diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index bd07af1..1a11418 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,5 +1,37 @@
 # Hướng Dẫn Đóng Góp
 
+## Kỷ Luật Commit & Push (Bắt Buộc)
+
+> Để tránh conflict khi nhiều agent/engineer làm việc song song, toàn bộ team PHẢI tuân thủ các quy định sau. Nguồn: [GOO-91](/GOO/issues/GOO-91) (chỉ thị từ CEO qua [GOO-88](/GOO/issues/GOO-88)).
+
+1. **Commit ngay khi hoàn thành task** — mỗi task = một commit (hoặc một chuỗi commit nhỏ liên quan). Không gom nhiều task không liên quan vào một commit lớn.
+2. **Pull/rebase trước khi push** — luôn chạy `git pull --rebase origin <branch>` trước `git push` để giảm merge conflict.
+3. **Push ngay sau commit** — không giữ commit local quá 1 ngày làm việc. Commit không push = rủi ro mất việc + conflict tăng.
+4. **Conventional Commits** — bắt buộc (`feat:`, `fix:`, `chore:`, `refactor:`, `docs:`, `test:`, `style:`, `perf:`). Xem [Quy Ước Commit](#quy-ước-commit) bên dưới.
+5. **KHÔNG push trực tiếp lên `main` / `master`** — luôn dùng feature branch + Pull Request. Branch chính được bảo vệ bằng GitHub branch protection rules.
+6. **PR phải pass CI** (`lint` → `typecheck` → `test` → `build`) trước khi merge. PR đỏ CI không được merge dù đã approve.
+7. **Squash-merge khi merge PR** — giữ history trên `main` sạch, mỗi PR = một commit logic.
+8. **Xóa feature branch sau khi merge** — tránh branch sprawl. GitHub có auto-delete branch sau merge; bật nó trong repo settings.
+
+### Flow nhanh cho mỗi task
+
+```bash
+# 1. Tạo/chuyển sang feature branch (KHÔNG commit trực tiếp vào main)
+git checkout -b feature/goo-xx-short-description
+
+# 2. Làm việc, khi hoàn thành task:
+git add <files>
+git commit -m "feat(scope): mô tả ngắn"
+
+# 3. Đồng bộ & push
+git pull --rebase origin main   # hoặc develop
+git push -u origin feature/goo-xx-short-description
+
+# 4. Mở PR, chờ CI xanh + review, squash-merge, xóa branch
+```
+
+---
+
 ## Quy Trình Git & Branching
 
 ### Nhánh Chính
diff --git a/apps/web/components/inquiries/inquiry-detail-dialog.tsx b/apps/web/components/inquiries/inquiry-detail-dialog.tsx
index 835c66b..b93a8f2 100644
--- a/apps/web/components/inquiries/inquiry-detail-dialog.tsx
+++ b/apps/web/components/inquiries/inquiry-detail-dialog.tsx
@@ -13,6 +13,7 @@ import {
 } from '@/components/ui/dialog';
 import { useMarkInquiryRead } from '@/lib/hooks/use-inquiries';
 import type { InquiryReadDto } from '@/lib/inquiries-api';
+import { formatPhone, zaloHref } from '@/lib/phone';
 
 interface InquiryDetailDialogProps {
   inquiry: InquiryReadDto | null;
@@ -42,6 +43,8 @@ export function InquiryDetailDialog({ inquiry, open, onOpenChange }: InquiryDeta
     minute: '2-digit',
   });
 
+  const phone = inquiry.phone ?? inquiry.userPhone;
+
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
       <DialogContent className="max-w-md sm:max-w-lg">
@@ -60,7 +63,7 @@ export function InquiryDetailDialog({ inquiry, open, onOpenChange }: InquiryDeta
               <InquiryStatusBadge isRead={inquiry.isRead} />
             </div>
             <div className="space-y-1 text-sm text-muted-foreground">
-              <p>SĐT: {inquiry.phone ?? inquiry.userPhone}</p>
+              <p>SĐT: {formatPhone(phone)}</p>
               <p>Ngày gửi: {formattedDate}</p>
             </div>
           </div>
@@ -78,13 +81,13 @@ export function InquiryDetailDialog({ inquiry, open, onOpenChange }: InquiryDeta
             <h4 className="text-sm font-medium">Liên hệ nhanh</h4>
             <div className="flex flex-wrap gap-2">
               <a
-                href={`tel:${inquiry.phone ?? inquiry.userPhone}`}
+                href={`tel:${phone}`}
                 className="inline-flex items-center gap-1.5 rounded-md border px-3 py-1.5 text-sm transition-colors hover:bg-accent"
               >
                 <Phone className="h-4 w-4" aria-hidden="true" /> Gọi điện
               </a>
               <a
-                href={`https://zalo.me/${(inquiry.phone ?? inquiry.userPhone).replace(/^0/, '84')}`}
+                href={zaloHref(phone)}
                 target="_blank"
                 rel="noopener noreferrer"
                 className="inline-flex items-center gap-1.5 rounded-md border px-3 py-1.5 text-sm transition-colors hover:bg-accent"
diff --git a/apps/web/components/leads/lead-detail-dialog.tsx b/apps/web/components/leads/lead-detail-dialog.tsx
index e1ed859..c5153cc 100644
--- a/apps/web/components/leads/lead-detail-dialog.tsx
+++ b/apps/web/components/leads/lead-detail-dialog.tsx
@@ -15,6 +15,7 @@ import {
 import { Select } from '@/components/ui/select';
 import { useDeleteLead, useUpdateLeadStatus } from '@/lib/hooks/use-leads';
 import { LEAD_STATUSES, LEAD_SOURCES, type LeadReadDto, type LeadStatus } from '@/lib/leads-api';
+import { formatPhone, zaloHref } from '@/lib/phone';
 
