added acceptance criteria page

backend/src/db_models.py

@@ -62,6 +62,10 @@ class User(Base):
     created_links: Mapped[List["RequirementLink"]] = relationship("RequirementLink", back_populates="creator")
     comments: Mapped[List["RequirementComment"]] = relationship("RequirementComment", back_populates="user")
     comment_replies: Mapped[List["RequirementCommentReply"]] = relationship("RequirementCommentReply", back_populates="user")
+    acceptance_criteria_edits: Mapped[List["AcceptanceCriteria"]] = relationship(
+        "AcceptanceCriteria",
+        back_populates="last_editor"
+    )
 
 
 class Tag(Base):
@@ -261,6 +265,11 @@ class Requirement(Base):
         back_populates="requirement",
         cascade="all, delete-orphan"
     )
+    acceptance_criteria: Mapped[List["AcceptanceCriteria"]] = relationship(
+        "AcceptanceCriteria",
+        back_populates="requirement",
+        cascade="all, delete-orphan"
+    )
 
     # Indexes
     __table_args__ = (
@@ -293,6 +302,45 @@ class RequirementGroup(Base):
     )
 
 
+class AcceptanceCriteria(Base):
+    """Acceptance criteria for requirements."""
+    __tablename__ = "acceptance_criteria"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    requirement_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("requirements.id", ondelete="CASCADE"),
+        nullable=False
+    )
+    criteria_text: Mapped[str] = mapped_column(Text, nullable=False)
+    is_accepted: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=datetime.utcnow,
+        nullable=True
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=datetime.utcnow,
+        onupdate=datetime.utcnow,
+        nullable=True
+    )
+    last_editor_id: Mapped[Optional[int]] = mapped_column(
+        Integer,
+        ForeignKey("users.id"),
+        nullable=True
+    )
+
+    # Relationships
+    requirement: Mapped["Requirement"] = relationship("Requirement", back_populates="acceptance_criteria")
+    last_editor: Mapped[Optional["User"]] = relationship("User", back_populates="acceptance_criteria_edits")
+
+    # Indexes
+    __table_args__ = (
+        Index("idx_ac_requirement", "requirement_id"),
+    )
+
+
 class Validation(Base):
     """Validation records for requirements."""
     __tablename__ = "validations"
@@ -344,6 +392,28 @@ class RequirementHistory(Base):
     edited_by: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
 
 
+class AcceptanceCriteriaHistory(Base):
+    """
+    Historical records of acceptance criteria changes.
+    Note: This is populated by a database trigger on UPDATE/DELETE.
+    """
+    __tablename__ = "acceptance_criteria_history"
+
+    history_id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    original_ac_id: Mapped[int] = mapped_column(Integer, nullable=False)
+    requirement_id: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+    criteria_text: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    is_accepted: Mapped[Optional[bool]] = mapped_column(Boolean, nullable=True)
+    valid_from: Mapped[Optional[datetime]] = mapped_column(DateTime(timezone=True), nullable=True)
+    valid_to: Mapped[Optional[datetime]] = mapped_column(DateTime(timezone=True), nullable=True)
+    edited_by: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
+
+    # Indexes
+    __table_args__ = (
+        Index("idx_ach_req", "requirement_id"),
+    )
+
+
 class RelationshipType(Base):
     """
     Defines valid relationship types per project.

backend/src/main.py

@@ -18,6 +18,7 @@ from src.models import (
     RoleResponse, ProjectMemberResponse, UserRoleUpdateRequest, ROLE_DISPLAY_NAMES,
     CommentResponse, CommentReplyResponse, CommentCreateRequest, ReplyCreateRequest,
     RequirementStatusResponse, DeletedRequirementResponse,
+    AcceptanceCriteriaResponse, AcceptanceCriteriaCreateRequest, AcceptanceCriteriaUpdateRequest, AcceptanceCriteriaHistoryResponse,
     UserCreateRequest, UserCreateResponse,
     SystemUserResponse, SystemProjectResponse, SystemProjectMemberResponse,
     AssignUserToProjectRequest, SystemUserCreateRequest
@@ -29,7 +30,7 @@ from src.repositories import (
     RoleRepository, GroupRepository, TagRepository, RequirementRepository, 
     PriorityRepository, ProjectRepository, ValidationStatusRepository, ValidationRepository,
     RelationshipTypeRepository, RequirementLinkRepository, CommentRepository, ReplyRepository,
-    RequirementStatusRepository, UserRepository
+    RequirementStatusRepository, UserRepository, AcceptanceCriteriaRepository
 )
 from src.service import KeycloakAdminService
 import logging
@@ -1842,6 +1843,211 @@ async def get_requirement_current_groups(
     return [CurrentRequirementGroupResponse(**g) for g in groups]
 
