diff --git a/backend/internal/library/llmjson/sanitize.go b/backend/internal/library/llmjson/sanitize.go
index 9ad9440..66b055d 100644
--- a/backend/internal/library/llmjson/sanitize.go
+++ b/backend/internal/library/llmjson/sanitize.go
@@ -24,17 +24,71 @@ func Unmarshal(payload []byte, v any) error {
 	return err
 }
 
-// Sanitize removes ellipsis placeholders and normalizes stray commas that sit
-// outside of string literals. It returns nil when nothing changed so callers
-// can avoid a redundant re-parse. String/URL contents are never altered.
+// Sanitize removes ellipsis placeholders, escapes unescaped control characters
+// inside JSON string literals, and normalizes stray commas that sit outside of
+// string literals. It returns nil when nothing changed so callers can avoid a
+// redundant re-parse. String meaning is preserved; only invalid JSON escapes
+// are added.
 func Sanitize(in []byte) []byte {
-	normalized := normalizeCommas(stripEllipsis(string(in)))
+	normalized := normalizeCommas(stripEllipsis(escapeControlCharsInStrings(string(in))))
 	if normalized == string(in) {
 		return nil
 	}
 	return []byte(normalized)
 }
 
+func escapeControlCharsInStrings(s string) string {
+	var b strings.Builder
+	b.Grow(len(s) + 16)
+	inString := false
+	escaped := false
+	for i := 0; i < len(s); i++ {
+		ch := s[i]
+		if inString {
+			if escaped {
+				escaped = false
+				b.WriteByte(ch)
+				continue
+			}
+			switch ch {
+			case '\\':
+				escaped = true
+				b.WriteByte(ch)
+			case '"':
+				inString = false
+				b.WriteByte(ch)
+			case '\n':
+				b.WriteString(`\n`)
+			case '\r':
+				b.WriteString(`\r`)
+			case '\t':
+				b.WriteString(`\t`)
+			default:
+				if ch < 0x20 {
+					b.WriteString(`\u00`)
+					b.WriteByte(hexDigit(ch >> 4))
+					b.WriteByte(hexDigit(ch & 0x0f))
+				} else {
+					b.WriteByte(ch)
+				}
+			}
+			continue
+		}
+		if ch == '"' {
+			inString = true
+		}
+		b.WriteByte(ch)
+	}
+	return b.String()
+}
+
+func hexDigit(v byte) byte {
+	if v < 10 {
+		return '0' + v
+	}
+	return 'a' + (v - 10)
+}
+
 func stripEllipsis(s string) string {
 	var b strings.Builder
 	b.Grow(len(s))
diff --git a/backend/internal/library/llmjson/sanitize_test.go b/backend/internal/library/llmjson/sanitize_test.go
index 9b2d566..567c111 100644
--- a/backend/internal/library/llmjson/sanitize_test.go
+++ b/backend/internal/library/llmjson/sanitize_test.go
@@ -35,6 +35,28 @@ func TestSanitizeReturnsNilWhenValid(t *testing.T) {
 	}
 }
 
