diff --git a/alembic/versions/20251109_02_add_auth_tables.py b/alembic/versions/20251109_02_add_auth_tables.py
new file mode 100644
index 0000000..c669bd2
--- /dev/null
+++ b/alembic/versions/20251109_02_add_auth_tables.py
@@ -0,0 +1,210 @@
+"""Add authentication and RBAC tables"""
+
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+from passlib.context import CryptContext
+from sqlalchemy.sql import column, table
+
+# revision identifiers, used by Alembic.
+revision = "20251109_02"
+down_revision = "20251109_01"
+branch_labels = None
+depends_on = None
+
+password_context = CryptContext(schemes=["argon2"], deprecated="auto")
+
+
+def upgrade() -> None:
+    op.create_table(
+        "users",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("email", sa.String(length=255), nullable=False),
+        sa.Column("username", sa.String(length=128), nullable=False),
+        sa.Column("password_hash", sa.String(length=255), nullable=False),
+        sa.Column(
+            "is_active",
+            sa.Boolean(),
+            nullable=False,
+            server_default=sa.true(),
+        ),
+        sa.Column(
+            "is_superuser",
+            sa.Boolean(),
+            nullable=False,
+            server_default=sa.false(),
+        ),
+        sa.Column("last_login_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.UniqueConstraint("email", name="uq_users_email"),
+        sa.UniqueConstraint("username", name="uq_users_username"),
+    )
+    op.create_index(
+        "ix_users_active_superuser",
+        "users",
+        ["is_active", "is_superuser"],
+        unique=False,
+    )
+
+    op.create_table(
+        "roles",
+        sa.Column("id", sa.Integer(), primary_key=True),
+        sa.Column("name", sa.String(length=64), nullable=False),
+        sa.Column("display_name", sa.String(length=128), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.UniqueConstraint("name", name="uq_roles_name"),
+    )
+
+    op.create_table(
+        "user_roles",
+        sa.Column("user_id", sa.Integer(), nullable=False),
+        sa.Column("role_id", sa.Integer(), nullable=False),
+        sa.Column(
+            "granted_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.Column("granted_by", sa.Integer(), nullable=True),
+        sa.ForeignKeyConstraint(
+            ["user_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["role_id"],
+            ["roles.id"],
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["granted_by"],
+            ["users.id"],
+            ondelete="SET NULL",
+        ),
+        sa.PrimaryKeyConstraint("user_id", "role_id"),
+        sa.UniqueConstraint("user_id", "role_id",
+                            name="uq_user_roles_user_role"),
+    )
+    op.create_index(
+        "ix_user_roles_role_id",
+        "user_roles",
+        ["role_id"],
+        unique=False,
+    )
+
+    # Seed default roles
+    roles_table = table(
+        "roles",
+        column("id", sa.Integer()),
+        column("name", sa.String()),
+        column("display_name", sa.String()),
+        column("description", sa.Text()),
+    )
+
+    op.bulk_insert(
+        roles_table,
+        [
+            {
+                "id": 1,
+                "name": "admin",
+                "display_name": "Administrator",
+                "description": "Full platform access with user management rights.",
+            },
+            {
+                "id": 2,
+                "name": "project_manager",
+                "display_name": "Project Manager",
+                "description": "Manage projects, scenarios, and associated data.",
+            },
+            {
+                "id": 3,
+                "name": "analyst",
+                "display_name": "Analyst",
+                "description": "Review dashboards and scenario outputs.",
+            },
+            {
+                "id": 4,
+                "name": "viewer",
+                "display_name": "Viewer",
+                "description": "Read-only access to assigned projects and reports.",
+            },
+        ],
+    )
+
+    admin_password_hash = password_context.hash("ChangeMe123!")
+
+    users_table = table(
+        "users",
+        column("id", sa.Integer()),
+        column("email", sa.String()),
+        column("username", sa.String()),
+        column("password_hash", sa.String()),
+        column("is_active", sa.Boolean()),
+        column("is_superuser", sa.Boolean()),
+    )
+
+    op.bulk_insert(
+        users_table,
+        [
+            {
+                "id": 1,
+                "email": "admin@calminer.local",
+                "username": "admin",
+                "password_hash": admin_password_hash,
+                "is_active": True,
+                "is_superuser": True,
+            }
+        ],
+    )
+
+    user_roles_table = table(
+        "user_roles",
+        column("user_id", sa.Integer()),
+        column("role_id", sa.Integer()),
+        column("granted_by", sa.Integer()),
+    )
+
+    op.bulk_insert(
+        user_roles_table,
+        [
+            {
+                "user_id": 1,
+                "role_id": 1,
+                "granted_by": 1,
+            }
+        ],
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_user_roles_role_id", table_name="user_roles")
+    op.drop_table("user_roles")
+
+    op.drop_table("roles")
+
+    op.drop_index("ix_users_active_superuser", table_name="users")
+    op.drop_table("users")
diff --git a/alembic_test.db b/alembic_test.db
new file mode 100644
index 0000000..7c40e15
Binary files /dev/null and b/alembic_test.db differ
diff --git a/changelog.md b/changelog.md
index 49e0146..7606c0d 100644
--- a/changelog.md
+++ b/changelog.md
@@ -16,3 +16,5 @@
 - Reordered project route registration to prioritize static UI paths, eliminating 422 errors on `/projects/ui` and `/projects/create`, and added pytest smoke coverage for the navigation endpoints.
 - Added end-to-end integration tests for project and scenario lifecycles, validating HTML redirects, template rendering, and API interactions, and updated `ProjectRepository.get` to deduplicate joined loads for detail views.
 - Updated all Jinja2 template responses to the new Starlette signature to eliminate deprecation warnings while keeping request-aware context available to the templates.
+- Introduced `services/security.py` to centralize Argon2 password hashing utilities and JWT creation/verification with typed payloads, and added pytest coverage for hashing, expiry, tampering, and token type mismatch scenarios.
+- Added `routes/auth.py` with registration, login, and password reset flows, refreshed auth templates with error messaging, wired navigation links, and introduced end-to-end pytest coverage for the new forms and token flows.
diff --git a/config/settings.py b/config/settings.py
new file mode 100644
index 0000000..0b928d4
--- /dev/null
+++ b/config/settings.py
@@ -0,0 +1,60 @@
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+from datetime import timedelta
+from functools import lru_cache
+
+from services.security import JWTSettings
+
+
+@dataclass(frozen=True, slots=True)
+class Settings:
+    """Application configuration sourced from environment variables."""
+
+    jwt_secret_key: str = "change-me"
+    jwt_algorithm: str = "HS256"
+    jwt_access_token_minutes: int = 15
+    jwt_refresh_token_days: int = 7
+
+    @classmethod
+    def from_environment(cls) -> "Settings":
+        """Construct settings from environment variables."""
+
+        return cls(
+            jwt_secret_key=os.getenv("CALMINER_JWT_SECRET", "change-me"),
+            jwt_algorithm=os.getenv("CALMINER_JWT_ALGORITHM", "HS256"),
+            jwt_access_token_minutes=cls._int_from_env(
+                "CALMINER_JWT_ACCESS_MINUTES", 15
+            ),
+            jwt_refresh_token_days=cls._int_from_env(
+                "CALMINER_JWT_REFRESH_DAYS", 7
+            ),
+        )
+
+    @staticmethod
+    def _int_from_env(name: str, default: int) -> int:
+        raw_value = os.getenv(name)
+        if raw_value is None:
+            return default
+        try:
+            return int(raw_value)
+        except ValueError:
+            return default
+
+    def jwt_settings(self) -> JWTSettings:
+        """Build runtime JWT settings compatible with token helpers."""
+
+        return JWTSettings(
+            secret_key=self.jwt_secret_key,
+            algorithm=self.jwt_algorithm,
+            access_token_ttl=timedelta(minutes=self.jwt_access_token_minutes),
+            refresh_token_ttl=timedelta(days=self.jwt_refresh_token_days),
+        )
+
+
+@lru_cache(maxsize=1)
+def get_settings() -> Settings:
+    """Return cached application settings."""
+
+    return Settings.from_environment()
diff --git a/dependencies.py b/dependencies.py
index e492586..b2b0774 100644
--- a/dependencies.py
+++ b/dependencies.py
@@ -2,6 +2,8 @@ from __future__ import annotations
 
 from collections.abc import Generator
 
+from config.settings import Settings, get_settings
+from services.security import JWTSettings
 from services.unit_of_work import UnitOfWork
 
