Scope prompt recent history by session

Fixes #4259

tests/agent/test_memory_store.py

@@ -58,6 +58,12 @@ class TestHistoryWithCursor:
         data = json.loads(content)
         assert data["cursor"] == 1
 
+    def test_append_history_includes_session_key_when_provided(self, store):
+        store.append_history("event 1", session_key="telegram:chat-1")
+        content = store.read_file(store.history_file)
+        data = json.loads(content)
+        assert data["session_key"] == "telegram:chat-1"
+
     def test_cursor_persists_across_appends(self, store):
         store.append_history("event 1")
         store.append_history("event 2")
@@ -106,6 +112,54 @@ class TestHistoryWithCursor:
         entries = store.read_unprocessed_history(since_cursor=0)
         assert len(entries) == 2
 
+    def test_prompt_history_filters_to_current_session(self, store):
+        store.append_history("legacy entry without session")
+        store.append_history("telegram entry", session_key="telegram:chat-1")
+        store.append_history("slack entry", session_key="slack:chat-2")
+
+        entries = store.read_recent_history_for_prompt(
+            since_cursor=0,
+            session_key="telegram:chat-1",
+        )
+
+        assert [e["content"] for e in entries] == ["telegram entry"]
+        assert [e["content"] for e in store.read_unprocessed_history(0)] == [
+            "legacy entry without session",
+            "telegram entry",
+            "slack entry",
+        ]
+
+    def test_unified_prompt_history_excludes_internal_cron_sessions(self, store):
+        store.append_history("legacy entry without session")
+        store.append_history("unified entry", session_key="unified:default")
+        store.append_history("telegram entry", session_key="telegram:chat-1")
+        store.append_history("cron internal entry", session_key="cron:job-1")
+
+        entries = store.read_recent_history_for_prompt(
+            since_cursor=0,
+            session_key="unified:default",
+            unified_session=True,
+        )
+
+        assert [e["content"] for e in entries] == [
+            "legacy entry without session",
+            "unified entry",
+            "telegram entry",
+        ]
+
+    def test_unified_cron_prompt_history_includes_own_cron_entry(self, store):
+        store.append_history("unified entry", session_key="unified:default")
+        store.append_history("other cron entry", session_key="cron:job-2")
+        store.append_history("own cron entry", session_key="cron:job-1")
+
+        entries = store.read_recent_history_for_prompt(
+            since_cursor=0,
+            session_key="cron:job-1",
+            unified_session=True,
+        )
+
+        assert [e["content"] for e in entries] == ["unified entry", "own cron entry"]
+
     def test_read_unprocessed_skips_entries_without_cursor(self, store):
         """Regression: entries missing the cursor key should be silently skipped."""
         store.history_file.write_text(