Support configurable deck page limit

configs/config.example.yaml

@@ -13,6 +13,8 @@ deck:
   # deck.theme 是 fixed 模式的主题，也是 weekly 当天未配置时的兜底主题。
   # 可选值：default / warm-paper / editorial-cool / tech-noir / plum-ink / sage-mist / fresh-green
   theme: default
+  # 单次 deck 允许的最大页数，范围 3-18；默认 12。
+  max_pages: 12
   weekly_themes:
     mon: default
     tue: warm-paper

internal/ai/deck_builder.go

@@ -9,11 +9,13 @@ import (
 	"strings"
 )
 
-const deckPromptConstraints = `你是一个严格的 JSON 生成器。
-请把输入的 Markdown 内容转换成 3-12 页动态小红书预览 deck JSON。
+const defaultMaxPages = 12
+
+const deckPromptConstraintsTemplate = `你是一个严格的 JSON 生成器。
+请把输入的 Markdown 内容转换成 3-%d 页动态小红书预览 deck JSON。
 要求：
 1. 只能输出 JSON，不要输出解释、代码块或额外文本
-2. pages 数量必须在 3 到 12 页之间（3-12 页）
+2. pages 数量必须在 3 到 %d 页之间（3-%d 页）
 3. 第一页必须是 cover
 4. 最后一页必须是 ending
 5. 每页结构必须包含：name、variant、meta、content
@@ -58,12 +60,20 @@ type Builder struct {
 	Command     string
 	Args        []string
 	PromptExtra string
+	MaxPages    int
 	Runner      CommandRunner
 }
 
 func buildDeckPrompt(markdown, promptExtra string) string {
+	return buildDeckPromptWithMaxPages(markdown, promptExtra, defaultMaxPages)
+}
+
+func buildDeckPromptWithMaxPages(markdown, promptExtra string, maxPages int) string {
+	if maxPages == 0 {
+		maxPages = defaultMaxPages
+	}
 	var sb strings.Builder
-	sb.WriteString(deckPromptConstraints)
+	sb.WriteString(fmt.Sprintf(deckPromptConstraintsTemplate, maxPages, maxPages, maxPages))
 	if extra := strings.TrimSpace(promptExtra); extra != "" {
 		sb.WriteString("\n\n")
 		sb.WriteString(promptExtraIntro)
@@ -107,7 +117,7 @@ func (b Builder) BuildDeckJSON(markdown string) (string, error) {
 	if shouldUseBareOutput(b.Command, b.Args) && !containsArg(args, "--bare") {
 		args = append(args, "--bare")
 	}
-	args = append(args, "-p", buildDeckPrompt(markdown, b.PromptExtra))
+	args = append(args, "-p", buildDeckPromptWithMaxPages(markdown, b.PromptExtra, b.MaxPages))
 	stdout, stderr, err := b.effectiveRunner().Run(b.Command, args...)
 	if err != nil {
 		return "", fmt.Errorf("%w: %v\nstderr: %s", ErrAICommandFailed, err, stderr)

internal/ai/deck_builder_test.go

@@ -61,6 +61,21 @@ func TestBuildDeckPromptIgnoresWhitespaceOnlyPromptExtra(t *testing.T) {
 	}
 }
 
+func TestBuildDeckJSONUsesConfiguredMaxPages(t *testing.T) {
+	runner := &fakeRunner{stdout: `{"pages":[]}`}
+	b := Builder{Runner: runner, MaxPages: 18}
+	b.SetCommand("ccs", []string{"codex"})
+
+	_, err := b.BuildDeckJSON("# title")
+	if err != nil {
+		t.Fatalf("BuildDeckJSON() error = %v", err)
+	}
+	prompt := runner.args[len(runner.args)-1]
+	if !strings.Contains(prompt, "3-18 页") || !strings.Contains(prompt, "3 到 18 页之间") {
+		t.Fatalf("prompt = %q, want configured max page range", prompt)
+	}
+}
+
 func TestBuildDeckJSONUsesConfiguredCommand(t *testing.T) {
 	runner := &fakeRunner{stdout: `{"pages":[]}`}
 	b := Builder{Runner: runner}

internal/app/service.go

@@ -146,7 +146,7 @@ func (s Service) GeneratePreview(opts Options) (Result, error) {
 		return Result{}, fmt.Errorf("%w: %w", ErrBuildDeckJSON, err)
 	}
 