 
@@ -10,3 +12,15 @@ def get_unit_of_work() -> Generator[UnitOfWork, None, None]:
 
     with UnitOfWork() as uow:
         yield uow
+
+
+def get_application_settings() -> Settings:
+    """Provide cached application settings instance."""
+
+    return get_settings()
+
+
+def get_jwt_settings() -> JWTSettings:
+    """Provide JWT runtime configuration derived from settings."""
+
+    return get_settings().jwt_settings()
diff --git a/main.py b/main.py
index 000a0e0..456aa5a 100644
--- a/main.py
+++ b/main.py
@@ -10,6 +10,7 @@ from models import (
     Scenario,
     SimulationParameter,
 )
+from routes.auth import router as auth_router
 from routes.dashboard import router as dashboard_router
 from routes.projects import router as projects_router
 from routes.scenarios import router as scenarios_router
@@ -33,6 +34,7 @@ async def health() -> dict[str, str]:
 
 
 app.include_router(dashboard_router)
+app.include_router(auth_router)
 app.include_router(projects_router)
 app.include_router(scenarios_router)
 
diff --git a/models/user.py b/models/user.py
index 67db19e..580c705 100644
--- a/models/user.py
+++ b/models/user.py
@@ -4,6 +4,14 @@ from datetime import datetime
 from typing import List, Optional
 
