feat(activity-watcher): phase-1 backend MVP

api/activity-watcher-openapi.yaml

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+openapi: "3.0.3"
+info:
+  title: Activity Watcher API
+  version: "1.0.0-phase1"
+  description: Ingest and query user activity events. Phase 1 backend MVP.
+
+paths:
+  /health:
+    get:
+      summary: Liveness probe
+      operationId: getHealth
+      responses:
+        "200":
+          description: Service is alive
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  status:
+                    type: string
+                    example: ok
+
+  /events:
+    post:
+      summary: Ingest an activity event
+      operationId: createEvent
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/EventInput'
+      responses:
+        "201":
+          description: Event created successfully
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/EventCreated'
+        "400":
+          description: Validation error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+
+  /users/{user_id}/events:
+    get:
+      summary: Retrieve events for a user, newest first
+      operationId: listUserEvents
+      parameters:
+        - name: user_id
+          in: path
+          required: true
+          schema:
+            type: string
+      responses:
+        "200":
+          description: List of events (may be empty)
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Event'
+        "500":
+          description: Internal error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+
+components:
+  schemas:
+    EventInput:
+      type: object
+      required: [user_id, event_type, occurred_at, metadata]
+      properties:
+        user_id:
+          type: string
+          minLength: 1
+          maxLength: 255
+          example: user-abc123
+        event_type:
+          type: string
+          minLength: 1
+          maxLength: 255
+          example: page_view
+        occurred_at:
+          type: string
+          format: date-time
+          description: Client-supplied event timestamp (RFC 3339). Must not be in the future or more than 30 days old.
+          example: "2026-06-12T10:00:00Z"
+        metadata:
+          type: object
+          description: Free-form JSON object with event-specific data.
+          example:
+            page: /home
+
+    EventCreated:
+      type: object
+      properties:
+        id:
+          type: string
+          format: uuid
+          example: "550e8400-e29b-41d4-a716-446655440000"
+
+    Event:
+      type: object
+      properties:
+        id:
+          type: string
+          format: uuid
+        user_id:
+          type: string
+        event_type:
+          type: string
+        occurred_at:
+          type: string
+          format: date-time
+        metadata:
+          type: object
+        created_at:
+          type: string
+          format: date-time
+          description: Server-stamped ingestion timestamp.
+
+    Error:
+      type: object
+      properties:
+        error:
+          type: string
+          example: "user_id is required"

cmd/activity-watcher/Dockerfile

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+FROM golang:1.26-alpine AS builder
+WORKDIR /app
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /activity-watcher ./cmd/activity-watcher
+
+FROM alpine:3.21
+RUN apk add --no-cache ca-certificates
+WORKDIR /app
+COPY --from=builder /activity-watcher .
+VOLUME ["/data"]
+ENV DB_PATH=/data/events.db
+ENV PORT=8080
+ENV LOG_LEVEL=info
+EXPOSE 8080
+ENTRYPOINT ["/app/activity-watcher"]

cmd/activity-watcher/helpers_test.go

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+package main
+
+import (
+	"io"
+	"log/slog"
+)
+
+func newTestLogger() *slog.Logger {
+	return slog.New(slog.NewTextHandler(io.Discard, nil))
+}

cmd/activity-watcher/main.go

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+package main
+
+import (
+	"context"
+	"errors"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/simple-container-com/api/internal/activitywatcher/handler"
+	"github.com/simple-container-com/api/internal/activitywatcher/repository"
+	"github.com/simple-container-com/api/internal/activitywatcher/service"
+)
+
+func main() {
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: logLevel(),
+	}))
+	slog.SetDefault(logger)
+
+	dbPath := envOr("DB_PATH", "/data/events.db")
+	port := envOr("PORT", "8080")
+
+	repo, err := repository.NewSQLiteRepository(dbPath)
+	if err != nil {
+		logger.Error("failed to open database", "path", dbPath, "error", err)
+		os.Exit(1)
+	}
+	defer repo.Close()
+
+	svc := service.NewEventService(repo)
+	evtHandler := handler.NewEventHandler(svc, logger)
+	healthHandler := handler.NewHealthHandler()
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /health", healthHandler.Health)
+	mux.HandleFunc("POST /events", evtHandler.Create)
+	mux.HandleFunc("GET /users/{user_id}/events", evtHandler.ListByUser)
+
+	srv := &http.Server{
+		Addr:         ":" + port,
+		Handler:      mux,
+		ReadTimeout:  15 * time.Second,
+		WriteTimeout: 15 * time.Second,
+		IdleTimeout:  60 * time.Second,
+	}
+
+	quit := make(chan os.Signal, 1)
+	signal.Notify(quit, os.Interrupt, syscall.SIGTERM)
+
+	go func() {
+		logger.Info("activity-watcher starting", "port", port, "db", dbPath)
+		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			logger.Error("server error", "error", err)
+			os.Exit(1)
+		}
+	}()
+
+	<-quit
+	logger.Info("shutting down")
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	if err := srv.Shutdown(ctx); err != nil {
+		logger.Error("shutdown error", "error", err)
+	}
+}
+
+func envOr(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}
+
+func logLevel() slog.Level {
+	switch os.Getenv("LOG_LEVEL") {
+	case "debug":
+		return slog.LevelDebug
+	case "warn":
+		return slog.LevelWarn
+	case "error":
+		return slog.LevelError
+	default:
+		return slog.LevelInfo
+	}
+}