 
+# ===========================================
+# Acceptance Criteria Endpoints
+# ===========================================
+
+def _build_acceptance_criteria_response(criteria) -> AcceptanceCriteriaResponse:
+    return AcceptanceCriteriaResponse(
+        id=criteria.id,
+        requirement_id=criteria.requirement_id,
+        criteria_text=criteria.criteria_text,
+        is_accepted=criteria.is_accepted,
+        created_at=criteria.created_at,
+        updated_at=criteria.updated_at,
+        last_editor_username=_get_display_name(criteria.last_editor) if getattr(criteria, "last_editor", None) else None
+    )
+
+
+@app.get("/api/requirements/{requirement_id}/acceptance-criteria", response_model=List[AcceptanceCriteriaResponse])
+async def get_acceptance_criteria(
+    requirement_id: int,
+    request: Request,
+    db: AsyncSession = Depends(get_db)
+):
+    """
+    Get all acceptance criteria for a requirement.
+    User must be a member of the requirement's project.
+    """
+    user = await _get_current_user_db(request, db)
+
+    req_repo = RequirementRepository(db)
+    requirement = await req_repo.get_by_id(requirement_id)
+    if not requirement:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Requirement with id {requirement_id} not found"
+        )
+
+    await _verify_project_membership(requirement.project_id, user.id, db)
+
+    criteria_repo = AcceptanceCriteriaRepository(db)
+    criteria = await criteria_repo.get_by_requirement_id(requirement_id)
+
+    return [_build_acceptance_criteria_response(c) for c in criteria]
+
+
+@app.post(
+    "/api/requirements/{requirement_id}/acceptance-criteria",
+    response_model=AcceptanceCriteriaResponse,
+    status_code=status.HTTP_201_CREATED
+)
+async def create_acceptance_criteria(
+    requirement_id: int,
+    request: Request,
+    criteria_data: AcceptanceCriteriaCreateRequest,
+    db: AsyncSession = Depends(get_db)
+):
+    """
+    Create a new acceptance criterion for a requirement.
+    Only editors and admins can create criteria.
+    """
+    user = await _get_current_user_db(request, db)
+    _require_role(user, [1, 3], "create acceptance criteria")
+
+    req_repo = RequirementRepository(db)
+    requirement = await req_repo.get_by_id(requirement_id)
+    if not requirement:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Requirement with id {requirement_id} not found"
+        )
+
+    await _verify_project_membership(requirement.project_id, user.id, db)
+
+    if not criteria_data.criteria_text.strip():
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Criteria text cannot be empty"
+        )
+
+    criteria_repo = AcceptanceCriteriaRepository(db)
+    criteria = await criteria_repo.create(
+        requirement_id=requirement_id,
+        criteria_text=criteria_data.criteria_text.strip(),
+        editor_id=user.id
+    )
+
+    await db.commit()
+    criteria = await criteria_repo.get_by_id(criteria.id)
+
+    return _build_acceptance_criteria_response(criteria)
+
+
+@app.put("/api/acceptance-criteria/{criteria_id}", response_model=AcceptanceCriteriaResponse)
+async def update_acceptance_criteria(
+    criteria_id: int,
+    request: Request,
+    criteria_data: AcceptanceCriteriaUpdateRequest,
+    db: AsyncSession = Depends(get_db)
+):
+    """
+    Update an acceptance criterion (text and/or accepted flag).
+    Only editors and admins can update criteria.
+    """
+    user = await _get_current_user_db(request, db)
+    _require_role(user, [1, 3], "update acceptance criteria")
+
+    criteria_repo = AcceptanceCriteriaRepository(db)
+    existing = await criteria_repo.get_by_id(criteria_id)
+    if not existing:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Acceptance criteria with id {criteria_id} not found"
+        )
+
+    req_repo = RequirementRepository(db)
+    requirement = await req_repo.get_by_id(existing.requirement_id)
+    await _verify_project_membership(requirement.project_id, user.id, db)
+
+    if criteria_data.criteria_text is None and criteria_data.is_accepted is None:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="No fields provided to update"
+        )
+
+    criteria_text = criteria_data.criteria_text
+    if criteria_text is not None:
+        criteria_text = criteria_text.strip()
+        if not criteria_text:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="Criteria text cannot be empty"
+            )
+
+    await criteria_repo.update(
+        criteria_id=criteria_id,
+        editor_id=user.id,
+        criteria_text=criteria_text,
+        is_accepted=criteria_data.is_accepted
+    )
+
+    await db.commit()
+    updated = await criteria_repo.get_by_id(criteria_id)
+
+    return _build_acceptance_criteria_response(updated)
+
+
+@app.delete("/api/acceptance-criteria/{criteria_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_acceptance_criteria(
+    criteria_id: int,
+    request: Request,
+    db: AsyncSession = Depends(get_db)
+):
+    """
+    Delete an acceptance criterion.
+    Only editors and admins can delete criteria.
+    """
+    user = await _get_current_user_db(request, db)
+    _require_role(user, [1, 3], "delete acceptance criteria")
+
+    criteria_repo = AcceptanceCriteriaRepository(db)
+    existing = await criteria_repo.get_by_id(criteria_id)
+    if not existing:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Acceptance criteria with id {criteria_id} not found"
+        )
+
+    req_repo = RequirementRepository(db)
+    requirement = await req_repo.get_by_id(existing.requirement_id)
+    await _verify_project_membership(requirement.project_id, user.id, db)
+
+    await criteria_repo.delete(criteria_id)
+    await db.commit()
+
+
+@app.get(
+    "/api/requirements/{requirement_id}/acceptance-criteria/history",
+    response_model=List[AcceptanceCriteriaHistoryResponse]
+)
+async def get_acceptance_criteria_history(
+    requirement_id: int,
+    request: Request,
+    db: AsyncSession = Depends(get_db)
+):
+    """
+    Get acceptance criteria history for a requirement.
+    Returns update/delete history with editor info.
+    """
+    user = await _get_current_user_db(request, db)
+
+    req_repo = RequirementRepository(db)
+    requirement = await req_repo.get_by_id(requirement_id)
+    if not requirement:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Requirement with id {requirement_id} not found"
+        )
+
+    await _verify_project_membership(requirement.project_id, user.id, db)
+
+    criteria_repo = AcceptanceCriteriaRepository(db)
+    history = await criteria_repo.get_history_by_requirement_id(requirement_id)
+
+    return [AcceptanceCriteriaHistoryResponse(**h) for h in history]
+
+
 # ===========================================
 # Comment Endpoints
 # ===========================================

backend/src/models.py

@@ -374,6 +374,47 @@ class RequirementLinkHistoryResponse(BaseModel):
         from_attributes = True
 