 interface LeadDetailDialogProps {
   lead: LeadReadDto | null;
@@ -96,7 +97,7 @@ export function LeadDetailDialog({ lead, open, onOpenChange }: LeadDetailDialogP
               <LeadStatusBadge status={lead.status} />
             </div>
             <div className="space-y-1 text-sm text-muted-foreground">
-              <p>SĐT: {lead.phone}</p>
+              <p>SĐT: {formatPhone(lead.phone)}</p>
               {lead.email && <p>Email: {lead.email}</p>}
               <p>Nguồn: {getSourceLabel(lead.source)}</p>
               {lead.score !== null && <p>Điểm: {lead.score}/100</p>}
@@ -163,7 +164,7 @@ export function LeadDetailDialog({ lead, open, onOpenChange }: LeadDetailDialogP
                 </a>
               )}
               <a
-                href={`https://zalo.me/${lead.phone.replace(/^0/, '84')}`}
+                href={zaloHref(lead.phone)}
                 target="_blank"
                 rel="noopener noreferrer"
                 className="inline-flex items-center gap-1.5 rounded-md border px-3 py-1.5 text-sm transition-colors hover:bg-accent"
diff --git a/apps/web/lib/phone.ts b/apps/web/lib/phone.ts
new file mode 100644
index 0000000..8c0b417
--- /dev/null
+++ b/apps/web/lib/phone.ts
@@ -0,0 +1,59 @@
+/**
+ * Vietnamese phone number helpers.
+ *
+ * Regex covers the current VN numbering plan:
+ *   0[35789]x xxxxxxx — Viettel, Mobifone, Vinaphone, Gmobile, Indochina
+ *
+ * See: https://en.wikipedia.org/wiki/Telephone_numbers_in_Vietnam
+ */
+
+/** Matches a VN mobile number, with optional +84 or leading 0. */
+export const VN_PHONE_REGEX =
+  /^(0|\+84)(3[2-9]|5[2689]|7[06-9]|8[1-9]|9[0-9])\d{7}$/;
+
+/**
+ * Normalise a VN phone number to the E.164-ish form used by Zalo / APIs:
+ * strip leading 0 and prepend the country code (84).
+ *
+ * "0987654321" → "84987654321"
+ * "+84987654321" → "84987654321"
+ * "84987654321" → "84987654321"  (already normalised — idempotent)
+ */
+export function normalizePhone(phone: string): string {
+  const cleaned = phone.trim();
+  if (cleaned.startsWith('+84')) return `84${cleaned.slice(3)}`;
+  if (cleaned.startsWith('84')) return cleaned;
+  if (cleaned.startsWith('0')) return `84${cleaned.slice(1)}`;
+  return cleaned;
+}
+
+/**
+ * Format a raw VN phone number for display.
+ * Handles 10-digit numbers (0xx xxxx xxxx).
+ *
+ * "0987654321" → "0987 654 321"
+ * Passthrough for anything that doesn't match.
+ */
+export function formatPhone(phone: string): string {
+  const cleaned = phone.trim().replace(/\s+/g, '');
+
+  // 10-digit local format: 0xxx yyy zzz
+  const tenDigit = cleaned.match(/^(0\d{3})(\d{3})(\d{3})$/);
+  if (tenDigit) return `${tenDigit[1]} ${tenDigit[2]} ${tenDigit[3]}`;
+
+  // +84 prefix → treat as 10-digit local after swapping prefix
+  const e164 = cleaned.match(/^\+84(\d{9})$/);
+  if (e164) return formatPhone(`0${e164[1]}`);
+
+  return phone;
+}
+
+/**
+ * Returns the https://zalo.me deep-link URL for a given phone number.
+ *
+ * Zalo expects the number without a leading zero, prefixed with 84.
+ * "0987654321" → "https://zalo.me/84987654321"
+ */
+export function zaloHref(phone: string): string {
+  return `https://zalo.me/${normalizePhone(phone)}`;
+}
diff --git a/apps/web/lib/validations/auth.ts b/apps/web/lib/validations/auth.ts
index 4465211..5c420d3 100644
--- a/apps/web/lib/validations/auth.ts
+++ b/apps/web/lib/validations/auth.ts
@@ -1,6 +1,6 @@
 import { z } from 'zod';
 
-const phoneRegex = /^(0|\+84)(3[2-9]|5[2689]|7[06-9]|8[1-9]|9[0-9])\d{7}$/;
+import { VN_PHONE_REGEX as phoneRegex } from '@/lib/phone';
 
 export const loginSchema = z.object({
   phone: z
diff --git a/apps/web/lib/validations/inquiry.ts b/apps/web/lib/validations/inquiry.ts
index dddbca4..0b28963 100644
--- a/apps/web/lib/validations/inquiry.ts
+++ b/apps/web/lib/validations/inquiry.ts
@@ -1,12 +1,6 @@
 import { z } from 'zod';
 
-/**
- * Vietnamese phone number rule:
- * - 9–11 digits, optional leading +84 or 0.
- * We keep validation pragmatic: whitespace is stripped, then the remaining
- * string must be 9–11 digits (country code / leading zero stripped).
- */
-const PHONE_REGEX = /^(?:\+?84|0)?\d{9,11}$/;
+import { VN_PHONE_REGEX as PHONE_REGEX } from '@/lib/phone';
 
 export const inquiryFormSchema = z.object({
   message: z