Add ENR take-up model, remove CTR, add OBR validation test

- ENR (entitled non-recipient) flags computed at microdata extraction time
  via a baseline simulation pass in write_clean_csvs; baked into clean CSVs
- Three-way take-up: reported receipt → always receives; ENR → full take-up
  rate; new entrant → new_entrant_rate (default 0.3)
- Remove CTR (council tax reduction) national modelling entirely — too many
  local schemes to model; taken as reported (zero in model)
- Remove CTR from parameters, simulation outputs, API, and frontend
- OBR validation test runs by default, skips gracefully if data/frs_clean
  absent (e.g. CI); checks ±generous tolerances on key 2025/26 aggregates
- Modal: add eu-west-1 region, fix concurrent inputs decorator order,
  fix FRS volume upload to store at volume root

Author: nikhilwoodruff

api/modal_app.py

@@ -102,18 +102,19 @@ def run_simulation(year: int, reform_json: Optional[str] = None) -> dict:
         try:
             result = subprocess.run(
                 cmd, capture_output=True, text=True, timeout=120,
-                env={**os.environ, "PARAMETERS_DIR": PARAMETERS_DIR},
+                cwd="/app",  # binary resolves parameters/ relative to cwd
             )
         except subprocess.TimeoutExpired:
             raise HTTPException(504, detail="Simulation timed out")
         if result.returncode != 0:
-            raise HTTPException(500, detail=f"Simulation failed: {result.stderr[:2000]}")
+            raise HTTPException(500, detail=f"Simulation failed: cmd={cmd} stderr={result.stderr[:2000]}")
         return json.loads(result.stdout)
 
     def get_baseline_params(year: int) -> dict:
         result = subprocess.run(
             [RUST_BINARY, "--year", str(year), "--export-params-json"],
             capture_output=True, text=True, timeout=10,
+            cwd="/app",
         )
         if result.returncode != 0:
             raise HTTPException(500, detail=f"Failed to load params: {result.stderr[:500]}")
@@ -132,7 +133,7 @@ async def cache_baselines():
     REFORM_SECTIONS = [
         "income_tax", "national_insurance", "universal_credit",
         "child_benefit", "benefit_cap", "housing_benefit",
-        "tax_credits", "council_tax_reduction", "scottish_child_payment",
+        "tax_credits", "scottish_child_payment",
         "pension_credit", "state_pension",
     ]
 
@@ -145,7 +146,6 @@ class SimulateRequest(BaseModel):
         benefit_cap: Optional[dict[str, Any]] = None
         housing_benefit: Optional[dict[str, Any]] = None
         tax_credits: Optional[dict[str, Any]] = None
-        council_tax_reduction: Optional[dict[str, Any]] = None
         scottish_child_payment: Optional[dict[str, Any]] = None
         pension_credit: Optional[dict[str, Any]] = None
         state_pension: Optional[dict[str, Any]] = None
@@ -159,7 +159,6 @@ class SimulateMultiYearRequest(BaseModel):
         benefit_cap: Optional[dict[str, Any]] = None
         housing_benefit: Optional[dict[str, Any]] = None
         tax_credits: Optional[dict[str, Any]] = None
-        council_tax_reduction: Optional[dict[str, Any]] = None
         scottish_child_payment: Optional[dict[str, Any]] = None
         pension_credit: Optional[dict[str, Any]] = None
         state_pension: Optional[dict[str, Any]] = None
@@ -232,10 +231,11 @@ async def health():
     # Startup caches all 7 year baselines — give it enough RAM
     memory=4096,
     cpu=4,
-    # Keep one container warm so the dashboard is snappy
-    keep_warm=1,
     timeout=300,
+    # EU West (Ireland) for lower latency from UK callers
+    region="eu-west-1",
 )
+@modal.concurrent(max_inputs=10)
 @modal.asgi_app()
 def api():
     return _make_fastapi_app()

api/upload_frs.py

@@ -27,15 +27,17 @@ def upload(local_dir: Path) -> None:
 
     volume = modal.Volume.from_name(FRS_VOLUME_NAME, create_if_missing=True)
 
-    print(f"Uploading FRS clean CSVs from {local_dir} → Modal Volume '{FRS_VOLUME_NAME}':{REMOTE_PATH}")
+    # Files are stored at the volume root (e.g. "persons.csv").
+    # The volume is mounted at FRS_MOUNT_PATH in the container, so
+    # container path /data/frs_clean/persons.csv == volume root persons.csv.
+    print(f"Uploading FRS clean CSVs from {local_dir} → Modal Volume '{FRS_VOLUME_NAME}' (root)")
     with volume.batch_upload(force=True) as batch:
         for csv_file in local_dir.glob("*.csv"):
-            remote = f"{REMOTE_PATH}/{csv_file.name}"
-            batch.put_file(str(csv_file), remote)
-            print(f"  {csv_file.name} → {remote}")
+            batch.put_file(str(csv_file), csv_file.name)
+            print(f"  {csv_file.name} → /{csv_file.name}")
 
     print("Done. Volume contents:")
-    for entry in volume.listdir(REMOTE_PATH):
+    for entry in volume.listdir("/"):
         print(f"  {entry.path}")
 
