feat: add v2 stack (backend, runner, ui-v2) with release workflow

- backend/: Go API server and runner binaries with PocketBase + MinIO storage
- ui-v2/: SvelteKit frontend rewrite
- docker-compose-new.yml: compose file for the v2 stack
- .gitea/workflows/release-v2.yaml: CI/CD for backend, runner, and ui-v2 Docker Hub images
- scripts/pb-init.sh: migrate from wget to curl, add superuser bootstrap for fresh installs
- .env.example: document DOCKER_BUILDKIT=1 for Colima users

backend/internal/runner/runner.go

@@ -0,0 +1,386 @@
+// Package runner implements the worker loop that polls PocketBase for pending
+// scrape and audio tasks, executes them, and reports results back.
+//
+// Design:
+//   - Run(ctx) loops on a ticker; each tick claims and dispatches pending tasks.
+//   - Scrape tasks are dispatched to the Orchestrator (one goroutine per task,
+//     up to MaxConcurrentScrape).
+//   - Audio tasks fetch chapter text, call Kokoro, upload to MinIO, and report
+//     the result back (up to MaxConcurrentAudio goroutines).
+//   - The runner is stateless between ticks; all state lives in PocketBase.
+package runner
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"sync"
+	"time"
+
+	"github.com/libnovel/backend/internal/bookstore"
+	"github.com/libnovel/backend/internal/domain"
+	"github.com/libnovel/backend/internal/kokoro"
+	"github.com/libnovel/backend/internal/orchestrator"
+	"github.com/libnovel/backend/internal/scraper"
+	"github.com/libnovel/backend/internal/taskqueue"
+)
+
+// Config tunes the runner behaviour.
+type Config struct {
+	// WorkerID uniquely identifies this runner instance in PocketBase records.
+	WorkerID string
+	// PollInterval is how often the runner checks for new tasks.
+	PollInterval time.Duration
+	// MaxConcurrentScrape limits simultaneous book-scrape goroutines.
+	MaxConcurrentScrape int
+	// MaxConcurrentAudio limits simultaneous audio-generation goroutines.
+	MaxConcurrentAudio int
+	// OrchestratorWorkers is the chapter-scraping parallelism inside each book run.
+	OrchestratorWorkers int
+	// HeartbeatInterval is how often active tasks PATCH their heartbeat_at
+	// timestamp to signal they are still alive. Defaults to 30s when 0.
+	HeartbeatInterval time.Duration
+	// StaleTaskThreshold is how old a heartbeat must be (or absent) before the
+	// task is considered orphaned and reset to pending. Defaults to 2m when 0.
+	StaleTaskThreshold time.Duration
+}
+
+// Dependencies are the external services the runner depends on.
+type Dependencies struct {
+	// Consumer claims tasks from PocketBase.
+	Consumer taskqueue.Consumer
+	// BookWriter persists scraped data (used by orchestrator).
+	BookWriter bookstore.BookWriter
+	// BookReader reads chapter text for audio generation.
+	BookReader bookstore.BookReader
+	// AudioStore persists generated audio and checks key existence.
+	AudioStore bookstore.AudioStore
+	// Novel is the scraper implementation.
+	Novel scraper.NovelScraper
+	// Kokoro is the TTS client.
+	Kokoro kokoro.Client
+	// Log is the structured logger.
+	Log *slog.Logger
+}
+
+// Runner is the main worker process.
+type Runner struct {
+	cfg  Config
+	deps Dependencies
+}
+
+// New creates a Runner from cfg and deps.
+// Any zero/nil field in deps will cause a panic at construction time to fail fast.
