diff --git a/backend/main.py b/backend/main.py
index 627ceca..1d50c2d 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Dict, List, Optional
 """VerIQ — FastAPI application (v1 MVP).
 
 Standalone public IQ test with signed, verifiable results.
@@ -23,11 +23,11 @@
 
 # --- in-memory test sessions (single-process MVP) ---------------------------
 # session_token -> {task_ids, started_at, ip}
-SESSIONS: dict[str, dict] = {}
+SESSIONS: Dict[str, dict] = {}
 SESSION_TTL_S = 60 * 60  # 1 hour to finish after start
 
 # --- simple per-IP rate limiting --------------------------------------------
-_RATE: dict[str, list[float]] = {}
+_RATE: Dict[str, List[float]] = {}
 RATE_LIMIT_STARTS_PER_HOUR = 10
 
 
@@ -64,13 +64,13 @@
 # --- models ------------------------------------------------------------------
 class StartResponse(BaseModel):
     session_token: str
-    tasks: list[dict]
+    tasks: List[dict]
     time_limit_s: int
 
 
 class FinishRequest(BaseModel):
     session_token: str
-    answers: dict[str, int] = Field(default_factory=dict)
+    answers: Dict[str, int] = Field(default_factory=dict)
     total_time_s: float = 0.0
 
 
diff --git a/backend/oauth.py b/backend/oauth.py
index 3316d99..e7d9ec2 100644
--- a/backend/oauth.py
+++ b/backend/oauth.py
@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Dict, Optional, Tuple
 """VerIQ — identity binding via OAuth (phase 2 scaffolding).
 
 X (Twitter): OAuth 2.0 Authorization Code with PKCE.
@@ -31,7 +31,7 @@
 IG_USERINFO = "https://graph.facebook.com/me"
 
 # in-memory PKCE/state store (single-process MVP; fine for v1)
-FLOWS: dict[str, dict] = {}
+FLOWS: Dict[str, dict] = {}
 FLOW_TTL_S = 600
 
 
@@ -70,7 +70,7 @@
     return {"state": state, "challenge": challenge, "verifier": verifier}
 
 
-def x_authorize_url(result_id: str) -> tuple[str, Optional[str]]:
+def x_authorize_url(result_id: str) -> Tuple[str, Optional[str]]:
     """Returns (authorize_url, state) or None if not configured."""
     cid = _env("X_CLIENT_ID")
     if not cid:
@@ -88,7 +88,7 @@
     return X_AUTHORIZE + "?" + urlencode(params), flow["state"]
 
 
-def ig_authorize_url(result_id: str) -> tuple[str, Optional[str]]:
+def ig_authorize_url(result_id: str) -> Tuple[str, Optional[str]]:
     app_id = _env("IG_APP_ID")
     if not app_id:
         return None
diff --git a/backend/scoring.py b/backend/scoring.py
index e50fbb0..44aea98 100644
--- a/backend/scoring.py
+++ b/backend/scoring.py
@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Dict, List, Optional
 """VerIQ — scoring: raw points -> IQ score + percentile.
 
 v1 model: fixed weights per difficulty tier, z-score normalization against
@@ -44,7 +44,7 @@
     return None
 
 
-def max_raw_score(task_ids: list[str]) -> int:
+def max_raw_score(task_ids: List[str]) -> int:
     total = 0
     for tid in task_ids:
         t = task_by_id(tid)
@@ -53,7 +53,7 @@
     return total
 
 
-def raw_score(answers: dict[str, int], task_ids: list[str]) -> int:
+def raw_score(answers: Dict[str, int], task_ids: List[str]) -> int:
     """answers: {task_id: chosen_index}. Missing = wrong."""
     total = 0
     for tid in task_ids:
@@ -77,7 +77,7 @@
     return None
 
 
-def score_test(answers: dict[str, int], task_ids: list[str],
+def score_test(answers: Dict[str, int], task_ids: List[str],
                total_time_s: float, flagged: bool) -> dict:
     """Compute raw score, IQ, percentile, category breakdown."""
     bank = load_bank()
@@ -99,7 +99,7 @@
     percentile = round(0.5 * (1 + math.erf(z / math.sqrt(2))) * 100, 1)
 
     # category breakdown
-    cats: dict[str, dict] = {}
+    cats: Dict[str, dict] = {}
     for tid in task_ids:
         t = task_by_id(tid)
         if not t:
@@ -122,7 +122,7 @@
     }
 
 
-def sanity_check(answers: dict[str, int], task_ids: list[str],
+def sanity_check(answers: Dict[str, int], task_ids: List[str],
                  total_time_s: float) -> bool:
     """Flag implausible completions: too fast or suspiciously perfect."""
     n = len(task_ids)