+func TestSanitizeEscapesNewlinesInsideStrings(t *testing.T) {
+	raw := []byte(`{"examples":"第一行
+第二行","identity":"觀察者"}`)
+	cleaned := Sanitize(raw)
+	if cleaned == nil {
+		t.Fatal("expected sanitized output")
+	}
+	var out struct {
+		Examples string `json:"examples"`
+		Identity string `json:"identity"`
+	}
+	if err := Unmarshal(raw, &out); err != nil {
+		t.Fatalf("Unmarshal error: %v", err)
+	}
+	if out.Examples != "第一行\n第二行" {
+		t.Fatalf("examples = %q", out.Examples)
+	}
+	if out.Identity != "觀察者" {
+		t.Fatalf("identity = %q", out.Identity)
+	}
+}
+
 func TestSanitizeKeepsDotsInsideStrings(t *testing.T) {
 	raw := []byte(`{"note":"see ... and https://a.b/c", "list":[1, ...]}`)
 	cleaned := Sanitize(raw)
diff --git a/backend/internal/library/prompt/files/style8d.schema.md b/backend/internal/library/prompt/files/style8d.schema.md
index a38ab13..387e792 100644
--- a/backend/internal/library/prompt/files/style8d.schema.md
+++ b/backend/internal/library/prompt/files/style8d.schema.md
@@ -1,3 +1,2 @@
-
-只回傳以下 JSON 結構，不要 markdown：
+只回傳以下 JSON 結構，不要 markdown。所有字串值必須是單行 JSON string；需要換行時用 `\n`，禁止在引號內直接換行。
 {"d1Tone":{"summary":"","evidence":[]},"d2Structure":{"summary":"","evidence":[]},"d3Interaction":{"summary":"","evidence":[]},"d4Topics":{"summary":"","evidence":[]},"d5Rhythm":{"summary":"","evidence":[]},"d6Visual":{"summary":"","evidence":[]},"d7Conversion":{"summary":"","evidence":[]},"d8Risk":{"summary":"","evidence":[]},"personaDraft":{"identity":"","tone":"","audience":"","hooks":"","languageFingerprint":"","rhythm":"","punctuation":"","contentPatterns":"","knowledgeTranslation":"","ctaStyle":"","examples":"","avoid":""}}
diff --git a/backend/internal/library/prompt/files/style8d.system.md b/backend/internal/library/prompt/files/style8d.system.md
index 8ff14f9..e0ac2ae 100644
--- a/backend/internal/library/prompt/files/style8d.system.md
+++ b/backend/internal/library/prompt/files/style8d.system.md
@@ -17,5 +17,5 @@ personaDraft 必須產出可執行的寫作規則，不是抽象形容詞：
 - contentPatterns：不同內容型態的鬆結構，例如心情陪伴、知識整理、清單工具、互動文、幽默共鳴；不要變成固定模板。
 - knowledgeTranslation：如何把外部資料、醫療知識、產品知識轉成此人設會講的話；哪些資訊要先安撫、哪些要列點、哪些要加風險提醒。
 - ctaStyle：收藏、留言、分享、轉發給伴侶等 CTA 的自然用法；也要說明何時不該 CTA。
-- examples：抽象仿寫範例，可展示語氣與換行，但不可逐字複製原文。
+- examples：抽象仿寫範例，可展示語氣與換行，但不可逐字複製原文；JSON 內若要換行請用 `\n`，不可在字串值內直接斷行。
 - avoid：不像此人設的寫法、AI 味、過度模板、冒犯或高風險語句。
diff --git a/backend/internal/library/style8d/analyze.go b/backend/internal/library/style8d/analyze.go
index 9d75a6e..a15bc5e 100644
--- a/backend/internal/library/style8d/analyze.go
+++ b/backend/internal/library/style8d/analyze.go
@@ -8,6 +8,8 @@ import (
 	"regexp"
 	"strings"
 	"time"
+
+	"haixun-backend/internal/library/llmjson"
 )
 
 type Post struct {
@@ -290,13 +292,13 @@ func ParseLLMOutput(raw string) (LLMOutput, error) {
 		return LLMOutput{}, err
 	}
 	var root map[string]json.RawMessage
-	if err := json.Unmarshal(payload, &root); err != nil {
+	if err := llmjson.Unmarshal(payload, &root); err != nil {
 		return LLMOutput{}, fmt.Errorf("parse style8d json: %w", err)
 	}
 	for _, key := range []string{"analysis", "style8d", "style8D", "result", "data", "output"} {
 		if nested, ok := root[key]; ok {
 			var merged map[string]json.RawMessage
-			if err := json.Unmarshal(nested, &merged); err == nil {
+			if err := llmjson.Unmarshal(nested, &merged); err == nil {
 				for k, v := range merged {
 					if _, exists := root[k]; !exists {
 						root[k] = v
@@ -473,11 +475,11 @@ func parseDimension(root map[string]json.RawMessage, keys ...string) Dimension {
 
