diff --git a/backend/api/admin/ai.py b/backend/api/admin/ai.py
index c356302..5cc06a2 100644
--- a/backend/api/admin/ai.py
+++ b/backend/api/admin/ai.py
@@ -1,12 +1,3 @@
-"""Admin AI configuration endpoints.
-
-Handles: get_ai_config_models, test_ai_connection, get_ai_config, update_system_ai_config.
-
-All handlers require get_current_admin (SEC-07, T-08-04-01).
-Sub-router has NO prefix — parent __init__.py carries /api/admin (D-04).
-
-_ai_config_to_dict is local to this module (only ai.py uses it — not in shared.py).
-"""
 from __future__ import annotations
 
 from typing import Optional
@@ -126,7 +117,7 @@ async def get_ai_config_models(
 
     api_key = config.api_key if config else ""
 
-    # Build request headers — Anthropic uses x-api-key; all others use Bearer
+    # Anthropic uses x-api-key; all others use Bearer (different auth schemes)
     if provider_id == "anthropic":
         headers = {
             "x-api-key": api_key,
@@ -143,9 +134,6 @@ async def get_ai_config_models(
             resp.raise_for_status()
             data = resp.json()
 
-        # Standard OpenAI-compat shape: {"data": [{"id": "...", ...}, ...]}
-        # Anthropic shape: {"data": [{"id": "...", ...}, ...]}
-        # Ollama OpenAI-compat: same shape
         raw_list = data.get("data") or data.get("models") or []
         model_ids: list[str] = sorted(
             {
@@ -286,7 +274,6 @@ async def update_system_ai_config(
     """
     from config import settings as _settings  # noqa: PLC0415
 
-    # Load existing row or create a new one from PROVIDER_DEFAULTS
     stmt = select(SystemSettings).where(SystemSettings.provider_id == body.provider_id)
     result = await session.execute(stmt)
     row = result.scalar_one_or_none()
@@ -303,10 +290,8 @@ async def update_system_ai_config(
             api_key_enc=None,
         )
 
-    # Track which fields the caller explicitly set (for audit log — never api_key value)
     fields_changed: list[str] = []
 
-    # Apply provided fields
     if body.api_key is not None:
         fields_changed.append("api_key")
         if body.api_key == "":
@@ -363,7 +348,6 @@ async def update_system_ai_config(
 
     await session.commit()
 
-    # Reload to pick up DB-generated updated_at after commit
     await session.refresh(row)
 
     return _ai_config_to_dict(row)
diff --git a/backend/api/admin/quotas.py b/backend/api/admin/quotas.py
index 42bfff0..906abb1 100644
--- a/backend/api/admin/quotas.py
+++ b/backend/api/admin/quotas.py
@@ -1,10 +1,3 @@
-"""Admin quota management endpoints.
-
-Handles: get_user_quota, update_user_quota.
-
-All handlers require get_current_admin (SEC-07, T-08-04-01).
-Sub-router has NO prefix — parent __init__.py carries /api/admin (D-04).
-"""
 from __future__ import annotations
 
 import uuid
@@ -44,11 +37,6 @@ async def get_user_quota(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Return quota details for a user (ADMIN-04).
-
-    Quota info is admin-visible operational data — no PII, no document content
-    (T-02-31 disposition: accept).
-    """
     quota = await session.get(Quota, user_id)
     if quota is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Quota not found")
@@ -70,12 +58,6 @@ async def update_user_quota(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Adjust a user's storage quota (ADMIN-04).
-
-    If the new limit is below current usage, still applies the change but
-    returns warning=True with an explanatory message. Uploads will be blocked
-    but existing documents are preserved.
-    """
     quota = await session.get(Quota, user_id)
     if quota is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Quota not found")
diff --git a/backend/api/admin/users.py b/backend/api/admin/users.py
index a7d833a..facddff 100644
--- a/backend/api/admin/users.py
+++ b/backend/api/admin/users.py
@@ -1,11 +1,3 @@
-"""Admin user-management endpoints.
-
-Handles: list_users, create_user, update_user_status, initiate_password_reset,
-         update_ai_config (per-user), delete_user, create_system_topic.
-
-All handlers require get_current_admin (SEC-07, T-08-04-01).
-Sub-router has NO prefix — parent __init__.py carries /api/admin (D-04).
-"""
 from __future__ import annotations
 
