fix: resolve share branch conflicts

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -1,84 +1,65 @@
-name: 🐛 Bug Report
-description: Report a bug or unexpected behavior
-labels: ["bug", "needs-triage"]
-assignees: []
-
+name: "\U0001f41b Bug Report"
+description: "Create a report to help us improve the project by fixing a bug."
+title: "[BUG] "
+labels: ["bug"]
+assignees:
+  - "param20h"
 body:
   - type: markdown
     attributes:
       value: |
-        Thanks for taking the time to file a bug report! Please fill this out as completely as possible.
+        Thanks for taking the time to fill out this bug report! 
+        Before you submit, please search the issue tracker to see if this has already been reported.
 
   - type: textarea
     id: description
     attributes:
-      label: Describe the Bug
-      description: A clear description of what the bug is.
-      placeholder: "When I do X, Y happens instead of Z."
+      label: "Description of the Bug"
+      description: "A clear and concise description of what the bug is."
+      placeholder: "When I click on X, nothing happens..."
     validations:
       required: true
 
   - type: textarea
     id: reproduction
     attributes:
-      label: Steps to Reproduce
-      description: How do we reproduce this bug?
-      placeholder: |
+      label: "Steps to Reproduce"
+      description: "How can we reproduce this issue?"
+      value: |
         1. Go to '...'
-        2. Click on '...'
-        3. See error
+        2. Click on '....'
+        3. Scroll down to '....'
+        4. See error
     validations:
       required: true
 
   - type: textarea
     id: expected
     attributes:
-      label: Expected Behavior
-      description: What should have happened?
+      label: "Expected Behavior"
+      description: "A clear and concise description of what you expected to happen."
     validations:
       required: true
 
   - type: textarea
     id: screenshots
     attributes:
-      label: Screenshots / Logs
-      description: Paste any relevant error output or screenshots here.
+      label: "Screenshots / Logs"
+      description: "If applicable, add screenshots or error logs to help explain your problem."
 
-  - type: dropdown
-    id: area
+  - type: input
+    id: environment
     attributes:
-      label: Area Affected
-      multiple: true
-      options:
-        - Backend (FastAPI)
-        - Frontend (Next.js)
-        - RAG / Embeddings
-        - Authentication
-        - File Upload
-        - Chat / Streaming
-        - Docker / Deployment
-        - Documentation
+      label: "Environment"
+      description: "What OS, browser, or environment were you using?"
+      placeholder: "e.g., macOS Sequoia, Chrome 120, Node.js v20"
     validations:
       required: true
 
-  - type: input
-    id: python-version
-    attributes:
-      label: Python Version (if backend issue)
-      placeholder: "e.g. 3.11"
-
-  - type: input
-    id: node-version
-    attributes:
-      label: Node.js Version (if frontend issue)
-      placeholder: "e.g. 20.x"
-
   - type: checkboxes
-    id: checklist
+    id: gssoc
     attributes:
-      label: Checklist
+      label: "GSSoC '24"
+      description: "Are you a GSSoC contributor?"
       options:
-        - label: I have searched existing issues and this is not a duplicate.
-          required: true
-        - label: I am targeting the `dev` branch, not `main`.
-          required: true
+        - label: "Yes, I am participating in GirlScript Summer of Code and would like to fix this."

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -1,69 +1,48 @@
-name: ✨ Feature Request
-description: Suggest a new feature or enhancement
-labels: ["enhancement", "needs-triage"]
-assignees: []
-
+name: "\U0001f680 Feature Request"
+description: "Suggest an idea for this project."
+title: "[FEAT] "
+labels: ["enhancement"]
+assignees:
+  - "param20h"
 body:
   - type: markdown
     attributes:
       value: |
-        Got an idea? Great! Please describe it clearly so we can discuss and prioritize it.
+        Thanks for taking the time to suggest a new feature! 
+        Please provide as much context as possible so we can properly evaluate your idea.
 
   - type: textarea
     id: problem
     attributes:
-      label: Problem / Motivation
-      description: What problem does this solve? What's the current limitation?
-      placeholder: "I find it frustrating when..."
+      label: "Is your feature request related to a problem? Please describe."
+      description: "A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]"
     validations:
       required: true
 
   - type: textarea
     id: solution
     attributes:
-      label: Proposed Solution
-      description: What do you want to happen?
+      label: "Describe the solution you'd like"
+      description: "A clear and concise description of what you want to happen."
     validations:
       required: true
 
   - type: textarea
     id: alternatives
     attributes:
-      label: Alternatives Considered
-      description: Any other approaches you considered?
-
-  - type: dropdown
-    id: area
-    attributes:
-      label: Which area does this affect?
-      multiple: true
-      options:
-        - Backend (FastAPI)
-        - Frontend (Next.js)
-        - RAG / Embeddings
-        - Authentication
-        - File Upload
-        - Chat / Streaming
-        - Docker / Deployment
-        - Documentation
-        - New Area
-    validations:
-      required: true
+      label: "Describe alternatives you've considered"
+      description: "A clear and concise description of any alternative solutions or features you've considered."
 
-  - type: dropdown
-    id: difficulty
+  - type: textarea
+    id: additional_context
     attributes:
-      label: Estimated Difficulty
-      options:
-        - "🟢 Easy (good first issue)"
-        - "🟡 Medium"
-        - "🔴 Hard / Needs discussion"
+      label: "Additional Context"
+      description: "Add any other context, screenshots, or mockups about the feature request here."
 
   - type: checkboxes
-    id: checklist
+    id: gssoc
     attributes:
-      label: Checklist
+      label: "GSSoC '24"
+      description: "Are you a GSSoC contributor?"
       options:
-        - label: I have searched existing issues and this is not a duplicate.
-          required: true
-        - label: I am willing to work on this myself (optional but appreciated!).
+        - label: "Yes, I am participating in GirlScript Summer of Code and would like to build this."

.github/workflows/ci.yml

@@ -48,16 +48,18 @@ jobs:
         env:
           SECRET_KEY: ci-dummy-secret
           DATABASE_URL: sqlite:///./ci_test.db
+          DEBUG: "false"
           HF_TOKEN: ci-dummy-token
           UPLOAD_DIR: /tmp/uploads
           CHROMA_PERSIST_DIR: /tmp/chroma
         run: |
-          python -c "import sys; sys.path.insert(0, 'backend'); from app.config import settings; print('✅ Config imports OK')" || true
+          python -c "import sys; sys.path.insert(0, 'backend'); from app.config import get_settings; get_settings(); print('Config imports OK')"
 
       - name: Run backend pytest suite
         env:
           SECRET_KEY: ci-dummy-secret
           DATABASE_URL: sqlite:///./ci_test.db
+          DEBUG: "false"
           HF_TOKEN: ci-dummy-token
           UPLOAD_DIR: /tmp/uploads
           CHROMA_PERSIST_DIR: /tmp/chroma

backend/app/main.py

@@ -92,11 +92,13 @@ from app.routes.auth import router as auth_router
 from app.routes.documents import router as documents_router
 from app.routes.chat import router as chat_router
 from app.routes.github import router as github_router
+from app.routes.admin import router as admin_router
 
 app.include_router(auth_router, prefix="/api/v1")
 app.include_router(documents_router, prefix="/api/v1")
 app.include_router(chat_router, prefix="/api/v1")
 app.include_router(github_router, prefix="/api/v1")
+app.include_router(admin_router, prefix="/api/v1")
 
 
 # ── Health Check ─────────────────────────────────────

backend/app/metrics.py

@@ -0,0 +1,33 @@
+"""
+Runtime metrics helpers for lightweight operational statistics.
+"""
+from threading import Lock
+
+
+_metrics_lock = Lock()
+_query_count = 0
+_query_response_time_total_ms = 0.0
+
+
+def record_query_response_time(duration_seconds: float) -> None:
+    """Record one completed query response duration."""
+    global _query_count, _query_response_time_total_ms
+
+    duration_ms = max(duration_seconds, 0) * 1000
+    with _metrics_lock:
+        _query_count += 1
+        _query_response_time_total_ms += duration_ms
+
+
+def get_query_metrics() -> dict[str, float | int]:
+    """Return aggregate query metrics for the current process lifetime."""
+    with _metrics_lock:
+        average_ms = (
+            _query_response_time_total_ms / _query_count
+            if _query_count
+            else 0.0
+        )
+        return {
+            "query_count": _query_count,
+            "average_query_response_time_ms": round(average_ms, 2),
+        }

backend/app/rag/vectorstore.py

@@ -4,11 +4,7 @@ Per-user collections for data isolation.
 """
 import logging
 from typing import List, Dict, Any, Optional
-import chromadb
-from chromadb.config import Settings as ChromaSettings
 from app.config import get_settings
-from app.rag.embeddings import get_embedding_model
-from app.rag.vision import generate_captions_for_chunks
 
 logger = logging.getLogger(__name__)
 settings = get_settings()
@@ -17,12 +13,15 @@ settings = get_settings()
 _chroma_client = None
 
 
-def get_chroma_client() -> chromadb.ClientAPI:
+def get_chroma_client():
     """Get or create persistent ChromaDB client."""
     global _chroma_client
 
     if _chroma_client is None:
         import os
+        import chromadb
+        from chromadb.config import Settings as ChromaSettings
+
         os.makedirs(settings.CHROMA_PERSIST_DIR, exist_ok=True)
 
         _chroma_client = chromadb.PersistentClient(
@@ -58,11 +57,15 @@ def store_chunks(
 
