Add historical UI and backend API slice

backend/app/config.py

@@ -12,6 +12,9 @@ DEFAULT_STORAGE_FILENAME = "hll_vietnam_dev.sqlite3"
 DEFAULT_REFRESH_INTERVAL_SECONDS = 120
 DEFAULT_HISTORICAL_CRCON_PAGE_SIZE = 50
 DEFAULT_HISTORICAL_CRCON_TIMEOUT_SECONDS = 15.0
+DEFAULT_HISTORICAL_REFRESH_INTERVAL_SECONDS = 1800
+DEFAULT_HISTORICAL_REFRESH_MAX_RETRIES = 2
+DEFAULT_HISTORICAL_REFRESH_RETRY_DELAY_SECONDS = 30
 DEFAULT_ALLOWED_ORIGINS = (
     "null",
     "http://127.0.0.1:5500",
@@ -95,6 +98,47 @@ def get_historical_crcon_request_timeout_seconds() -> float:
     return timeout_seconds
 
 
+def get_historical_refresh_interval_seconds() -> int:
+    """Return the default interval used by the historical refresh loop."""
+    configured_value = os.getenv(
+        "HLL_HISTORICAL_REFRESH_INTERVAL_SECONDS",
+        str(DEFAULT_HISTORICAL_REFRESH_INTERVAL_SECONDS),
+    )
+    interval_seconds = int(configured_value)
+    if interval_seconds <= 0:
+        raise ValueError("HLL_HISTORICAL_REFRESH_INTERVAL_SECONDS must be positive.")
+
+    return interval_seconds
+
+
+def get_historical_refresh_max_retries() -> int:
+    """Return the retry count used by the historical refresh loop."""
+    configured_value = os.getenv(
+        "HLL_HISTORICAL_REFRESH_MAX_RETRIES",
+        str(DEFAULT_HISTORICAL_REFRESH_MAX_RETRIES),
+    )
+    max_retries = int(configured_value)
+    if max_retries < 0:
+        raise ValueError("HLL_HISTORICAL_REFRESH_MAX_RETRIES must be zero or positive.")
+
+    return max_retries
+
+
+def get_historical_refresh_retry_delay_seconds() -> int:
+    """Return the wait time between historical refresh retries."""
+    configured_value = os.getenv(
+        "HLL_HISTORICAL_REFRESH_RETRY_DELAY_SECONDS",
+        str(DEFAULT_HISTORICAL_REFRESH_RETRY_DELAY_SECONDS),
+    )
+    retry_delay_seconds = int(configured_value)
+    if retry_delay_seconds < 0:
+        raise ValueError(
+            "HLL_HISTORICAL_REFRESH_RETRY_DELAY_SECONDS must be zero or positive."
+        )
+
+    return retry_delay_seconds
+
+
 def get_a2s_targets_payload() -> str | None:
     """Return the optional JSON payload that overrides local A2S targets."""
     raw_payload = os.getenv(DEFAULT_A2S_TARGETS_ENV_VAR)