 
+# Acceptance Criteria schemas
+class AcceptanceCriteriaResponse(BaseModel):
+    """Response schema for acceptance criteria."""
+    id: int
+    requirement_id: int
+    criteria_text: str
+    is_accepted: bool
+    created_at: Optional[datetime] = None
+    updated_at: Optional[datetime] = None
+    last_editor_username: Optional[str] = None
+
+    class Config:
+        from_attributes = True
+
+
+class AcceptanceCriteriaCreateRequest(BaseModel):
+    """Request schema for creating acceptance criteria."""
+    criteria_text: str
+
+
+class AcceptanceCriteriaUpdateRequest(BaseModel):
+    """Request schema for updating acceptance criteria."""
+    criteria_text: Optional[str] = None
+    is_accepted: Optional[bool] = None
+
+
+class AcceptanceCriteriaHistoryResponse(BaseModel):
+    """Response schema for acceptance criteria history."""
+    history_id: int
+    original_ac_id: int
+    requirement_id: int
+    criteria_text: Optional[str] = None
+    is_accepted: Optional[bool] = None
+    valid_from: Optional[datetime] = None
+    valid_to: Optional[datetime] = None
+    edited_by_username: Optional[str] = None
+
+    class Config:
+        from_attributes = True
+
+
 # Requirement Search schemas
 class RequirementSearchResult(BaseModel):
     """Response schema for requirement search results (for autocomplete)."""

backend/src/repositories/__init__.py

@@ -13,6 +13,7 @@ from src.repositories.relationship_type_repository import RelationshipTypeReposi
 from src.repositories.requirement_link_repository import RequirementLinkRepository
 from src.repositories.comment_repository import CommentRepository, ReplyRepository
 from src.repositories.requirement_status_repository import RequirementStatusRepository
+from src.repositories.acceptance_criteria_repository import AcceptanceCriteriaRepository
 
 __all__ = [
     "UserRepository",
@@ -29,4 +30,5 @@ __all__ = [
     "CommentRepository",
     "ReplyRepository",
     "RequirementStatusRepository",
+    "AcceptanceCriteriaRepository",
 ]

backend/src/repositories/acceptance_criteria_repository.py

@@ -0,0 +1,117 @@
+"""
+Repository for Acceptance Criteria database operations.
+"""
+from typing import List, Optional, Dict, Any
+from sqlalchemy import select, text
+from sqlalchemy.orm import selectinload
+from sqlalchemy.ext.asyncio import AsyncSession
+from src.db_models import AcceptanceCriteria
+
+
+class AcceptanceCriteriaRepository:
+    """Repository for acceptance criteria CRUD and history operations."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def get_by_requirement_id(self, requirement_id: int) -> List[AcceptanceCriteria]:
+        result = await self.db.execute(
+            select(AcceptanceCriteria)
+            .options(selectinload(AcceptanceCriteria.last_editor))
+            .where(AcceptanceCriteria.requirement_id == requirement_id)
+            .order_by(AcceptanceCriteria.created_at.asc())
+        )
+        return list(result.scalars().all())
+
+    async def get_by_id(self, criteria_id: int) -> Optional[AcceptanceCriteria]:
+        result = await self.db.execute(
+            select(AcceptanceCriteria)
+            .options(selectinload(AcceptanceCriteria.last_editor))
+            .where(AcceptanceCriteria.id == criteria_id)
+        )
+        return result.scalar_one_or_none()
+
+    async def create(
+        self,
+        requirement_id: int,
+        criteria_text: str,
+        editor_id: int
+    ) -> AcceptanceCriteria:
+        criteria = AcceptanceCriteria(
+            requirement_id=requirement_id,
+            criteria_text=criteria_text,
+            is_accepted=False,
+            last_editor_id=editor_id
+        )
+        self.db.add(criteria)
+        await self.db.flush()
+        await self.db.refresh(criteria)
+        return criteria
+
+    async def update(
+        self,
+        criteria_id: int,
+        editor_id: int,
+        criteria_text: Optional[str] = None,
+        is_accepted: Optional[bool] = None
+    ) -> Optional[AcceptanceCriteria]:
+        criteria = await self.get_by_id(criteria_id)
+        if not criteria:
+            return None
+
+        if criteria_text is not None:
+            criteria.criteria_text = criteria_text
+        if is_accepted is not None:
+            criteria.is_accepted = is_accepted
+
+        criteria.last_editor_id = editor_id
+
+        await self.db.flush()
+        await self.db.refresh(criteria)
+        return criteria
+
+    async def delete(self, criteria_id: int) -> bool:
+        result = await self.db.execute(
+            select(AcceptanceCriteria).where(AcceptanceCriteria.id == criteria_id)
+        )
+        criteria = result.scalar_one_or_none()
+        if criteria:
+            await self.db.delete(criteria)
+            await self.db.flush()
+            return True
+        return False
+
+    async def get_history_by_requirement_id(self, requirement_id: int) -> List[Dict[str, Any]]:
+        query = text("""
+            SELECT
+                ach.history_id,
+                ach.original_ac_id,
+                ach.requirement_id,
+                ach.criteria_text,
+                ach.is_accepted,
+                ach.valid_from,
+                ach.valid_to,
+                u.full_name as edited_by_full_name,
+                u.username as edited_by_username
+            FROM acceptance_criteria_history ach
+            LEFT JOIN users u ON ach.edited_by = u.id
+            WHERE ach.requirement_id = :requirement_id
+            ORDER BY ach.valid_to DESC
+        """)
+
+        result = await self.db.execute(query, {"requirement_id": requirement_id})
+        rows = result.fetchall()
+
+        return [
+            {
+                "history_id": row.history_id,
+                "original_ac_id": row.original_ac_id,
+                "requirement_id": row.requirement_id,
+                "criteria_text": row.criteria_text,
+                "is_accepted": row.is_accepted,
+                "valid_from": row.valid_from,
+                "valid_to": row.valid_to,
+                "edited_by_username": row.edited_by_full_name or row.edited_by_username,
+            }
+            for row in rows
+        ]