 from passlib.context import CryptContext
+
+try:  # pragma: no cover - defensive compatibility shim
+    import importlib.metadata as importlib_metadata
+    import argon2  # type: ignore
+
+    setattr(argon2, "__version__", importlib_metadata.version("argon2-cffi"))
+except Exception:
+    pass
 from sqlalchemy import (
     Boolean,
     DateTime,
diff --git a/routes/auth.py b/routes/auth.py
new file mode 100644
index 0000000..71a8752
--- /dev/null
+++ b/routes/auth.py
@@ -0,0 +1,473 @@
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+from typing import Any, Iterable
+
+from fastapi import APIRouter, Depends, HTTPException, Request, UploadFile, status
+from fastapi.responses import HTMLResponse, RedirectResponse
+from fastapi.templating import Jinja2Templates
+from pydantic import ValidationError
+from starlette.datastructures import FormData
+
+from dependencies import get_jwt_settings, get_unit_of_work
+from models import Role, User
+from schemas.auth import (
+    LoginForm,
+    PasswordResetForm,
+    PasswordResetRequestForm,
+    RegistrationForm,
+)
+from services.exceptions import EntityConflictError
+from services.security import (
+    JWTSettings,
+    TokenDecodeError,
+    TokenExpiredError,
+    TokenTypeMismatchError,
+    create_access_token,
+    create_refresh_token,
+    decode_access_token,
+    hash_password,
+    verify_password,
+)
+from services.repositories import RoleRepository, UserRepository
+from services.unit_of_work import UnitOfWork
+
+router = APIRouter(tags=["Authentication"])
+templates = Jinja2Templates(directory="templates")
+
+_PASSWORD_RESET_SCOPE = "password-reset"
+_AUTH_SCOPE = "auth"
+
+
+def _template(
+    request: Request,
+    template_name: str,
+    context: dict[str, Any],
+    *,
+    status_code: int = status.HTTP_200_OK,
+) -> HTMLResponse:
+    return templates.TemplateResponse(
+        request,
+        template_name,
+        context,
+        status_code=status_code,
+    )
+
+
+def _validation_errors(exc: ValidationError) -> list[str]:
+    return [error.get("msg", "Invalid input.") for error in exc.errors()]
+
+
+def _scopes(include: Iterable[str]) -> list[str]:
+    return list(include)
+
+
+def _normalise_form_data(form_data: FormData) -> dict[str, str]:
+    normalised: dict[str, str] = {}
+    for key, value in form_data.multi_items():
+        if isinstance(value, UploadFile):
+            str_value = value.filename or ""
+        else:
+            str_value = str(value)
+        normalised[key] = str_value
+    return normalised
+
+
+def _require_users_repo(uow: UnitOfWork) -> UserRepository:
+    if not uow.users:
+        raise RuntimeError("User repository is not initialised")
+    return uow.users
+
+
+def _require_roles_repo(uow: UnitOfWork) -> RoleRepository:
+    if not uow.roles:
+        raise RuntimeError("Role repository is not initialised")
+    return uow.roles
+
+
+@router.get("/login", response_class=HTMLResponse, include_in_schema=False, name="auth.login_form")
+def login_form(request: Request) -> HTMLResponse:
+    return _template(
+        request,
+        "login.html",
+        {
+            "form_action": request.url_for("auth.login_submit"),
+            "errors": [],
+            "username": "",
+        },
+    )
+
+
+@router.post("/login", include_in_schema=False, name="auth.login_submit")
+async def login_submit(
+    request: Request,
+    uow: UnitOfWork = Depends(get_unit_of_work),
+    jwt_settings: JWTSettings = Depends(get_jwt_settings),
+):
+    form_data = _normalise_form_data(await request.form())
+    try:
+        form = LoginForm(**form_data)
+    except ValidationError as exc:
+        return _template(
+            request,
+            "login.html",
+            {
+                "form_action": request.url_for("auth.login_submit"),
+                "errors": _validation_errors(exc),
+            },
+            status_code=status.HTTP_400_BAD_REQUEST,
+        )
+
+    identifier = form.username
+    users_repo = _require_users_repo(uow)
+    user = _lookup_user(users_repo, identifier)
+    errors: list[str] = []
+
+    if not user or not verify_password(form.password, user.password_hash):
+        errors.append("Invalid username or password.")
+    elif not user.is_active:
+        errors.append("Account is inactive. Contact an administrator.")
+
+    if errors:
+        return _template(
+            request,
+            "login.html",
+            {
+                "form_action": request.url_for("auth.login_submit"),
+                "errors": errors,
+                "username": identifier,
+            },
+            status_code=status.HTTP_400_BAD_REQUEST,
+        )
+
+    assert user is not None  # mypy hint - guarded above
+    user.last_login_at = datetime.now(timezone.utc)
+
+    access_token = create_access_token(
+        str(user.id),
+        jwt_settings,
+        scopes=_scopes((_AUTH_SCOPE,)),
+    )
+    refresh_token = create_refresh_token(
+        str(user.id),
+        jwt_settings,
+        scopes=_scopes((_AUTH_SCOPE,)),
+    )
+
+    response = RedirectResponse(
+        request.url_for("dashboard.home"),
+        status_code=status.HTTP_303_SEE_OTHER,
+    )
+    _set_auth_cookies(response, access_token, refresh_token, jwt_settings)
+    return response
+
+
+def _lookup_user(users_repo: UserRepository, identifier: str) -> User | None:
+    if "@" in identifier:
+        return users_repo.get_by_email(identifier.lower(), with_roles=True)
+    return users_repo.get_by_username(identifier, with_roles=True)
+
+
+def _set_auth_cookies(
+    response: RedirectResponse,
+    access_token: str,
+    refresh_token: str,
+    jwt_settings: JWTSettings,
+) -> None:
+    access_ttl = int(jwt_settings.access_token_ttl.total_seconds())
+    refresh_ttl = int(jwt_settings.refresh_token_ttl.total_seconds())
+    response.set_cookie(
+        "calminer_access_token",
+        access_token,
+        httponly=True,
+        secure=False,
+        samesite="lax",
+        max_age=max(access_ttl, 0) or None,
+    )
+    response.set_cookie(
+        "calminer_refresh_token",
+        refresh_token,
+        httponly=True,
+        secure=False,
+        samesite="lax",
+        max_age=max(refresh_ttl, 0) or None,
+    )
+
+
+@router.get("/register", response_class=HTMLResponse, include_in_schema=False, name="auth.register_form")
+def register_form(request: Request) -> HTMLResponse:
+    return _template(
+        request,
+        "register.html",
+        {
+            "form_action": request.url_for("auth.register_submit"),
+            "errors": [],
+            "form_data": None,
+        },
+    )
+
+
+@router.post("/register", include_in_schema=False, name="auth.register_submit")
+async def register_submit(
+    request: Request,
+    uow: UnitOfWork = Depends(get_unit_of_work),
+):
+    form_data = _normalise_form_data(await request.form())
+    try:
+        form = RegistrationForm(**form_data)
+    except ValidationError as exc:
+        return _registration_error_response(request, _validation_errors(exc))
+
+    errors: list[str] = []
+    users_repo = _require_users_repo(uow)
+    roles_repo = _require_roles_repo(uow)
+    uow.ensure_default_roles()
+
+    if users_repo.get_by_email(form.email):
+        errors.append("Email is already registered.")
+    if users_repo.get_by_username(form.username):
+        errors.append("Username is already taken.")
+
+    if errors:
+        return _registration_error_response(request, errors, form)
+
+    user = User(
+        email=form.email,
+        username=form.username,
+        password_hash=hash_password(form.password),
+        is_active=True,
+        is_superuser=False,
+    )
+
+    try:
+        created = users_repo.create(user)
+    except EntityConflictError:
+        return _registration_error_response(
+            request,
+            ["An account with this username or email already exists."],
+            form,
+        )
+
+    viewer_role = _ensure_viewer_role(roles_repo)
+    if viewer_role is not None:
+        users_repo.assign_role(
+            user_id=created.id,
+            role_id=viewer_role.id,
+            granted_by=created.id,
+        )
+
+    redirect_url = request.url_for(
+        "auth.login_form").include_query_params(registered="1")
+    return RedirectResponse(
+        redirect_url,
+        status_code=status.HTTP_303_SEE_OTHER,
+    )
+
+
+def _registration_error_response(
+    request: Request,
+    errors: list[str],
+    form: RegistrationForm | None = None,
+) -> HTMLResponse:
+    context = {
+        "form_action": request.url_for("auth.register_submit"),
+        "errors": errors,
+        "form_data": form.model_dump(exclude={"password", "confirm_password"}) if form else None,
+    }
+    return _template(
+        request,
+        "register.html",
+        context,
+        status_code=status.HTTP_400_BAD_REQUEST,
+    )
+
+
+def _ensure_viewer_role(roles_repo: RoleRepository) -> Role | None:
+    viewer = roles_repo.get_by_name("viewer")
+    if viewer:
+        return viewer
+    return roles_repo.get_by_name("viewer")
+
+
+@router.get(
+    "/forgot-password",
+    response_class=HTMLResponse,
+    include_in_schema=False,
+    name="auth.password_reset_request_form",
+)
+def password_reset_request_form(request: Request) -> HTMLResponse:
+    return _template(
+        request,
+        "forgot_password.html",
+        {
+            "form_action": request.url_for("auth.password_reset_request_submit"),
+            "errors": [],
+            "message": None,
+        },
+    )
+
+
+@router.post(
+    "/forgot-password",
+    include_in_schema=False,
+    name="auth.password_reset_request_submit",
+)
+async def password_reset_request_submit(
+    request: Request,
+    uow: UnitOfWork = Depends(get_unit_of_work),
+    jwt_settings: JWTSettings = Depends(get_jwt_settings),
+):
+    form_data = _normalise_form_data(await request.form())
+    try:
+        form = PasswordResetRequestForm(**form_data)
+    except ValidationError as exc:
+        return _template(
+            request,
+            "forgot_password.html",
+            {
+                "form_action": request.url_for("auth.password_reset_request_submit"),
+                "errors": _validation_errors(exc),
+                "message": None,
+            },
+            status_code=status.HTTP_400_BAD_REQUEST,
+        )
+
+    users_repo = _require_users_repo(uow)
+    user = users_repo.get_by_email(form.email)
+    if not user:
+        return _template(
+            request,
+            "forgot_password.html",
+            {
+                "form_action": request.url_for("auth.password_reset_request_submit"),
+                "errors": [],
+                "message": "If an account exists, a reset link has been sent.",
+            },
+        )
+
+    token = create_access_token(
+        str(user.id),
+        jwt_settings,
+        scopes=_scopes((_PASSWORD_RESET_SCOPE,)),
+        expires_delta=timedelta(hours=1),
+    )
+
+    reset_url = request.url_for(
+        "auth.password_reset_form").include_query_params(token=token)
+    return RedirectResponse(reset_url, status_code=status.HTTP_303_SEE_OTHER)
+
+
+@router.get(
+    "/reset-password",
+    response_class=HTMLResponse,
+    include_in_schema=False,
+    name="auth.password_reset_form",
+)
+def password_reset_form(
+    request: Request,
+    token: str | None = None,
+    jwt_settings: JWTSettings = Depends(get_jwt_settings),
+) -> HTMLResponse:
+    errors: list[str] = []
+    if not token:
+        errors.append("Missing password reset token.")
+    else:
+        try:
+            payload = decode_access_token(token, jwt_settings)
+            if _PASSWORD_RESET_SCOPE not in payload.scopes:
+                errors.append("Invalid token scope.")
+        except TokenExpiredError:
+            errors.append(
+                "Token has expired. Please request a new password reset.")
+        except (TokenDecodeError, TokenTypeMismatchError):
+            errors.append("Invalid password reset token.")
+
+    return _template(
+        request,
+        "reset_password.html",
+        {
+            "form_action": request.url_for("auth.password_reset_submit"),
+            "token": token,
+            "errors": errors,
+        },
+        status_code=status.HTTP_400_BAD_REQUEST if errors else status.HTTP_200_OK,
+    )
+
+
+@router.post(
+    "/reset-password",
+    include_in_schema=False,
+    name="auth.password_reset_submit",
+)
+async def password_reset_submit(
+    request: Request,
+    uow: UnitOfWork = Depends(get_unit_of_work),
+    jwt_settings: JWTSettings = Depends(get_jwt_settings),
+):
+    form_data = _normalise_form_data(await request.form())
+    try:
+        form = PasswordResetForm(**form_data)
+    except ValidationError as exc:
+        return _template(
+            request,
+            "reset_password.html",
+            {
+                "form_action": request.url_for("auth.password_reset_submit"),
+                "token": form_data.get("token"),
+                "errors": _validation_errors(exc),
+            },
+            status_code=status.HTTP_400_BAD_REQUEST,
+        )
+
+    try:
+        payload = decode_access_token(form.token, jwt_settings)
+    except TokenExpiredError:
+        return _reset_error_response(
+            request,
+            form.token,
+            "Token has expired. Please request a new password reset.",
+        )
+    except (TokenDecodeError, TokenTypeMismatchError):
+        return _reset_error_response(
+            request,
+            form.token,
+            "Invalid password reset token.",
+        )
+
+    if _PASSWORD_RESET_SCOPE not in payload.scopes:
+        return _reset_error_response(
+            request,
+            form.token,
+            "Invalid password reset token scope.",
+        )
+
+    users_repo = _require_users_repo(uow)
+    user_id = int(payload.sub)
+    user = users_repo.get(user_id)
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
+
+    user.set_password(form.password)
+    if not user.is_active:
+        user.is_active = True
+
+    redirect_url = request.url_for(
+        "auth.login_form").include_query_params(reset="1")
+    return RedirectResponse(
+        redirect_url,
+        status_code=status.HTTP_303_SEE_OTHER,
+    )
+
+
+def _reset_error_response(request: Request, token: str, message: str) -> HTMLResponse:
+    return _template(
+        request,
+        "reset_password.html",
+        {
+            "form_action": request.url_for("auth.password_reset_submit"),
+            "token": token,
+            "errors": [message],
+        },
+        status_code=status.HTTP_400_BAD_REQUEST,
+    )
diff --git a/schemas/auth.py b/schemas/auth.py
new file mode 100644
index 0000000..3a16191
--- /dev/null
+++ b/schemas/auth.py
@@ -0,0 +1,67 @@
+from __future__ import annotations
+
+from pydantic import BaseModel, ConfigDict, Field, ValidationInfo, field_validator
+
+
+class FormModel(BaseModel):
+    """Base Pydantic model for HTML form submissions."""
+
+    model_config = ConfigDict(extra="forbid", str_strip_whitespace=True)
+
+
+class RegistrationForm(FormModel):
+    username: str = Field(min_length=3, max_length=128)
+    email: str = Field(min_length=5, max_length=255)
+    password: str = Field(min_length=8, max_length=256)
+    confirm_password: str
+
+    @field_validator("email")
+    @classmethod
+    def validate_email(cls, value: str) -> str:
+        if "@" not in value or value.startswith("@") or value.endswith("@"):
+            raise ValueError("Invalid email address.")
+        local, domain = value.split("@", 1)
+        if not local or "." not in domain:
+            raise ValueError("Invalid email address.")
+        return value.lower()
+
+    @field_validator("confirm_password")
+    @classmethod
+    def passwords_match(cls, value: str, info: ValidationInfo) -> str:
+        password = info.data.get("password")
+        if password != value:
+            raise ValueError("Passwords do not match.")
+        return value
+
+
+class LoginForm(FormModel):
+    username: str = Field(min_length=1, max_length=255)
+    password: str = Field(min_length=1, max_length=256)
+
+
+class PasswordResetRequestForm(FormModel):
+    email: str = Field(min_length=5, max_length=255)
+
+    @field_validator("email")
+    @classmethod
+    def validate_email(cls, value: str) -> str:
+        if "@" not in value or value.startswith("@") or value.endswith("@"):
+            raise ValueError("Invalid email address.")
+        local, domain = value.split("@", 1)
+        if not local or "." not in domain:
+            raise ValueError("Invalid email address.")
+        return value.lower()
+
+
+class PasswordResetForm(FormModel):
+    token: str = Field(min_length=1)
+    password: str = Field(min_length=8, max_length=256)
+    confirm_password: str
+
+    @field_validator("confirm_password")
+    @classmethod
+    def reset_passwords_match(cls, value: str, info: ValidationInfo) -> str:
+        password = info.data.get("password")
+        if password != value:
+            raise ValueError("Passwords do not match.")
+        return value
diff --git a/services/repositories.py b/services/repositories.py
index 5556638..1f82691 100644
--- a/services/repositories.py
+++ b/services/repositories.py
@@ -8,7 +8,16 @@ from sqlalchemy import select, func
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import Session, joinedload, selectinload
 