 import time
@@ -79,11 +71,6 @@ async def list_users(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """List all users, ordered by created_at DESC.
-
-    Response shape: { items: [...safe user fields...] }
-    Never includes password_hash, credentials_enc, or document content (T-02-27).
-    """
     result = await session.execute(
         select(User).order_by(User.created_at.desc())
     )
@@ -98,14 +85,6 @@ async def create_user(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Admin creates a new user account (ADMIN-01).
-
-    - password_must_change=True forces the user to change their password on
-      first login (T-02-32, D-06).
-    - Quota row initialized at 100 MB (D-06).
-    - Returns 409 if email or handle is already taken.
-    """
-    # Check uniqueness
     existing_email = await session.execute(
         select(User).where(User.email == str(body.email))
     )
@@ -172,11 +151,6 @@ async def update_user_status(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Deactivate or reactivate a user account (ADMIN-02).
-
-    - Prevents deactivating the last active admin (T-02-29).
-    - On deactivation: all refresh tokens are revoked (family revocation).
-    """
     user = await session.get(User, user_id)
     if user is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
@@ -237,15 +211,6 @@ async def initiate_password_reset(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Admin initiates a password reset for a user (ADMIN-03).
-
-    Sends the reset email via Celery. Does NOT:
-      - return a reset token (T-02-30)
-      - grant admin access to the account
-      - log in as the target user (ADMIN-07 — no impersonation)
-
-    Returns 202 immediately regardless of email delivery status.
-    """
     user = await session.get(User, user_id)
     if user is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
@@ -271,11 +236,6 @@ async def update_ai_config(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Assign AI provider and model for a user (ADMIN-05).
-
-    Users cannot change their own AI provider or model (PROJECT.md Key Decision).
-    Only admins have this capability.
-    """
     user = await session.get(User, user_id)
     if user is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
@@ -313,15 +273,6 @@ async def delete_user(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> None:
-    """Delete a user account and clean up all their MinIO objects (SEC-09, D-19).
-
-    Security invariants:
-      - Admin password verified via Argon2 before any deletion (T-05-11-01)
-      - Cannot delete admin accounts (T-04-07-04)
-      - MinIO objects are deleted BEFORE DB records are removed (SEC-09)
-      - MinIO deletion is best-effort (try/except) — DB row is deleted regardless
-      - Audit log written with event_type="admin.user_deleted"
-    """
     # T-05-11-01: Verify admin password before performing any destructive action.
     # Fail fast — no DB reads for the target user until the admin is confirmed.
     if not verify_password(body.admin_password, _admin.password_hash):
@@ -414,15 +365,6 @@ async def create_system_topic(
     session: AsyncSession = Depends(get_db),
     _admin: User = Depends(get_current_admin),
 ) -> dict:
-    """Create a system topic visible to all users (D-09, DOC-04).
-
-    System topics have user_id = NULL, making them visible to every user as
-    defaults in their topic namespace. Only admins can create system topics.
-    Regular users create per-user topics via POST /api/topics.
-
-    Deduplication: case-insensitive match within the system namespace (user_id IS NULL).
-    Returns the existing system topic if one with the same name already exists.
-    """
     from services import storage  # noqa: PLC0415
 
     topic = await storage.create_topic(
diff --git a/backend/api/auth/password.py b/backend/api/auth/password.py
index bb94f97..e9e0230 100644
--- a/backend/api/auth/password.py
+++ b/backend/api/auth/password.py
@@ -1,11 +1,3 @@
-"""
-Auth API — password management endpoints.
-
-Handles:
-  POST /change-password           — update password (requires current password)
-  POST /password-reset            — request a password reset email
-  POST /password-reset/confirm    — confirm a password reset using the token
-"""
 from __future__ import annotations
 
 import hashlib
@@ -43,34 +35,23 @@ async def change_password(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    """Update the current user's password.
-
-    Checks:
-      1. current_password matches stored hash
-      2. new_password has not appeared in HIBP (SEC-03)
-      3. new_password meets strength requirements (AUTH-01)
-    """
-    # Verify current password
     if not auth_service.verify_password(body.current_password, current_user.password_hash):
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Current password is incorrect",
         )
 