frontend/src/i18n/locales/en/requirementDetail.json

@@ -55,7 +55,14 @@
   "acceptanceCriteria": {
     "title": "Acceptance Criteria",
     "noCriteria": "No acceptance criteria defined yet.",
-    "addButton": "Add Criterion"
+    "addButton": "Add Criterion",
+    "placeholder": "Describe a new criterion...",
+    "loading": "Loading acceptance criteria...",
+    "creating": "Creating...",
+    "editButton": "Edit",
+    "saveButton": "Save",
+    "cancelButton": "Cancel",
+    "deleteButton": "Delete"
   },
   "comments": {
     "title": "Shared Comments",
@@ -117,7 +124,14 @@
     "showLess": "Show less",
     "showFullDiff": "Show full diff",
     "deletedRequirement": "Deleted Requirement",
-    "unknownGroup": "Unknown Group"
+    "unknownGroup": "Unknown Group",
+    "criteriaAdded": "Criterion Added",
+    "criteriaUpdated": "Criterion Updated",
+    "criteriaDeleted": "Criterion Deleted",
+    "criteriaAccepted": "Accepted",
+    "criteriaNotAccepted": "Not accepted",
+    "criteriaUnknown": "Unknown",
+    "criteriaEmpty": "Empty"
   },
   "addRelationshipModal": {
     "title": "Add Relationship",
@@ -151,6 +165,8 @@
     "deleteRelationship": "Delete Relationship",
     "confirmDeleteComment": "Are you sure you want to delete this comment? This will also hide all replies.",
     "confirmDeleteReply": "Are you sure you want to delete this reply?",
-    "confirmDeleteRelationship": "Are you sure you want to delete this relationship? This action cannot be undone."
+    "confirmDeleteRelationship": "Are you sure you want to delete this relationship? This action cannot be undone.",
+    "deleteCriteria": "Delete Criterion",
+    "confirmDeleteCriteria": "Are you sure you want to delete this criterion? This action cannot be undone."
   }
 }

frontend/src/i18n/locales/pt/requirementDetail.json

@@ -55,7 +55,14 @@
   "acceptanceCriteria": {
     "title": "Critérios de Aceitação",
     "noCriteria": "Nenhum critério de aceitação definido ainda.",
-    "addButton": "Adicionar Critério"
+    "addButton": "Adicionar Critério",
+    "placeholder": "Descreva um novo critério...",
+    "loading": "Carregando critérios de aceitação...",
+    "creating": "Criando...",
+    "editButton": "Editar",
+    "saveButton": "Salvar",
+    "cancelButton": "Cancelar",
+    "deleteButton": "Excluir"
   },
   "comments": {
     "title": "Comentários Compartilhados",
@@ -117,7 +124,14 @@
     "showLess": "Mostrar menos",
     "showFullDiff": "Mostrar diferença completa",
     "deletedRequirement": "Requisito Excluído",
-    "unknownGroup": "Grupo Desconhecido"
+    "unknownGroup": "Grupo Desconhecido",
+    "criteriaAdded": "Critério Adicionado",
+    "criteriaUpdated": "Critério Atualizado",
+    "criteriaDeleted": "Critério Excluído",
+    "criteriaAccepted": "Aceito",
+    "criteriaNotAccepted": "Não aceito",
+    "criteriaUnknown": "Desconhecido",
+    "criteriaEmpty": "Vazio"
   },
   "addRelationshipModal": {
     "title": "Adicionar Relacionamento",
@@ -151,6 +165,8 @@
     "deleteRelationship": "Excluir Relacionamento",
     "confirmDeleteComment": "Tem certeza de que deseja excluir este comentário? Isso também ocultará todas as respostas.",
     "confirmDeleteReply": "Tem certeza de que deseja excluir esta resposta?",
-    "confirmDeleteRelationship": "Tem certeza de que deseja excluir este relacionamento? Esta ação não pode ser desfeita."
+    "confirmDeleteRelationship": "Tem certeza de que deseja excluir este relacionamento? Esta ação não pode ser desfeita.",
+    "deleteCriteria": "Excluir Critério",
+    "confirmDeleteCriteria": "Tem certeza de que deseja excluir este critério? Esta ação não pode ser desfeita."
   }
 }

frontend/src/pages/RequirementDetailPage.tsx

@@ -2,20 +2,20 @@ import { useState, useEffect } from 'react'
 import { useTranslation } from 'react-i18next'
 import { useAuth, useProject } from '@/hooks'
 import { useParams, Link, useNavigate } from 'react-router-dom'
-import { requirementService, validationService, relationshipService, commentService, tagService, priorityService, groupService, requirementStatusService } from '@/services'
+import { requirementService, validationService, relationshipService, commentService, tagService, priorityService, groupService, requirementStatusService, acceptanceCriteriaService } from '@/services'
 import { LanguageSelector } from '@/components'
 import type { Requirement } from '@/services/requirementService'
 import type { RelationshipType, RequirementLink, RequirementSearchResult } from '@/services/relationshipService'
 import type { Tag } from '@/services/tagService'
 import type { Priority } from '@/services/priorityService'
 import type { Group } from '@/services/groupService'
-import type { ValidationStatus, ValidationHistory, Comment, RequirementHistory, RequirementStatus } from '@/types'
+import type { ValidationStatus, ValidationHistory, Comment, RequirementHistory, RequirementStatus, AcceptanceCriteria, AcceptanceCriteriaHistory } from '@/types'
 
 // Tab types
 type TabType = 'description' | 'relationships' | 'acceptance-criteria' | 'shared-comments' | 'validate' | 'history'
 
