
-		}
-	}
-	return false, nil
-}
-
-func TestExampleService_Create(t *testing.T) {
-	repo := newMockExampleRepository()
-	svc := NewExampleService(repo, logging.Nop())
-
-	t.Run("creates example successfully", func(t *testing.T) {
-		example, err := svc.Create(context.Background(), CreateInput{
-			Name:        "Test Example",
-			Description: "A test description",
-		})
-		if err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-		if example.Name != "Test Example" {
-			t.Errorf("expected name 'Test Example', got '%s'", example.Name)
-		}
-		if example.ID.IsZero() {
-			t.Error("expected non-empty ID")
-		}
-	})
-
-	t.Run("rejects duplicate name", func(t *testing.T) {
-		_, err := svc.Create(context.Background(), CreateInput{
-			Name:        "Test Example",
-			Description: "Another description",
-		})
-		if err != domain.ErrDuplicateExample {
-			t.Errorf("expected ErrDuplicateExample, got %v", err)
-		}
-	})
-
-	t.Run("rejects empty name", func(t *testing.T) {
-		_, err := svc.Create(context.Background(), CreateInput{
-			Name:        "",
-			Description: "Description",
-		})
-		if err != domain.ErrInvalidExampleName {
-			t.Errorf("expected ErrInvalidExampleName, got %v", err)
-		}
-	})
-}
-
-func TestExampleService_Get(t *testing.T) {
-	repo := newMockExampleRepository()
-	svc := NewExampleService(repo, logging.Nop())
-
-	// Create an example first
-	created, _ := svc.Create(context.Background(), CreateInput{
-		Name:        "Get Test",
-		Description: "Description",
-	})
-
-	t.Run("returns existing example", func(t *testing.T) {
-		example, err := svc.Get(context.Background(), created.ID)
-		if err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-		if example.Name != "Get Test" {
-			t.Errorf("expected name 'Get Test', got '%s'", example.Name)
-		}
-	})
-
-	t.Run("returns not found for missing example", func(t *testing.T) {
-		_, err := svc.Get(context.Background(), "nonexistent-id")
-		if err != domain.ErrExampleNotFound {
-			t.Errorf("expected ErrExampleNotFound, got %v", err)
-		}
-	})
-}
-
-func TestExampleService_Update(t *testing.T) {
-	repo := newMockExampleRepository()
-	svc := NewExampleService(repo, logging.Nop())
-
-	// Create examples
-	example1, _ := svc.Create(context.Background(), CreateInput{
-		Name:        "Update Test 1",
-		Description: "Original",
-	})
-	_, _ = svc.Create(context.Background(), CreateInput{
-		Name:        "Update Test 2",
-		Description: "Other",
-	})
-
-	t.Run("updates example successfully", func(t *testing.T) {
-		updated, err := svc.Update(context.Background(), example1.ID, UpdateInput{
-			Name:        "Updated Name",
-			Description: "Updated description",
-		})
-		if err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-		if updated.Name != "Updated Name" {
-			t.Errorf("expected name 'Updated Name', got '%s'", updated.Name)
-		}
-	})
-
-	t.Run("allows same name on same example", func(t *testing.T) {
-		_, err := svc.Update(context.Background(), example1.ID, UpdateInput{
-			Name:        "Updated Name",
-			Description: "Same name",
-		})
-		if err != nil {
-			t.Errorf("unexpected error updating with same name: %v", err)
-		}
-	})
-
-	t.Run("rejects name conflict", func(t *testing.T) {
-		_, err := svc.Update(context.Background(), example1.ID, UpdateInput{
-			Name:        "Update Test 2",
-			Description: "Conflict",
-		})
-		if err != domain.ErrDuplicateExample {
-			t.Errorf("expected ErrDuplicateExample, got %v", err)
-		}
-	})
-
-	t.Run("returns not found for missing example", func(t *testing.T) {
-		_, err := svc.Update(context.Background(), "nonexistent-id", UpdateInput{
-			Name:        "Anything",
-			Description: "",
-		})
-		if err != domain.ErrExampleNotFound {
-			t.Errorf("expected ErrExampleNotFound, got %v", err)
-		}
-	})
-}
-
-func TestExampleService_Delete(t *testing.T) {
-	repo := newMockExampleRepository()
-	svc := NewExampleService(repo, logging.Nop())
-
-	// Create an example first
-	created, _ := svc.Create(context.Background(), CreateInput{
-		Name:        "Delete Test",
-		Description: "To be deleted",
-	})
-
-	t.Run("deletes example successfully", func(t *testing.T) {
-		err := svc.Delete(context.Background(), created.ID)
-		if err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-
-		// Verify deleted
-		_, err = svc.Get(context.Background(), created.ID)
-		if err != domain.ErrExampleNotFound {
-			t.Errorf("expected ErrExampleNotFound after delete, got %v", err)
-		}
-	})
-
-	t.Run("returns not found for missing example", func(t *testing.T) {
-		err := svc.Delete(context.Background(), "nonexistent-id")
-		if err != domain.ErrExampleNotFound {
-			t.Errorf("expected ErrExampleNotFound, got %v", err)
-		}
-	})
-}
-
-func TestExampleService_List(t *testing.T) {
-	repo := newMockExampleRepository()
-	svc := NewExampleService(repo, logging.Nop())
-
-	t.Run("returns empty list initially", func(t *testing.T) {
-		examples, err := svc.List(context.Background())
-		if err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-		if len(examples) != 0 {
-			t.Errorf("expected 0 examples, got %d", len(examples))
-		}
-	})
-
-	// Create some examples
-	_, _ = svc.Create(context.Background(), CreateInput{Name: "List Test 1", Description: ""})
-	_, _ = svc.Create(context.Background(), CreateInput{Name: "List Test 2", Description: ""})
-
-	t.Run("returns all examples", func(t *testing.T) {
-		examples, err := svc.List(context.Background())
-		if err != nil {
-			t.Fatalf("unexpected error: %v", err)
-		}
-		if len(examples) != 2 {
-			t.Errorf("expected 2 examples, got %d", len(examples))
-		}
-	})
-}
--- a/services/preferences-api/internal/service/preferences.go
+++ b/services/preferences-api/internal/service/preferences.go
@ -0,0 +1,62 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
+)
+
+// PreferencesService handles preference-related business logic.