-    # HIBP breach check on new password (SEC-03)
     if await auth_service.check_hibp(body.new_password):
         raise HTTPException(
             status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
             detail="This password has appeared in a data breach. Choose a different password.",
         )
 
-    # Password strength check
     try:
         auth_service.validate_password_strength(body.new_password)
     except ValueError as exc:
         raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc))
 
-    # Update password
     _ip = get_client_ip(request)
     user = await session.get(User, current_user.id)
     user.password_hash = auth_service.hash_password(body.new_password)
@@ -108,12 +89,7 @@ async def password_reset_request(
     body: PasswordResetRequest,
     session: AsyncSession = Depends(get_db),
 ):
-    """Request a password reset email.
-
-    Always returns 202 regardless of whether the email exists (anti-enumeration, T-02-22).
-    If the user is found, a signed reset token (1-hour JWT) is generated and a Celery
-    task is enqueued to send the email (D-02, D-03).
-    """
+    # Always returns 202 regardless of whether email exists — anti-enumeration (T-02-22)
     from sqlalchemy import select as _select  # noqa: PLC0415 (already imported above)
 
     result = await session.execute(_select(User).where(User.email == str(body.email)))
@@ -142,12 +118,7 @@ async def password_reset_confirm(
     body: PasswordResetConfirmRequest,
     session: AsyncSession = Depends(get_db),
 ):
-    """Confirm a password reset using the token from the email link.
-
-    Validates the reset token, enforces password strength + HIBP check, updates
-    the password, and revokes all refresh tokens. Does NOT issue new tokens —
-    the user must sign in again through /login (AUTH-05, T-02-21).
-    """
+    # Does NOT issue new tokens — user must re-authenticate through /login (AUTH-05, T-02-21)
     try:
         user_id_str = auth_service.decode_password_reset_token(body.token)
     except ValueError:
@@ -156,20 +127,17 @@ async def password_reset_confirm(
             detail="Invalid or expired reset link",
         )
 
-    # Password strength validation
     try:
         auth_service.validate_password_strength(body.new_password)
     except ValueError as exc:
         raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc))
 
-    # HIBP breach check (SEC-03)
     if await auth_service.check_hibp(body.new_password):
         raise HTTPException(
             status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
             detail="This password has appeared in a data breach. Choose a different password.",
         )
 
-    # Load user
     user = await session.get(User, uuid.UUID(user_id_str))
     if user is None or not user.is_active:
         raise HTTPException(
@@ -177,7 +145,6 @@ async def password_reset_confirm(
             detail="Invalid or expired reset link",
         )
 
-    # Update password and revoke all sessions (forces re-auth through TOTP if enabled)
     user.password_hash = auth_service.hash_password(body.new_password)
     await auth_service.revoke_all_refresh_tokens(session, user.id)
     # Revoke any pre-reset access tokens still within their TTL window (T-7.2-01)
diff --git a/backend/api/auth/shared.py b/backend/api/auth/shared.py
index 95e413c..9dfa1a2 100644
--- a/backend/api/auth/shared.py
+++ b/backend/api/auth/shared.py
@@ -1,11 +1,3 @@
-"""
-Auth API — shared helpers, Pydantic request models, and the Limiter instance.
-
-This module is imported by every auth sub-module (tokens.py, totp.py, password.py).
-The Limiter instance is re-exported from api/auth/__init__.py so that:
-  from api.auth import limiter
-continues to work in main.py and the 5 test files without modification.
-"""
 from __future__ import annotations
 
 from typing import Literal, Optional
@@ -18,7 +10,6 @@ from config import settings
 from deps.utils import get_client_ip
 
