清除业务契约双读：抽奖/草稿/时间戳/邮件只认新格式，并删除 legacy 短代码改写。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/markdown/hide.go

@@ -248,7 +248,7 @@ func MatchPasswordBlocks(content, password string) ([]int, error) {
 	return hit, nil
 }
 
-// WrapContentAsHide 将整篇正文包进单一隐藏块（旧帖迁移用）
+// WrapContentAsHide 将整篇正文包进单一隐藏块
 func WrapContentAsHide(kind string, points int, content string) string {
 	body := strings.TrimRight(content, "\n")
 	open := openMarkerLine(kind, points, "", false)
@@ -258,7 +258,7 @@ func WrapContentAsHide(kind string, points int, content string) string {
 	return open + "\n" + body + "\n[/hide]\n"
 }
 
-// HasHideBlocks 快速判断正文是否已含隐藏块（迁移幂等）
+// HasHideBlocks 判断正文是否已含隐藏块
 func HasHideBlocks(content string) bool {
 	blocks, err := ParseHideBlocks(content)
 	if err != nil {

backend/markdown/hide_test.go

@@ -177,20 +177,3 @@ func TestTimelineDoesNotBreakHideValidate(t *testing.T) {
 		t.Fatalf("timeline-only should pass: %v", err)
 	}
 }
-
-func TestRewriteLegacyDirectives(t *testing.T) {
-	src := "公开\n\n:::hide login\n秘\n:::\n\n:::timeline\n## 2026-01-01 A\n:::\n"
-	got := RewriteLegacyDirectives(src)
-	if strings.Contains(got, ":::") {
-		t.Fatalf("legacy remains: %q", got)
-	}
-	if !strings.Contains(got, "[hide login]") || !strings.Contains(got, "[/hide]") {
-		t.Fatalf("hide missing: %q", got)
-	}
-	if !strings.Contains(got, "[timeline]") || !strings.Contains(got, "[/timeline]") {
-		t.Fatalf("timeline missing: %q", got)
-	}
-	if err := ValidateHideContent(got); err != nil {
-		t.Fatal(err)
-	}
-}

backend/markdown/legacy_rewrite.go

@@ -1,158 +0,0 @@
-package markdown
-
-import (
-	"strconv"
-	"strings"
-)
-
-// RewriteLegacyDirectives 将旧式 :::hide / :::timeline / 裸 ::: 改写为行级 BBCode。
-// 幂等：已是 BBCode 的内容原样返回（若无旧标记）。代码围栏内不改写。
-func RewriteLegacyDirectives(content string) string {
-	if content == "" {
-		return content
-	}
-	if !strings.Contains(content, ":::") {
-		return content
-	}
-	lines := splitLines(content)
-	var out []string
-	inCode := false
-	i := 0
-	for i < len(lines) {
-		trimmed := strings.TrimSpace(lines[i])
-		if strings.HasPrefix(trimmed, "```") {
-			inCode = !inCode
-			out = append(out, lines[i])
-			i++
-			continue
-		}
-		if inCode {
-			out = append(out, lines[i])
-			i++
-			continue
-		}
-
-		if kind, pts, pwd, locked, ok := parseLegacyHideOpen(trimmed); ok {
-			bodyLines := make([]string, 0)
-			j := i + 1
-			innerCode := false
-			found := false
-			for j < len(lines) {
-				inner := strings.TrimSpace(lines[j])
-				if strings.HasPrefix(inner, "```") {
-					innerCode = !innerCode
-					bodyLines = append(bodyLines, lines[j])
-					j++
-					continue
-				}
-				if innerCode {
-					bodyLines = append(bodyLines, lines[j])
-					j++
-					continue
-				}
-				if inner == ":::" {
-					found = true
-					break
-				}
-				bodyLines = append(bodyLines, lines[j])
-				j++
-			}
-			out = append(out, openMarkerLine(kind, pts, pwd, locked))
-			out = append(out, bodyLines...)
-			if found {
-				out = append(out, "[/hide]")
-				i = j + 1
-			} else {
-				// 未闭合：仍写出已转换开标记与正文，避免丢内容
-				i = j
-			}
-			continue
-		}
-
-		if trimmed == ":::timeline" || strings.HasPrefix(trimmed, ":::timeline ") {
-			bodyLines := make([]string, 0)
-			j := i + 1
-			innerCode := false
-			found := false
-			for j < len(lines) {
-				inner := strings.TrimSpace(lines[j])
-				if strings.HasPrefix(inner, "```") {
-					innerCode = !innerCode
-					bodyLines = append(bodyLines, lines[j])
-					j++
-					continue
-				}
-				if innerCode {
-					bodyLines = append(bodyLines, lines[j])
-					j++
-					continue
-				}
-				if inner == ":::" {
-					found = true
-					break
-				}
-				bodyLines = append(bodyLines, lines[j])
-				j++
-			}
-			out = append(out, "[timeline]")
-			out = append(out, bodyLines...)
-			if found {
-				out = append(out, "[/timeline]")
-				i = j + 1
-			} else {
-				i = j
-			}
-			continue
-		}
-
-		out = append(out, lines[i])
-		i++
-	}
-	return strings.Join(out, "\n")
-}
-
-// parseLegacyHideOpen 解析旧式 :::hide <kind> [arg] [locked]
-func parseLegacyHideOpen(trimmed string) (kind string, points int, password string, locked bool, ok bool) {
-	if !strings.HasPrefix(trimmed, ":::hide") {
-		return "", 0, "", false, false
-	}
-	rest := strings.TrimSpace(trimmed[len(":::hide"):])
-	if rest == "" {
-		return "", 0, "", false, false
-	}
-	parts := strings.Fields(rest)
-	if len(parts) == 0 {
-		return "", 0, "", false, false
-	}
-	kind = parts[0]
-	switch kind {
-	case HideKindLogin, HideKindReply, HideKindPoints, HideKindPassword:
-	default:
-		return "", 0, "", false, false
-	}
-	idx := 1
-	if kind == HideKindPoints {
-		if idx >= len(parts) {
-			return "", 0, "", false, false
-		}
-		n, err := strconv.Atoi(parts[idx])
-		if err != nil {
-			return "", 0, "", false, false
-		}
-		points = n
-		idx++
-	} else if kind == HideKindPassword {
-		if idx < len(parts) && parts[idx] != "locked" {
-			password = parts[idx]
-			idx++
-		}
-	}
-	for ; idx < len(parts); idx++ {
-		if parts[idx] == "locked" {
-			locked = true
-		} else {
-			return "", 0, "", false, false
-		}
-	}
-	return kind, points, password, locked, true
-}