Expose data_lag_days in CityObservation; remove fragile num_districts==6 inference

baseline/policy.py

@@ -13,12 +13,7 @@ def get_client() -> OpenAI:
 
 def build_prompt(obs: CityObservation) -> str:
     num_districts = len(obs.districts)
-    # Infers data lag from district count because CityObservation does not expose
-    # data_lag_days directly. This works because hard (6 districts) is currently the
-    # only task with a data lag. If a new task is added with 6 districts and no lag,
-    # or a lag task with fewer districts, this will silently misbehave.
-    # Fix: expose data_lag_days in CityObservation and read it directly.
-    has_data_lag  = num_districts == 6
+    has_data_lag  = obs.data_lag_days > 0
 
     sorted_districts = sorted(
         obs.districts,

models.py

@@ -58,4 +58,5 @@ class CityObservation(Observation):
     available_resources:  int                       = Field(...,  description="Resource units remaining this turn")
     current_step:         int                       = Field(...,  description="Current step number")
     max_steps:            int                       = Field(...,  description="Total steps allowed this episode")
+    data_lag_days:        int                       = Field(0,    description="Reporting lag in days (0 = real-time, 3 = hard task)")
     message:              Optional[str]             = Field(None, description="Feedback string for debugging")

openenv.yaml

@@ -73,6 +73,9 @@ observation:
     reward:
       type: number
       nullable: true
+    data_lag_days:
+      type: integer
+      description: "Reporting lag in days (0 = real-time, 3 = hard task)"
     message:
       type: string
       nullable: true

server/utils.py

@@ -86,6 +86,7 @@ def build_observation(
         available_resources = state.available_resources,
         current_step        = step_count,
         max_steps           = state.max_steps,
+        data_lag_days       = state.data_lag_days,
         done                = done,
         reward              = reward,
         message             = message,