Fix date framing in briefings and make Blogger posts idempotent

The 9/1 briefing called the US 8/31 session "9월 첫 거래일" - the LLM
was anchoring on the KRX date. Both prompts now pin every temporal
phrase (weekday, first/last trading day, month boundaries) to the US
session date, and the verifier treats a mismatch as a major issue.
BloggerDeliverer now updates the existing post for the same KRX date
instead of creating a duplicate on resends.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_blogger.py

@@ -64,8 +64,8 @@ class FakeHttp:
         self._responses = list(responses)
         self.calls: list[dict[str, Any]] = []
 
-    def post(self, url: str, **kwargs: Any) -> Any:
-        self.calls.append({"url": url, **kwargs})
+    def request(self, method: str, url: str, **kwargs: Any) -> Any:
+        self.calls.append({"method": method, "url": url, **kwargs})
         if not self._responses:
             raise AssertionError("unexpected extra HTTP call")
         item = self._responses.pop(0)
@@ -73,6 +73,9 @@ class FakeHttp:
             raise item
         return item
 
+    def post(self, url: str, **kwargs: Any) -> Any:
+        return self.request("POST", url, **kwargs)
+
 
 def make_deliverer(responses: list[Any]) -> tuple[BloggerDeliverer, FakeHttp]:
     client = FakeHttp(responses)
@@ -97,23 +100,59 @@ def test_post_title_with_and_without_headline():
 
 
 # ------------------------------------------------------------------ delivery
-def test_deliver_refreshes_token_posts_and_returns_url():
-    deliverer, client = make_deliverer([_Resp(200, TOKEN_OK), _Resp(200, POST_OK)])
+EMPTY_LIST = {"kind": "blogger#postList"}  # no items key on an empty blog
+
+
+def test_deliver_refreshes_token_lists_then_inserts():
+    deliverer, client = make_deliverer(
+        [_Resp(200, TOKEN_OK), _Resp(200, EMPTY_LIST), _Resp(200, POST_OK)]
+    )
     receipt = deliverer.deliver(make_result())
 
     assert receipt == POST_OK["url"]
-    token_call, post_call = client.calls
+    token_call, list_call, insert_call = client.calls
     assert token_call["data"]["grant_type"] == "refresh_token"
-    assert "refresh_token" not in post_call["url"]  # secrets never in URLs
-    assert post_call["url"].endswith("/blogs/12345/posts/")
-    assert post_call["headers"]["Authorization"] == "Bearer at-1"
-    body = post_call["json"]
+    assert list_call["method"] == "GET" and list_call["params"]["fetchBodies"] == "false"
+    assert insert_call["method"] == "POST"
+    assert "refresh_token" not in insert_call["url"]  # secrets never in URLs
+    assert insert_call["url"].endswith("/blogs/12345/posts/")
+    assert insert_call["headers"]["Authorization"] == "Bearer at-1"
+    body = insert_call["json"]
     assert body["title"].startswith("미국 마감 브리핑 2026-09-01")
     assert body["labels"] == ["미국증시"] and "<table>" in body["content"]
 