+type PreferencesService struct {
+	repo   port.PreferencesRepository
+	logger *logging.Logger
+}
+
+// NewPreferencesService creates a new preferences service.
+func NewPreferencesService(repo port.PreferencesRepository, logger *logging.Logger) *PreferencesService {
+	return &PreferencesService{
+		repo:   repo,
+		logger: logger.WithService("PreferencesService"),
+	}
+}
+
+// GetPreferences returns the preferences for a user.
+// If no preferences are stored, default preferences are returned.
+func (s *PreferencesService) GetPreferences(ctx context.Context, userID domain.UserID) (*domain.UserPreferences, error) {
+	prefs, err := s.repo.Get(ctx, userID)
+	if err != nil {
+		if errors.Is(err, domain.ErrPreferencesNotFound) {
+			defaults := domain.DefaultPreferences()
+			return &domain.UserPreferences{
+				UserID:      userID,
+				Preferences: defaults,
+			}, nil
+		}
+		return nil, err
+	}
+	return prefs, nil
+}
+
+// SetPreferences validates and stores preferences for a user.
+func (s *PreferencesService) SetPreferences(ctx context.Context, userID domain.UserID, prefs domain.Preferences) (*domain.UserPreferences, error) {
+	if err := prefs.Validate(); err != nil {
+		return nil, err
+	}
+
+	userPrefs := &domain.UserPreferences{
+		UserID:      userID,
+		Preferences: prefs,
+		UpdatedAt:   time.Now().UTC(),
+	}
+
+	if err := s.repo.Upsert(ctx, userPrefs); err != nil {
+		return nil, err
+	}
+
+	s.logger.Info("preferences updated", "user_id", string(userID))
+	return userPrefs, nil
+}
--- a/services/preferences-api/internal/service/preferences_test.go
+++ b/services/preferences-api/internal/service/preferences_test.go
@ -0,0 +1,181 @@
+package service
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"git.threesix.ai/jordan/slack5-1770541397/pkg/logging"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/domain"
+	"git.threesix.ai/jordan/slack5-1770541397/services/preferences-api/internal/port"
+)
+
+// mockPreferencesRepository implements port.PreferencesRepository for testing.