     # Generate captions for any extracted images before embedding
     try:
+        from app.rag.vision import generate_captions_for_chunks
+
         generate_captions_for_chunks(chunks)
     except Exception as e:
         logger.warning(f"Could not generate image captions: {e}")
 
     client = get_chroma_client()
+    from app.rag.embeddings import get_embedding_model
+
     embedding_model = get_embedding_model()
 
     collection_name = get_collection_name(user_id)

backend/app/routes/admin.py

@@ -0,0 +1,73 @@
+"""
+Admin-only operational statistics routes.
+"""
+import shutil
+from pathlib import Path
+
+from fastapi import APIRouter, Depends
+from sqlalchemy import func
+from sqlalchemy.orm import Session
+
+from app.auth import get_admin_user
+from app.config import get_settings
+from app.database import get_db
+from app.metrics import get_query_metrics
+from app.models import Document, User
+from app.schemas import AdminStatsResponse, DiskUsageResponse
+
+router = APIRouter(prefix="/admin", tags=["Admin"])
+settings = get_settings()
+
+
+def _directory_size(path: Path) -> int:
+    if not path.exists():
+        return 0
+
+    total = 0
+    for item in path.rglob("*"):
+        if item.is_file():
+            try:
+                total += item.stat().st_size
+            except OSError:
+                continue
+    return total
+
+
+@router.get("/stats", response_model=AdminStatsResponse)
+def get_admin_stats(
+    _admin: User = Depends(get_admin_user),
+    db: Session = Depends(get_db),
+):
+    """Return aggregate system statistics for administrators."""
+    upload_dir = Path(settings.UPLOAD_DIR).resolve()
+    upload_dir.mkdir(parents=True, exist_ok=True)
+
+    disk_usage = shutil.disk_usage(upload_dir)
+    used_percent = (
+        round((disk_usage.used / disk_usage.total) * 100, 2)
+        if disk_usage.total
+        else 0.0
+    )
+    query_metrics = get_query_metrics()
+
+    total_pdfs_uploaded = (
+        db.query(Document)
+        .filter(func.lower(Document.original_name).like("%.pdf"))
+        .count()
+    )
+
+    return AdminStatsResponse(
+        total_users=db.query(User).count(),
+        total_pdfs_uploaded=total_pdfs_uploaded,
+        average_query_response_time_ms=float(
+            query_metrics["average_query_response_time_ms"]
+        ),
+        query_count=int(query_metrics["query_count"]),
+        disk_space_usage=DiskUsageResponse(
+            total_bytes=disk_usage.total,
+            used_bytes=disk_usage.used,
+            free_bytes=disk_usage.free,
+            usage_percent=used_percent,
+            upload_dir_bytes=_directory_size(upload_dir),
+        ),
+    )

backend/app/routes/chat.py

@@ -3,6 +3,7 @@ Chat routes — ask questions with RAG, stream responses via SSE, manage history
 """
 import html
 import json
+import time
 from datetime import datetime
 from io import BytesIO
 import logging
@@ -16,8 +17,11 @@ from reportlab.lib.units import inch
 from reportlab.platypus import Paragraph, SimpleDocTemplate, Spacer
 from sqlalchemy.orm import Session
 
+from app.auth import get_current_user
 from app.database import get_db
+from app.metrics import record_query_response_time
 from app.models import User, ChatMessage, Document, SharedMessage
+from app.rate_limit import limiter
 from app.schemas import (
     ChatRequest,
     ChatResponse,
@@ -27,9 +31,6 @@ from app.schemas import (
     ShareLinkResponse,
     SourceChunk,
 )
-from app.auth import get_current_user
-from app.rag.agent import generate_answer, generate_answer_stream
-from app.rate_limit import limiter
 
 logger = logging.getLogger(__name__)
 
@@ -41,7 +42,6 @@ def get_shared_answer(
     message_id: str,
     db: Session = Depends(get_db),
 ):
-    """Fetch a single assistant answer for public sharing."""
     message = db.query(ChatMessage).filter(
         ChatMessage.id == message_id,
         ChatMessage.role == "assistant",
@@ -59,7 +59,6 @@ def create_share_link(
     user: User = Depends(get_current_user),
     db: Session = Depends(get_db),
 ):
-    """Create a public share URL for a user's assistant answer."""
     message = db.query(ChatMessage).filter(
         ChatMessage.id == message_id,
         ChatMessage.user_id == user.id,
@@ -83,6 +82,18 @@ def create_share_link(
     )
 
 
+def generate_answer(question: str, user_id: str, document_id: Optional[str] = None):
+    from app.rag.agent import generate_answer as _generate_answer
+
+    return _generate_answer(question=question, user_id=user_id, document_id=document_id)
+
+
+def generate_answer_stream(question: str, user_id: str, document_id: Optional[str] = None):
+    from app.rag.agent import generate_answer_stream as _generate_answer_stream
+
+    return _generate_answer_stream(question=question, user_id=user_id, document_id=document_id)
+
+
 @router.post("/ask", response_model=ChatResponse)
 @limiter.limit("10/minute")
 def ask_question(
@@ -118,38 +129,41 @@ def ask_question(
         HTTPException: 400 if the document exists but its status is not
             "ready" (e.g., still processing or failed).
     """
-    # Validate document exists if specified
-    if payload.document_id:
-        doc = db.query(Document).filter(
-            Document.id == payload.document_id,
-            Document.user_id == user.id,
-        ).first()
-
-        if not doc:
-            raise HTTPException(status_code=404, detail="Document not found")
-
-        if doc.status != "ready":
-            raise HTTPException(
-                status_code=400,
-                detail=f"Document is still {doc.status}. Please wait for processing to complete.",
-            )
-
-    # Generate answer
-    result = generate_answer(
-        question=payload.question,
-        user_id=user.id,
-        document_id=payload.document_id,
-    )
+    started_at = time.perf_counter()
+    try:
+        # Validate document exists if specified
+        if payload.document_id:
+            doc = db.query(Document).filter(
+                Document.id == payload.document_id,
+                Document.user_id == user.id,
+            ).first()
+
+            if not doc:
+                raise HTTPException(status_code=404, detail="Document not found")
+
+            if doc.status != "ready":
+                raise HTTPException(
+                    status_code=400,
+                    detail=f"Document is still {doc.status}. Please wait for processing to complete.",
+                )
+
+        result = generate_answer(
+            question=payload.question,
+            user_id=user.id,
+            document_id=payload.document_id,
+        )
 
-    # Save to chat history
-    _save_message(db, user.id, payload.document_id, "user", payload.question)
-    _save_message(db, user.id, payload.document_id, "assistant", result["answer"], result["sources"])
+        # Save to chat history
+        _save_message(db, user.id, payload.document_id, "user", payload.question)
+        _save_message(db, user.id, payload.document_id, "assistant", result["answer"], result["sources"])
 
-    return ChatResponse(
-        answer=result["answer"],
-        sources=[SourceChunk(**s) for s in result["sources"]],
-        document_id=payload.document_id,
-    )
+        return ChatResponse(
+            answer=result["answer"],
+            sources=[SourceChunk(**s) for s in result["sources"]],
+            document_id=payload.document_id,
+        )
+    finally:
+        record_query_response_time(time.perf_counter() - started_at)
 
 
 @router.post("/ask/stream")
@@ -211,6 +225,8 @@ def ask_question_stream(
                 detail=f"Document is still {doc.status}. Please wait for processing to complete.",
             )
 
+    started_at = time.perf_counter()
+
     # Save user message immediately
     _save_message(db, user.id, payload.document_id, "user", payload.question)
 
@@ -219,31 +235,34 @@ def ask_question_stream(
         full_answer = ""
         sources = []
 
-        for chunk in generate_answer_stream(
-            question=payload.question,
-            user_id=user.id,
-            document_id=payload.document_id,
-        ):
-            yield chunk
-
-            # Parse to accumulate full answer for history
-            try:
-                if chunk.startswith("data: "):
-                    data = json.loads(chunk[6:].strip())
-                    if data.get("type") == "token":
-                        full_answer += data.get("data", "")
-                    elif data.get("type") == "sources":
-                        sources = data.get("data", [])
-            except Exception:
-                pass
-
-        # Save assistant response to history
-        from app.database import SessionLocal
-        save_db = SessionLocal()
         try:
-            _save_message(save_db, user.id, payload.document_id, "assistant", full_answer, sources)
+            for chunk in generate_answer_stream(
+                question=payload.question,
+                user_id=user.id,
+                document_id=payload.document_id,
+            ):
+                yield chunk
+
+                # Parse to accumulate full answer for history
+                try:
+                    if chunk.startswith("data: "):
+                        data = json.loads(chunk[6:].strip())
+                        if data.get("type") == "token":
+                            full_answer += data.get("data", "")
+                        elif data.get("type") == "sources":
+                            sources = data.get("data", [])
+                except Exception:
+                    pass
+
+            # Save assistant response to history
+            from app.database import SessionLocal
+            save_db = SessionLocal()
+            try:
+                _save_message(save_db, user.id, payload.document_id, "assistant", full_answer, sources)
+            finally:
+                save_db.close()
         finally:
-            save_db.close()
+            record_query_response_time(time.perf_counter() - started_at)
 
     return StreamingResponse(
         event_stream(),

backend/app/schemas.py

@@ -118,6 +118,24 @@ class DocumentListResponse(BaseModel):
     pages: int
 
 
+# Admin
+
+class DiskUsageResponse(BaseModel):
+    total_bytes: int
+    used_bytes: int
+    free_bytes: int
+    usage_percent: float
+    upload_dir_bytes: int
+
+
+class AdminStatsResponse(BaseModel):
+    total_users: int
+    total_pdfs_uploaded: int
+    average_query_response_time_ms: float
+    query_count: int
+    disk_space_usage: DiskUsageResponse
+
+
 # ── Chat ─────────────────────────────────────────────
 
 class ChatRequest(BaseModel):

backend/tests/conftest.py

@@ -16,11 +16,12 @@ BACKEND_DIR = ROOT / "backend"
 if str(BACKEND_DIR) not in sys.path:
     sys.path.insert(0, str(BACKEND_DIR))
 