-from models import FinancialInput, Project, Scenario, ScenarioStatus, SimulationParameter
+from models import (
+    FinancialInput,
+    Project,
+    Role,
+    Scenario,
+    ScenarioStatus,
+    SimulationParameter,
+    User,
+    UserRole,
+)
 from services.exceptions import EntityConflictError, EntityNotFoundError
 
 
@@ -211,3 +220,220 @@ class SimulationParameterRepository:
             raise EntityNotFoundError(
                 f"Simulation parameter {parameter_id} not found")
         self.session.delete(entity)
+
+
+class RoleRepository:
+    """Persistence operations for Role entities."""
+
+    def __init__(self, session: Session) -> None:
+        self.session = session
+
+    def list(self) -> Sequence[Role]:
+        stmt = select(Role).order_by(Role.name)
+        return self.session.execute(stmt).scalars().all()
+
+    def get(self, role_id: int) -> Role:
+        stmt = select(Role).where(Role.id == role_id)
+        role = self.session.execute(stmt).scalar_one_or_none()
+        if role is None:
+            raise EntityNotFoundError(f"Role {role_id} not found")
+        return role
+
+    def get_by_name(self, name: str) -> Role | None:
+        stmt = select(Role).where(Role.name == name)
+        return self.session.execute(stmt).scalar_one_or_none()
+
+    def create(self, role: Role) -> Role:
+        self.session.add(role)
+        try:
+            self.session.flush()
+        except IntegrityError as exc:  # pragma: no cover - DB constraint enforcement
+            raise EntityConflictError(
+                "Role violates uniqueness constraints") from exc
+        return role
+
+
+class UserRepository:
+    """Persistence operations for User entities and their role assignments."""
+
+    def __init__(self, session: Session) -> None:
+        self.session = session
+
+    def list(self, *, with_roles: bool = False) -> Sequence[User]:
+        stmt = select(User).order_by(User.created_at)
+        if with_roles:
+            stmt = stmt.options(selectinload(User.roles))
+        return self.session.execute(stmt).scalars().all()
+
+    def _apply_role_option(self, stmt, with_roles: bool):
+        if with_roles:
+            stmt = stmt.options(
+                joinedload(User.role_assignments).joinedload(UserRole.role),
+                selectinload(User.roles),
+            )
+        return stmt
+
+    def get(self, user_id: int, *, with_roles: bool = False) -> User:
+        stmt = select(User).where(User.id == user_id).execution_options(
+            populate_existing=True)
+        stmt = self._apply_role_option(stmt, with_roles)
+        result = self.session.execute(stmt)
+        if with_roles:
+            result = result.unique()
+        user = result.scalar_one_or_none()
+        if user is None:
+            raise EntityNotFoundError(f"User {user_id} not found")
+        return user
+
+    def get_by_email(self, email: str, *, with_roles: bool = False) -> User | None:
+        stmt = select(User).where(User.email == email).execution_options(
+            populate_existing=True)
+        stmt = self._apply_role_option(stmt, with_roles)
+        result = self.session.execute(stmt)
+        if with_roles:
+            result = result.unique()
+        return result.scalar_one_or_none()
+
+    def get_by_username(self, username: str, *, with_roles: bool = False) -> User | None:
+        stmt = select(User).where(User.username ==
+                                  username).execution_options(populate_existing=True)
+        stmt = self._apply_role_option(stmt, with_roles)
+        result = self.session.execute(stmt)
+        if with_roles:
+            result = result.unique()
+        return result.scalar_one_or_none()
+
+    def create(self, user: User) -> User:
+        self.session.add(user)
+        try:
+            self.session.flush()
+        except IntegrityError as exc:  # pragma: no cover - DB constraint enforcement
+            raise EntityConflictError(
+                "User violates uniqueness constraints") from exc
+        return user
+
+    def assign_role(
+        self,
+        *,
+        user_id: int,
+        role_id: int,
+        granted_by: int | None = None,
+    ) -> UserRole:
+        stmt = select(UserRole).where(
+            UserRole.user_id == user_id,
+            UserRole.role_id == role_id,
+        )
+        assignment = self.session.execute(stmt).scalar_one_or_none()
+        if assignment:
+            return assignment
+
+        assignment = UserRole(
+            user_id=user_id,
+            role_id=role_id,
+            granted_by=granted_by,
+        )
+        self.session.add(assignment)
+        try:
+            self.session.flush()
+        except IntegrityError as exc:  # pragma: no cover - DB constraint enforcement
+            raise EntityConflictError(
+                "Assignment violates constraints") from exc
+        return assignment
+
+    def revoke_role(self, *, user_id: int, role_id: int) -> None:
+        stmt = select(UserRole).where(
+            UserRole.user_id == user_id,
+            UserRole.role_id == role_id,
+        )
+        assignment = self.session.execute(stmt).scalar_one_or_none()
+        if assignment is None:
+            raise EntityNotFoundError(
+                f"Role {role_id} not assigned to user {user_id}")
+        self.session.delete(assignment)
+        self.session.flush()
+
+
+DEFAULT_ROLE_DEFINITIONS: tuple[dict[str, str], ...] = (
+    {
+        "name": "admin",
+        "display_name": "Administrator",
+        "description": "Full platform access with user management rights.",
+    },
+    {
+        "name": "project_manager",
+        "display_name": "Project Manager",
+        "description": "Manage projects, scenarios, and associated data.",
+    },
+    {
+        "name": "analyst",
+        "display_name": "Analyst",
+        "description": "Review dashboards and scenario outputs.",
+    },
+    {
+        "name": "viewer",
+        "display_name": "Viewer",
+        "description": "Read-only access to assigned projects and reports.",
+    },
+)
+
+
+def ensure_default_roles(role_repo: RoleRepository) -> list[Role]:
+    """Ensure standard roles exist, creating missing ones.
+
+    Returns all current role records in creation order.
+    """
+
+    roles: list[Role] = []
+    for definition in DEFAULT_ROLE_DEFINITIONS:
+        existing = role_repo.get_by_name(definition["name"])
+        if existing:
+            roles.append(existing)
+            continue
+        role = Role(**definition)
+        roles.append(role_repo.create(role))
+    return roles
+
+
+def ensure_admin_user(
+    user_repo: UserRepository,
+    role_repo: RoleRepository,
+    *,
+    email: str,
+    username: str,
+    password: str,
+) -> User:
+    """Ensure an administrator user exists and holds the admin role."""
+
+    user = user_repo.get_by_email(email, with_roles=True)
+    if user is None:
+        user = User(
+            email=email,
+            username=username,
+            password_hash=User.hash_password(password),
+            is_active=True,
+            is_superuser=True,
+        )
+        user_repo.create(user)
+    else:
+        if not user.is_active:
+            user.is_active = True
+        if not user.is_superuser:
+            user.is_superuser = True
+        user_repo.session.flush()
+
+    admin_role = role_repo.get_by_name("admin")
+    if admin_role is None:  # pragma: no cover - safety if ensure_default_roles wasn't called
+        admin_role = role_repo.create(
+            Role(
+                name="admin",
+                display_name="Administrator",
+                description="Full platform access with user management rights.",
+            )
+        )
+
+    user_repo.assign_role(
+        user_id=user.id,
+        role_id=admin_role.id,
+        granted_by=user.id,
+    )
+    return user
diff --git a/services/security.py b/services/security.py
new file mode 100644
index 0000000..02a078d
--- /dev/null
+++ b/services/security.py
@@ -0,0 +1,213 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from datetime import datetime, timedelta, timezone
+from typing import Any, Dict, Iterable, Literal, Type
+
+from jose import ExpiredSignatureError, JWTError, jwt
+from passlib.context import CryptContext
+
+try:  # pragma: no cover - compatibility shim for passlib/argon2 warning
+    import importlib.metadata as importlib_metadata
+    import argon2  # type: ignore
+
+    setattr(argon2, "__version__", importlib_metadata.version("argon2-cffi"))
+except Exception:  # pragma: no cover - executed only when metadata lookup fails
+    pass
+
+from pydantic import BaseModel, Field, ValidationError
+
+password_context = CryptContext(schemes=["argon2"], deprecated="auto")
+
+
+def hash_password(password: str) -> str:
+    """Derive a secure hash for a plain-text password."""
+
+    return password_context.hash(password)
+
+
+def verify_password(candidate: str, hashed: str) -> bool:
+    """Verify that a candidate password matches a stored hash."""
+
+    try:
+        return password_context.verify(candidate, hashed)
+    except ValueError:
+        # Raised when the stored hash is malformed or uses an unknown scheme.
+        return False
+
+
+class TokenError(Exception):
+    """Base class for token encoding/decoding issues."""
+
+
+class TokenDecodeError(TokenError):
+    """Raised when a token cannot be decoded or validated."""
+
+
+class TokenExpiredError(TokenError):
+    """Raised when a token has expired."""
+
+
+class TokenTypeMismatchError(TokenError):
+    """Raised when a token type does not match the expected flavour."""
+
+
+TokenKind = Literal["access", "refresh"]
+
+
+class TokenPayload(BaseModel):
+    """Shared fields for CalMiner JWT payloads."""
+
+    sub: str
+    exp: int
+    type: TokenKind
+    scopes: list[str] = Field(default_factory=list)
+
+    @property
+    def expires_at(self) -> datetime:
+        return datetime.fromtimestamp(self.exp, tz=timezone.utc)
+
+
+@dataclass(slots=True)
+class JWTSettings:
+    """Runtime configuration for JWT encoding and validation."""
+
+    secret_key: str
+    algorithm: str = "HS256"
+    access_token_ttl: timedelta = field(
+        default_factory=lambda: timedelta(minutes=15))
+    refresh_token_ttl: timedelta = field(
+        default_factory=lambda: timedelta(days=7))
+
+
+def create_access_token(
+    subject: str,
+    settings: JWTSettings,
+    *,
+    scopes: Iterable[str] | None = None,
+    expires_delta: timedelta | None = None,
+    extra_claims: Dict[str, Any] | None = None,
+) -> str:
+    """Issue a signed access token for the provided subject."""
+
+    lifetime = expires_delta or settings.access_token_ttl
+    return _create_token(
+        subject=subject,
+        token_type="access",
+        settings=settings,
+        lifetime=lifetime,
+        scopes=scopes,
+        extra_claims=extra_claims,
+    )
+
+
+def create_refresh_token(
+    subject: str,
+    settings: JWTSettings,
+    *,
+    scopes: Iterable[str] | None = None,
+    expires_delta: timedelta | None = None,
+    extra_claims: Dict[str, Any] | None = None,
+) -> str:
+    """Issue a signed refresh token for the provided subject."""
+
+    lifetime = expires_delta or settings.refresh_token_ttl
+    return _create_token(
+        subject=subject,
+        token_type="refresh",
+        settings=settings,
+        lifetime=lifetime,
+        scopes=scopes,
+        extra_claims=extra_claims,
+    )
+
+
+def decode_access_token(token: str, settings: JWTSettings) -> TokenPayload:
+    """Validate and decode an access token."""
+
+    return _decode_token(token, settings, expected_type="access")
+
+
+def decode_refresh_token(token: str, settings: JWTSettings) -> TokenPayload:
+    """Validate and decode a refresh token."""
+
+    return _decode_token(token, settings, expected_type="refresh")
+
+
+def _create_token(
+    *,
+    subject: str,
+    token_type: TokenKind,
+    settings: JWTSettings,
+    lifetime: timedelta,
+    scopes: Iterable[str] | None,
+    extra_claims: Dict[str, Any] | None,
+) -> str:
+    now = datetime.now(timezone.utc)
+    expire = now + lifetime
+    payload: Dict[str, Any] = {
+        "sub": subject,
+        "type": token_type,
+        "iat": int(now.timestamp()),
+        "exp": int(expire.timestamp()),
+    }
+    if scopes:
+        payload["scopes"] = list(scopes)
+    if extra_claims:
+        payload.update(extra_claims)
+
+    return jwt.encode(payload, settings.secret_key, algorithm=settings.algorithm)
+
+
+def _decode_token(
+    token: str,
+    settings: JWTSettings,
+    expected_type: TokenKind,
+) -> TokenPayload:
+    try:
+        decoded = jwt.decode(
+            token,
+            settings.secret_key,
+            algorithms=[settings.algorithm],
+            options={"verify_aud": False},
+        )
+    except ExpiredSignatureError as exc:  # pragma: no cover - jose marks this path
+        raise TokenExpiredError("Token has expired") from exc
+    except JWTError as exc:  # pragma: no cover - jose error bubble
+        raise TokenDecodeError("Unable to decode token") from exc
+
+    try:
+        payload = _model_validate(TokenPayload, decoded)
+    except ValidationError as exc:
+        raise TokenDecodeError("Token payload validation failed") from exc
+
+    if payload.type != expected_type:
+        raise TokenTypeMismatchError(
+            f"Expected a {expected_type} token but received '{payload.type}'."
+        )
+
+    return payload
+
+
+def _model_validate(model: Type[TokenPayload], data: Dict[str, Any]) -> TokenPayload:
+    if hasattr(model, "model_validate"):
+        return model.model_validate(data)  # type: ignore[attr-defined]
+    return model.parse_obj(data)  # type: ignore[attr-defined]
+
+
+__all__ = [
+    "JWTSettings",
+    "TokenDecodeError",
+    "TokenError",
+    "TokenExpiredError",
+    "TokenKind",
+    "TokenPayload",
+    "TokenTypeMismatchError",
+    "create_access_token",
+    "create_refresh_token",
+    "decode_access_token",
+    "decode_refresh_token",
+    "hash_password",
+    "password_context",
+    "verify_password",
+]
diff --git a/services/unit_of_work.py b/services/unit_of_work.py
index 2e7b9e8..a51849e 100644
--- a/services/unit_of_work.py
+++ b/services/unit_of_work.py
@@ -6,12 +6,16 @@ from typing import Callable, Sequence
 from sqlalchemy.orm import Session
 
