feat(gateway): inject stable human-readable message timestamps

Consolidates these related Amy fork patches:
- 429830f39 feat(gateway): inject message timestamps into user messages for LLM context
- 3c3d6fac0 fix: handle both ISO string and epoch float timestamps in history replay
- 2874f7725 feat: human-friendly timestamp format with weekday and timezone name
- 3735f4c8b fix: render gateway message timestamps once

tests/gateway/test_fast_command.py

@@ -23,12 +23,20 @@ class _CapturingAgent:
         type(self).last_init = dict(kwargs)
         self.tools = []
 
-    def run_conversation(self, user_message, conversation_history=None, task_id=None, persist_user_message=None):
+    def run_conversation(
+        self,
+        user_message,
+        conversation_history=None,
+        task_id=None,
+        persist_user_message=None,
+        persist_user_timestamp=None,
+    ):
         type(self).last_run = {
             "user_message": user_message,
             "conversation_history": conversation_history,
             "task_id": task_id,
             "persist_user_message": persist_user_message,
+            "persist_user_timestamp": persist_user_timestamp,
         }
         return {
             "final_response": "ok",

tests/gateway/test_message_timestamps.py

@@ -0,0 +1,91 @@
+from datetime import datetime
+from zoneinfo import ZoneInfo
+
+from gateway.message_timestamps import (
+    coerce_message_timestamp,
+    render_user_content_with_timestamp,
+    strip_leading_message_timestamps,
+)
+from run_agent import AIAgent
+
+
+BERLIN = ZoneInfo("Europe/Berlin")
+
+
+def _epoch(year, month, day, hour, minute, second):
+    return datetime(year, month, day, hour, minute, second, tzinfo=BERLIN).timestamp()
+
+
+def test_render_user_content_adds_single_context_timestamp():
+    ts = _epoch(2026, 4, 28, 13, 40, 53)
+
+    rendered = render_user_content_with_timestamp(
+        "[Example User] Timestamp should be in context",
+        ts,
+        tz=BERLIN,
+    )
+
+    assert rendered == (
+        "[Tue 2026-04-28 13:40:53 CEST] "
+        "[Example User] Timestamp should be in context"
+    )
+
+
+def test_render_user_content_deduplicates_existing_timestamp_and_preserves_embedded_time():
+    db_processing_ts = _epoch(2026, 4, 27, 15, 55, 36)
+    stored_content = (
+        "[Mon 2026-04-27 15:54:44 CEST] "
+        "[Example User] This should go on our todo list"
+    )
+
+    rendered = render_user_content_with_timestamp(
+        stored_content,
+        db_processing_ts,
+        tz=BERLIN,
+    )
+
+    assert rendered == stored_content
+    assert rendered.count("2026-04-27") == 1
+
+
+def test_strip_leading_message_timestamps_removes_multiple_prefixes_and_prefers_inner_time():
+    content = (
+        "[Mon 2026-04-27 15:55:36 CEST] "
+        "[Mon 2026-04-27 15:54:44 CEST] "
+        "[Example User] This should go on our todo list"
+    )
+
+    stripped, embedded_ts = strip_leading_message_timestamps(content, tz=BERLIN)
+
+    assert stripped == "[Example User] This should go on our todo list"
+    assert embedded_ts == _epoch(2026, 4, 27, 15, 54, 44)
+
+
+def test_coerce_message_timestamp_accepts_datetime_and_epoch():
+    dt = datetime(2026, 4, 28, 13, 40, 53, tzinfo=BERLIN)
+
+    assert coerce_message_timestamp(dt, tz=BERLIN) == dt.timestamp()
+    assert coerce_message_timestamp(dt.timestamp(), tz=BERLIN) == dt.timestamp()
+
+
+def test_persist_user_message_override_keeps_clean_content_and_timestamp_metadata():
+    agent = AIAgent.__new__(AIAgent)
+    agent._persist_user_message_idx = 0
+    agent._persist_user_message_override = "[Example User] Clean content"
+    agent._persist_user_message_timestamp = _epoch(2026, 4, 28, 13, 40, 53)
+    messages = [
+        {
+            "role": "user",
+            "content": "[Tue 2026-04-28 13:40:53 CEST] [Example User] Clean content",
+        }
+    ]
+
+    agent._apply_persist_user_message_override(messages)
+
+    assert messages == [
+        {
+            "role": "user",
+            "content": "[Example User] Clean content",
+            "timestamp": _epoch(2026, 4, 28, 13, 40, 53),
+        }
+    ]

tests/gateway/test_session_api.py

@@ -241,7 +241,11 @@ async def test_session_chat_loads_history_and_preserves_session_headers(auth_ada
     assert kwargs["session_id"] == session_id
     assert kwargs["gateway_session_key"] == "client-42"
     assert kwargs["ephemeral_system_prompt"] == "stay focused"
-    assert kwargs["conversation_history"] == [
+    history = kwargs["conversation_history"]
+    assert len(history) == 2
+    assert isinstance(history[0].pop("timestamp"), (int, float))
+    assert isinstance(history[1].pop("timestamp"), (int, float))
+    assert history == [
         {"role": "user", "content": "earlier"},
         {"role": "assistant", "content": "prior answer"},
     ]