diff --git a/memory-update.md b/memory-update.md
index 09a4a308..ea616b36 100644
--- a/memory-update.md
+++ b/memory-update.md
@@ -104,3 +104,8 @@
 ## CI Black Check Failure Fix (2026-02-26)
 - `tests.yml` failed at `poetry run black --check .` on 9 files (SeedPass tests/core file plus TORCH script/backups).
 - Applied Black formatting to all reported files and verified `poetry run black --check .` passes locally.
+
+## Python 3.10 datetime.UTC Compatibility Fix (2026-02-26)
+- CI `test (ubuntu-latest, 3.10)` failed during test collection because `datetime.UTC` is unavailable on Python 3.10.
+- Replaced `datetime.UTC` usage with `timezone.utc` in `src/seedpass/cli/agent.py` and `scripts/ai_tui_agent_test.py`.
+- Verified with targeted tests: `src/tests/test_cli_agent_mode.py` and `src/tests/test_ai_tui_agent_harness.py`.
diff --git a/scripts/ai_tui_agent_test.py b/scripts/ai_tui_agent_test.py
index 504d899d..32a37389 100755
--- a/scripts/ai_tui_agent_test.py
+++ b/scripts/ai_tui_agent_test.py
@@ -27,7 +27,7 @@ import sys
 import tempfile
 import time
 from dataclasses import dataclass, asdict
-from datetime import datetime, UTC
+from datetime import datetime, timezone
 from pathlib import Path
 from typing import Pattern
 
@@ -860,7 +860,7 @@ def main() -> int:
         print(f"Error: cannot find {src_main}", file=sys.stderr)
         return 2
 
-    timestamp = datetime.now(UTC).strftime("%Y%m%dT%H%M%SZ")
+    timestamp = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
     artifact_dir = args.output_dir.resolve() / timestamp
     artifact_dir.mkdir(parents=True, exist_ok=True)
 
diff --git a/src/seedpass/cli/agent.py b/src/seedpass/cli/agent.py
index 91271dc3..f1655020 100644
--- a/src/seedpass/cli/agent.py
+++ b/src/seedpass/cli/agent.py
@@ -2,7 +2,7 @@ from __future__ import annotations
 
 import json
 import os
-from datetime import UTC, datetime, timedelta
+from datetime import datetime, timedelta, timezone
 from pathlib import Path
 from typing import Optional
 
@@ -365,7 +365,7 @@ def agent_get(
         )
         raise typer.Exit(1)
 
-    now = datetime.now(UTC)
+    now = datetime.now(timezone.utc)
     payload = {
         "status": "ok",
         "fingerprint": fingerprint,