 // Timeline event types for unified history view
-type TimelineEventType = 'requirement_edit' | 'link_created' | 'link_removed' | 'group_added' | 'group_removed'
+type TimelineEventType = 'requirement_edit' | 'link_created' | 'link_removed' | 'group_added' | 'group_removed' | 'criteria_added' | 'criteria_updated' | 'criteria_deleted'
 
 interface TimelineEvent {
   id: string
@@ -39,6 +39,15 @@ interface TimelineEvent {
     groupName: string | null
     groupHexColor: string | null
   }
+  // For acceptance criteria events
+  criteriaData?: {
+    criteriaId: number
+    oldText: string | null
+    newText: string | null
+    oldAccepted: boolean | null
+    newAccepted: boolean | null
+    editedByUsername: string | null
+  }
 }
 
 export default function RequirementDetailPage() {
@@ -87,10 +96,22 @@ export default function RequirementDetailPage() {
   const [deletingCommentId, setDeletingCommentId] = useState<number | null>(null)
   const [deletingReplyId, setDeletingReplyId] = useState<number | null>(null)
 
+  // Acceptance criteria state
+  const [acceptanceCriteria, setAcceptanceCriteria] = useState<AcceptanceCriteria[]>([])
+  const [criteriaLoading, setCriteriaLoading] = useState(false)
+  const [criteriaError, setCriteriaError] = useState<string | null>(null)
+  const [newCriteriaText, setNewCriteriaText] = useState('')
+  const [creatingCriteria, setCreatingCriteria] = useState(false)
+  const [editingCriteriaId, setEditingCriteriaId] = useState<number | null>(null)
+  const [editCriteriaText, setEditCriteriaText] = useState('')
+  const [updatingCriteriaId, setUpdatingCriteriaId] = useState<number | null>(null)
+  const [togglingCriteriaIds, setTogglingCriteriaIds] = useState<number[]>([])
+  const [deletingCriteriaId, setDeletingCriteriaId] = useState<number | null>(null)
+
   // Delete confirmation modal state
   const [showDeleteConfirmModal, setShowDeleteConfirmModal] = useState(false)
   const [deleteConfirmData, setDeleteConfirmData] = useState<{
-    type: 'comment' | 'reply' | 'link'
+    type: 'comment' | 'reply' | 'link' | 'criteria'
     id: number
     parentId?: number
     title: string
@@ -210,6 +231,27 @@ export default function RequirementDetailPage() {
     fetchCommentsData()
   }, [activeTab, id])
 
+  // Fetch acceptance criteria when tab is active
+  useEffect(() => {
+    const fetchCriteriaData = async () => {
+      if (activeTab !== 'acceptance-criteria' || !id) return
+
+      try {
+        setCriteriaLoading(true)
+        setCriteriaError(null)
+        const criteria = await acceptanceCriteriaService.getCriteria(parseInt(id, 10))
+        setAcceptanceCriteria(criteria)
+      } catch (err) {
+        console.error('Failed to fetch acceptance criteria:', err)
+        setCriteriaError('Failed to load acceptance criteria')
+      } finally {
+        setCriteriaLoading(false)
+      }
+    }
+
+    fetchCriteriaData()
+  }, [activeTab, id])
+
   // Fetch requirement history when history tab is active
   useEffect(() => {
     const fetchHistoryData = async () => {
@@ -219,13 +261,23 @@ export default function RequirementDetailPage() {
         setReqHistoryLoading(true)
         const reqId = parseInt(id, 10)
         
-        // Fetch all five data sources in parallel
+        // Fetch all data sources in parallel
-        const [history, linkHistoryData, currentLinksData, groupHistoryData, currentGroupsData] = await Promise.all([
+        const [
+          history,
+          linkHistoryData,
+          currentLinksData,
+          groupHistoryData,
+          currentGroupsData,
+          currentCriteriaData,
+          criteriaHistoryData
+        ] = await Promise.all([
           requirementService.getRequirementHistory(reqId),
           relationshipService.getLinkHistory(reqId),
           relationshipService.getRequirementLinks(reqId),
           groupService.getGroupHistory(reqId),
-          groupService.getCurrentGroups(reqId)
+          groupService.getCurrentGroups(reqId),
+          acceptanceCriteriaService.getCriteria(reqId),
+          acceptanceCriteriaService.getCriteriaHistory(reqId)
         ])
         
         // Build unified timeline
@@ -308,6 +360,75 @@ export default function RequirementDetailPage() {
             }
           })
         })
+
+        // Add current acceptance criteria as "criteria_added" events
+        currentCriteriaData.forEach((criteria) => {
+          events.push({
+            id: `criteria-current-${criteria.id}`,
+            type: 'criteria_added',
+            date: criteria.created_at || '',
+            criteriaData: {
+              criteriaId: criteria.id,
+              oldText: null,
+              newText: criteria.criteria_text,
+              oldAccepted: null,
+              newAccepted: criteria.is_accepted,
+              editedByUsername: criteria.last_editor_username
+            }
+          })
+        })
+
+        // Build acceptance criteria update/delete events from history
+        const criteriaGroups = new Map<number, AcceptanceCriteriaHistory[]>()
+        criteriaHistoryData.forEach((item) => {
+          const list = criteriaGroups.get(item.original_ac_id) || []
+          list.push(item)
+          criteriaGroups.set(item.original_ac_id, list)
+        })
+
+        const currentCriteriaMap = new Map<number, AcceptanceCriteria>()
+        currentCriteriaData.forEach((criteria) => {
+          currentCriteriaMap.set(criteria.id, criteria)
+        })
+
+        criteriaGroups.forEach((items, criteriaId) => {
+          const sorted = [...items].sort((a, b) => {
+            const dateA = a.valid_to ? new Date(a.valid_to).getTime() : 0
+            const dateB = b.valid_to ? new Date(b.valid_to).getTime() : 0
+            return dateB - dateA
+          })
+
+          const current = currentCriteriaMap.get(criteriaId)
+          let nextState = {
+            text: current ? current.criteria_text : null,
+            accepted: current ? current.is_accepted : null
+          }
+
+          sorted.forEach((item) => {
+            const oldState = {
+              text: item.criteria_text ?? null,
+              accepted: item.is_accepted ?? null
+            }
+
+            const isDeleted = nextState.text === null && nextState.accepted === null
+
+            events.push({
+              id: `criteria-hist-${item.history_id}`,
+              type: isDeleted ? 'criteria_deleted' : 'criteria_updated',
+              date: item.valid_to || '',
+              criteriaData: {
+                criteriaId,
+                oldText: oldState.text,
+                newText: nextState.text,
+                oldAccepted: oldState.accepted,
+                newAccepted: nextState.accepted,
+                editedByUsername: item.edited_by_username
+              }
+            })
+
+            nextState = oldState
+          })
+        })
         
