Session configuration templates are now proceeded by narratio session init; all other commands require concrete configuration

internal/app/operator_helpers.go

@@ -44,8 +44,8 @@ func addCommonConfigFlags(fs *flag.FlagSet, flags *commonConfigFlags) {
 	fs.StringVar(&flags.pipelinePath, "config", "", "path to pipeline.yml (optional; defaults searched)")
 	fs.StringVar(&flags.campaignPath, "campaign", "", "path to campaign.yml (optional; defaults searched)")
 	fs.StringVar(&flags.sessionPath, "session", "", "path to session.yml")
-	fs.StringVar(&flags.sessionID, "session-id", "", "session identifier for session.yml templates")
-	fs.StringVar(&flags.previousSessionID, "previous-session-id", "", "previous session identifier for session.yml templates")
+	fs.StringVar(&flags.sessionID, "session-id", "", "expected session identifier and remote session lookup value")
+	fs.StringVar(&flags.previousSessionID, "previous-session-id", "", "expected previous session identifier")
 }
 
 func (f commonConfigFlags) sessionOptions() config.SessionLoadOptions {
@@ -290,7 +290,18 @@ func SessionInit(ctx context.Context, args []string, out io.Writer) error {
 		return fmt.Errorf("session init: %w", err)
 	}
 
-	data, err := buildSessionYAML(base.Campaign.Campaign, sessionID, previousSessionID, date, title, audioS3Prefix, audioDir)
+	input := sessionInitInput{
+		Campaign:          base.Campaign.Campaign,
+		CampaignPath:      base.CampaignPath,
+		TemplateFile:      base.Campaign.SessionTemplateFile,
+		SessionID:         sessionID,
+		PreviousSessionID: previousSessionID,
+		Date:              date,
+		Title:             title,
+		AudioS3Prefix:     audioS3Prefix,
+		AudioDir:          audioDir,
+	}
+	data, err := buildSessionInitYAML(input)
 	if err != nil {
 		return fmt.Errorf("session init: %w", err)
 	}
@@ -588,6 +599,104 @@ func buildSessionYAML(campaign, sessionID, previousSessionID, date, title, audio
 	return data, nil
 }
 
+type sessionInitInput struct {
+	Campaign          string
+	CampaignPath      string
+	TemplateFile      string
+	SessionID         string
+	PreviousSessionID string
+	Date              string
+	Title             string
+	AudioS3Prefix     string
+	AudioDir          string
+}
+
+func buildSessionInitYAML(in sessionInitInput) ([]byte, error) {
+	if strings.TrimSpace(in.TemplateFile) == "" {
+		return buildSessionYAML(in.Campaign, in.SessionID, in.PreviousSessionID, in.Date, in.Title, in.AudioS3Prefix, in.AudioDir)
+	}
+	templatePath := resolveSessionInitTemplatePath(in.CampaignPath, in.TemplateFile)
+	templateBytes, err := os.ReadFile(templatePath)
+	if err != nil {
+		return nil, fmt.Errorf("read session template %q: %w", templatePath, err)
+	}
+	rendered, err := renderSessionInitTemplate(string(templateBytes), in)
+	if err != nil {
+		return nil, fmt.Errorf("render session template %q: %w", templatePath, err)
+	}
+	return []byte(rendered), nil
+}
+
+func resolveSessionInitTemplatePath(campaignPath, templateFile string) string {
+	templateFile = strings.TrimSpace(templateFile)
+	if filepath.IsAbs(templateFile) {
+		return filepath.Clean(templateFile)
+	}
+	return filepath.Clean(filepath.Join(filepath.Dir(campaignPath), templateFile))
+}
+
+var sessionInitTemplatePattern = regexp.MustCompile(`\{\{\s*([a-zA-Z_][a-zA-Z0-9_]*)\s*\}\}`)
+
+func renderSessionInitTemplate(content string, in sessionInitInput) (string, error) {
+	values := map[string]string{
+		"session_id":          strings.TrimSpace(in.SessionID),
+		"previous_session_id": strings.TrimSpace(in.PreviousSessionID),
+		"date":                strings.TrimSpace(in.Date),
+		"title":               strings.TrimSpace(in.Title),
+		"audio_s3_prefix":     strings.TrimSpace(in.AudioS3Prefix),
+		"audio_dir":           strings.TrimSpace(in.AudioDir),
+	}
+	used := map[string]struct{}{}
+	unknown := map[string]struct{}{}
+	missing := map[string]struct{}{}
+	rendered := sessionInitTemplatePattern.ReplaceAllStringFunc(content, func(match string) string {
+		parts := sessionInitTemplatePattern.FindStringSubmatch(match)
+		if len(parts) < 2 {
+			return match
+		}
+		name := parts[1]
+		value, ok := values[name]
+		if !ok {
+			unknown[name] = struct{}{}
+			return match
+		}
+		used[name] = struct{}{}
+		if value == "" {
+			missing[name] = struct{}{}
+			return match
+		}
+		return value
+	})
+	if len(unknown) > 0 {
+		return "", fmt.Errorf("unsupported template variable(s): %s", sortedStringSet(unknown))
+	}
+	if len(missing) > 0 {
+		return "", fmt.Errorf("missing required template variable value(s): %s", sortedStringSet(missing))
+	}
+	unused := map[string]struct{}{}
+	for _, name := range []string{"previous_session_id", "date", "title", "audio_s3_prefix", "audio_dir"} {
+		if values[name] == "" {
+			continue
+		}
+		if _, ok := used[name]; !ok {
+			unused[name] = struct{}{}
+		}
+	}
+	if len(unused) > 0 {
+		return "", fmt.Errorf("unused template variable value(s): %s", sortedStringSet(unused))
+	}
+	return rendered, nil
+}
+
+func sortedStringSet(set map[string]struct{}) string {
+	items := make([]string, 0, len(set))
+	for item := range set {
+		items = append(items, item)
+	}
+	sort.Strings(items)
+	return strings.Join(items, ", ")
+}
+
 func renderFindings(out io.Writer, campaign, sessionID string, findings []finding) error {
 	if campaign != "" || sessionID != "" {
 		fmt.Fprintf(out, "Campaign: %s\n", campaign)