 # IP-level rate limiter (SEC-02 — 10 req/min on register/login/refresh)
-# Re-exported from api/auth/__init__.py via: from api.auth.shared import limiter
 limiter = Limiter(key_func=get_client_ip)
 
 
diff --git a/backend/api/auth/tokens.py b/backend/api/auth/tokens.py
index d5266ce..e4fad4b 100644
--- a/backend/api/auth/tokens.py
+++ b/backend/api/auth/tokens.py
@@ -1,17 +1,3 @@
-"""
-Auth API — token-issuing endpoints.
-
-Handles:
-  POST /register        — new user registration with HIBP check
-  POST /login           — login with optional TOTP/backup-code second factor
-  POST /refresh         — rotate refresh token (httpOnly cookie in/out)
-  POST /logout          — revoke current refresh token, clear cookie
-  POST /logout-all      — revoke all refresh tokens for current user
-  GET  /me              — return current user profile
-  GET  /me/quota        — return current user quota
-  GET  /me/preferences  — return current user preferences
-  PATCH /me/preferences — update current user preferences
-"""
 from __future__ import annotations
 
 import hashlib
@@ -51,27 +37,17 @@ async def register(
     body: RegisterRequest,
     session: AsyncSession = Depends(get_db),
 ):
-    """Register a new user account.
-
-    - Validates password strength (min 12 chars, upper, lower, digit, special)
-    - Checks HIBP k-anonymity API for breached passwords
-    - Hashes password with Argon2
-    - Inserts User + Quota rows in a single transaction
-    """
-    # Password strength check
     try:
         auth_service.validate_password_strength(body.password)
     except ValueError as exc:
         raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=str(exc))
 
-    # HIBP breach check
     if await auth_service.check_hibp(body.password):
         raise HTTPException(
             status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
             detail="This password has appeared in a data breach. Choose a different password.",
         )
 
-    # Duplicate email/handle check
     result = await session.execute(
         select(User).where(
             (User.email == str(body.email)) | (User.handle == body.handle)
@@ -83,7 +59,6 @@ async def register(
             detail="Email or handle already in use",
         )
 
-    # Create user and quota
     user_id = uuid.uuid4()
     new_user = User(
         id=user_id,
@@ -132,23 +107,11 @@ async def login(
     response: Response,
     session: AsyncSession = Depends(get_db),
 ):
-    """Authenticate a user and issue tokens.
-
-    Per-account rate limiting (SEC-02): checks Redis counter keyed by email
-    BEFORE any DB lookup to prevent enumeration timing attacks.
-
-    Three login flows:
-      1. No TOTP enabled: password → tokens
-      2. TOTP enabled, no code provided: requires_totp = True (challenge)
-      3. TOTP enabled, totp_code provided: verify TOTP → tokens
-      4. TOTP enabled, backup_code provided (no totp_code): verify backup → tokens
-    """
-    # Per-account rate limiting (SEC-02)
+    # Per-account rate limiting (SEC-02): Redis counter keyed by email, checked before any DB lookup
     redis_client = request.app.state.redis
     rate_key = f"login_attempts:{body.email}"
     count = await redis_client.incr(rate_key)
     if count == 1:
-        # Set TTL only on first increment (15-minute window)
         await redis_client.expire(rate_key, 900)
     if count > 10:
         raise HTTPException(
@@ -156,11 +119,9 @@ async def login(
             detail="Too many login attempts. Try again in 15 minutes.",
         )
 
-    # Look up user by email
     result = await session.execute(select(User).where(User.email == str(body.email)))
     user: Optional[User] = result.scalar_one_or_none()
 
-    # IP extraction for audit log (used in both success and failure paths)
     _ip = get_client_ip(request)
 
     # Verify password (anti-enumeration: same error regardless of whether user exists)
@@ -180,7 +141,6 @@ async def login(
             detail="Incorrect email or password",
         )
 
-    # Active check
     if not user.is_active:
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
@@ -191,10 +151,8 @@ async def login(
     if user.password_must_change:
         return {"requires_password_change": True, "user_id": str(user.id)}
 
-    # TOTP second-factor dispatch
     if user.totp_enabled:
         if body.totp_code is None and body.backup_code is None:
-            # Challenge: prompt for second factor
             return {"requires_totp": True}
 
         if body.totp_code is not None:
@@ -223,7 +181,6 @@ async def login(
                 ip_address=_ip,
             )
 
-    # Issue tokens
     access_token = auth_service.create_access_token(
         str(user.id),
         user.role,
@@ -266,12 +223,7 @@ async def refresh_token(
     response: Response,
     session: AsyncSession = Depends(get_db),
 ):
-    """Rotate the refresh token.
-
-    Reads the refresh_token httpOnly cookie; on success issues a new access
-    token and rotates the refresh cookie.
-    On token reuse (revoked token presented), revokes entire family and raises 401.
-    """
+    # Token reuse (revoked token presented) revokes entire family — family revocation security contract
     raw_token = request.cookies.get("refresh_token")
     if not raw_token:
         raise HTTPException(
@@ -292,7 +244,6 @@ async def refresh_token(
             detail="Invalid or expired refresh token",
         ) from exc
 