         // Sort by date descending (newest first)
         events.sort((a, b) => {
@@ -585,6 +706,98 @@ export default function RequirementDetailPage() {
     }
   }
 
+  // Acceptance criteria handlers
+  const handleCreateCriteria = async () => {
+    if (!newCriteriaText.trim() || !id) return
+
+    try {
+      setCreatingCriteria(true)
+      const created = await acceptanceCriteriaService.createCriteria(parseInt(id, 10), {
+        criteria_text: newCriteriaText.trim()
+      })
+      setAcceptanceCriteria(prev => [...prev, created])
+      setNewCriteriaText('')
+    } catch (err) {
+      console.error('Failed to create acceptance criteria:', err)
+      setCriteriaError('Failed to create acceptance criteria')
+    } finally {
+      setCreatingCriteria(false)
+    }
+  }
+
+  const startEditCriteria = (criteria: AcceptanceCriteria) => {
+    setEditingCriteriaId(criteria.id)
+    setEditCriteriaText(criteria.criteria_text)
+  }
+
+  const cancelEditCriteria = () => {
+    setEditingCriteriaId(null)
+    setEditCriteriaText('')
+  }
+
+  const handleSaveCriteria = async (criteriaId: number) => {
+    if (!editCriteriaText.trim()) return
+
+    try {
+      setUpdatingCriteriaId(criteriaId)
+      const updated = await acceptanceCriteriaService.updateCriteria(criteriaId, {
+        criteria_text: editCriteriaText.trim()
+      })
+      setAcceptanceCriteria(prev => prev.map(c => (c.id === criteriaId ? updated : c)))
+      setEditingCriteriaId(null)
+      setEditCriteriaText('')
+    } catch (err) {
+      console.error('Failed to update acceptance criteria:', err)
+      setCriteriaError('Failed to update acceptance criteria')
+    } finally {
+      setUpdatingCriteriaId(null)
+    }
+  }
+
+  const handleToggleCriteria = async (criteria: AcceptanceCriteria) => {
+    if (!canManageCriteria) return
+
+    const nextValue = !criteria.is_accepted
+    const previousValue = criteria.is_accepted
+
+    setTogglingCriteriaIds(prev => [...prev, criteria.id])
+    setAcceptanceCriteria(prev => prev.map(c => (c.id === criteria.id ? { ...c, is_accepted: nextValue } : c)))
+
+    try {
+      const updated = await acceptanceCriteriaService.updateCriteria(criteria.id, {
+        is_accepted: nextValue
+      })
+      setAcceptanceCriteria(prev => prev.map(c => (c.id === criteria.id ? updated : c)))
+    } catch (err) {
+      console.error('Failed to toggle acceptance criteria:', err)
+      setAcceptanceCriteria(prev => prev.map(c => (c.id === criteria.id ? { ...c, is_accepted: previousValue } : c)))
+    } finally {
+      setTogglingCriteriaIds(prev => prev.filter(id => id !== criteria.id))
+    }
+  }
+
+  const openDeleteCriteriaModal = (criteriaId: number) => {
+    setDeleteConfirmData({
+      type: 'criteria',
+      id: criteriaId,
+      title: t('deleteModal.deleteCriteria'),
+      message: t('deleteModal.confirmDeleteCriteria')
+    })
+    setShowDeleteConfirmModal(true)
+  }
+
+  const executeDeleteCriteria = async (criteriaId: number) => {
+    try {
+      setDeletingCriteriaId(criteriaId)
+      await acceptanceCriteriaService.deleteCriteria(criteriaId)
+      setAcceptanceCriteria(prev => prev.filter(c => c.id !== criteriaId))
+    } catch (err) {
+      console.error('Failed to delete acceptance criteria:', err)
+    } finally {
+      setDeletingCriteriaId(null)
+    }
+  }
+
   // Handle delete confirmation
   const handleConfirmDelete = async () => {
     if (!deleteConfirmData) return
@@ -603,6 +816,9 @@ export default function RequirementDetailPage() {
             await executeDeleteReply(deleteConfirmData.id, deleteConfirmData.parentId)
           }
           break
+        case 'criteria':
+          await executeDeleteCriteria(deleteConfirmData.id)
+          break
       }
     } finally {
       setDeleteConfirmLoading(false)
@@ -719,6 +935,7 @@ export default function RequirementDetailPage() {
   // Check if requirement is in draft status
   const isDraftStatus = requirement?.status?.status_code === 'DRAFT'
   const isAdmin = user?.role_id === 3
+  const canManageCriteria = user?.role_id === 1 || user?.role_id === 3
 