-os.environ.setdefault("SECRET_KEY", "test-secret-key-that-is-long-enough")
-os.environ.setdefault("DATABASE_URL", "sqlite:///./test_bootstrap.db")
-os.environ.setdefault("HF_TOKEN", "test-hf-token")
-os.environ.setdefault("UPLOAD_DIR", str(ROOT / "backend" / "test_uploads"))
-os.environ.setdefault("CHROMA_PERSIST_DIR", str(ROOT / "backend" / "test_chroma"))
+os.environ["SECRET_KEY"] = "test-secret-key-that-is-long-enough"
+os.environ["DATABASE_URL"] = "sqlite:///./test_bootstrap.db"
+os.environ["DEBUG"] = "false"
+os.environ["HF_TOKEN"] = "test-hf-token"
+os.environ["UPLOAD_DIR"] = str(ROOT / "backend" / "test_uploads")
+os.environ["CHROMA_PERSIST_DIR"] = str(ROOT / "backend" / "test_chroma")
 
 
 fake_embeddings = types.ModuleType("app.rag.embeddings")

backend/tests/test_admin.py

@@ -0,0 +1,65 @@
+from app.auth import create_access_token, hash_password
+from app.metrics import record_query_response_time
+from app.models import Document, User
+
+
+def test_admin_stats_requires_admin(client, auth_headers):
+    response = client.get("/api/v1/admin/stats", headers=auth_headers)
+
+    assert response.status_code == 403
+    assert response.json()["detail"] == "Admin access required"
+
+
+def test_admin_stats_returns_aggregate_metrics(client, db_session):
+    admin = User(
+        username="admin",
+        email="admin@example.com",
+        hashed_password=hash_password("password123"),
+        is_admin=True,
+    )
+    regular = User(
+        username="regular",
+        email="regular@example.com",
+        hashed_password=hash_password("password123"),
+    )
+    db_session.add_all([admin, regular])
+    db_session.commit()
+    db_session.refresh(admin)
+    db_session.refresh(regular)
+
+    db_session.add_all(
+        [
+            Document(
+                user_id=regular.id,
+                filename="first.pdf",
+                original_name="first.pdf",
+                file_size=100,
+                status="ready",
+            ),
+            Document(
+                user_id=regular.id,
+                filename="notes.txt",
+                original_name="notes.txt",
+                file_size=50,
+                status="ready",
+            ),
+        ]
+    )
+    db_session.commit()
+
+    record_query_response_time(0.25)
+
+    token = create_access_token(admin.id)
+    response = client.get(
+        "/api/v1/admin/stats",
+        headers={"Authorization": f"Bearer {token}"},
+    )
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert payload["total_users"] == 2
+    assert payload["total_pdfs_uploaded"] == 1
+    assert payload["average_query_response_time_ms"] > 0
+    assert payload["query_count"] >= 1
+    assert payload["disk_space_usage"]["total_bytes"] > 0
+    assert payload["disk_space_usage"]["usage_percent"] >= 0

frontend/package-lock.json

@@ -11,6 +11,8 @@
         "@base-ui/react": "^1.4.1",
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
+        "i18next": "^26.3.0",
+        "i18next-browser-languagedetector": "^8.2.1",
         "lucide-react": "^1.8.0",
         "next": "16.2.4",
         "next-themes": "^0.4.6",
@@ -18,6 +20,7 @@
         "react": "19.2.4",
         "react-dom": "19.2.4",
         "react-dropzone": "^15.0.0",
+        "react-i18next": "^17.0.8",
         "react-markdown": "^10.1.0",
         "react-pdf": "^10.4.1",
         "rehype-highlight": "^7.0.2",
@@ -80,6 +83,7 @@
       "resolved": "https://registry.npmjs.org/@babel/core/-/core-7.29.0.tgz",
       "integrity": "sha512-CGOfOJqWjg2qW/Mb6zNsDm+u5vFQ8DxXfbM09z69p5Z6+mE1ikP2jUXw+j42Pf1XTYED2Rni5f95npYeuwMDQA==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@babel/code-frame": "^7.29.0",
         "@babel/generator": "^7.29.0",
@@ -673,6 +677,7 @@
       "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.4.tgz",
       "integrity": "sha512-QP88BAKvMam/3NxH6vj2o21R6MjxZUAd6nlwAS/pnGvN9IVLocLHxGYIzFhg6fUQ+5th6P4dv4eW9jX3DSIj7A==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -2107,6 +2112,7 @@
       "resolved": "https://registry.npmjs.org/@noble/ciphers/-/ciphers-1.3.0.tgz",
       "integrity": "sha512-2I0gnIVPtfnMw9ee9h1dJG7tp81+8Ob3OJb3Mv37rx5L40/b0i7djjCVvGOVqc9AEIQyvyu1i6ypKdFw8R8gQw==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": "^14.21.3 || >=16"
       },
@@ -2214,6 +2220,7 @@
       "integrity": "sha512-O71yZIbAh/PxDMNGns37GHBIfrVkEVyn+AXyIa5dOTfb4/xNvRWV+Vv/NMbNCtODB/pO7vLlF2OTmMVLhmr7Ag==",
       "devOptional": true,
       "license": "Apache-2.0",
+      "peer": true,
       "dependencies": {
         "playwright": "1.60.0"
       },
@@ -2682,6 +2689,7 @@
       "resolved": "https://registry.npmjs.org/@types/node/-/node-20.19.39.tgz",
       "integrity": "sha512-orrrD74MBUyK8jOAD/r0+lfa1I2MO6I+vAkmAWzMYbCcgrN4lCrmK52gRFQq/JRxfYPfonkr4b0jcY7Olqdqbw==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "undici-types": "~6.21.0"
       }
@@ -2691,6 +2699,7 @@
       "resolved": "https://registry.npmjs.org/@types/react/-/react-19.2.14.tgz",
       "integrity": "sha512-ilcTH/UniCkMdtexkoCN0bI7pMcJDvmQFPvuPvmEaYA/NSfFTAgdUSLAoVjaRJm7+6PvcM+q1zYOwS4wTYMF9w==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "csstype": "^3.2.2"
       }
@@ -2777,6 +2786,7 @@
       "integrity": "sha512-TI1XGwKbDpo9tRW8UDIXCOeLk55qe9ZFGs8MTKU6/M08HWTw52DD/IYhfQtOEhEdPhLMT26Ka/x7p70nd3dzDg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "8.59.0",
         "@typescript-eslint/types": "8.59.0",
@@ -3321,6 +3331,7 @@
       "integrity": "sha512-UVJyE9MttOsBQIDKw1skb9nAwQuR5wuGD3+82K6JgJlm/Y+KI92oNsMNGZCYdDsVtRHSak0pcV5Dno5+4jh9sw==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -3775,6 +3786,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "baseline-browser-mapping": "^2.10.12",
         "caniuse-lite": "^1.0.30001782",
@@ -4826,6 +4838,7 @@
       "integrity": "sha512-XoMjdBOwe/esVgEvLmNsD3IRHkm7fbKIUGvrleloJXUZgDHig2IPWNniv+GwjyJXzuNqVjlr5+4yVUZjycJwfQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.8.0",
         "@eslint-community/regexpp": "^4.12.1",
@@ -5011,6 +5024,7 @@
       "integrity": "sha512-whOE1HFo/qJDyX4SnXzP4N6zOWn79WhnCUY/iDR0mPfQZO8wcYE4JClzI2oZrhBnnMUCBCHZhO6VQyoBU95mZA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@rtsao/scc": "^1.1.0",
         "array-includes": "^3.1.9",
@@ -5310,6 +5324,7 @@
       "resolved": "https://registry.npmjs.org/express/-/express-5.2.1.tgz",
       "integrity": "sha512-hIS4idWWai69NezIdRt2xFVofaF4j+6INOpJlVOLDO8zXGpUVEVzIYk12UUi2JzjEzWL3IOAxcTubgz9Po0yXw==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "accepts": "^2.0.0",
         "body-parser": "^2.2.1",
@@ -5669,6 +5684,7 @@
       "version": "2.3.2",
       "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
       "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
       "hasInstallScript": true,
       "license": "MIT",
       "optional": true,
@@ -6133,10 +6149,20 @@
       "resolved": "https://registry.npmjs.org/hono/-/hono-4.12.14.tgz",
       "integrity": "sha512-am5zfg3yu6sqn5yjKBNqhnTX7Cv+m00ox+7jbaKkrLMRJ4rAdldd1xPd/JzbBWspqaQv6RSTrgFN95EsfhC+7w==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=16.9.0"
       }
     },
+    "node_modules/html-parse-stringify": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/html-parse-stringify/-/html-parse-stringify-3.0.1.tgz",
+      "integrity": "sha512-KknJ50kTInJ7qIScF3jeaFRpMpE8/lfiTdzf/twXyPBLAGrLRTmkz3AdTnKeh40X8k9L2fdYwEp/42WGXIRGcg==",
+      "license": "MIT",
+      "dependencies": {
+        "void-elements": "3.1.0"
+      }
+    },
     "node_modules/html-url-attributes": {
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/html-url-attributes/-/html-url-attributes-3.0.1.tgz",
@@ -6189,6 +6215,44 @@
         "node": ">=18.18.0"
       }
     },
+    "node_modules/i18next": {
+      "version": "26.3.0",
+      "resolved": "https://registry.npmjs.org/i18next/-/i18next-26.3.0.tgz",
+      "integrity": "sha512-gHSgGpUXVmuqE2El1W61DmxeyeTlFfZgdJRWMo9jScAn5pu7TuTuiccb1zh3E2J9hEBVGJ23+96x0ieBhfuIHA==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://www.locize.com/i18next"
+        },
+        {
+          "type": "individual",
+          "url": "https://www.i18next.com/how-to/faq#i18next-is-awesome.-how-can-i-support-the-project"
+        },
+        {
+          "type": "individual",
+          "url": "https://www.locize.com"
+        }
+      ],
+      "license": "MIT",
+      "peer": true,
+      "peerDependencies": {
+        "typescript": "^5 || ^6"
+      },
+      "peerDependenciesMeta": {
+        "typescript": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/i18next-browser-languagedetector": {
+      "version": "8.2.1",
+      "resolved": "https://registry.npmjs.org/i18next-browser-languagedetector/-/i18next-browser-languagedetector-8.2.1.tgz",
+      "integrity": "sha512-bZg8+4bdmaOiApD7N7BPT9W8MLZG+nPTOFlLiJiT8uzKXFjhxw4v2ierCXOwB5sFDMtuA5G4kgYZ0AznZxQ/cw==",
+      "license": "MIT",
+      "dependencies": {
+        "@babel/runtime": "^7.23.2"
+      }
+    },
     "node_modules/iconv-lite": {
       "version": "0.7.2",
       "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.7.2.tgz",
@@ -9527,6 +9591,7 @@
       "resolved": "https://registry.npmjs.org/react/-/react-19.2.4.tgz",
       "integrity": "sha512-9nfp2hYpCwOjAN+8TZFGhtWEwgvWHXqESH8qT89AT/lWklpLON22Lc8pEtnpsZz7VmawabSU0gCjnj8aC0euHQ==",
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=0.10.0"
       }
@@ -9536,6 +9601,7 @@
       "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-19.2.4.tgz",
       "integrity": "sha512-AXJdLo8kgMbimY95O2aKQqsz2iWi9jMgKJhRBAxECE4IFxfcazB2LmzloIoibJI3C12IlY20+KFaLv+71bUJeQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "scheduler": "^0.27.0"
       },
@@ -9560,6 +9626,33 @@
         "react": ">= 16.8 || 18.0.0"
       }
     },
+    "node_modules/react-i18next": {
+      "version": "17.0.8",
+      "resolved": "https://registry.npmjs.org/react-i18next/-/react-i18next-17.0.8.tgz",
+      "integrity": "sha512-0ooKbGLU8JXhe1zwpQUWIeXSgLPOfwJmgheWRIUpcoA0CpyabpGhayjdG+/eA5esC1AQ8h2jWpXjJfzQzeDOCw==",
+      "license": "MIT",
+      "dependencies": {
+        "@babel/runtime": "^7.29.2",
+        "html-parse-stringify": "^3.0.1",
+        "use-sync-external-store": "^1.6.0"
+      },
+      "peerDependencies": {
+        "i18next": ">= 26.2.0",
+        "react": ">= 16.8.0",
+        "typescript": "^5 || ^6"
+      },
+      "peerDependenciesMeta": {
+        "react-dom": {
+          "optional": true
+        },
+        "react-native": {
+          "optional": true
+        },
+        "typescript": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/react-is": {
       "version": "16.13.1",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-16.13.1.tgz",
@@ -10833,6 +10926,7 @@
       "integrity": "sha512-QP88BAKvMam/3NxH6vj2o21R6MjxZUAd6nlwAS/pnGvN9IVLocLHxGYIzFhg6fUQ+5th6P4dv4eW9jX3DSIj7A==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -11101,6 +11195,7 @@
       "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "devOptional": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -11434,6 +11529,15 @@
         "url": "https://opencollective.com/unified"
       }
     },
+    "node_modules/void-elements": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/void-elements/-/void-elements-3.1.0.tgz",
+      "integrity": "sha512-Dhxzh5HZuiHQhbvTW9AMetFfBHDMYpo23Uo9btPXgdYP+3T5S+p+jgNy7spra+veYhBP2dCSgxR/i2Y02h5/6w==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
     "node_modules/warning": {
       "version": "4.0.3",
       "resolved": "https://registry.npmjs.org/warning/-/warning-4.0.3.tgz",
@@ -11774,6 +11878,7 @@
       "resolved": "https://registry.npmjs.org/zod/-/zod-4.3.6.tgz",
       "integrity": "sha512-rftlrkhHZOcjDwkGlnUtZZkvaPHCsDATp4pGpuOOMDaTdDDXF91wuVDJoWoPsKX/3YPQ5fHuF3STjcYyKr+Qhg==",
       "license": "MIT",
+      "peer": true,
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }

frontend/package.json

@@ -14,6 +14,8 @@
     "@base-ui/react": "^1.4.1",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "i18next": "^26.3.0",
+    "i18next-browser-languagedetector": "^8.2.1",
     "lucide-react": "^1.8.0",
     "next": "16.2.4",
     "next-themes": "^0.4.6",
@@ -21,6 +23,7 @@
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "react-dropzone": "^15.0.0",
+    "react-i18next": "^17.0.8",
     "react-markdown": "^10.1.0",
     "react-pdf": "^10.4.1",
     "rehype-highlight": "^7.0.2",

frontend/src/app/admin/page.tsx

@@ -0,0 +1,277 @@
+"use client";
+
+import { useCallback, useEffect, useMemo, useState } from "react";
+import { useRouter } from "next/navigation";
+import {
+  ArrowLeft,
+  Clock3,
+  Database,
+  FileText,
+  HardDrive,
+  RefreshCw,
+  Users,
+} from "lucide-react";
+
+import { api, CONNECTION_ERROR_MESSAGE } from "@/lib/api";
+import { useAuth } from "@/lib/auth";
+import { Button } from "@/components/ui/button";
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "@/components/ui/card";
+import { Progress } from "@/components/ui/progress";
+import { Skeleton } from "@/components/ui/skeleton";
+
+interface AdminStats {
+  total_users: number;
+  total_pdfs_uploaded: number;
+  average_query_response_time_ms: number;
+  query_count: number;
+  disk_space_usage: {
+    total_bytes: number;
+    used_bytes: number;
+    free_bytes: number;
+    usage_percent: number;
+    upload_dir_bytes: number;
+  };
+}
+
+const formatBytes = (bytes: number) => {
+  if (!Number.isFinite(bytes) || bytes <= 0) return "0 B";
+
+  const units = ["B", "KB", "MB", "GB", "TB"];
+  const index = Math.min(
+    Math.floor(Math.log(bytes) / Math.log(1024)),
+    units.length - 1
+  );
+
+  return `${(bytes / 1024 ** index).toFixed(index === 0 ? 0 : 1)} ${units[index]}`;
+};
+
+const formatTime = (milliseconds: number) => {
+  if (milliseconds >= 1000) return `${(milliseconds / 1000).toFixed(2)} s`;
+  return `${Math.round(milliseconds)} ms`;
+};
+
+function MetricCard({
+  icon: Icon,
+  label,
+  value,
+  detail,
+}: {
+  icon: typeof Users;
+  label: string;
+  value: string;
+  detail: string;
+}) {
+  return (
+    <Card className="min-h-36">
+      <CardHeader className="grid-cols-[1fr_auto]">
+        <div>
+          <CardDescription>{label}</CardDescription>
+          <CardTitle className="mt-2 text-3xl tabular-nums">{value}</CardTitle>
+        </div>
+        <div className="flex h-9 w-9 items-center justify-center rounded-lg bg-primary/15 text-primary">
+          <Icon className="h-4 w-4" />
+        </div>
+      </CardHeader>
+      <CardContent>
+        <p className="text-sm text-muted-foreground">{detail}</p>
+      </CardContent>
+    </Card>
+  );
+}
+
+function AdminSkeleton() {
+  return (
+    <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-4">
+      {[1, 2, 3, 4].map((item) => (
+        <Card key={item} className="min-h-36">
+          <CardHeader>
+            <Skeleton className="h-4 w-28" />
+            <Skeleton className="h-8 w-20" />
+          </CardHeader>
+          <CardContent>
+            <Skeleton className="h-4 w-36" />
+          </CardContent>
+        </Card>
+      ))}
+    </div>
+  );
+}
+
+export default function AdminPage() {
+  const { user, loading } = useAuth();
+  const router = useRouter();
+  const [stats, setStats] = useState<AdminStats | null>(null);
+  const [statsLoading, setStatsLoading] = useState(true);
+  const [error, setError] = useState("");
+  const [lastUpdated, setLastUpdated] = useState<Date | null>(null);
+
+  useEffect(() => {
+    if (loading) return;
+    if (!user) router.replace("/login");
+    else if (!user.is_admin) router.replace("/dashboard");
+  }, [loading, router, user]);
+
+  const loadStats = useCallback(async () => {
+    try {
+      setStatsLoading(true);
+      const data = await api.get<AdminStats>("/api/v1/admin/stats");
+      setStats(data);
+      setLastUpdated(new Date());
+      setError("");
+    } catch (err) {
+      const message =
+        err instanceof Error ? err.message : CONNECTION_ERROR_MESSAGE;
+      setError(message);
+    } finally {
+      setStatsLoading(false);
+    }
+  }, []);
+
+  useEffect(() => {
+    if (!user?.is_admin) return;
+
+    const initialLoad = window.setTimeout(() => void loadStats(), 0);
+    const interval = window.setInterval(() => void loadStats(), 10000);
+
+    return () => {
+      window.clearTimeout(initialLoad);
+      window.clearInterval(interval);
+    };
+  }, [loadStats, user?.is_admin]);
+
+  const diskDetail = useMemo(() => {
+    if (!stats) return "";
+    const disk = stats.disk_space_usage;
+    return `${formatBytes(disk.used_bytes)} used of ${formatBytes(disk.total_bytes)}`;
+  }, [stats]);
+
+  if (loading || !user || !user.is_admin) {
+    return (
+      <div className="min-h-screen flex items-center justify-center">
+        <div className="animate-pulse-glow w-12 h-12 rounded-full bg-primary/20" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="min-h-screen bg-background">
+      <header className="sticky top-0 z-40 flex h-14 items-center justify-between border-b border-border/50 bg-card/50 px-4 backdrop-blur-md">
+        <div className="flex items-center gap-3">
+          <Button
+            variant="ghost"
+            size="icon"
+            onClick={() => router.push("/dashboard")}
+            title="Back to dashboard"
+          >
+            <ArrowLeft className="h-4 w-4" />
+          </Button>
+          <div className="flex items-center gap-2">
+            <div className="flex h-7 w-7 items-center justify-center rounded-lg bg-primary/15">
+              <Database className="h-4 w-4 text-primary" />
+            </div>
+            <span className="text-sm font-semibold">Admin Metrics</span>
+          </div>
+        </div>
+
+        <Button
+          variant="outline"
+          size="sm"
+          onClick={() => void loadStats()}
+          disabled={statsLoading}
+        >
+          <RefreshCw className={statsLoading ? "h-4 w-4 animate-spin" : "h-4 w-4"} />
+          Refresh
+        </Button>
+      </header>
+
+      <main className="mx-auto flex w-full max-w-6xl flex-col gap-6 px-4 py-6">
+        <div className="flex flex-col gap-1">
+          <h1 className="text-2xl font-semibold tracking-normal">System overview</h1>
+          <p className="text-sm text-muted-foreground">
+            {lastUpdated
+              ? `Last updated ${lastUpdated.toLocaleTimeString()}`
+              : "Waiting for live metrics"}
+          </p>
+        </div>
+
+        {error && (
+          <div
+            role="alert"
+            className="rounded-lg border border-destructive/30 bg-destructive/10 px-4 py-3 text-sm text-destructive"
+          >
+            {error}
+          </div>
+        )}
+
+        {statsLoading && !stats ? (
+          <AdminSkeleton />
+        ) : stats ? (
+          <>
+            <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-4">
+              <MetricCard
+                icon={Users}
+                label="Total users"
+                value={stats.total_users.toLocaleString()}
+                detail="Registered accounts"
+              />
+              <MetricCard
+                icon={FileText}
+                label="PDFs uploaded"
+                value={stats.total_pdfs_uploaded.toLocaleString()}
+                detail="All uploaded PDF records"
+              />
+              <MetricCard
+                icon={Clock3}
+                label="Avg response time"