-    # Look up user for response body
     user = await session.get(User, uuid.UUID(user_id_str))
     if user is None or not user.is_active:
         raise HTTPException(
@@ -300,7 +251,6 @@ async def refresh_token(
             detail="User not found or deactivated",
         )
 
-    # Set new refresh cookie
     _set_refresh_cookie(response, new_raw)
 
     access_token = auth_service.create_access_token(
@@ -325,7 +275,6 @@ async def refresh_token(
 
 @router.post("/logout")
 async def logout(request: Request, response: Response, session: AsyncSession = Depends(get_db)):
-    """Revoke current refresh token and clear the cookie."""
     import hashlib as _hashlib
 
     _ip = get_client_ip(request)
@@ -365,7 +314,6 @@ async def logout_all(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    """Sign out of all devices: revoke all refresh tokens for current user."""
     _ip = get_client_ip(request)
     count = await auth_service.revoke_all_refresh_tokens(session, current_user.id)
     # D-13: sign-out-all event
@@ -387,7 +335,6 @@ async def logout_all(
 
 @router.get("/me")
 async def get_me(current_user: User = Depends(get_current_user)):
-    """Return the current user's profile (requires valid Bearer token)."""
     return _user_dict(current_user)
 
 
@@ -398,11 +345,6 @@ async def get_my_quota(
     current_user: User = Depends(get_current_user),
     session: AsyncSession = Depends(get_db),
 ):
-    """Return the current user's quota usage (STORE-04).
-
-    Returns {"used_bytes": int, "limit_bytes": int} for the sidebar quota bar.
-    Quota row is created at registration (100 MB default — STORE-01).
-    """
     q = await session.get(Quota, current_user.id)
     if q is None:
         raise HTTPException(status_code=404, detail="Quota not found")
@@ -415,11 +357,7 @@ async def get_my_quota(
 async def get_my_preferences(
     current_user: User = Depends(get_current_user),
 ):
-    """Return the current user's PDF open mode preference (D-10).
-
-    Both regular users and admins can read their own preferences.
-    Falls back to 'in_app' if the column is absent (migration not yet run).
-    """
+    # Falls back to 'in_app' if the column is absent (migration not yet run)
     try:
         pdf_open_mode = current_user.pdf_open_mode
     except AttributeError:
@@ -435,11 +373,7 @@ async def update_my_preferences(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    """Update the current user's PDF open mode preference (D-10).
-
-    Both regular users and admins can update their own preferences.
-    Pydantic Literal["in_app", "new_tab"] enforces strict allowlist (T-04-05-05).
-    """
+    # Pydantic Literal["in_app", "new_tab"] enforces strict allowlist (T-04-05-05)
     user = await session.get(User, current_user.id)
     if user is None:
         raise HTTPException(status_code=404, detail="User not found")
diff --git a/backend/api/auth/totp.py b/backend/api/auth/totp.py
index 4bc4e0e..da8cf3c 100644
--- a/backend/api/auth/totp.py
+++ b/backend/api/auth/totp.py
@@ -1,11 +1,3 @@
-"""
-Auth API — TOTP endpoints.
-
-Handles:
-  GET    /totp/setup   — provision TOTP secret for current user
-  POST   /totp/enable  — enable TOTP (verify code, generate backup codes)
-  DELETE /totp         — disable TOTP (clear secret, revoke other sessions)
-"""
 from __future__ import annotations
 