   if (loading) {
     return (
@@ -961,12 +1178,110 @@ export default function RequirementDetailPage() {
         return (
           <div>
             <h3 className="text-xl font-bold text-gray-800 mb-4">{t('acceptanceCriteria.title')}</h3>
-            <p className="text-gray-500">{t('acceptanceCriteria.noCriteria')}</p>
+            {criteriaLoading ? (
-            {!isAuditor && (
+              <div className="text-center py-8">
-              <div className="mt-4">
+                <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-teal-600 mx-auto"></div>
-                <button className="px-4 py-1.5 border border-gray-400 rounded text-sm text-gray-700 hover:bg-gray-50">
+                <p className="mt-2 text-gray-500 text-sm">{t('acceptanceCriteria.loading')}</p>
-                  {t('acceptanceCriteria.addButton')}
+              </div>
-                </button>
+            ) : criteriaError ? (
+              <p className="text-red-500 text-sm">{criteriaError}</p>
+            ) : acceptanceCriteria.length === 0 ? (
+              <p className="text-gray-500">{t('acceptanceCriteria.noCriteria')}</p>
+            ) : (
+              <div className="space-y-3">
+                {acceptanceCriteria.map((criteria) => {
+                  const isEditing = editingCriteriaId === criteria.id
+                  const isToggling = togglingCriteriaIds.includes(criteria.id)
+                  const isUpdating = updatingCriteriaId === criteria.id
+                  const isDeleting = deletingCriteriaId === criteria.id
+
+                  return (
+                    <div key={criteria.id} className="flex items-start gap-3 p-3 border border-gray-200 rounded">
+                      <input
+                        type="checkbox"
+                        checked={criteria.is_accepted}
+                        onChange={() => handleToggleCriteria(criteria)}
+                        disabled={!canManageCriteria || isToggling}
+                        className="mt-1 h-4 w-4 text-teal-600 border-gray-300 rounded"
+                      />
+                      <div className="flex-1">
+                        {isEditing ? (
+                          <input
+                            type="text"
+                            value={editCriteriaText}
+                            onChange={(e) => setEditCriteriaText(e.target.value)}
+                            className="w-full px-3 py-2 border border-gray-300 rounded text-sm focus:outline-none focus:ring-2 focus:ring-teal-500"
+                          />
+                        ) : (
+                          <p className={`text-sm ${criteria.is_accepted ? 'line-through text-gray-500' : 'text-gray-800'}`}>
+                            {criteria.criteria_text}
+                          </p>
+                        )}
+                      </div>
+
+                      {canManageCriteria && (
+                        <div className="flex items-center gap-2">
+                          {isEditing ? (
+                            <>
+                              <button
+                                onClick={() => handleSaveCriteria(criteria.id)}
+                                disabled={isUpdating || !editCriteriaText.trim()}
+                                className="text-sm text-teal-600 hover:text-teal-700 disabled:opacity-50"
+                              >
+                                {t('acceptanceCriteria.saveButton')}
+                              </button>
+                              <button
+                                onClick={cancelEditCriteria}
+                                disabled={isUpdating}
+                                className="text-sm text-gray-500 hover:text-gray-700 disabled:opacity-50"
+                              >
+                                {t('acceptanceCriteria.cancelButton')}
+                              </button>
+                            </>
+                          ) : (
+                            <>
+                              <button
+                                onClick={() => startEditCriteria(criteria)}
+                                disabled={isDeleting}
+                                className="text-sm text-gray-500 hover:text-gray-700 disabled:opacity-50"
+                              >
+                                {t('acceptanceCriteria.editButton')}
+                              </button>
+                              <button
+                                onClick={() => openDeleteCriteriaModal(criteria.id)}
+                                disabled={isDeleting}
+                                className="text-sm text-red-600 hover:text-red-700 disabled:opacity-50"
+                              >
+                                {t('acceptanceCriteria.deleteButton')}
+                              </button>
+                            </>
+                          )}
+                        </div>
+                      )}
+                    </div>
+                  )
+                })}
+              </div>
+            )}
+
+            {canManageCriteria && (
+              <div className="mt-6 border-t border-gray-200 pt-4">
+                <div className="flex items-center gap-3">
+                  <input
+                    type="text"
+                    value={newCriteriaText}
+                    onChange={(e) => setNewCriteriaText(e.target.value)}
+                    placeholder={t('acceptanceCriteria.placeholder')}
+                    className="flex-1 px-3 py-2 border border-gray-300 rounded text-sm focus:outline-none focus:ring-2 focus:ring-teal-500"
+                  />
+                  <button
+                    onClick={handleCreateCriteria}
+                    disabled={creatingCriteria || !newCriteriaText.trim()}
+                    className="px-4 py-2 bg-teal-600 text-white rounded text-sm font-medium hover:bg-teal-700 disabled:opacity-50"
+                  >
+                    {creatingCriteria ? t('acceptanceCriteria.creating') : t('acceptanceCriteria.addButton')}
+                  </button>
+                </div>
               </div>
             )}
           </div>
@@ -1648,6 +1963,70 @@ export default function RequirementDetailPage() {
                       </div>
                     )
                   }
+
+                  if ((event.type === 'criteria_added' || event.type === 'criteria_updated' || event.type === 'criteria_deleted') && event.criteriaData) {
+                    const criteria = event.criteriaData
+                    const isDeleted = event.type === 'criteria_deleted'
+                    const isAdded = event.type === 'criteria_added'
+
+                    const acceptanceLabel = (value: boolean | null) => {
+                      if (value === null) return t('history.criteriaUnknown')
+                      return value ? t('history.criteriaAccepted') : t('history.criteriaNotAccepted')
+                    }
+
+                    return (
+                      <div key={event.id} className="border border-gray-200 rounded overflow-hidden">
+                        <div className={`flex items-center justify-between px-4 py-3 border-l-4 ${
+                          isAdded
+                            ? 'bg-green-50 border-green-400'
+                            : isDeleted
+                              ? 'bg-red-50 border-red-400'
+                              : 'bg-blue-50 border-blue-400'
+                        }`}>
+                          <div className="flex items-center gap-3">
+                            <span className="text-lg">✅</span>
+                            <span className="font-medium text-gray-800">
+                              {isAdded
+                                ? t('history.criteriaAdded')
+                                : isDeleted
+                                  ? t('history.criteriaDeleted')
+                                  : t('history.criteriaUpdated')}
+                            </span>
+                            <span className="text-sm text-gray-600">
+                              {isAdded ? (
+                                <>
+                                  <span className="font-medium">{criteria.newText || t('history.criteriaEmpty')}</span>
+                                  <span className="ml-2 text-xs text-gray-500">({acceptanceLabel(criteria.newAccepted)})</span>
+                                </>
+                              ) : isDeleted ? (
+                                <>
+                                  <span className="line-through">{criteria.oldText || t('history.criteriaEmpty')}</span>
+                                  <span className="ml-2 text-xs text-gray-500">({acceptanceLabel(criteria.oldAccepted)})</span>
+                                </>
+                              ) : (
+                                <>
+                                  <span className="line-through">{criteria.oldText || t('history.criteriaEmpty')}</span>
+                                  <span className="mx-2">→</span>
+                                  <span className="font-medium">{criteria.newText || t('history.criteriaEmpty')}</span>
+                                  <span className="ml-2 text-xs text-gray-500">
+                                    ({acceptanceLabel(criteria.oldAccepted)} → {acceptanceLabel(criteria.newAccepted)})
+                                  </span>
+                                </>
+                              )}
+                            </span>
+                          </div>
+                          <div className="flex items-center gap-4 text-sm text-gray-500">
+                            {criteria.editedByUsername && (
+                              <span>by {criteria.editedByUsername}</span>
+                            )}
+                            <span>
+                              {event.date ? new Date(event.date).toLocaleString() : ''}
+                            </span>
+                          </div>
+                        </div>
+                      </div>
+                    )
+                  }
                   