 
+def test_deliver_updates_existing_post_for_same_day():
+    listing = {"items": [{"id": "42", "title": "미국 마감 브리핑 2026-09-01 — 이전 헤드라인"}]}
+    deliverer, client = make_deliverer(
+        [_Resp(200, TOKEN_OK), _Resp(200, listing), _Resp(200, POST_OK)]
+    )
+    receipt = deliverer.deliver(make_result())
+    assert receipt == POST_OK["url"]
+    update_call = client.calls[-1]
+    assert update_call["method"] == "PUT"
+    assert update_call["url"].endswith("/blogs/12345/posts/42")
+
+
+def test_deliver_other_day_posts_do_not_match():
+    listing = {"items": [{"id": "41", "title": "미국 마감 브리핑 2026-08-29 — 다른 날"}]}
+    deliverer, client = make_deliverer(
+        [_Resp(200, TOKEN_OK), _Resp(200, listing), _Resp(200, POST_OK)]
+    )
+    deliverer.deliver(make_result())
+    assert client.calls[-1]["method"] == "POST"  # inserted, not updated
+
+
 def test_deliver_reuses_cached_token():
-    deliverer, client = make_deliverer([_Resp(200, TOKEN_OK), _Resp(200, POST_OK), _Resp(200, POST_OK)])
+    deliverer, client = make_deliverer(
+        [
+            _Resp(200, TOKEN_OK),
+            _Resp(200, EMPTY_LIST),
+            _Resp(200, POST_OK),
+            _Resp(200, EMPTY_LIST),
+            _Resp(200, POST_OK),
+        ]
+    )
     deliverer.deliver(make_result())
     deliverer.deliver(make_result())
     token_calls = [c for c in client.calls if "oauth2" in c["url"]]
@@ -124,8 +163,9 @@ def test_deliver_retries_once_on_401_with_fresh_token():
     deliverer, client = make_deliverer(
         [
             _Resp(200, TOKEN_OK),
-            _Resp(401, {"error": "invalid token"}),
+            _Resp(401, {"error": "invalid token"}),  # list call rejected
             _Resp(200, {"access_token": "at-2", "expires_in": 3600}),
+            _Resp(200, EMPTY_LIST),
             _Resp(200, POST_OK),
         ]
     )
@@ -134,20 +174,32 @@ def test_deliver_retries_once_on_401_with_fresh_token():
     assert client.calls[-1]["headers"]["Authorization"] == "Bearer at-2"
 
 
+def test_deliver_lookup_failure_still_publishes(monkeypatch):
+    monkeypatch.setattr("us2kr.deliver.blogger.time.sleep", lambda _s: None)
+    deliverer, client = make_deliverer(
+        [_Resp(200, TOKEN_OK)] + [_Resp(503, {"error": "backend"})] * 3 + [_Resp(200, POST_OK)]
+    )
+    receipt = deliverer.deliver(make_result())
+    assert receipt == POST_OK["url"]
+    assert client.calls[-1]["method"] == "POST"
+
+
 def test_deliver_retries_5xx_then_raises(monkeypatch):
     monkeypatch.setattr("us2kr.deliver.blogger.time.sleep", lambda _s: None)
     deliverer, _client = make_deliverer(
-        [_Resp(200, TOKEN_OK)] + [_Resp(503, {"error": "backend"})] * 3
+        [_Resp(200, TOKEN_OK), _Resp(200, EMPTY_LIST)] + [_Resp(503, {"error": "backend"})] * 3
     )
     with pytest.raises(DeliveryError, match="HTTP 503"):
         deliverer.deliver(make_result())
 
 
 def test_deliver_does_not_retry_4xx():
-    deliverer, client = make_deliverer([_Resp(200, TOKEN_OK), _Resp(403, {"error": "forbidden"})])
+    deliverer, client = make_deliverer(
+        [_Resp(200, TOKEN_OK), _Resp(200, EMPTY_LIST), _Resp(403, {"error": "forbidden"})]
+    )
     with pytest.raises(DeliveryError, match="HTTP 403"):
         deliverer.deliver(make_result())
-    assert len(client.calls) == 2  # no extra attempts
+    assert len(client.calls) == 3  # no extra attempts
 
 
 def test_token_failure_raises_delivery_error():
@@ -159,7 +211,7 @@ def test_token_failure_raises_delivery_error():
 def test_network_error_wrapped(monkeypatch):
     monkeypatch.setattr("us2kr.deliver.blogger.time.sleep", lambda _s: None)
     deliverer, _ = make_deliverer(
-        [_Resp(200, TOKEN_OK)] + [httpx.ConnectError("boom")] * 3
+        [_Resp(200, TOKEN_OK), _Resp(200, EMPTY_LIST)] + [httpx.ConnectError("boom")] * 3
     )
     with pytest.raises(DeliveryError, match="ConnectError"):
         deliverer.deliver(make_result())