+                value={formatTime(stats.average_query_response_time_ms)}
+                detail={`${stats.query_count.toLocaleString()} measured queries`}
+              />
+              <MetricCard
+                icon={HardDrive}
+                label="Upload storage"
+                value={formatBytes(stats.disk_space_usage.upload_dir_bytes)}
+                detail="Files in the upload directory"
+              />
+            </div>
+
+            <Card>
+              <CardHeader>
+                <CardTitle>Disk space usage</CardTitle>
+                <CardDescription>{diskDetail}</CardDescription>
+              </CardHeader>
+              <CardContent className="space-y-4">
+                <Progress value={stats.disk_space_usage.usage_percent} />
+                <div className="grid gap-3 text-sm sm:grid-cols-3">
+                  <div>
+                    <p className="text-muted-foreground">Used</p>
+                    <p className="font-medium tabular-nums">
+                      {formatBytes(stats.disk_space_usage.used_bytes)}
+                    </p>
+                  </div>
+                  <div>
+                    <p className="text-muted-foreground">Free</p>
+                    <p className="font-medium tabular-nums">
+                      {formatBytes(stats.disk_space_usage.free_bytes)}
+                    </p>
+                  </div>
+                  <div>
+                    <p className="text-muted-foreground">Usage</p>
+                    <p className="font-medium tabular-nums">
+                      {stats.disk_space_usage.usage_percent.toFixed(2)}%
+                    </p>
+                  </div>
+                </div>
+              </CardContent>
+            </Card>
+          </>
+        ) : null}
+      </main>
+    </div>
+  );
+}

frontend/src/app/layout.tsx

@@ -3,6 +3,7 @@ import { Inter } from "next/font/google";
 import "./globals.css";
 import { AuthProvider } from "@/lib/auth";
 import { TooltipProvider } from "@/components/ui/tooltip";
+import I18nProvider from "@/components/providers/I18nProvider";
 import { ThemeProvider } from "@/components/layout/ThemeProvider";
 
 const inter = Inter({
@@ -33,12 +34,12 @@ export default function RootLayout({
           disableTransitionOnChange
         >
           <AuthProvider>
-            <TooltipProvider>
-              {children}
-            </TooltipProvider>
+            <I18nProvider>
+              <TooltipProvider>{children}</TooltipProvider>
+            </I18nProvider>
           </AuthProvider>
         </ThemeProvider>
       </body>
     </html>
   );
-}
+}

frontend/src/app/login/page.tsx

@@ -3,6 +3,7 @@
 import { useCallback, useState } from "react";
 import { useRouter } from "next/navigation";
 import { useAuth } from "@/lib/auth";
+import { useTranslation } from "react-i18next";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Card, CardContent, CardHeader, CardTitle, CardDescription } from "@/components/ui/card";
@@ -12,6 +13,7 @@ import GoogleSignInButton from "@/components/auth/GoogleSignInButton";
 
 export default function LoginPage() {
   const { login } = useAuth();
+  const { t } = useTranslation();
   const router = useRouter();
   const [email, setEmail] = useState("");
   const [password, setPassword] = useState("");
@@ -32,7 +34,7 @@ export default function LoginPage() {
       await login(email, password);
       router.replace("/dashboard");
     } catch (err: unknown) {
-      const message = err instanceof Error ? err.message : "Login failed";
+      const message = err instanceof Error ? err.message : t("login.fallbackError");
       setError(message);
     } finally {
       setLoading(false);
@@ -51,8 +53,8 @@ export default function LoginPage() {
               <Brain className="w-6 h-6 text-primary" />
             </div>
           </div>
-          <CardTitle className="text-2xl font-bold">Welcome back</CardTitle>
-          <CardDescription>Sign in to your Document AI Analyst account</CardDescription>
+          <CardTitle className="text-2xl font-bold">{t("login.title")}</CardTitle>
+          <CardDescription>{t("login.description")}</CardDescription>
         </CardHeader>
 
         <CardContent>
@@ -71,7 +73,7 @@ export default function LoginPage() {
             )}
 
             <div className="space-y-2">
-              <label className="text-sm font-medium">Email</label>
+              <label className="text-sm font-medium">{t("common.email")}</label>
               <Input
                 id="login-email"
                 type="email"
@@ -84,7 +86,7 @@ export default function LoginPage() {
             </div>
 
             <div className="space-y-2">
-              <label className="text-sm font-medium">Password</label>
+              <label className="text-sm font-medium">{t("common.password")}</label>
               <div className="relative">
                 <Input
                   id="login-password"
@@ -109,18 +111,18 @@ export default function LoginPage() {
               {loading ? (
                 <span className="flex items-center gap-2">
                   <span className="w-4 h-4 border-2 border-primary-foreground/30 border-t-primary-foreground rounded-full animate-spin" />
-                  Signing in...
+                  {t("login.submitting")}
                 </span>
               ) : (
-                "Sign In"
+                t("login.submit")
               )}
             </Button>
           </form>
 
           <p className="text-center text-sm text-muted-foreground mt-6">
-            Don&apos;t have an account?{" "}
+            {t("login.noAccount")}{" "}
             <Link href="/register" className="text-primary hover:underline font-medium">
-              Create one
+              {t("login.createOne")}
             </Link>
           </p>
         </CardContent>

frontend/src/app/register/page.tsx

@@ -3,6 +3,7 @@
 import { useCallback, useState } from "react";
 import { useRouter } from "next/navigation";
 import { useAuth } from "@/lib/auth";
+import { useTranslation } from "react-i18next";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Card, CardContent, CardHeader, CardTitle, CardDescription } from "@/components/ui/card";
@@ -12,6 +13,7 @@ import GoogleSignInButton from "@/components/auth/GoogleSignInButton";
 
 export default function RegisterPage() {
   const { register } = useAuth();
+  const { t } = useTranslation();
   const router = useRouter();
   const [username, setUsername] = useState("");
   const [email, setEmail] = useState("");
@@ -33,7 +35,7 @@ export default function RegisterPage() {
       await register(username, email, password);
       router.replace("/dashboard");
     } catch (err: unknown) {
-      const message = err instanceof Error ? err.message : "Registration failed";
+      const message = err instanceof Error ? err.message : t("register.fallbackError");
       setError(message);
     } finally {
       setLoading(false);
@@ -51,8 +53,8 @@ export default function RegisterPage() {
               <Brain className="w-6 h-6 text-primary" />
             </div>
           </div>
-          <CardTitle className="text-2xl font-bold">Create Account</CardTitle>
-          <CardDescription>Start analyzing documents with AI</CardDescription>
+          <CardTitle className="text-2xl font-bold">{t("register.title")}</CardTitle>
+          <CardDescription>{t("register.description")}</CardDescription>
         </CardHeader>
 
         <CardContent>
@@ -71,7 +73,7 @@ export default function RegisterPage() {
             )}
 