-	d, err := deck.FromJSON(rawJSON, opts.OutDir)
+	d, err := deck.FromJSONWithMaxPages(rawJSON, opts.OutDir, cfg.Deck.MaxPages)
 	if err != nil {
 		return Result{}, fmt.Errorf("%w: %v", ErrParseDeck, err)
 	}
@@ -177,7 +177,7 @@ func (s Service) GenerateFromDeck(opts Options) (Result, error) {
 	if err != nil {
 		return Result{}, fmt.Errorf("%w: %v", ErrReadDeck, err)
 	}
-	d, err := deck.FromJSON(string(deckBytes), opts.OutDir)
+	d, err := deck.FromJSONWithMaxPages(string(deckBytes), opts.OutDir, cfg.Deck.MaxPages)
 	if err != nil {
 		return Result{}, fmt.Errorf("%w: %v", ErrParseDeck, err)
 	}
@@ -362,7 +362,7 @@ func (s Service) renderDeck(opts Options, cfg *config.Config, d deck.Deck, sourc
 	}
 	configTheme := resolveConfigDeckTheme(cfg.Deck, s.effectiveNow()())
 	d.ThemeName = resolveThemeWithPrecedence(opts.Theme, metaTheme, configTheme, d.ThemeName)
-	if err := d.Validate(); err != nil {
+	if err := d.ValidateWithMaxPages(cfg.Deck.MaxPages); err != nil {
 		return Result{}, fmt.Errorf("%w: %v", ErrParseDeck, err)
 	}
 	d.ViewportWidth = opts.ViewportWidth
@@ -446,7 +446,7 @@ func (s Service) effectiveBuildDeckJSON() func(*config.Config, string) (string,
 		return s.BuildDeckJSON
 	}
 	return func(cfg *config.Config, markdown string) (string, error) {
-		b := ai.Builder{PromptExtra: s.PromptExtra, Runner: s.AICommandRunner}
+		b := ai.Builder{PromptExtra: s.PromptExtra, MaxPages: cfg.Deck.MaxPages, Runner: s.AICommandRunner}
 		b.SetCommand(cfg.AI.Command, cfg.AI.Args)
 		return b.BuildDeckJSON(markdown)
 	}

internal/app/service_test.go

@@ -46,6 +46,16 @@ func (r *fakeRenderer) Render(d deck.Deck) (render.RenderResult, error) {
 	return r.result, r.err
 }
 
+func deckJSONWithPageCount(count int) string {
+	pages := make([]string, 0, count)
+	pages = append(pages, fmt.Sprintf(`{"name":"p01-cover","variant":"cover","meta":{"badge":"第 1 页","counter":"1/%d","theme":"default","cta":"cta"},"content":{"title":"封面"}}`, count))
+	for i := 2; i < count; i++ {
+		pages = append(pages, fmt.Sprintf(`{"name":"p%02d-bullets","variant":"bullets","meta":{"badge":"第 %d 页","counter":"%d/%d","theme":"default","cta":"cta"},"content":{"title":"列表页 %d","items":["要点"]}}`, i, i, i, count, i))
+	}
+	pages = append(pages, fmt.Sprintf(`{"name":"p%02d-ending","variant":"ending","meta":{"badge":"第 %d 页","counter":"%d/%d","theme":"default","cta":"cta"},"content":{"title":"结尾","body":"正文"}}`, count, count, count, count))
+	return `{"pages":[` + strings.Join(pages, ",") + `]}`
+}
+
 func TestServiceGeneratePreviewPassesPromptExtraToAIBuilder(t *testing.T) {
 	cfg := &config.Config{Output: config.OutputCfg{Dir: t.TempDir()}, AI: config.AICfg{Command: "ccs", Args: []string{"codex"}}}
 	runner := &fakeAICommandRunner{stdout: `{"pages":[{"name":"p1-cover","variant":"cover","meta":{"badge":"第 1 页","counter":"1/3","theme":"orange","cta":"cta1"},"content":{"title":"封面"}},{"name":"p2-bullets","variant":"bullets","meta":{"badge":"第 2 页","counter":"2/3","theme":"orange","cta":"cta2"},"content":{"title":"中间","items":["要点"]}},{"name":"p3-ending","variant":"ending","meta":{"badge":"第 3 页","counter":"3/3","theme":"green","cta":"cta3"},"content":{"title":"结尾","body":"正文"}}]}`}
@@ -73,6 +83,50 @@ func TestServiceGeneratePreviewPassesPromptExtraToAIBuilder(t *testing.T) {
 	}
 }
 