 from config.database import SessionLocal
-from models import Scenario
+from models import Role, Scenario
 from services.repositories import (
     FinancialInputRepository,
     ProjectRepository,
+    RoleRepository,
     ScenarioRepository,
     SimulationParameterRepository,
+    UserRepository,
+    ensure_admin_user as ensure_admin_user_record,
+    ensure_default_roles,
 )
 from services.scenario_validation import ScenarioComparisonValidator
 
@@ -23,6 +27,12 @@ class UnitOfWork(AbstractContextManager["UnitOfWork"]):
         self._session_factory = session_factory
         self.session: Session | None = None
         self._scenario_validator: ScenarioComparisonValidator | None = None
+        self.projects: ProjectRepository | None = None
+        self.scenarios: ScenarioRepository | None = None
+        self.financial_inputs: FinancialInputRepository | None = None
+        self.simulation_parameters: SimulationParameterRepository | None = None
+        self.users: UserRepository | None = None
+        self.roles: RoleRepository | None = None
 
     def __enter__(self) -> "UnitOfWork":
         self.session = self._session_factory()
@@ -31,6 +41,8 @@ class UnitOfWork(AbstractContextManager["UnitOfWork"]):
         self.financial_inputs = FinancialInputRepository(self.session)
         self.simulation_parameters = SimulationParameterRepository(
             self.session)
+        self.users = UserRepository(self.session)
+        self.roles = RoleRepository(self.session)
         self._scenario_validator = ScenarioComparisonValidator()
         return self
 
@@ -42,6 +54,12 @@ class UnitOfWork(AbstractContextManager["UnitOfWork"]):
             self.session.rollback()
         self.session.close()
         self._scenario_validator = None
+        self.projects = None
+        self.scenarios = None
+        self.financial_inputs = None
+        self.simulation_parameters = None
+        self.users = None
+        self.roles = None
 
     def flush(self) -> None:
         if not self.session:
@@ -61,7 +79,7 @@ class UnitOfWork(AbstractContextManager["UnitOfWork"]):
     def validate_scenarios_for_comparison(
         self, scenario_ids: Sequence[int]
     ) -> list[Scenario]:
-        if not self.session or not self._scenario_validator:
+        if not self.session or not self._scenario_validator or not self.scenarios:
             raise RuntimeError("UnitOfWork session is not initialised")
 