 func decodeDimension(raw json.RawMessage) Dimension {
 	var asString string
-	if err := json.Unmarshal(raw, &asString); err == nil && strings.TrimSpace(asString) != "" {
+	if err := llmjson.Unmarshal(raw, &asString); err == nil && strings.TrimSpace(asString) != "" {
 		return Dimension{Summary: strings.TrimSpace(asString)}
 	}
 	var obj map[string]json.RawMessage
-	if err := json.Unmarshal(raw, &obj); err != nil {
+	if err := llmjson.Unmarshal(raw, &obj); err != nil {
 		return Dimension{}
 	}
 	summary := firstString(obj, "summary", "description", "analysis", "conclusion")
@@ -492,11 +494,11 @@ func parsePersonaDraft(root map[string]json.RawMessage) PersonaDraft {
 			continue
 		}
 		var asString string
-		if err := json.Unmarshal(raw, &asString); err == nil && strings.TrimSpace(asString) != "" {
+		if err := llmjson.Unmarshal(raw, &asString); err == nil && strings.TrimSpace(asString) != "" {
 			return PersonaDraft{Identity: strings.TrimSpace(asString)}
 		}
 		var obj map[string]json.RawMessage
-		if err := json.Unmarshal(raw, &obj); err != nil {
+		if err := llmjson.Unmarshal(raw, &obj); err != nil {
 			continue
 		}
 		return PersonaDraft{
@@ -524,7 +526,7 @@ func firstString(obj map[string]json.RawMessage, keys ...string) string {
 			continue
 		}
 		var value string
-		if err := json.Unmarshal(raw, &value); err == nil {
+		if err := llmjson.Unmarshal(raw, &value); err == nil {
 			value = strings.TrimSpace(value)
 			if value != "" {
 				return value
@@ -541,7 +543,7 @@ func firstStringSlice(obj map[string]json.RawMessage, keys ...string) []string {
 			continue
 		}
 		var values []string
-		if err := json.Unmarshal(raw, &values); err == nil {
+		if err := llmjson.Unmarshal(raw, &values); err == nil {
 			out := make([]string, 0, len(values))
 			for _, item := range values {
 				item = strings.TrimSpace(item)
@@ -554,7 +556,7 @@ func firstStringSlice(obj map[string]json.RawMessage, keys ...string) []string {
 			}
 		}
 		var single string
-		if err := json.Unmarshal(raw, &single); err == nil {
+		if err := llmjson.Unmarshal(raw, &single); err == nil {
 			single = strings.TrimSpace(single)
 			if single != "" {
 				return []string{single}
diff --git a/backend/internal/library/style8d/analyze_test.go b/backend/internal/library/style8d/analyze_test.go
index d8ee8b0..978d605 100644
--- a/backend/internal/library/style8d/analyze_test.go
+++ b/backend/internal/library/style8d/analyze_test.go
@@ -5,6 +5,18 @@ import (
 	"testing"
 )
 