+type mockPreferencesRepository struct {
+	mu    sync.RWMutex
+	store map[domain.UserID]*domain.UserPreferences
+}
+
+var _ port.PreferencesRepository = (*mockPreferencesRepository)(nil)
+
+func newMockPreferencesRepository() *mockPreferencesRepository {
+	return &mockPreferencesRepository{
+		store: make(map[domain.UserID]*domain.UserPreferences),
+	}
+}
+
+func (m *mockPreferencesRepository) Get(ctx context.Context, userID domain.UserID) (*domain.UserPreferences, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	prefs, ok := m.store[userID]
+	if !ok {
+		return nil, domain.ErrPreferencesNotFound
+	}
+	copy := *prefs
+	return &copy, nil
+}
+
+func (m *mockPreferencesRepository) Upsert(ctx context.Context, prefs *domain.UserPreferences) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	copy := *prefs
+	m.store[prefs.UserID] = &copy
+	return nil
+}
+
+func TestPreferencesService_GetPreferences(t *testing.T) {
+	repo := newMockPreferencesRepository()
+	svc := NewPreferencesService(repo, logging.Nop())
+
+	t.Run("returns defaults when no preferences exist", func(t *testing.T) {
+		prefs, err := svc.GetPreferences(context.Background(), "user-123")
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if prefs.UserID != "user-123" {
+			t.Errorf("expected user_id 'user-123', got '%s'", prefs.UserID)
+		}
+		if prefs.Preferences.Theme != "system" {
+			t.Errorf("expected default theme 'system', got '%s'", prefs.Preferences.Theme)
+		}
+		if prefs.Preferences.Language != "en" {
+			t.Errorf("expected default language 'en', got '%s'", prefs.Preferences.Language)
+		}
+		if !prefs.Preferences.Notifications.Email {
+			t.Error("expected default notifications.email to be true")
+		}
+		if !prefs.Preferences.Notifications.Push {
+			t.Error("expected default notifications.push to be true")
+		}
+		if prefs.Preferences.Notifications.SMS {
+			t.Error("expected default notifications.sms to be false")
+		}
+	})
+
+	t.Run("returns stored preferences", func(t *testing.T) {
+		// Store preferences first
+		_, err := svc.SetPreferences(context.Background(), "user-456", domain.Preferences{
+			Theme:    "dark",
+			Language: "fr",
+			Notifications: domain.NotificationPreferences{
+				Email: false,
+				Push:  true,
+				SMS:   true,
+			},
+		})
+		if err != nil {
+			t.Fatalf("unexpected error setting preferences: %v", err)
+		}
+
+		prefs, err := svc.GetPreferences(context.Background(), "user-456")
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if prefs.Preferences.Theme != "dark" {
+			t.Errorf("expected theme 'dark', got '%s'", prefs.Preferences.Theme)
+		}
+		if prefs.Preferences.Language != "fr" {
+			t.Errorf("expected language 'fr', got '%s'", prefs.Preferences.Language)
+		}
+		if prefs.Preferences.Notifications.Email {
+			t.Error("expected notifications.email to be false")
+		}
+		if prefs.Preferences.Notifications.SMS != true {
+			t.Error("expected notifications.sms to be true")
+		}
+	})
+}
+
+func TestPreferencesService_SetPreferences(t *testing.T) {
+	repo := newMockPreferencesRepository()
+	svc := NewPreferencesService(repo, logging.Nop())
+
+	t.Run("sets valid preferences", func(t *testing.T) {
+		prefs, err := svc.SetPreferences(context.Background(), "user-789", domain.Preferences{
+			Theme:    "light",
+			Language: "en",
+			Notifications: domain.NotificationPreferences{
+				Email: true,
+				Push:  false,
+				SMS:   false,
+			},
+		})
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if prefs.UserID != "user-789" {
+			t.Errorf("expected user_id 'user-789', got '%s'", prefs.UserID)
+		}
+		if prefs.Preferences.Theme != "light" {
+			t.Errorf("expected theme 'light', got '%s'", prefs.Preferences.Theme)
+		}
+		if prefs.UpdatedAt.IsZero() {
+			t.Error("expected non-zero updated_at")
+		}
+	})
+
+	t.Run("rejects invalid theme", func(t *testing.T) {
+		_, err := svc.SetPreferences(context.Background(), "user-789", domain.Preferences{
+			Theme:    "neon",
+			Language: "en",
+		})
+		if err != domain.ErrInvalidTheme {
+			t.Errorf("expected ErrInvalidTheme, got %v", err)
+		}
+	})
+
+	t.Run("rejects language exceeding max length", func(t *testing.T) {
+		_, err := svc.SetPreferences(context.Background(), "user-789", domain.Preferences{
+			Theme:    "dark",
+			Language: "abcdefghijk", // 11 chars
+		})
+		if err != domain.ErrInvalidLanguage {
+			t.Errorf("expected ErrInvalidLanguage, got %v", err)
+		}
+	})
+
+	t.Run("allows empty theme", func(t *testing.T) {
+		prefs, err := svc.SetPreferences(context.Background(), "user-000", domain.Preferences{
+			Theme:    "",
+			Language: "en",
+		})
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if prefs.Preferences.Theme != "" {
+			t.Errorf("expected empty theme, got '%s'", prefs.Preferences.Theme)
+		}
+	})
+
+	t.Run("allows max length language", func(t *testing.T) {
+		_, err := svc.SetPreferences(context.Background(), "user-000", domain.Preferences{
+			Theme:    "dark",
+			Language: "abcdefghij", // exactly 10 chars
+		})
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	})
+}
--- a/services/preferences-api/migrations/.gitkeep
+++ b/services/preferences-api/migrations/.gitkeep
--- a/services/preferences-api/migrations/001_create_user_preferences.sql
+++ b/services/preferences-api/migrations/001_create_user_preferences.sql
@ -0,0 +1,6 @@
+CREATE TABLE IF NOT EXISTS user_preferences (
+    user_id     TEXT        PRIMARY KEY,
+    preferences JSONB       NOT NULL,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
--- a/services/preferences-api/migrations/migrations.go
+++ b/services/preferences-api/migrations/migrations.go
@ -0,0 +1,7 @@
+// Package migrations embeds SQL migration files for the preferences-api service.
+package migrations
+
+import "embed"
+
+//go:embed *.sql
+var FS embed.FS
--- a/services/preferences-api/server
+++ b/services/preferences-api/server