             <div className="space-y-2">
-              <label className="text-sm font-medium">Username</label>
+              <label className="text-sm font-medium">{t("common.username")}</label>
               <Input
                 id="reg-username"
                 type="text"
@@ -85,7 +87,7 @@ export default function RegisterPage() {
             </div>
 
             <div className="space-y-2">
-              <label className="text-sm font-medium">Email</label>
+              <label className="text-sm font-medium">{t("common.email")}</label>
               <Input
                 id="reg-email"
                 type="email"
@@ -98,12 +100,12 @@ export default function RegisterPage() {
             </div>
 
             <div className="space-y-2">
-              <label className="text-sm font-medium">Password</label>
+              <label className="text-sm font-medium">{t("common.password")}</label>
               <div className="relative">
                 <Input
                   id="reg-password"
                   type={showPw ? "text" : "password"}
-                  placeholder="Minimum 6 characters"
+                  placeholder={t("register.passwordPlaceholder")}
                   value={password}
                   onChange={(e) => setPassword(e.target.value)}
                   required
@@ -124,18 +126,18 @@ export default function RegisterPage() {
               {loading ? (
                 <span className="flex items-center gap-2">
                   <span className="w-4 h-4 border-2 border-primary-foreground/30 border-t-primary-foreground rounded-full animate-spin" />
-                  Creating account...
+                  {t("register.submitting")}
                 </span>
               ) : (
-                "Create Account"
+                t("register.submit")
               )}
             </Button>
           </form>
 
           <p className="text-center text-sm text-muted-foreground mt-6">
-            Already have an account?{" "}
+            {t("register.hasAccount")}{" "}
             <Link href="/login" className="text-primary hover:underline font-medium">
-              Sign in
+              {t("register.signIn")}
             </Link>
           </p>
         </CardContent>

frontend/src/components/chat/ChatPanel.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState, useRef, useEffect } from "react";
+import { useTranslation } from "react-i18next";
 import type { DocInfo } from "@/app/dashboard/page";
 import { api, API_BASE } from "@/lib/api";
 import { useChatStore, type ChatMsg, type SourceChunk } from "@/store/chat-store";
@@ -16,6 +17,7 @@ interface Props {
 }
 
 export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
+  const { t } = useTranslation();
   const messages = useChatStore((state) => state.messages);
   const input = useChatStore((state) => state.input);
   const streaming = useChatStore((state) => state.streaming);
@@ -185,7 +187,9 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
           m.id === assistantId
             ? {
                 ...m,
-                content: `Failed to get response: ${err instanceof Error ? err.message : "Unknown error"}`,
+                content: t("chat.fallbackError", {
+                  message: err instanceof Error ? err.message : "Unknown error",
+                }),
                 isStreaming: false,
               }
             : m
@@ -198,7 +202,7 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
   };
 
   const handleClear = async () => {
-    if (!activeDoc || !confirm("Clear all chat history for this document?")) return;
+    if (!activeDoc || !confirm(t("chat.clearConfirm"))) return;
     try {
       await api.delete(`/api/v1/chat/history/${activeDoc.id}`);
       setMessages([]);
@@ -250,12 +254,12 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
               <MessageSquare className="w-8 h-8 text-primary/60" />
             </div>
             <h3 className="text-lg font-semibold mb-1">
-              {activeDoc ? "Ask about your document" : "Select a document"}
+              {activeDoc ? t("chat.askAboutDocument") : t("chat.selectDocument")}
             </h3>
             <p className="text-sm text-muted-foreground text-center max-w-sm">
               {activeDoc
-                ? `"${activeDoc.original_name}" is ready. Ask any question and get cited answers.`
-                : "Upload and select a document from the sidebar to start chatting."}
+                ? t("chat.readyPrompt", { name: activeDoc.original_name })
+                : t("chat.uploadPrompt")}
             </p>
           </div>
         ) : (
@@ -293,8 +297,8 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
             onKeyDown={handleKeyDown}
             placeholder={
               activeDoc
-                ? `Ask about "${activeDoc.original_name}"...`
-                : "Select a document first..."
+                ? t("chat.askPlaceholder", { name: activeDoc.original_name })
+                : t("chat.selectPlaceholder")
             }
             disabled={streaming}
             className="min-h-[44px] max-h-32 resize-none bg-background/50 border-border/50"
@@ -324,7 +328,7 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
                     size="icon"
                     onClick={() => setShowExportMenu((v) => !v)}
                     className="h-[44px] w-[44px] text-muted-foreground hover:text-primary"
-                    title="Export chat history"
+                    title={t("chat.exportTitle")}
                   >
                     <Download className="w-4 h-4" />
                   </Button>
@@ -336,7 +340,7 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
                         className="w-full flex items-center gap-2 rounded-md px-3 py-2 text-sm hover:bg-accent transition-colors text-left"
                       >
                         <span className="text-base">📝</span>
-                        Markdown (.md)
+                        {t("chat.markdown")}
                       </button>
                       <button
                         id="export-txt-btn"
@@ -344,7 +348,7 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
                         className="w-full flex items-center gap-2 rounded-md px-3 py-2 text-sm hover:bg-accent transition-colors text-left"
                       >
                         <span className="text-base">📄</span>
-                        Plain Text (.txt)
+                        {t("chat.plainText")}
                       </button>
                       <button
                         id="export-pdf-btn"
@@ -352,7 +356,7 @@ export default function ChatPanel({ activeDoc, onCitationClick }: Props) {
                         className="w-full flex items-center gap-2 rounded-md px-3 py-2 text-sm hover:bg-accent transition-colors text-left"
                       >
                         <span className="text-base">📕</span>
-                        PDF (.pdf)
+                        {t("chat.pdf")}
                       </button>
                     </div>
                   )}

frontend/src/components/document/DocumentSidebar.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState, useCallback } from "react";
+import { useTranslation } from "react-i18next";
 import type { DocInfo } from "@/app/dashboard/page";
 import { api } from "@/lib/api";
 import { ScrollArea } from "@/components/ui/scroll-area";
@@ -20,6 +21,7 @@ interface Props {
 }
 
 export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc, onDocumentsChange }: Props) {
+  const { t } = useTranslation();
   const [uploading, setUploading] = useState(false);
   const [uploadProgress, setUploadProgress] = useState(0);
   const [uploadError, setUploadError] = useState("");
@@ -43,7 +45,7 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
           }
           onDocumentsChange();
         } catch (err) {
-          const message = err instanceof Error ? err.message : "Upload failed";
+          const message = err instanceof Error ? err.message : t("documents.uploadFailed");
           setUploadError(message);
         } finally {
           setUploading(false);
@@ -51,7 +53,7 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
         }
       })();
     },
-    [onDocumentsChange]
+    [onDocumentsChange, t]
   );
 
   const { getRootProps, getInputProps, isDragActive } = useDropzone({
@@ -67,7 +69,7 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
 
   const handleDelete = async (docId: string, e: React.MouseEvent) => {
     e.stopPropagation();
-    if (!confirm("Delete this document and all its data?")) return;
+    if (!confirm(t("documents.deleteConfirm"))) return;
     setDeleting(docId);
     try {
       await api.delete(`/api/v1/documents/${docId}`);
@@ -119,17 +121,17 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
           {uploading ? (
             <div className="space-y-2">
               <Loader2 className="w-5 h-5 mx-auto animate-spin text-primary" />
-              <p className="text-xs text-muted-foreground">Uploading...</p>
+              <p className="text-xs text-muted-foreground">{t("documents.uploading")}</p>
               <Progress value={uploadProgress} className="h-1" />
             </div>
           ) : (
             <>
               <Upload className="w-5 h-5 mx-auto text-muted-foreground mb-2" />
               <p className="text-xs text-muted-foreground">
-                {isDragActive ? "Drop files here" : "Drop files or click to upload"}
+                {isDragActive ? t("documents.dropHere") : t("documents.dropOrClick")}
               </p>
               <p className="text-[10px] text-muted-foreground/60 mt-1">
-                PDF, DOCX, TXT, MD (max 50MB)
+                {t("documents.uploadFormats")}
               </p>
             </>
           )}
@@ -139,7 +141,7 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
       {/* ── Documents List ──────────────────────────── */}
       <div className="px-3 pt-3 pb-1">
         <h3 className="text-[11px] font-semibold uppercase tracking-wider text-muted-foreground mb-2">
-          Documents ({documents.length})
+          {t("documents.documentsTitle", { count: documents.length })}
         </h3>
       </div>
 