+func TestServiceGeneratePreviewPassesMaxPagesToAIBuilder(t *testing.T) {
+	cfg := &config.Config{Output: config.OutputCfg{Dir: t.TempDir()}, AI: config.AICfg{Command: "ccs", Args: []string{"codex"}}, Deck: config.DeckCfg{MaxPages: 18}}
+	runner := &fakeAICommandRunner{stdout: `{"pages":[{"name":"p1-cover","variant":"cover","meta":{"badge":"第 1 页","counter":"1/3","theme":"orange","cta":"cta1"},"content":{"title":"封面"}},{"name":"p2-bullets","variant":"bullets","meta":{"badge":"第 2 页","counter":"2/3","theme":"orange","cta":"cta2"},"content":{"title":"中间","items":["要点"]}},{"name":"p3-ending","variant":"ending","meta":{"badge":"第 3 页","counter":"3/3","theme":"green","cta":"cta3"},"content":{"title":"结尾","body":"正文"}}]}`}
+	_svcRenderer := &fakeRenderer{}
+	svc := Service{
+		LoadConfig:      func(string) (*config.Config, error) { return cfg, nil },
+		ReadFile:        func(string) ([]byte, error) { return []byte("# 标题"), nil },
+		AICommandRunner: runner,
+		NewRenderer:     func(Options) DeckRenderer { return _svcRenderer },
+	}
+
+	_, err := svc.GeneratePreview(Options{InputPath: "article.md", ConfigPath: "config.yaml", Jobs: 2})
+	if err != nil {
+		t.Fatalf("GeneratePreview() error = %v", err)
+	}
+	prompt := runner.args[len(runner.args)-1]
+	if !strings.Contains(prompt, "3-18 页") {
+		t.Fatalf("prompt = %q, want configured max pages", prompt)
+	}
+}
+
+func TestServiceGeneratePreviewAcceptsConfiguredMaxPages(t *testing.T) {
+	cfg := &config.Config{
+		Output: config.OutputCfg{Dir: t.TempDir()},
+		AI:     config.AICfg{Command: "ccs", Args: []string{"codex"}},
+		Deck:   config.DeckCfg{MaxPages: 18},
+	}
+	r := &fakeRenderer{}
+	svc := Service{
+		LoadConfig:    func(string) (*config.Config, error) { return cfg, nil },
+		ReadFile:      func(string) ([]byte, error) { return []byte("# 标题"), nil },
+		BuildDeckJSON: func(*config.Config, string) (string, error) { return deckJSONWithPageCount(18), nil },
+		NewRenderer:   func(Options) DeckRenderer { return r },
+	}
+
+	_, err := svc.GeneratePreview(Options{InputPath: "article.md", ConfigPath: "config.yaml", Jobs: 2})
+	if err != nil {
+		t.Fatalf("GeneratePreview() error = %v", err)
+	}
+	if len(r.rendered.Pages) != 18 {
+		t.Fatalf("renderer received %d pages, want 18", len(r.rendered.Pages))
+	}
+}
+
 func TestServiceGeneratePreviewSuccess(t *testing.T) {
 	cfg := &config.Config{
 		Output: config.OutputCfg{Dir: t.TempDir()},
@@ -365,6 +419,36 @@ func TestServiceGenerateFromDeckReadsDeckAndSkipsMarkdownBuilder(t *testing.T) {
 	}
 }
 
+func TestServiceGenerateFromDeckAcceptsConfiguredMaxPages(t *testing.T) {
+	deckDir := t.TempDir()
+	deckPath := filepath.Join(deckDir, "deck.json")
+	deckJSON := deckJSONWithPageCount(18)
+	cfg := &config.Config{Output: config.OutputCfg{Dir: t.TempDir()}, Deck: config.DeckCfg{MaxPages: 18}}
+	r := &fakeRenderer{}
+	svc := Service{
+		LoadConfig: func(string) (*config.Config, error) { return cfg, nil },
+		ReadFile: func(path string) ([]byte, error) {
+			if path == deckPath {
+				return []byte(deckJSON), nil
+			}
+			return nil, os.ErrNotExist
+		},
+		BuildDeckJSON: func(*config.Config, string) (string, error) {
+			t.Fatalf("BuildDeckJSON should not be called in from-deck mode")
+			return "", nil
+		},
+		NewRenderer: func(Options) DeckRenderer { return r },
+	}
+
+	_, err := svc.GenerateFromDeck(Options{FromDeckPath: deckPath, ConfigPath: "config.yaml", Jobs: 2})
+	if err != nil {
+		t.Fatalf("GenerateFromDeck() error = %v", err)
+	}
+	if len(r.rendered.Pages) != 18 {
+		t.Fatalf("renderer received %d pages, want 18", len(r.rendered.Pages))
+	}
+}
+
 func TestServiceGenerateFromDeckUsesRenderMetaBeforeConfigDefaults(t *testing.T) {
 	deckDir := t.TempDir()
 	deckPath := filepath.Join(deckDir, "deck.json")

internal/config/config.go

@@ -37,6 +37,7 @@ type DeckCfg struct {
 	ThemeMode    string            `yaml:"theme_mode"`
 	WeeklyThemes map[string]string `yaml:"weekly_themes"`
 	Author       string            `yaml:"author"`
+	MaxPages     int               `yaml:"max_pages"`
 	Watermark    WatermarkCfg      `yaml:"watermark"`
 }
 