+func New(cfg Config, deps Dependencies) *Runner {
+	if cfg.PollInterval <= 0 {
+		cfg.PollInterval = 30 * time.Second
+	}
+	if cfg.MaxConcurrentScrape <= 0 {
+		cfg.MaxConcurrentScrape = 2
+	}
+	if cfg.MaxConcurrentAudio <= 0 {
+		cfg.MaxConcurrentAudio = 1
+	}
+	if cfg.WorkerID == "" {
+		cfg.WorkerID = "runner"
+	}
+	if cfg.HeartbeatInterval <= 0 {
+		cfg.HeartbeatInterval = 30 * time.Second
+	}
+	if cfg.StaleTaskThreshold <= 0 {
+		cfg.StaleTaskThreshold = 2 * time.Minute
+	}
+	if deps.Log == nil {
+		deps.Log = slog.Default()
+	}
+	return &Runner{cfg: cfg, deps: deps}
+}
+
+// livenessFile is the path written on every successful poll so that the Docker
+// healthcheck (CMD /healthcheck file /tmp/runner.alive <max_age>) can verify
+// the runner is still making progress.
+const livenessFile = "/tmp/runner.alive"
+
+// touchAlive writes the current UTC time to livenessFile. Errors are logged but
+// never fatal — liveness is best-effort and should not crash the runner.
+func (r *Runner) touchAlive() {
+	data := []byte(time.Now().UTC().Format(time.RFC3339))
+	if err := os.WriteFile(livenessFile, data, 0o644); err != nil {
+		r.deps.Log.Warn("runner: failed to write liveness file", "err", err)
+	}
+}
+
+// Run starts the poll loop, blocking until ctx is cancelled.
+// On each tick it claims and executes all available pending tasks.
+// Scrape and audio tasks run in separate goroutine pools bounded by
+// MaxConcurrentScrape and MaxConcurrentAudio respectively.
+func (r *Runner) Run(ctx context.Context) error {
+	r.deps.Log.Info("runner: starting",
+		"worker_id", r.cfg.WorkerID,
+		"poll_interval", r.cfg.PollInterval,
+		"max_scrape", r.cfg.MaxConcurrentScrape,
+		"max_audio", r.cfg.MaxConcurrentAudio,
+	)
+
+	scrapeSem := make(chan struct{}, r.cfg.MaxConcurrentScrape)
+	audioSem := make(chan struct{}, r.cfg.MaxConcurrentAudio)
+	var wg sync.WaitGroup
+
+	// Write liveness file immediately so the first healthcheck passes before
+	// the first poll completes.
+	r.touchAlive()
+
+	tick := time.NewTicker(r.cfg.PollInterval)
+	defer tick.Stop()
+
+	// Run one poll immediately on startup, then on each tick.
+	for {
+		r.poll(ctx, scrapeSem, audioSem, &wg)
+		r.touchAlive()
+
+		select {
+		case <-ctx.Done():
+			r.deps.Log.Info("runner: context cancelled, draining active tasks")
+			done := make(chan struct{})
+			go func() {
+				wg.Wait()
+				close(done)
+			}()
+			select {
+			case <-done:
+				r.deps.Log.Info("runner: all tasks drained, exiting")
+			case <-time.After(2 * time.Minute):
+				r.deps.Log.Warn("runner: drain timeout exceeded, forcing exit")
+			}
+			return nil
+		case <-tick.C:
+		}
+	}
+}
+
+// poll claims all available pending tasks and dispatches them to goroutines.
+// It claims tasks in a tight loop until no more are available.
+func (r *Runner) poll(ctx context.Context, scrapeSem, audioSem chan struct{}, wg *sync.WaitGroup) {
+	// ── Reap orphaned tasks ───────────────────────────────────────────────
+	if n, err := r.deps.Consumer.ReapStaleTasks(ctx, r.cfg.StaleTaskThreshold); err != nil {
+		r.deps.Log.Warn("runner: reap stale tasks failed", "err", err)
+	} else if n > 0 {
+		r.deps.Log.Info("runner: reaped stale tasks", "count", n)
+	}
+
+	// ── Scrape tasks ──────────────────────────────────────────────────────
+	for {
+		if ctx.Err() != nil {
+			return
+		}
+		task, ok, err := r.deps.Consumer.ClaimNextScrapeTask(ctx, r.cfg.WorkerID)
+		if err != nil {
+			r.deps.Log.Error("runner: ClaimNextScrapeTask failed", "err", err)
+			break
+		}
+		if !ok {
+			break // queue empty
+		}
+		// Acquire semaphore (non-blocking when full — leave task running).