@@ -147,8 +149,8 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
         {documents.length === 0 ? (
           <div className="text-center py-12">
             <FolderOpen className="w-8 h-8 mx-auto text-muted-foreground/40 mb-3" />
-            <p className="text-sm text-muted-foreground">No documents yet</p>
-            <p className="text-xs text-muted-foreground/60 mt-1">Upload a file to get started</p>
+            <p className="text-sm text-muted-foreground">{t("documents.noDocuments")}</p>
+            <p className="text-xs text-muted-foreground/60 mt-1">{t("documents.getStarted")}</p>
           </div>
         ) : (
           <div className="space-y-1 pb-3">
@@ -179,22 +181,22 @@ export default function DocumentSidebar({ documents = [], activeDoc, onSelectDoc
                         <>
                           <span className="text-[10px] text-muted-foreground">•</span>
                           <span className="text-[10px] text-muted-foreground">
-                            {doc.page_count} pg
+                            {t("documents.pagesShort", { count: doc.page_count })}
                           </span>
                           <span className="text-[10px] text-muted-foreground">•</span>
                           <span className="text-[10px] text-muted-foreground">
-                            {doc.chunk_count} chunks
+                            {t("documents.chunks", { count: doc.chunk_count })}
                           </span>
                         </>
                       )}
                       {doc.status === "processing" && (
                         <Badge variant="secondary" className="text-[9px] h-4 px-1.5">
-                          Processing
+                          {t("documents.processing")}
                         </Badge>
                       )}
                       {doc.status === "failed" && (
                         <Badge variant="destructive" className="text-[9px] h-4 px-1.5">
-                          Failed
+                          {t("documents.failed")}
                         </Badge>
                       )}
                     </div>

frontend/src/components/layout/Header.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useAuth } from "@/lib/auth";
+import { useTranslation } from "react-i18next";
 import { useRouter } from "next/navigation";
 import { Button } from "@/components/ui/button";
 import { Avatar, AvatarFallback } from "@/components/ui/avatar";
@@ -19,6 +20,7 @@ import {
   PanelRightOpen,
   LogOut,
   Moon,
+  Shield,
   Sun,
 } from "lucide-react";
 import { useSyncExternalStore } from "react";
@@ -39,6 +41,7 @@ const getServerSnapshot = () => false;
 
 export default function Header({ sidebarOpen, onToggleSidebar, viewerOpen, onToggleViewer }: HeaderProps) {
   const { user, logout } = useAuth();
+  const { t, i18n } = useTranslation();
   const router = useRouter();
   const { theme, setTheme } = useTheme();
   const mounted = useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot); // ← replaces useState + useEffect
@@ -51,11 +54,24 @@ export default function Header({ sidebarOpen, onToggleSidebar, viewerOpen, onTog
     router.replace("/login");
   };
 
+  const languageLabel = (language: string) => {
+    switch (language) {
+      case "hi":
+        return t("common.hindi");
+      case "es":
+        return t("common.spanish");
+      case "fr":
+        return t("common.french");
+      default:
+        return t("common.english");
+    }
+  };
+
   return (
     <header className="h-14 flex items-center justify-between px-4 border-b border-border/50 bg-card/50 backdrop-blur-md flex-shrink-0 z-50">
       {/* Left */}
       <div className="flex items-center gap-3">
-        <Button variant="ghost" size="icon" className="h-8 w-8" onClick={onToggleSidebar} title={sidebarOpen ? "Close sidebar" : "Open sidebar"}>
+        <Button variant="ghost" size="icon" className="h-8 w-8" onClick={onToggleSidebar} title={sidebarOpen ? t("header.closeSidebar") : t("header.openSidebar")}>
           {sidebarOpen ? <PanelLeftClose className="w-4 h-4" /> : <PanelLeftOpen className="w-4 h-4" />}
         </Button>
 
@@ -63,22 +79,34 @@ export default function Header({ sidebarOpen, onToggleSidebar, viewerOpen, onTog
           <div className="w-7 h-7 rounded-lg bg-primary/15 flex items-center justify-center">
             <Brain className="w-4 h-4 text-primary" />
           </div>
-          <span className="font-semibold text-sm hidden sm:inline">Document AI Analyst</span>
+          <span className="font-semibold text-sm hidden sm:inline">{t("common.appName")}</span>
         </div>
       </div>
 
       {/* Right */}
       <div className="flex items-center gap-2">
-        <Button variant="ghost" size="icon" className="h-8 w-8" onClick={onToggleViewer} title={viewerOpen ? "Close viewer" : "Open viewer"}>
+        <Button variant="ghost" size="icon" className="h-8 w-8" onClick={onToggleViewer} title={viewerOpen ? t("header.closeViewer") : t("header.openViewer")}>
           {viewerOpen ? <PanelRightClose className="w-4 h-4" /> : <PanelRightOpen className="w-4 h-4" />}
         </Button>
 
         {mounted && (
-          <Button variant="ghost" size="icon" className="h-8 w-8" onClick={toggleTheme} title={isDark ? "Light mode" : "Dark mode"}>
+          <Button variant="ghost" size="icon" className="h-8 w-8" onClick={toggleTheme} title={isDark ? t("header.lightMode") : t("header.darkMode")}>
             {isDark ? <Sun className="w-4 h-4" /> : <Moon className="w-4 h-4" />}
           </Button>
         )}
 
+        <select
+          aria-label={t("common.language")}
+          value={i18n.resolvedLanguage || "en"}
+          onChange={(e) => void i18n.changeLanguage(e.target.value)}
+          className="h-8 rounded-md border border-border bg-background px-2 text-xs text-foreground"
+        >
+          <option value="en">{languageLabel("en")}</option>
+          <option value="hi">{languageLabel("hi")}</option>
+          <option value="es">{languageLabel("es")}</option>
+          <option value="fr">{languageLabel("fr")}</option>
+        </select>
+
         <DropdownMenu>
           <DropdownMenuTrigger
             render={
@@ -99,11 +127,16 @@ export default function Header({ sidebarOpen, onToggleSidebar, viewerOpen, onTog
               <p className="text-xs text-muted-foreground truncate">{user?.email}</p>
             </div>
             <DropdownMenuSeparator />
-            <ApiKeyManager />
-            <DropdownMenuSeparator />
+            {user?.is_admin && (
+              <DropdownMenuItem className="cursor-pointer" onClick={() => router.push("/admin")}>
+                <Shield className="w-4 h-4 mr-2" />
+                Admin metrics
+              </DropdownMenuItem>
+            )}
+            {user?.is_admin && <DropdownMenuSeparator />}
             <DropdownMenuItem className="text-destructive cursor-pointer" onClick={handleLogout}>
               <LogOut className="w-4 h-4 mr-2" />
-              Sign out
+              {t("header.signOut")}
             </DropdownMenuItem>
           </DropdownMenuContent>
         </DropdownMenu>

frontend/src/components/providers/I18nProvider.tsx

@@ -0,0 +1,22 @@
+"use client";
+
+import { useEffect } from "react";
+import { I18nextProvider } from "react-i18next";
+import i18n from "@/lib/i18n";
+
+export default function I18nProvider({ children }: { children: React.ReactNode }) {
+  useEffect(() => {
+    document.documentElement.lang = i18n.resolvedLanguage || "en";
+
+    const handleLanguageChanged = (language: string) => {
+      document.documentElement.lang = language;
+    };
+
+    i18n.on("languageChanged", handleLanguageChanged);
+    return () => {
+      i18n.off("languageChanged", handleLanguageChanged);
+    };
+  }, []);
+
+  return <I18nextProvider i18n={i18n}>{children}</I18nextProvider>;
+}