         scenarios = [self.scenarios.get(scenario_id)
@@ -75,3 +93,26 @@ class UnitOfWork(AbstractContextManager["UnitOfWork"]):
         if not self._scenario_validator:
             raise RuntimeError("UnitOfWork session is not initialised")
         self._scenario_validator.validate(scenarios)
+
+    def ensure_default_roles(self) -> list[Role]:
+        if not self.roles:
+            raise RuntimeError("UnitOfWork session is not initialised")
+        return ensure_default_roles(self.roles)
+
+    def ensure_admin_user(
+        self,
+        *,
+        email: str,
+        username: str,
+        password: str,
+    ) -> None:
+        if not self.users or not self.roles:
+            raise RuntimeError("UnitOfWork session is not initialised")
+        ensure_default_roles(self.roles)
+        ensure_admin_user_record(
+            self.users,
+            self.roles,
+            email=email,
+            username=username,
+            password=password,
+        )
diff --git a/static/img/logo_big.png b/static/img/logo_big.png
new file mode 100644
index 0000000..98f1a78
Binary files /dev/null and b/static/img/logo_big.png differ
diff --git a/templates/forgot_password.html b/templates/forgot_password.html
index 4d21fd3..2d257cb 100644
--- a/templates/forgot_password.html
+++ b/templates/forgot_password.html
@@ -1,17 +1,25 @@
-{% extends "base.html" %}
-
-{% block title %}Forgot Password{% endblock %}
-
-{% block content %}
+{% extends "base.html" %} {% block title %}Forgot Password{% endblock %} {%
+block content %}
 <div class="container">
-    <h1>Forgot Password</h1>
-    <form id="forgot-password-form">
-        <div class="form-group">
-            <label for="email">Email:</label>
-            <input type="email" id="email" name="email" required>
-        </div>
-        <button type="submit">Reset Password</button>
-    </form>
-    <p>Remember your password? <a href="/login">Login here</a></p>
+  <h1>Forgot Password</h1>
+  {% if errors %}
+  <div class="alert alert-error">
+    <ul>
+      {% for error in errors %}
+      <li>{{ error }}</li>
+      {% endfor %}
+    </ul>
+  </div>
+  {% endif %} {% if message %}
+  <div class="alert alert-info">{{ message }}</div>
+  {% endif %}
+  <form id="forgot-password-form" method="post" action="{{ form_action }}">
+    <div class="form-group">
+      <label for="email">Email:</label>
+      <input type="email" id="email" name="email" required />
+    </div>
+    <button type="submit">Reset Password</button>
+  </form>
+  <p>Remember your password? <a href="/login">Login here</a></p>
 </div>
 {% endblock %}
diff --git a/templates/login.html b/templates/login.html
index 6c2eb00..7279b8f 100644
--- a/templates/login.html
+++ b/templates/login.html
@@ -1,22 +1,34 @@
-{% extends "base.html" %}
-
-{% block title %}Login{% endblock %}
-
-{% block content %}
+{% extends "base.html" %} {% block title %}Login{% endblock %} {% block content
+%}
 <div class="container">
-    <h1>Login</h1>
-    <form id="login-form">
-        <div class="form-group">
-            <label for="username">Username:</label>
-            <input type="text" id="username" name="username" required>
-        </div>
-        <div class="form-group">
-            <label for="password">Password:</label>
-            <input type="password" id="password" name="password" required>
-        </div>
-        <button type="submit">Login</button>
-    </form>
-    <p>Don't have an account? <a href="/register">Register here</a></p>
-    <p><a href="/forgot-password">Forgot password?</a></p>
+  <h1>Login</h1>
+  {% if errors %}
+  <div class="alert alert-error">
+    <ul>
+      {% for error in errors %}
+      <li>{{ error }}</li>
+      {% endfor %}
+    </ul>
+  </div>
+  {% endif %}
+  <form id="login-form" method="post" action="{{ form_action }}">
+    <div class="form-group">
+      <label for="username">Username:</label>
+      <input
+        type="text"
+        id="username"
+        name="username"
+        value="{{ username | default('') }}"
+        required
+      />
+    </div>
+    <div class="form-group">
+      <label for="password">Password:</label>
+      <input type="password" id="password" name="password" required />
+    </div>
+    <button type="submit">Login</button>
+  </form>
+  <p>Don't have an account? <a href="/register">Register here</a></p>
+  <p><a href="/forgot-password">Forgot password?</a></p>
 </div>
 {% endblock %}
diff --git a/templates/partials/sidebar_nav.html b/templates/partials/sidebar_nav.html
index 8fec8b3..1980125 100644
--- a/templates/partials/sidebar_nav.html
+++ b/templates/partials/sidebar_nav.html
@@ -1,80 +1,60 @@
 {% set dashboard_href = request.url_for('dashboard.home') if request else '/' %}
-{% set projects_href = request.url_for('projects.project_list_page') if request else '/projects/ui' %}
-{% set project_create_href = request.url_for('projects.create_project_form') if request else '/projects/create' %}
-
-{% set nav_groups = [
-  {
-    "label": "Workspace",
-    "links": [
-      {"href": dashboard_href, "label": "Dashboard", "match_prefix": "/"},
-      {"href": projects_href, "label": "Projects", "match_prefix": "/projects"},
-      {"href": project_create_href, "label": "New Project", "match_prefix": "/projects/create"},
-    ],
-  },
-  {
-    "label": "Insights",
-    "links": [
-      {"href": "/ui/simulations", "label": "Simulations"},
-      {"href": "/ui/reporting", "label": "Reporting"},
-    ],
-  },
-  {
-    "label": "Configuration",
-    "links": [
-      {
-        "href": "/ui/settings",
-        "label": "Settings",
-        "children": [
-          {"href": "/theme-settings", "label": "Themes"},
-          {"href": "/ui/currencies", "label": "Currency Management"},
-        ],
-      },
-    ],
-  },
-] %}
+{% set projects_href = request.url_for('projects.project_list_page') if request
+else '/projects/ui' %} {% set project_create_href =
+request.url_for('projects.create_project_form') if request else
+'/projects/create' %} {% set login_href = request.url_for('auth.login_form') if
+request else '/login' %} {% set register_href =
+request.url_for('auth.register_form') if request else '/register' %} {% set
+forgot_href = request.url_for('auth.password_reset_request_form') if request
+else '/forgot-password' %} {% set nav_groups = [ { "label": "Workspace",
+"links": [ {"href": dashboard_href, "label": "Dashboard", "match_prefix": "/"},
+{"href": projects_href, "label": "Projects", "match_prefix": "/projects"},
+{"href": project_create_href, "label": "New Project", "match_prefix":
+"/projects/create"}, ], }, { "label": "Insights", "links": [ {"href":
+"/ui/simulations", "label": "Simulations"}, {"href": "/ui/reporting", "label":
+"Reporting"}, ], }, { "label": "Configuration", "links": [ { "href":
+"/ui/settings", "label": "Settings", "children": [ {"href": "/theme-settings",
+"label": "Themes"}, {"href": "/ui/currencies", "label": "Currency Management"},
+], }, ], }, { "label": "Account", "links": [ {"href": login_href, "label":
+"Login", "match_prefix": "/login"}, {"href": register_href, "label": "Register",
+"match_prefix": "/register"}, {"href": forgot_href, "label": "Forgot Password",
+"match_prefix": "/forgot-password"}, ], }, ] %}
 