+func TestParseLLMOutputWithLiteralNewlinesInStrings(t *testing.T) {
+	raw := `{"d1Tone":{"summary":"口語親近","evidence":["真的太好笑"]},"d2Structure":{"summary":"短段落","evidence":[]},"d3Interaction":{"summary":"提問","evidence":[]},"d4Topics":{"summary":"生活","evidence":[]},"d5Rhythm":{"summary":"晚間","evidence":[]},"d6Visual":{"summary":"emoji","evidence":[]},"d7Conversion":{"summary":"留言","evidence":[]},"d8Risk":{"summary":"硬銷","evidence":[]},"personaDraft":{"identity":"生活觀察者","tone":"輕鬆","audience":"上班族","hooks":"痛點","languageFingerprint":"有時候","rhythm":"短段落","punctuation":"逗號","contentPatterns":"心情文","knowledgeTranslation":"先講情境","ctaStyle":"留言","examples":"有時候真的會累
+後來就習慣了","avoid":"硬銷"}}`
+	out, err := ParseLLMOutput(raw)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !strings.Contains(out.PersonaDraft.Examples, "後來就習慣了") {
+		t.Fatalf("examples=%q", out.PersonaDraft.Examples)
+	}
+}
+
 func TestParseLLMOutput(t *testing.T) {
 	raw := `{"d1Tone":{"summary":"口語親近","evidence":["真的太好笑"]},"d2Structure":{"summary":"短段落開場","evidence":[]},"d3Interaction":{"summary":"常用提問","evidence":[]},"d4Topics":{"summary":"生活與成長","evidence":[]},"d5Rhythm":{"summary":"晚間發文較多","evidence":[]},"d6Visual":{"summary":"愛用換行與 emoji","evidence":[]},"d7Conversion":{"summary":"自然導留言","evidence":[]},"d8Risk":{"summary":"避免照抄","evidence":[]},"personaDraft":{"identity":"生活觀察者","tone":"輕鬆","audience":"同齡上班族","hooks":"先丟痛點","languageFingerprint":"常用有時候、後來當轉折","rhythm":"短段落加空行","punctuation":"保留逗號與問號","contentPatterns":"心情文先承接情緒","knowledgeTranslation":"先講情境再整理重點","ctaStyle":"自然邀請留言","examples":"有時候真的會累","avoid":"不要硬銷"}}`
 	out, err := ParseLLMOutput(raw)
diff --git a/backend/web/vite.config.ts b/backend/web/vite.config.ts
index 773fa1e..f6ab990 100644
--- a/backend/web/vite.config.ts
+++ b/backend/web/vite.config.ts
@@ -6,8 +6,12 @@ export default defineConfig({
   server: {
     host: "0.0.0.0",
     port: 5173,
-    // 支援透過 https://threads-tool.30cm.net 存取開發伺服器（需反向代理轉發）
-    allowedHosts: ["threads-tool.30cm.net", "localhost"],
+    // 支援透過 nginx 網域存取開發伺服器（需反向代理轉發）
+    allowedHosts: [
+      "threads-tool.30cm.net",
+      "threads-tool-dev.30cm.net",
+      "localhost",
+    ],
     // 如果反向代理在 https 並轉發 HMR websocket，請視代理設定調整 hmr
     // hmr: {
     //   host: "threads-tool.30cm.net",
diff --git a/scripts/dev-all.sh b/scripts/dev-all.sh
index 553dcd4..bc4a970 100755
--- a/scripts/dev-all.sh
+++ b/scripts/dev-all.sh
@@ -145,6 +145,18 @@ raise SystemExit('no free Vite port found in 5173..5199')
 PY
 }
 
+resolve_web_port() {
+  local requested="${WEB_PORT:-}"
+  if [[ -n "$requested" && "$requested" -ge 1024 ]]; then
+    echo "$requested"
+    return
+  fi
+  if [[ -n "$requested" ]]; then
+    echo "[dev-all] WEB_PORT=$requested is for prod/nginx; using a free dev port instead" >&2
+  fi
+  pick_web_port
+}
+
 load_env
 
 cd "$BACKEND_DIR"
@@ -198,7 +210,7 @@ start "node-worker:style-8d" env \
   npm run style-8d
 
 cd "$WEB_DIR"
-WEB_PORT="${WEB_PORT:-$(pick_web_port)}"
+WEB_PORT="$(resolve_web_port)"
 start "web" npm run dev -- --host 0.0.0.0 --port "$WEB_PORT" --strictPort
 wait_for_http "web" "http://127.0.0.1:$WEB_PORT/"