 import hashlib
@@ -34,12 +26,6 @@ async def totp_setup(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    """Provision a TOTP secret for the current user.
-
-    If TOTP is already enabled, returns 400.
-    Returns { provisioning_uri, secret } — the provisioning_uri is suitable
-    for QR code generation. The secret is the base32-encoded TOTP secret.
-    """
     if current_user.totp_enabled:
         raise HTTPException(
             status_code=status.HTTP_400_BAD_REQUEST,
@@ -59,14 +45,7 @@ async def enable_totp(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    """Enable TOTP for the current user.
-
-    Rate-limited to 10 attempts/minute per IP (SEC-02 / T-02-25).
-    Verifies the submitted 6-digit code (with Redis replay prevention, AUTH-08).
-    On success: marks TOTP enabled, generates and returns 10 one-time backup codes.
-    The backup codes are ONLY returned here — they are stored as Argon2 hashes
-    in the DB and never returned again (T-02-19).
-    """
+    # Backup codes are returned here ONLY — stored as Argon2 hashes, never returned again (T-02-19)
     redis_client = request.app.state.redis
     ok = await auth_service.verify_totp(session, current_user.id, body.code, redis_client)
     if not ok:
@@ -75,12 +54,10 @@ async def enable_totp(
             detail="Incorrect or expired code",
         )
 
-    # Mark TOTP as enabled
     user = await session.get(User, current_user.id)
     user.totp_enabled = True
     await session.flush()
 
-    # Generate and store 10 backup codes; return plaintext to user (one-time, T-02-19)
     plain_codes = auth_service.generate_backup_codes(10)
     await auth_service.store_backup_codes(session, current_user.id, plain_codes)
 
@@ -119,16 +96,11 @@ async def disable_totp(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    """Disable TOTP for the current user.
-
-    Clears totp_secret, sets totp_enabled=False, and deletes all backup codes.
-    """
     _ip = get_client_ip(request)
     user = await session.get(User, current_user.id)
     user.totp_enabled = False
     user.totp_secret = None
 
-    # Delete all backup codes for this user (including unused ones)
     await session.execute(delete(BackupCode).where(BackupCode.user_id == current_user.id))
 
     # Revoke other sessions; keep current one alive via skip_token_hash (CR-03)
diff --git a/backend/api/documents/content.py b/backend/api/documents/content.py
index 6cd99f7..8f5f9a8 100644
--- a/backend/api/documents/content.py
+++ b/backend/api/documents/content.py
@@ -62,19 +62,6 @@ async def stream_document_content(
     session: AsyncSession = Depends(get_db),
     current_user: User = Depends(get_regular_user),
 ):
-    """Stream document bytes directly from MinIO (DOC-02).
-
-    T-04-05-01: uses get_regular_user — admin role → 403 (critical security invariant).
-    T-04-05-02: bytes fetched via get_object() ONLY — presigned_get_url() never called.
-    T-04-05-03: Range header validated via _parse_range(); invalid range → 416.
-    T-04-05-04: access gated on ownership OR active Share.recipient_id.
-
-    Returns 200 (or 206 for Range requests) with:
-      Content-Type: doc.content_type
-      Content-Disposition: inline; filename="<filename>"
-      Accept-Ranges: bytes
-      Content-Length: <size>
-    """
     request.state.current_user = current_user
     try:
         uid = uuid.UUID(doc_id)
@@ -97,9 +84,6 @@ async def stream_document_content(
         if share is None:
             raise HTTPException(status_code=404, detail="Document not found")
 
-    # Fetch bytes from the correct backend — get_storage_backend_for_document handles
-    # all backends (MinIO, Google Drive, OneDrive, Nextcloud, WebDAV) transparently
-    # (D-15, T-04-05-02). NEVER via presigned URL for cloud backends (D-14).
     try:
         import api.documents as _doc_pkg  # late import allows test monkeypatching via api.documents
         storage_backend = await _doc_pkg.get_storage_backend_for_document(doc, current_user, session)
diff --git a/backend/api/documents/crud.py b/backend/api/documents/crud.py
index c6d1963..5b989d5 100644
--- a/backend/api/documents/crud.py
+++ b/backend/api/documents/crud.py
@@ -99,12 +99,10 @@ async def list_documents(
             items.append(d)
         return {"items": items, "total": total, "page": page, "per_page": per_page}
 
-    # New path: direct ORM query with sort/filter/FTS
     from db.models import DocumentTopic, Topic  # noqa: PLC0415 (avoid circular at module top)
 
     stmt = select(Document).where(Document.user_id == current_user.id)
 
-    # Topic filter (join-based, same as list_metadata)
     if topic is not None:
         stmt = (
             stmt.join(DocumentTopic, DocumentTopic.document_id == Document.id)
@@ -112,7 +110,6 @@ async def list_documents(
             .where(Topic.name == topic)
         )
 
