Implemented shared S3 audio caching for prepare and restore --include-audio

internal/config/cache_config_test.go

@@ -0,0 +1,67 @@
+package config
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestCacheDefaults(t *testing.T) {
+	pipelinePath, sessionPath := writeConfigFiles(t, `workspace:
+  root: /tmp/narratio
+whisperx:
+  transcribe_url: https://example.com/transcribe
+analyzer:
+  timeout: 20m
+notification:
+  timeout: 10s
+`, `session_id: 2026-05-03
+inputs:
+  audio_dir: ./audio
+`)
+	cfg, err := Load(pipelinePath, sessionPath)
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	if cfg.Pipeline.Cache.Root != DefaultCacheRoot {
+		t.Fatalf("cache.root = %q, want %q", cfg.Pipeline.Cache.Root, DefaultCacheRoot)
+	}
+	if cfg.Pipeline.Cache.S3Audio == nil || *cfg.Pipeline.Cache.S3Audio != DefaultCacheS3Audio {
+		t.Fatalf("cache.s3_audio = %v, want %v", cfg.Pipeline.Cache.S3Audio, DefaultCacheS3Audio)
+	}
+}
+
+func TestCacheStrictDecodeRejectsUnknownFields(t *testing.T) {
+	pipelinePath, sessionPath := writeConfigFiles(t, `workspace:
+  root: /tmp/narratio
+cache:
+  root: /var/cache/narratio
+  unknown: true
+`, `session_id: 2026-05-03
+inputs:
+  audio_dir: ./audio
+`)
+	_, err := Load(pipelinePath, sessionPath)
+	if err == nil || !strings.Contains(err.Error(), "strict decode failed") {
+		t.Fatalf("Load() error = %v, want strict decode failed", err)
+	}
+}
+
+func TestCacheValidationRequiresRootWhenS3AudioEnabled(t *testing.T) {
+	pipelinePath, sessionPath := writeConfigFiles(t, `workspace:
+  root: /tmp/narratio
+cache:
+  root: "   "
+  s3_audio: true
+`, `session_id: 2026-05-03
+inputs:
+  audio_dir: ./audio
+`)
+	cfg, err := Load(pipelinePath, sessionPath)
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	err = Validate(cfg)
+	if err == nil || !strings.Contains(err.Error(), "pipeline.cache.root is required") {
+		t.Fatalf("Validate() error = %v, want cache root error", err)
+	}
+}