 <nav class="sidebar-nav" aria-label="Primary navigation">
-  {% set current_path = request.url.path if request else "" %}
-  {% for group in nav_groups %}
-    <div class="sidebar-section">
-      <div class="sidebar-section-label">{{ group.label }}</div>
-      <div class="sidebar-section-links">
-        {% for link in group.links %}
-          {% set href = link.href %}
-          {% set match_prefix = link.get('match_prefix', href) %}
-          {% if match_prefix == '/' %}
-            {% set is_active = current_path == '/' %}
-          {% else %}
-            {% set is_active = current_path.startswith(match_prefix) %}
-          {% endif %}
-          <div class="sidebar-link-block">
-            <a
-              href="{{ href }}"
-              class="sidebar-link{% if is_active %} is-active{% endif %}"
-            >
-              {{ link.label }}
-            </a>
-            {% if link.children %}
-              <div class="sidebar-sublinks">
-                {% for child in link.children %}
-                  {% set child_prefix = child.get('match_prefix', child.href) %}
-                  {% if child_prefix == '/' %}
-                    {% set child_active = current_path == '/' %}
-                  {% else %}
-                    {% set child_active = current_path.startswith(child_prefix) %}
-                  {% endif %}
-                  <a
-                    href="{{ child.href }}"
-                    class="sidebar-sublink{% if child_active %} is-active{% endif %}"
-                  >
-                    {{ child.label }}
-                  </a>
-                {% endfor %}
-              </div>
-            {% endif %}
-          </div>
-        {% endfor %}
+  {% set current_path = request.url.path if request else "" %} {% for group in
+  nav_groups %}
+  <div class="sidebar-section">
+    <div class="sidebar-section-label">{{ group.label }}</div>
+    <div class="sidebar-section-links">
+      {% for link in group.links %} {% set href = link.href %} {% set
+      match_prefix = link.get('match_prefix', href) %} {% if match_prefix == '/'
+      %} {% set is_active = current_path == '/' %} {% else %} {% set is_active =
+      current_path.startswith(match_prefix) %} {% endif %}
+      <div class="sidebar-link-block">
+        <a
+          href="{{ href }}"
+          class="sidebar-link{% if is_active %} is-active{% endif %}"
+        >
+          {{ link.label }}
+        </a>
+        {% if link.children %}
+        <div class="sidebar-sublinks">
+          {% for child in link.children %} {% set child_prefix =
+          child.get('match_prefix', child.href) %} {% if child_prefix == '/' %}
+          {% set child_active = current_path == '/' %} {% else %} {% set
+          child_active = current_path.startswith(child_prefix) %} {% endif %}
+          <a
+            href="{{ child.href }}"
+            class="sidebar-sublink{% if child_active %} is-active{% endif %}"
+          >
+            {{ child.label }}
+          </a>
+          {% endfor %}
+        </div>
+        {% endif %}
       </div>
+      {% endfor %}
     </div>
+  </div>
   {% endfor %}
 </nav>
diff --git a/templates/register.html b/templates/register.html
index 04a7b4e..d422405 100644
--- a/templates/register.html
+++ b/templates/register.html
@@ -1,25 +1,43 @@
-{% extends "base.html" %}
-
-{% block title %}Register{% endblock %}
-
-{% block content %}
+{% extends "base.html" %} {% block title %}Register{% endblock %} {% block
+content %}
 <div class="container">
-    <h1>Register</h1>
-    <form id="register-form">
-        <div class="form-group">
-            <label for="username">Username:</label>
-            <input type="text" id="username" name="username" required>
-        </div>
-        <div class="form-group">
-            <label for="email">Email:</label>
-            <input type="email" id="email" name="email" required>
-        </div>
-        <div class="form-group">
-            <label for="password">Password:</label>
-            <input type="password" id="password" name="password" required>
-        </div>
-        <button type="submit">Register</button>
-    </form>
-    <p>Already have an account? <a href="/login">Login here</a></p>
+  <h1>Register</h1>
+  {% if errors %}
+  <div class="alert alert-error">
+    <ul>
+      {% for error in errors %}
+      <li>{{ error }}</li>
+      {% endfor %}
+    </ul>
+  </div>
+  {% endif %}
+  <form id="register-form" method="post" action="{{ form_action }}">
+    <div class="form-group">
+      <label for="username">Username:</label>
+      <input
+        type="text"
+        id="username"
+        name="username"
+        value="{{ form_data.username if form_data else '' }}"
+        required
+      />
+    </div>
+    <div class="form-group">
+      <label for="email">Email:</label>
+      <input
+        type="email"
+        id="email"
+        name="email"
+        value="{{ form_data.email if form_data else '' }}"
+        required
+      />
+    </div>
+    <div class="form-group">
+      <label for="password">Password:</label>
+      <input type="password" id="password" name="password" required />
+    </div>
+    <button type="submit">Register</button>
+  </form>
+  <p>Already have an account? <a href="/login">Login here</a></p>
 </div>
 {% endblock %}
diff --git a/templates/reset_password.html b/templates/reset_password.html
new file mode 100644
index 0000000..66c3007
--- /dev/null
+++ b/templates/reset_password.html
@@ -0,0 +1,36 @@
+{% extends "base.html" %} {% block title %}Reset Password{% endblock %} {% block
+content %}
+<div class="container">
+  <h1>Reset Password</h1>
+  {% if errors %}
+  <div class="alert alert-error">
+    <ul>
+      {% for error in errors %}
+      <li>{{ error }}</li>
+      {% endfor %}
+    </ul>
+  </div>
+  {% endif %}
+  <form id="reset-password-form" method="post" action="{{ form_action }}">
+    <input type="hidden" name="token" value="{{ token | default('') }}" />
+    <div class="form-group">
+      <label for="password">New Password:</label>
+      <input type="password" id="password" name="password" required />
+    </div>
+    <div class="form-group">
+      <label for="confirm_password">Confirm Password:</label>
+      <input
+        type="password"
+        id="confirm_password"
+        name="confirm_password"
+        required
+      />
+    </div>
+    <button type="submit">Update Password</button>
+  </form>
+  <p>
+    Remembered your password?
+    <a href="{{ request.url_for('auth.login_form') }}">Return to login</a>
+  </p>
+</div>
+{% endblock %}
diff --git a/tests/conftest.py b/tests/conftest.py
index 5ad55cc..6ec51e5 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -12,6 +12,7 @@ from sqlalchemy.pool import StaticPool
 
 from config.database import Base
 from dependencies import get_unit_of_work
+from routes.auth import router as auth_router
 from routes.dashboard import router as dashboard_router
 from routes.projects import router as projects_router
 from routes.scenarios import router as scenarios_router
@@ -36,13 +37,15 @@ def engine() -> Iterator[Engine]:
 
 @pytest.fixture()
 def session_factory(engine: Engine) -> Iterator[sessionmaker]:
-    testing_session = sessionmaker(bind=engine, expire_on_commit=False, future=True)
+    testing_session = sessionmaker(
+        bind=engine, expire_on_commit=False, future=True)
     yield testing_session
 