+		select {
+		case scrapeSem <- struct{}{}:
+		default:
+			// Too many concurrent scrapes — the task stays claimed but we can't
+			// run it right now. Log and break; the next poll will pick it up if
+			// still running (it won't be re-claimed while status=running).
+			r.deps.Log.Warn("runner: scrape semaphore full, will retry next tick",
+				"task_id", task.ID)
+			break
+		}
+		wg.Add(1)
+		go func(t domain.ScrapeTask) {
+			defer wg.Done()
+			defer func() { <-scrapeSem }()
+			r.runScrapeTask(ctx, t)
+		}(task)
+	}
+
+	// ── Audio tasks ───────────────────────────────────────────────────────
+	for {
+		if ctx.Err() != nil {
+			return
+		}
+		task, ok, err := r.deps.Consumer.ClaimNextAudioTask(ctx, r.cfg.WorkerID)
+		if err != nil {
+			r.deps.Log.Error("runner: ClaimNextAudioTask failed", "err", err)
+			break
+		}
+		if !ok {
+			break // queue empty
+		}
+		select {
+		case audioSem <- struct{}{}:
+		default:
+			r.deps.Log.Warn("runner: audio semaphore full, will retry next tick",
+				"task_id", task.ID)
+			break
+		}
+		wg.Add(1)
+		go func(t domain.AudioTask) {
+			defer wg.Done()
+			defer func() { <-audioSem }()
+			r.runAudioTask(ctx, t)
+		}(task)
+	}
+}
+
+// runScrapeTask executes one scrape task end-to-end and reports the result.
+func (r *Runner) runScrapeTask(ctx context.Context, task domain.ScrapeTask) {
+	log := r.deps.Log.With("task_id", task.ID, "kind", task.Kind, "url", task.TargetURL)
+	log.Info("runner: scrape task starting")
+
+	// Heartbeat goroutine: periodically PATCH heartbeat_at so the reaper knows
+	// this task is still alive. Cancelled when the task finishes.
+	hbCtx, hbCancel := context.WithCancel(ctx)
+	defer hbCancel()
+	go func() {
+		tick := time.NewTicker(r.cfg.HeartbeatInterval)
+		defer tick.Stop()
+		for {
+			select {
+			case <-hbCtx.Done():
+				return
+			case <-tick.C:
+				if err := r.deps.Consumer.HeartbeatTask(ctx, task.ID); err != nil {
+					log.Warn("runner: heartbeat failed", "err", err)
+				}
+			}
+		}
+	}()
+
+	oCfg := orchestrator.Config{Workers: r.cfg.OrchestratorWorkers}
+	o := orchestrator.New(oCfg, r.deps.Novel, r.deps.BookWriter, r.deps.Log)
+
+	var result domain.ScrapeResult
+
+	switch task.Kind {
+	case "catalogue":
+		result = r.runCatalogueTask(ctx, task, o, log)
+	case "book", "book_range":
+		result = o.RunBook(ctx, task)
+	default:
+		result.ErrorMessage = fmt.Sprintf("unknown task kind: %q", task.Kind)
+		log.Warn("runner: unknown task kind")
+	}
+
+	if err := r.deps.Consumer.FinishScrapeTask(ctx, task.ID, result); err != nil {
+		log.Error("runner: FinishScrapeTask failed", "err", err)
+	}
+	log.Info("runner: scrape task finished",
+		"scraped", result.ChaptersScraped,
+		"skipped", result.ChaptersSkipped,
+		"errors", result.Errors,
+	)
+}
+
+// runCatalogueTask runs a full catalogue scrape by iterating catalogue entries
+// and running a book task for each one.