@@ -271,6 +272,12 @@ func Load(configPath string) (*Config, error) {
 	if cfg.Deck.WeeklyThemes == nil {
 		cfg.Deck.WeeklyThemes = cloneStringMap(defaultDeckWeeklyThemes)
 	}
+	if cfg.Deck.MaxPages == 0 {
+		cfg.Deck.MaxPages = 12
+	}
+	if cfg.Deck.MaxPages < 3 || cfg.Deck.MaxPages > 18 {
+		return nil, fmt.Errorf("validate deck.max_pages: must be between 3 and 18")
+	}
 	for day, theme := range cfg.Deck.WeeklyThemes {
 		if !validDeckWeekday(day) {
 			return nil, fmt.Errorf("validate deck.weekly_themes.%s: unsupported weekday", day)

internal/config/config_test.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -48,6 +49,45 @@ func TestLoadAppliesDefaultDeckConfig(t *testing.T) {
 	if cfg.Deck.Author != "" {
 		t.Fatalf("Deck.Author = %q, want empty", cfg.Deck.Author)
 	}
+	if cfg.Deck.MaxPages != 12 {
+		t.Fatalf("Deck.MaxPages = %d, want 12", cfg.Deck.MaxPages)
+	}
+}
+
+func TestLoadKeepsExplicitDeckMaxPages(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.yaml")
+	content := "deck:\n  max_pages: 18\n"
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("WriteFile() error = %v", err)
+	}
+
+	cfg, err := Load(path)
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	if cfg.Deck.MaxPages != 18 {
+		t.Fatalf("Deck.MaxPages = %d, want 18", cfg.Deck.MaxPages)
+	}
+}
+
+func TestLoadRejectsInvalidDeckMaxPages(t *testing.T) {
+	for _, maxPages := range []int{2, 19} {
+		dir := t.TempDir()
+		path := filepath.Join(dir, "config.yaml")
+		content := fmt.Sprintf("deck:\n  max_pages: %d\n", maxPages)
+		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+			t.Fatalf("WriteFile() error = %v", err)
+		}
+
+		_, err := Load(path)
+		if err == nil {
+			t.Fatalf("Load() error = nil for max_pages %d, want non-nil", maxPages)
+		}
+		if !strings.Contains(err.Error(), "deck.max_pages") {
+			t.Fatalf("error = %v, want deck.max_pages", err)
+		}
+	}
 }
 
 func TestLoadKeepsExplicitDeckThemeAndAuthor(t *testing.T) {

internal/deck/deck.go

@@ -358,6 +358,10 @@ func DefaultDeck(outDir string) Deck {
 }
 
 func FromJSON(raw string, outDir string) (Deck, error) {
+	return FromJSONWithMaxPages(raw, outDir, maxPages)
+}
+
+func FromJSONWithMaxPages(raw string, outDir string, configuredMaxPages int) (Deck, error) {
 	var rd rawDeck
 	if err := json.Unmarshal([]byte(raw), &rd); err != nil {
 		return Deck{}, fmt.Errorf("parse deck json: %w", err)
@@ -385,16 +389,23 @@ func FromJSON(raw string, outDir string) (Deck, error) {
 		Pages:          pages,
 		Themes:         defaultThemes(),
 	}
-	if err := d.Validate(); err != nil {
+	if err := d.ValidateWithMaxPages(configuredMaxPages); err != nil {
 		return Deck{}, err
 	}
 	d.Pages = normalizePageNames(d.Pages)
 	return d, nil
 }
 
 func (d Deck) Validate() error {
-	if len(d.Pages) < minPages || len(d.Pages) > maxPages {
-		return fmt.Errorf("deck must contain 3 to 12 pages")
+	return d.ValidateWithMaxPages(maxPages)
+}
+
+func (d Deck) ValidateWithMaxPages(configuredMaxPages int) error {
+	if configuredMaxPages == 0 {
+		configuredMaxPages = maxPages
+	}
+	if len(d.Pages) < minPages || len(d.Pages) > configuredMaxPages {
+		return fmt.Errorf("deck must contain %d to %d pages", minPages, configuredMaxPages)
 	}
 	if d.Pages[0].Variant != "cover" {
 		return fmt.Errorf("first page must use cover variant")