 
 @pytest.fixture()
 def app(session_factory: sessionmaker) -> FastAPI:
     application = FastAPI()
+    application.include_router(auth_router)
     application.include_router(dashboard_router)
     application.include_router(projects_router)
     application.include_router(scenarios_router)
diff --git a/tests/test_auth_repositories.py b/tests/test_auth_repositories.py
new file mode 100644
index 0000000..9c656db
--- /dev/null
+++ b/tests/test_auth_repositories.py
@@ -0,0 +1,135 @@
+from __future__ import annotations
+
+from collections.abc import Iterator
+
+import pytest
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+from config.database import Base
+from models import Role, User
+from services.repositories import (
+    RoleRepository,
+    UserRepository,
+    ensure_admin_user,
+    ensure_default_roles,
+)
+from services.unit_of_work import UnitOfWork
+
+
+@pytest.fixture()
+def engine() -> Iterator:
+    engine = create_engine("sqlite:///:memory:", future=True)
+    Base.metadata.create_all(bind=engine)
+    try:
+        yield engine
+    finally:
+        Base.metadata.drop_all(bind=engine)
+
+
+@pytest.fixture()
+def session(engine) -> Iterator[Session]:
+    TestingSession = sessionmaker(
+        bind=engine, expire_on_commit=False, future=True)
+    db = TestingSession()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+def test_role_repository_create_and_lookup(session: Session) -> None:
+    repo = RoleRepository(session)
+    role = Role(name="custom", display_name="Custom",
+                description="Custom role")
+    repo.create(role)
+
+    retrieved = repo.get(role.id)
+    assert retrieved.name == "custom"
+    assert repo.get_by_name("custom") is retrieved
+    assert repo.list()[0].name == "custom"
+
+
+def test_user_repository_assign_and_revoke_role(session: Session) -> None:
+    role_repo = RoleRepository(session)
+    user_repo = UserRepository(session)
+
+    analyst = role_repo.create(
+        Role(name="analyst", display_name="Analyst", description="Analyzes data")
+    )
+    user = User(
+        email="user@example.com",
+        username="user",
+        password_hash=User.hash_password("secret"),
+    )
+    user_repo.create(user)
+
+    assignment = user_repo.assign_role(
+        user_id=user.id, role_id=analyst.id, granted_by=None)
+    assert assignment.role_id == analyst.id
+
+    refreshed = user_repo.get(user.id, with_roles=True)
+    assert refreshed.roles[0].name == "analyst"
+
+    user_repo.revoke_role(user_id=user.id, role_id=analyst.id)
+    refreshed = user_repo.get(user.id, with_roles=True)
+    assert refreshed.roles == []
+
+
+def test_default_role_and_admin_helpers(session: Session) -> None:
+    role_repo = RoleRepository(session)
+    user_repo = UserRepository(session)
+
+    roles = ensure_default_roles(role_repo)
+    assert {role.name for role in roles} == {
+        "admin", "project_manager", "analyst", "viewer"}
+
+    ensure_admin_user(
+        user_repo,
+        role_repo,
+        email="admin@example.com",
+        username="admin",
+        password="SecurePass1!",
+    )
+
+    admin = user_repo.get_by_email("admin@example.com", with_roles=True)
+    assert admin is not None
+    assert admin.is_superuser
+    assert {role.name for role in admin.roles} >= {"admin"}
+
+    # Idempotent behaviour on subsequent calls
+    ensure_admin_user(
+        user_repo,
+        role_repo,
+        email="admin@example.com",
+        username="admin",
+        password="SecurePass1!",
+    )
+    admin_again = user_repo.get_by_email("admin@example.com", with_roles=True)
+    assert admin_again is not None
+    assert len(admin_again.roles) == len(
+        {role.name for role in admin_again.roles})
+
+
+def test_unit_of_work_exposes_auth_repositories(engine) -> None:
+    TestingSession = sessionmaker(
+        bind=engine, expire_on_commit=False, future=True)
+
+    with UnitOfWork(session_factory=TestingSession) as uow:
+        assert uow.users is not None
+        assert uow.roles is not None
+
+        roles = uow.ensure_default_roles()
+        assert any(role.name == "admin" for role in roles)
+
+        uow.ensure_admin_user(
+            email="uow-admin@example.com",
+            username="uow-admin",
+            password="AnotherSecret1!",
+        )
+
+        admin = uow.users.get_by_email(
+            "uow-admin@example.com", with_roles=True)
+        assert admin is not None
+        assert admin.is_superuser
+        assert any(role.name == "admin" for role in admin.roles)
diff --git a/tests/test_auth_routes.py b/tests/test_auth_routes.py
new file mode 100644
index 0000000..08b4956
--- /dev/null
+++ b/tests/test_auth_routes.py
@@ -0,0 +1,239 @@
+from __future__ import annotations
+
+from collections.abc import Iterator
+from urllib.parse import parse_qs, urlparse
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy import select
+from sqlalchemy.orm import Session, sessionmaker
+
+from models import Role, User, UserRole
+from services.security import hash_password
+
+
+@pytest.fixture()
+def db_session(session_factory: sessionmaker) -> Iterator[Session]:
+    session = session_factory()
+    try:
+        yield session
+    finally:
+        session.close()
+
+
+def _get_user(session: Session, *, email: str | None = None, username: str | None = None) -> User | None:
+    stmt = select(User)
+    if email is not None:
+        stmt = stmt.where(User.email == email)
+    if username is not None:
+        stmt = stmt.where(User.username == username)
+    return session.execute(stmt).scalar_one_or_none()
+
+
+class TestRegistrationFlow:
+    def test_register_creates_user_and_assigns_role(
+        self,
+        client: TestClient,
+        db_session: Session,
+    ) -> None:
+        response = client.post(
+            "/register",
+            data={
+                "username": "newuser",
+                "email": "newuser@example.com",
+                "password": "ComplexP@ss1",
+                "confirm_password": "ComplexP@ss1",
+            },
+            follow_redirects=False,
+        )
+
+        assert response.status_code == 303
+        location = response.headers.get("location")
+        assert location
+        parsed = urlparse(location)
+        assert parsed.path == "/login"
+        assert parse_qs(parsed.query).get("registered") == ["1"]
+
+        created = _get_user(db_session, email="newuser@example.com")
+        assert created is not None
+        assert created.is_active
+
+        role_stmt = select(Role).where(Role.name == "viewer")
+        viewer_role = db_session.execute(role_stmt).scalar_one_or_none()
+        assert viewer_role is not None
+
+        assignments = db_session.execute(
+            select(UserRole).where(
+                UserRole.user_id == created.id,
+                UserRole.role_id == viewer_role.id,
+            )
+        ).scalars().all()
+        assert len(assignments) == 1
+
+    def test_register_duplicate_email_shows_error(
+        self,
+        client: TestClient,
+    ) -> None:
+        first = client.post(
+            "/register",
+            data={
+                "username": "existing",
+                "email": "existing@example.com",
+                "password": "ComplexP@ss1",
+                "confirm_password": "ComplexP@ss1",
+            },
+            follow_redirects=False,
+        )
+        assert first.status_code == 303
+
+        second = client.post(
+            "/register",
+            data={
+                "username": "existing",
+                "email": "existing@example.com",
+                "password": "ComplexP@ss1",
+                "confirm_password": "ComplexP@ss1",
+            },
+            follow_redirects=False,
+        )
+
+        assert second.status_code == 400
+        assert "Email is already registered" in second.text
+
+
+class TestLoginFlow:
+    def test_login_sets_tokens_and_updates_last_login(
+        self,
+        client: TestClient,
+        db_session: Session,
+    ) -> None:
+        password = "MySecur3Pass!"
+        user = User(
+            email="login@example.com",
+            username="loginuser",
+            password_hash=hash_password(password),
+            is_active=True,
+        )
+        db_session.add(user)
+        db_session.commit()
+
+        response = client.post(
+            "/login",
+            data={"username": "loginuser", "password": password},
+            follow_redirects=False,
+        )
+
+        assert response.status_code == 303
+        assert response.headers.get("location") == "http://testserver/"
+        set_cookie_header = response.headers.get("set-cookie", "")
+        assert "calminer_access_token=" in set_cookie_header
+        assert "calminer_refresh_token=" in set_cookie_header
+
+        updated = _get_user(db_session, username="loginuser")
+        assert updated is not None and updated.last_login_at is not None
+
+    def test_login_invalid_credentials_returns_error(self, client: TestClient) -> None:
+        response = client.post(
+            "/login",
+            data={"username": "unknown", "password": "bad"},
+            follow_redirects=False,
+        )
+
+        assert response.status_code == 400
+        assert "Invalid username or password" in response.text
+
+
+class TestPasswordResetFlow:
+    def test_password_reset_round_trip(
+        self,
+        client: TestClient,
+        db_session: Session,
+    ) -> None:
+        user = User(
+            email="reset@example.com",
+            username="resetuser",
+            password_hash=hash_password("OldP@ssword1"),
+            is_active=True,
+        )
+        db_session.add(user)
+        db_session.commit()
+
+        request_response = client.post(
+            "/forgot-password",
+            data={"email": "reset@example.com"},
+            follow_redirects=False,
+        )
+
+        assert request_response.status_code == 303
+        reset_location = request_response.headers.get("location")
+        assert reset_location is not None
+        parsed = urlparse(reset_location)
+        assert parsed.path == "/reset-password"
+        token = parse_qs(parsed.query).get("token", [None])[0]
+        assert token
+
+        form_response = client.get(reset_location)
+        assert form_response.status_code == 200
+
+        submit_response = client.post(
+            "/reset-password",
+            data={
+                "token": token,
+                "password": "N3wP@ssword!",
+                "confirm_password": "N3wP@ssword!",
+            },
+            follow_redirects=False,
+        )
+
+        assert submit_response.status_code == 303
+        assert "reset=1" in (submit_response.headers.get("location") or "")
+
+        db_session.refresh(user)
+        assert user.verify_password("N3wP@ssword!")
+
+    def test_password_reset_with_unknown_email_shows_generic_message(
+        self,
+        client: TestClient,
+    ) -> None:
+        response = client.post(
+            "/forgot-password",
+            data={"email": "doesnotexist@example.com"},
+            follow_redirects=False,
+        )
+
+        assert response.status_code == 200
+        assert "If an account exists" in response.text
+
+    def test_password_reset_mismatched_passwords_return_error(
+        self,
+        client: TestClient,
+        db_session: Session,
+    ) -> None:
+        user = User(
+            email="mismatch@example.com",
+            username="mismatch",
+            password_hash=hash_password("OldP@ssword1"),
+            is_active=True,
+        )
+        db_session.add(user)
+        db_session.commit()
+
+        request_response = client.post(
+            "/forgot-password",
+            data={"email": "mismatch@example.com"},
+            follow_redirects=False,
+        )
+        token = parse_qs(urlparse(request_response.headers["location"]).query)["token"][0]
+
+        submit_response = client.post(
+            "/reset-password",
+            data={
+                "token": token,
+                "password": "NewPass123!",
+                "confirm_password": "Different123!",
+            },
+            follow_redirects=False,
+        )
+
+        assert submit_response.status_code == 400
+        assert "Passwords do not match" in submit_response.text
\ No newline at end of file
diff --git a/tests/test_security.py b/tests/test_security.py
new file mode 100644
index 0000000..607716a
--- /dev/null
+++ b/tests/test_security.py
@@ -0,0 +1,76 @@
+from __future__ import annotations
+
+from datetime import timedelta
+
+import pytest
+
+from services.security import (
+    JWTSettings,
+    TokenDecodeError,
+    TokenExpiredError,
+    TokenTypeMismatchError,
+    create_access_token,
+    create_refresh_token,
+    decode_access_token,
+    decode_refresh_token,
+    hash_password,
+    verify_password,
+)
+
+
+def test_hash_password_round_trip() -> None:
+    hashed = hash_password("super-secret")
+
+    assert hashed != "super-secret"
+    assert verify_password("super-secret", hashed)
+    assert not verify_password("incorrect", hashed)
+
+
+def test_verify_password_handles_malformed_hash() -> None:
+    assert not verify_password("secret", "not-a-valid-hash")
+
+
+def test_access_token_roundtrip() -> None:
+    settings = JWTSettings(secret_key="unit-test-secret")
+
+    token = create_access_token(
+        "user-id-123",
+        settings,
+        scopes=("read", "write"),
+        extra_claims={"custom": "value"},
+    )
+
+    payload = decode_access_token(token, settings)
+
+    assert payload.sub == "user-id-123"
+    assert payload.type == "access"
+    assert payload.scopes == ["read", "write"]
+
+
+def test_refresh_token_type_mismatch() -> None:
+    settings = JWTSettings(secret_key="unit-test-secret")
+    token = create_refresh_token("user-id-456", settings)
+
+    with pytest.raises(TokenTypeMismatchError):
+        decode_access_token(token, settings)
+
+
+def test_decode_expired_token() -> None:
+    settings = JWTSettings(secret_key="unit-test-secret")
+    expired_token = create_access_token(
+        "user-id-789",
+        settings,
+        expires_delta=timedelta(seconds=-5),
+    )
+
+    with pytest.raises(TokenExpiredError):
+        decode_access_token(expired_token, settings)
+
+
+def test_decode_tampered_token() -> None:
+    settings = JWTSettings(secret_key="unit-test-secret")
+    token = create_access_token("user-id-321", settings)
+    tampered = token[:-1] + ("a" if token[-1] != "a" else "b")
+
+    with pytest.raises(TokenDecodeError):
+        decode_access_token(tampered, settings)