                   return null
                 })}

frontend/src/services/acceptanceCriteriaService.ts

@@ -0,0 +1,101 @@
+import type {
+  AcceptanceCriteria,
+  AcceptanceCriteriaCreateRequest,
+  AcceptanceCriteriaUpdateRequest,
+  AcceptanceCriteriaHistory
+} from '@/types'
+
+const API_BASE_URL = '/api'
+
+class AcceptanceCriteriaService {
+  async getCriteria(requirementId: number): Promise<AcceptanceCriteria[]> {
+    const response = await fetch(`${API_BASE_URL}/requirements/${requirementId}/acceptance-criteria`, {
+      method: 'GET',
+      credentials: 'include',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+
+    if (!response.ok) {
+      throw new Error(`HTTP error! status: ${response.status}`)
+    }
+
+    return await response.json()
+  }
+
+  async createCriteria(
+    requirementId: number,
+    data: AcceptanceCriteriaCreateRequest
+  ): Promise<AcceptanceCriteria> {
+    const response = await fetch(`${API_BASE_URL}/requirements/${requirementId}/acceptance-criteria`, {
+      method: 'POST',
+      credentials: 'include',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify(data),
+    })
+
+    if (!response.ok) {
+      const errorData = await response.json().catch(() => ({}))
+      throw new Error(errorData.detail || `HTTP error! status: ${response.status}`)
+    }
+
+    return await response.json()
+  }
+
+  async updateCriteria(
+    criteriaId: number,
+    data: AcceptanceCriteriaUpdateRequest
+  ): Promise<AcceptanceCriteria> {
+    const response = await fetch(`${API_BASE_URL}/acceptance-criteria/${criteriaId}`, {
+      method: 'PUT',
+      credentials: 'include',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify(data),
+    })
+
+    if (!response.ok) {
+      const errorData = await response.json().catch(() => ({}))
+      throw new Error(errorData.detail || `HTTP error! status: ${response.status}`)
+    }
+
+    return await response.json()
+  }
+
+  async deleteCriteria(criteriaId: number): Promise<void> {
+    const response = await fetch(`${API_BASE_URL}/acceptance-criteria/${criteriaId}`, {
+      method: 'DELETE',
+      credentials: 'include',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+
+    if (!response.ok) {
+      const errorData = await response.json().catch(() => ({}))
+      throw new Error(errorData.detail || `HTTP error! status: ${response.status}`)
+    }
+  }
+
+  async getCriteriaHistory(requirementId: number): Promise<AcceptanceCriteriaHistory[]> {
+    const response = await fetch(`${API_BASE_URL}/requirements/${requirementId}/acceptance-criteria/history`, {
+      method: 'GET',
+      credentials: 'include',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+
+    if (!response.ok) {
+      throw new Error(`HTTP error! status: ${response.status}`)
+    }
+
+    return await response.json()
+  }
+}
+
+export const acceptanceCriteriaService = new AcceptanceCriteriaService()

frontend/src/services/index.ts

@@ -23,6 +23,7 @@ export type {
 export { userService } from './userService'
 export type { Role, ProjectMember, UserRoleUpdateRequest } from './userService'
 export { commentService } from './commentService'
+export { acceptanceCriteriaService } from './acceptanceCriteriaService'
 export { superAdminService } from './superAdminService'
 export type { 
   SystemUser, 

frontend/src/types/index.ts

@@ -90,6 +90,37 @@ export interface RequirementLinkHistory {
   valid_to: string | null    // When link was deleted
 }
 
+// Acceptance Criteria types
+export interface AcceptanceCriteria {
+  id: number
+  requirement_id: number
+  criteria_text: string
+  is_accepted: boolean
+  created_at: string | null
+  updated_at: string | null
+  last_editor_username: string | null
+}
+
+export interface AcceptanceCriteriaCreateRequest {
+  criteria_text: string
+}
+
+export interface AcceptanceCriteriaUpdateRequest {
+  criteria_text?: string
+  is_accepted?: boolean
+}
+
+export interface AcceptanceCriteriaHistory {
+  history_id: number
+  original_ac_id: number
+  requirement_id: number
+  criteria_text: string | null
+  is_accepted: boolean | null
+  valid_from: string | null
+  valid_to: string | null
+  edited_by_username: string | null
+}
+
 // Requirement Group History types
 export interface RequirementGroupHistory {
   history_id: number