+func (r *Runner) runCatalogueTask(ctx context.Context, task domain.ScrapeTask, o *orchestrator.Orchestrator, log *slog.Logger) domain.ScrapeResult {
+	entries, errCh := r.deps.Novel.ScrapeCatalogue(ctx)
+	var result domain.ScrapeResult
+
+	for entry := range entries {
+		if ctx.Err() != nil {
+			break
+		}
+		bookTask := domain.ScrapeTask{
+			ID:        task.ID,
+			Kind:      "book",
+			TargetURL: entry.URL,
+		}
+		bookResult := o.RunBook(ctx, bookTask)
+		result.BooksFound += bookResult.BooksFound + 1
+		result.ChaptersScraped += bookResult.ChaptersScraped
+		result.ChaptersSkipped += bookResult.ChaptersSkipped
+		result.Errors += bookResult.Errors
+	}
+
+	if err := <-errCh; err != nil {
+		log.Warn("runner: catalogue scrape finished with error", "err", err)
+		result.Errors++
+		if result.ErrorMessage == "" {
+			result.ErrorMessage = err.Error()
+		}
+	}
+	return result
+}
+
+// runAudioTask executes one audio-generation task:
+//  1. Read chapter text from MinIO.
+//  2. Call Kokoro to generate audio.
+//  3. Upload MP3 to MinIO under the standard audio object key.
+//  4. Report result back to PocketBase.
+func (r *Runner) runAudioTask(ctx context.Context, task domain.AudioTask) {
+	log := r.deps.Log.With("task_id", task.ID, "slug", task.Slug, "chapter", task.Chapter, "voice", task.Voice)
+	log.Info("runner: audio task starting")
+
+	// Heartbeat goroutine: periodically PATCH heartbeat_at so the reaper knows
+	// this task is still alive. Cancelled when the task finishes.
+	hbCtx, hbCancel := context.WithCancel(ctx)
+	defer hbCancel()
+	go func() {
+		tick := time.NewTicker(r.cfg.HeartbeatInterval)
+		defer tick.Stop()
+		for {
+			select {
+			case <-hbCtx.Done():
+				return
+			case <-tick.C:
+				if err := r.deps.Consumer.HeartbeatTask(ctx, task.ID); err != nil {
+					log.Warn("runner: heartbeat failed", "err", err)
+				}
+			}
+		}
+	}()
+
+	fail := func(msg string) {
+		log.Error("runner: audio task failed", "reason", msg)
+		result := domain.AudioResult{ErrorMessage: msg}
+		if err := r.deps.Consumer.FinishAudioTask(ctx, task.ID, result); err != nil {
+			log.Error("runner: FinishAudioTask failed", "err", err)
+		}
+	}
+
+	// Step 1: read chapter text.
+	raw, err := r.deps.BookReader.ReadChapter(ctx, task.Slug, task.Chapter)
+	if err != nil {
+		fail(fmt.Sprintf("read chapter: %v", err))
+		return
+	}
+	text := stripMarkdown(raw)
+	if text == "" {
+		fail("chapter text is empty after stripping markdown")
+		return
+	}
+
+	// Step 2: generate audio.
+	if r.deps.Kokoro == nil {
+		fail("kokoro client not configured")
+		return
+	}
+	audioData, err := r.deps.Kokoro.GenerateAudio(ctx, text, task.Voice)
+	if err != nil {
+		fail(fmt.Sprintf("kokoro generate: %v", err))
+		return
+	}
+
+	// Step 3: upload to MinIO.
+	key := r.deps.AudioStore.AudioObjectKey(task.Slug, task.Chapter, task.Voice)
+	if err := r.deps.AudioStore.PutAudio(ctx, key, audioData); err != nil {
+		fail(fmt.Sprintf("put audio: %v", err))
+		return
+	}
+
+	// Step 4: report success.
+	result := domain.AudioResult{ObjectKey: key}
+	if err := r.deps.Consumer.FinishAudioTask(ctx, task.ID, result); err != nil {
+		log.Error("runner: FinishAudioTask failed", "err", err)
+	}
+	log.Info("runner: audio task finished", "key", key)
+}