frontend/src/lib/i18n.ts

@@ -0,0 +1,320 @@
+"use client";
+
+import i18n from "i18next";
+import LanguageDetector from "i18next-browser-languagedetector";
+import { initReactI18next } from "react-i18next";
+
+const resources = {
+  en: {
+    translation: {
+      common: {
+        appName: "Document AI Analyst",
+        language: "Language",
+        english: "English",
+        hindi: "Hindi",
+        spanish: "Spanish",
+        french: "French",
+        email: "Email",
+        password: "Password",
+        username: "Username",
+      },
+      header: {
+        closeSidebar: "Close sidebar",
+        openSidebar: "Open sidebar",
+        closeViewer: "Close viewer",
+        openViewer: "Open viewer",
+        lightMode: "Light mode",
+        darkMode: "Dark mode",
+        signOut: "Sign out",
+      },
+      login: {
+        title: "Welcome back",
+        description: "Sign in to your Document AI Analyst account",
+        fallbackError: "Login failed",
+        submit: "Sign In",
+        submitting: "Signing in...",
+        noAccount: "Don't have an account?",
+        createOne: "Create one",
+      },
+      register: {
+        title: "Create Account",
+        description: "Start analyzing documents with AI",
+        fallbackError: "Registration failed",
+        passwordPlaceholder: "Minimum 6 characters",
+        submit: "Create Account",
+        submitting: "Creating account...",
+        hasAccount: "Already have an account?",
+        signIn: "Sign in",
+      },
+      chat: {
+        askAboutDocument: "Ask about your document",
+        selectDocument: "Select a document",
+        readyPrompt: "\"{{name}}\" is ready. Ask any question and get cited answers.",
+        uploadPrompt: "Upload and select a document from the sidebar to start chatting.",
+        fallbackError: "Failed to get response: {{message}}",
+        clearConfirm: "Clear all chat history for this document?",
+        askPlaceholder: "Ask about \"{{name}}\"...",
+        selectPlaceholder: "Select a document first...",
+        exportTitle: "Export chat history",
+        markdown: "Markdown (.md)",
+        plainText: "Plain Text (.txt)",
+        pdf: "PDF (.pdf)",
+      },
+      documents: {
+        uploadFailed: "Upload failed",
+        deleteConfirm: "Delete this document and all its data?",
+        uploading: "Uploading...",
+        dropHere: "Drop files here",
+        dropOrClick: "Drop files or click to upload",
+        uploadFormats: "PDF, DOCX, TXT, MD (max 50MB)",
+        documentsTitle: "Documents ({{count}})",
+        noDocuments: "No documents yet",
+        getStarted: "Upload a file to get started",
+        pagesShort: "{{count}} pg",
+        chunks: "{{count}} chunks",
+        processing: "Processing",
+        failed: "Failed",
+      },
+    },
+  },
+  hi: {
+    translation: {
+      common: {
+        appName: "डॉक्यूमेंट एआई एनालिस्ट",
+        language: "भाषा",
+        english: "अंग्रेज़ी",
+        hindi: "हिंदी",
+        spanish: "स्पेनिश",
+        french: "फ़्रेंच",
+        email: "ईमेल",
+        password: "पासवर्ड",
+        username: "उपयोगकर्ता नाम",
+      },
+      header: {
+        closeSidebar: "साइडबार बंद करें",
+        openSidebar: "साइडबार खोलें",
+        closeViewer: "व्यूअर बंद करें",
+        openViewer: "व्यूअर खोलें",
+        lightMode: "लाइट मोड",
+        darkMode: "डार्क मोड",
+        signOut: "साइन आउट",
+      },
+      login: {
+        title: "वापसी पर स्वागत है",
+        description: "अपने डॉक्यूमेंट एआई एनालिस्ट खाते में साइन इन करें",
+        fallbackError: "लॉगिन विफल",
+        submit: "साइन इन करें",
+        submitting: "साइन इन हो रहा है...",
+        noAccount: "क्या आपका खाता नहीं है?",
+        createOne: "एक बनाएं",
+      },
+      register: {
+        title: "खाता बनाएं",
+        description: "एआई के साथ दस्तावेज़ों का विश्लेषण शुरू करें",
+        fallbackError: "पंजीकरण विफल",
+        passwordPlaceholder: "कम से कम 6 अक्षर",
+        submit: "खाता बनाएं",
+        submitting: "खाता बनाया जा रहा है...",
+        hasAccount: "क्या पहले से खाता है?",
+        signIn: "साइन इन करें",
+      },
+      chat: {
+        askAboutDocument: "अपने दस्तावेज़ के बारे में पूछें",
+        selectDocument: "एक दस्तावेज़ चुनें",
+        readyPrompt: "\"{{name}}\" तैयार है। कोई भी प्रश्न पूछें और स्रोत सहित उत्तर पाएं।",
+        uploadPrompt: "चैट शुरू करने के लिए साइडबार से फ़ाइल अपलोड और चुनें।",
+        fallbackError: "जवाब प्राप्त नहीं हुआ: {{message}}",
+        clearConfirm: "क्या इस दस्तावेज़ का पूरा चैट इतिहास साफ़ करें?",
+        askPlaceholder: "\"{{name}}\" के बारे में पूछें...",
+        selectPlaceholder: "पहले एक दस्तावेज़ चुनें...",
+        exportTitle: "चैट इतिहास निर्यात करें",
+        markdown: "मार्कडाउन (.md)",
+        plainText: "सादा पाठ (.txt)",
+        pdf: "पीडीएफ (.pdf)",
+      },
+      documents: {
+        uploadFailed: "अपलोड विफल",
+        deleteConfirm: "क्या इस दस्तावेज़ और उसके सभी डेटा को हटाएं?",
+        uploading: "अपलोड हो रहा है...",
+        dropHere: "फ़ाइलें यहाँ छोड़ें",
+        dropOrClick: "फ़ाइलें छोड़ें या अपलोड के लिए क्लिक करें",
+        uploadFormats: "PDF, DOCX, TXT, MD (अधिकतम 50MB)",
+        documentsTitle: "दस्तावेज़ ({{count}})",
+        noDocuments: "अभी तक कोई दस्तावेज़ नहीं",
+        getStarted: "शुरू करने के लिए फ़ाइल अपलोड करें",
+        pagesShort: "{{count}} पेज",
+        chunks: "{{count}} खंड",
+        processing: "प्रोसेस हो रहा है",
+        failed: "विफल",
+      },
+    },
+  },
+  es: {
+    translation: {
+      common: {
+        appName: "Analista IA de Documentos",
+        language: "Idioma",
+        english: "Inglés",
+        hindi: "Hindi",
+        spanish: "Español",
+        french: "Francés",
+        email: "Correo electrónico",
+        password: "Contraseña",
+        username: "Nombre de usuario",
+      },
+      header: {
+        closeSidebar: "Cerrar barra lateral",
+        openSidebar: "Abrir barra lateral",
+        closeViewer: "Cerrar visor",
+        openViewer: "Abrir visor",
+        lightMode: "Modo claro",
+        darkMode: "Modo oscuro",
+        signOut: "Cerrar sesión",
+      },
+      login: {
+        title: "Bienvenido de nuevo",
+        description: "Inicia sesión en tu cuenta de Analista IA de Documentos",
+        fallbackError: "Error al iniciar sesión",
+        submit: "Iniciar sesión",
+        submitting: "Iniciando sesión...",
+        noAccount: "¿No tienes una cuenta?",
+        createOne: "Crear una",
+      },
+      register: {
+        title: "Crear cuenta",
+        description: "Empieza a analizar documentos con IA",
+        fallbackError: "Error de registro",
+        passwordPlaceholder: "Mínimo 6 caracteres",
+        submit: "Crear cuenta",
+        submitting: "Creando cuenta...",
+        hasAccount: "¿Ya tienes una cuenta?",
+        signIn: "Inicia sesión",
+      },
+      chat: {
+        askAboutDocument: "Pregunta sobre tu documento",
+        selectDocument: "Selecciona un documento",
+        readyPrompt: "\"{{name}}\" está listo. Haz cualquier pregunta y obtén respuestas con citas.",
+        uploadPrompt: "Sube y selecciona un documento de la barra lateral para comenzar a chatear.",
+        fallbackError: "No se pudo obtener respuesta: {{message}}",
+        clearConfirm: "¿Borrar todo el historial de chat de este documento?",
+        askPlaceholder: "Pregunta sobre \"{{name}}\"...",
+        selectPlaceholder: "Primero selecciona un documento...",
+        exportTitle: "Exportar historial del chat",
+        markdown: "Markdown (.md)",
+        plainText: "Texto plano (.txt)",
+        pdf: "PDF (.pdf)",
+      },
+      documents: {
+        uploadFailed: "Error de carga",
+        deleteConfirm: "¿Eliminar este documento y todos sus datos?",
+        uploading: "Subiendo...",
+        dropHere: "Suelta archivos aquí",
+        dropOrClick: "Suelta archivos o haz clic para subir",
+        uploadFormats: "PDF, DOCX, TXT, MD (máx. 50MB)",
+        documentsTitle: "Documentos ({{count}})",
+        noDocuments: "Aún no hay documentos",
+        getStarted: "Sube un archivo para comenzar",
+        pagesShort: "{{count}} pág",
+        chunks: "{{count}} fragmentos",
+        processing: "Procesando",
+        failed: "Falló",
+      },
+    },
+  },
+  fr: {
+    translation: {
+      common: {
+        appName: "Analyste IA de Documents",
+        language: "Langue",
+        english: "Anglais",
+        hindi: "Hindi",
+        spanish: "Espagnol",
+        french: "Français",
+        email: "E-mail",
+        password: "Mot de passe",
+        username: "Nom d'utilisateur",
+      },
+      header: {
+        closeSidebar: "Fermer la barre latérale",
+        openSidebar: "Ouvrir la barre latérale",
+        closeViewer: "Fermer le lecteur",
+        openViewer: "Ouvrir le lecteur",
+        lightMode: "Mode clair",
+        darkMode: "Mode sombre",
+        signOut: "Se déconnecter",
+      },
+      login: {
+        title: "Bon retour",
+        description: "Connectez-vous à votre compte Analyste IA de Documents",
+        fallbackError: "Échec de la connexion",
+        submit: "Se connecter",
+        submitting: "Connexion en cours...",
+        noAccount: "Vous n'avez pas de compte ?",
+        createOne: "En créer un",
+      },
+      register: {
+        title: "Créer un compte",
+        description: "Commencez à analyser des documents avec l'IA",
+        fallbackError: "Échec de l'inscription",
+        passwordPlaceholder: "6 caractères minimum",
+        submit: "Créer un compte",
+        submitting: "Création du compte...",
+        hasAccount: "Vous avez déjà un compte ?",
+        signIn: "Se connecter",
+      },
+      chat: {
+        askAboutDocument: "Posez une question sur votre document",
+        selectDocument: "Sélectionnez un document",
+        readyPrompt: "\"{{name}}\" est prêt. Posez n'importe quelle question et obtenez des réponses sourcées.",
+        uploadPrompt: "Importez puis sélectionnez un document dans la barre latérale pour commencer à discuter.",
+        fallbackError: "Impossible d'obtenir une réponse : {{message}}",
+        clearConfirm: "Effacer tout l'historique de discussion de ce document ?",
+        askPlaceholder: "Posez une question sur \"{{name}}\"...",
+        selectPlaceholder: "Sélectionnez d'abord un document...",
+        exportTitle: "Exporter l'historique du chat",
+        markdown: "Markdown (.md)",
+        plainText: "Texte brut (.txt)",
+        pdf: "PDF (.pdf)",
+      },
+      documents: {
+        uploadFailed: "Échec de l'envoi",
+        deleteConfirm: "Supprimer ce document et toutes ses données ?",
+        uploading: "Envoi en cours...",
+        dropHere: "Déposez les fichiers ici",
+        dropOrClick: "Déposez les fichiers ou cliquez pour téléverser",
+        uploadFormats: "PDF, DOCX, TXT, MD (max 50 Mo)",
+        documentsTitle: "Documents ({{count}})",
+        noDocuments: "Aucun document pour le moment",
+        getStarted: "Importez un fichier pour commencer",
+        pagesShort: "{{count}} p",
+        chunks: "{{count}} segments",
+        processing: "Traitement",
+        failed: "Échec",
+      },
+    },
+  },
+} as const;
+
+if (!i18n.isInitialized) {
+  void i18n
+    .use(LanguageDetector)
+    .use(initReactI18next)
+    .init({
+      resources,
+      fallbackLng: "en",
+      supportedLngs: ["en", "hi", "es", "fr"],
+      interpolation: {
+        escapeValue: false,
+      },
+      detection: {
+        order: ["localStorage", "navigator"],
+        caches: ["localStorage"],
+        lookupLocalStorage: "i18nextLng",
+      },
+      react: {
+        useSuspense: false,
+      },
+    });
+}
+
+export default i18n;