 

app/lib/constants.ts

@@ -863,68 +863,6 @@ export const SLIDERS: SliderConfig[] = [
     format: "percent",
   },
 
-  // ── Council Tax Reduction ───────────────────────────────────
-  {
-    key: "ctr_taper_rate",
-    label: "Taper Rate",
-    section: "Council Tax Reduction",
-    path: ["council_tax_reduction", "taper_rate"],
-    min: 0,
-    max: 1,
-    step: 0.01,
-    format: "percent",
-  },
-  {
-    key: "ctr_pa_single_under25",
-    label: "Personal Allowance (single <25, weekly)",
-    section: "Council Tax Reduction",
-    path: ["council_tax_reduction", "personal_allowance_single_under25"],
-    min: 0,
-    max: 150,
-    step: 1,
-    format: "currency",
-  },
-  {
-    key: "ctr_pa_single_25plus",
-    label: "Personal Allowance (single 25+, weekly)",
-    section: "Council Tax Reduction",
-    path: ["council_tax_reduction", "personal_allowance_single_25_plus"],
-    min: 0,
-    max: 200,
-    step: 1,
-    format: "currency",
-  },
-  {
-    key: "ctr_pa_couple",
-    label: "Personal Allowance (couple, weekly)",
-    section: "Council Tax Reduction",
-    path: ["council_tax_reduction", "personal_allowance_couple"],
-    min: 0,
-    max: 300,
-    step: 1,
-    format: "currency",
-  },
-  {
-    key: "ctr_child_allowance",
-    label: "Child Allowance (weekly)",
-    section: "Council Tax Reduction",
-    path: ["council_tax_reduction", "child_allowance"],
-    min: 0,
-    max: 200,
-    step: 1,
-    format: "currency",
-  },
-  {
-    key: "ctr_family_premium",
-    label: "Family Premium (weekly)",
-    section: "Council Tax Reduction",
-    path: ["council_tax_reduction", "family_premium"],
-    min: 0,
-    max: 50,
-    step: 0.5,
-    format: "currency",
-  },
-
   // ── Scottish Child Payment ──────────────────────────────────
   {
     key: "scp_weekly_amount",
@@ -959,7 +897,6 @@ export const SECTIONS = [
   "Benefit Cap",
   "Housing Benefit",
   "Tax Credits",
-  "Council Tax Reduction",
   "Scottish Child Payment",
 ];
 

parameters/2023_24.yaml

@@ -100,13 +100,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  taper_rate: 0.20
-  personal_allowance_single_under25: 67.25
-  personal_allowance_single_25_plus: 84.80
-  personal_allowance_couple: 133.30
-  child_allowance: 77.78
-  family_premium: 17.85
 
 scottish_child_payment:
   weekly_amount: 25.00

parameters/2024_25.yaml

@@ -102,13 +102,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  taper_rate: 0.20
-  personal_allowance_single_under25: 71.70
-  personal_allowance_single_25_plus: 90.50
-  personal_allowance_couple: 142.25
-  child_allowance: 83.73
-  family_premium: 18.53
 
 scottish_child_payment:
   weekly_amount: 26.70

parameters/2025_26.yaml

@@ -153,15 +153,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  # Council Tax Reduction Schemes (Prescribed Requirements) (England) Regs 2012
-  # SI 2012/2885
-  taper_rate: 0.20
-  personal_allowance_single_under25: 71.70
-  personal_allowance_single_25_plus: 90.50
-  personal_allowance_couple: 142.25
-  child_allowance: 83.73
-  family_premium: 18.53
 
 scottish_child_payment:
   # Social Security (Scotland) Act 2018; SSI 2020/351

parameters/2026_27.yaml

@@ -103,13 +103,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  taper_rate: 0.20
-  personal_allowance_single_under25: 71.70
-  personal_allowance_single_25_plus: 90.50
-  personal_allowance_couple: 142.25
-  child_allowance: 83.73
-  family_premium: 18.53
 
 scottish_child_payment:
   weekly_amount: 26.70

parameters/2027_28.yaml

@@ -101,13 +101,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  taper_rate: 0.20
-  personal_allowance_single_under25: 71.70
-  personal_allowance_single_25_plus: 90.50
-  personal_allowance_couple: 142.25
-  child_allowance: 83.73
-  family_premium: 18.53
 
 scottish_child_payment:
   weekly_amount: 26.70

parameters/2028_29.yaml

@@ -102,13 +102,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  taper_rate: 0.20
-  personal_allowance_single_under25: 71.70
-  personal_allowance_single_25_plus: 90.50
-  personal_allowance_couple: 142.25
-  child_allowance: 83.73
-  family_premium: 18.53
 
 scottish_child_payment:
   weekly_amount: 26.70

parameters/2029_30.yaml

@@ -101,13 +101,6 @@ tax_credits:
   wtc_min_hours_single: 30.0
   wtc_min_hours_couple: 24.0
 
-council_tax_reduction:
-  taper_rate: 0.20
-  personal_allowance_single_under25: 71.70
-  personal_allowance_single_25_plus: 90.50
-  personal_allowance_couple: 142.25
-  child_allowance: 83.73
-  family_premium: 18.53
 
 scottish_child_payment:
   weekly_amount: 26.70