-    # Folder filter
     if folder_id is not None:
         try:
             folder_uuid = uuid.UUID(folder_id)
@@ -120,7 +117,6 @@ async def list_documents(
             raise HTTPException(status_code=404, detail="Folder not found")
         stmt = stmt.where(Document.folder_id == folder_uuid)
 
-    # Sort
     sort_col = Document.created_at  # default: date
     if sort == "name":
         sort_col = Document.filename
@@ -147,13 +143,11 @@ async def list_documents(
         result = await session.execute(stmt)
     docs_orm = result.scalars().all()
 
-    # is_shared subquery
     shared_result = await session.execute(
         select(Share.document_id).where(Share.owner_id == current_user.id)
     )
     shared_ids = {row[0] for row in shared_result.fetchall()}
 
-    # Serialize
     all_items = []
     for doc in docs_orm:
         from services.storage import _doc_to_dict, _load_topic_names  # noqa: PLC0415
@@ -199,7 +193,6 @@ async def get_document(
 
     is_recipient = False
     if doc.user_id != current_user.id:
-        # Allow recipients of an active share to view the document
         share_result = await session.execute(
             select(Share).where(
                 Share.document_id == uid,
@@ -250,7 +243,6 @@ async def patch_document(
     if doc is None or doc.user_id != current_user.id:
         raise HTTPException(404, "Document not found")
 
-    # Require at least one field to be set (model_fields_set tracks provided fields)
     if not body.model_fields_set:
         raise HTTPException(422, "At least one field (filename, folder_id) must be provided")
 
@@ -311,7 +303,6 @@ async def delete_document(
     _doc_id = doc.id
     _ip = get_client_ip(request)
 
-    # Cloud routing: attempt provider delete unless remove_only is set
     if is_cloud and not remove_only:
         try:
             import api.documents as _doc_pkg  # late import allows test monkeypatching via api.documents
diff --git a/backend/api/documents/upload.py b/backend/api/documents/upload.py
index 5e9823a..99060fe 100644
--- a/backend/api/documents/upload.py
+++ b/backend/api/documents/upload.py
@@ -129,7 +129,6 @@ async def upload_document(
     """
     request.state.current_user = current_user
     if target_backend == "minio":
-        # MinIO: generate a presigned URL for client-side PUT (existing flow reused)
         doc_id = uuid.uuid4()
         suffix = Path(file.filename or "file").suffix.lower()
         object_key = f"{current_user.id}/{doc_id}/{uuid.uuid4()}{suffix}"
@@ -152,7 +151,6 @@ async def upload_document(
         )
         return {"upload_url": upload_url, "document_id": str(doc_id)}
 
-    # Cloud backend path
     if target_backend not in _CLOUD_PROVIDERS:
         raise HTTPException(
             status_code=422,
@@ -174,11 +172,9 @@ async def upload_document(
             detail=f"No active {target_backend} connection found. Please connect in Settings.",
         )
 
-    # Decrypt per-user credentials
     master_key = settings.cloud_creds_key.encode()
     credentials = decrypt_credentials(master_key, str(current_user.id), conn.credentials_enc)
 
-    # Read file bytes
     file_bytes = await file.read()
     filename = file.filename or "upload"
     content_type = file.content_type or "application/octet-stream"
@@ -186,7 +182,6 @@ async def upload_document(
 
     doc_id = uuid.uuid4()
 
-    # Instantiate backend and upload
     if target_backend == "google_drive":
         from storage.google_drive_backend import GoogleDriveBackend  # lazy import
         cloud_backend = GoogleDriveBackend(credentials)
@@ -319,13 +314,11 @@ async def confirm_upload(
     row = result.fetchone()
 
     if row is None:
-        # Quota exceeded — fetch current quota state for the 413 body
         quota_result = await session.execute(
             text("SELECT used_bytes, limit_bytes FROM quotas WHERE user_id = :uid"),
             {"uid": doc.user_id.hex},
         )
         q = quota_result.fetchone()
-        # Delete the pending Document row and best-effort remove the MinIO object
         await session.delete(doc)
         try:
             await get_storage_backend().delete_object(doc.object_key)