diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 02a0fd1..cfb7153 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,7 +15,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ["3.11", "3.12"]
+        python-version: ["3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v4
diff --git a/CITATION.cff b/CITATION.cff
index 3899e5c..8500a27 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -13,8 +13,8 @@ authors:
     given-names: "Don Michael"
 license: MIT
 repository-code: "https://github.com/dfeen87/Goodwill-KPI"
-version: "1.0.0"
-date-released: "2026-03-01"
+version: "1.1.0"
+date-released: "2026-03-04"
 keywords:
   - goodwill
   - KPI
diff --git a/app/main.py b/app/main.py
index 9692e3d..904539c 100644
--- a/app/main.py
+++ b/app/main.py
@@ -19,17 +19,19 @@
 
 import csv
 import io
+import math
 import os
 from datetime import datetime, timezone
-from typing import Optional
+from typing import NamedTuple, Optional
 
 from fastapi import FastAPI, Query, Request
 from fastapi.responses import HTMLResponse, JSONResponse, RedirectResponse, StreamingResponse
 from fastapi.templating import Jinja2Templates
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, model_validator
 
 from goodwill.metrics import compute_CG, compute_G, compute_UGS
 from goodwill import config as _cfg
+from goodwill import __version__
 
 # ---------------------------------------------------------------------------
 # App setup
@@ -38,13 +40,32 @@
 app = FastAPI(
     title="Goodwill KPI Dashboard",
     description="Read-only governance view for Goodwill metric calculations.",
-    version="1.0.0",
+    version=__version__,
 )
 
 _TEMPLATES_DIR = os.path.join(os.path.dirname(__file__), "templates")
 templates = Jinja2Templates(directory=_TEMPLATES_DIR)
 
 
+# ---------------------------------------------------------------------------
+# Security headers middleware
+# ---------------------------------------------------------------------------
+
+
+@app.middleware("http")
+async def add_security_headers(request: Request, call_next):
+    """Add standard security headers to every response."""
+    response = await call_next(request)
+    response.headers["X-Content-Type-Options"] = "nosniff"
+    response.headers["X-Frame-Options"] = "DENY"
+    response.headers["Content-Security-Policy"] = (
+        # 'unsafe-inline' is required for the dashboard's inline <script> block.
+        # Moving scripts to an external file would allow a stricter policy.
+        "default-src 'self'; script-src 'unsafe-inline'"
+    )
+    return response
+
+
 # ---------------------------------------------------------------------------
 # Request / Response models
 # ---------------------------------------------------------------------------
@@ -88,6 +109,22 @@ class GoodwillInput(BaseModel):
     ugs_w1: Optional[float] = Field(None, description="Weight for G in UGS (default: config)")
     ugs_w2: Optional[float] = Field(None, description="Weight for CG in UGS (default: config)")
 
+    @model_validator(mode="after")
+    def _validate_weights_finite(self) -> "GoodwillInput":
+        """Reject non-finite weight overrides (NaN, Infinity) at the API boundary."""
+        weight_fields = (
+            "g_w1", "g_w2", "g_w3", "g_w_t",
+            "cg_w1", "cg_w2", "cg_w3", "cg_w4",
+            "ugs_w1", "ugs_w2",
+        )
+        for field_name in weight_fields:
+            value = getattr(self, field_name)
+            if value is not None and not math.isfinite(value):
+                raise ValueError(
+                    f"Weight '{field_name}' = {value!r} must be a finite real number."
+                )
+        return self
+
 
 # ---------------------------------------------------------------------------
 # Routes
@@ -120,14 +157,10 @@ def calculate(inputs: GoodwillInput) -> JSONResponse:
     No state is persisted.  Results are fully traceable to inputs.
     """
     # Resolve weights — use explicit override or fall back to config defaults
-    g_w1, g_w2, g_w3, g_w_t, cg_w1, cg_w2, cg_w3, cg_w4, ugs_w1, ugs_w2 = (
-        _resolve_weights(inputs)
-    )
+    weights = _resolve_weights(inputs)
 
     # Execute equations (server-side, via pure functions — no duplication)
-    return JSONResponse(content=_build_result(inputs, g_w1, g_w2, g_w3, g_w_t,
-                                               cg_w1, cg_w2, cg_w3, cg_w4,
-                                               ugs_w1, ugs_w2))
+    return JSONResponse(content=_build_result(inputs, weights))
 
 
 # ---------------------------------------------------------------------------
@@ -135,67 +168,82 @@ def calculate(inputs: GoodwillInput) -> JSONResponse:
 # ---------------------------------------------------------------------------
 
 
-def _resolve_weights(inputs: GoodwillInput):
-    """Return resolved weight tuples (g, cg, ugs) from inputs or config defaults."""
-    return (
-        inputs.g_w1 if inputs.g_w1 is not None else _cfg.G_W1,
-        inputs.g_w2 if inputs.g_w2 is not None else _cfg.G_W2,
-        inputs.g_w3 if inputs.g_w3 is not None else _cfg.G_W3,
-        inputs.g_w_t if inputs.g_w_t is not None else _cfg.G_W_T,
-        inputs.cg_w1 if inputs.cg_w1 is not None else _cfg.CG_W1,
-        inputs.cg_w2 if inputs.cg_w2 is not None else _cfg.CG_W2,
-        inputs.cg_w3 if inputs.cg_w3 is not None else _cfg.CG_W3,
-        inputs.cg_w4 if inputs.cg_w4 is not None else _cfg.CG_W4,
-        inputs.ugs_w1 if inputs.ugs_w1 is not None else _cfg.UGS_W1,
-        inputs.ugs_w2 if inputs.ugs_w2 is not None else _cfg.UGS_W2,
+class ResolvedWeights(NamedTuple):
+    """Named container for resolved weight values used across all equations."""
+    g_w1: float
+    g_w2: float
+    g_w3: float
+    g_w_t: float
+    cg_w1: float
+    cg_w2: float
+    cg_w3: float
+    cg_w4: float
+    ugs_w1: float
+    ugs_w2: float
+
+
+def _resolve_weights(inputs: GoodwillInput) -> ResolvedWeights:
+    """Return resolved weight values from inputs or config defaults."""
+    return ResolvedWeights(
+        g_w1=inputs.g_w1 if inputs.g_w1 is not None else _cfg.G_W1,
+        g_w2=inputs.g_w2 if inputs.g_w2 is not None else _cfg.G_W2,
+        g_w3=inputs.g_w3 if inputs.g_w3 is not None else _cfg.G_W3,
+        g_w_t=inputs.g_w_t if inputs.g_w_t is not None else _cfg.G_W_T,
+        cg_w1=inputs.cg_w1 if inputs.cg_w1 is not None else _cfg.CG_W1,
+        cg_w2=inputs.cg_w2 if inputs.cg_w2 is not None else _cfg.CG_W2,
+        cg_w3=inputs.cg_w3 if inputs.cg_w3 is not None else _cfg.CG_W3,
+        cg_w4=inputs.cg_w4 if inputs.cg_w4 is not None else _cfg.CG_W4,
+        ugs_w1=inputs.ugs_w1 if inputs.ugs_w1 is not None else _cfg.UGS_W1,
+        ugs_w2=inputs.ugs_w2 if inputs.ugs_w2 is not None else _cfg.UGS_W2,
     )
 
 
-def _build_result(inputs, g_w1, g_w2, g_w3, g_w_t,
-                  cg_w1, cg_w2, cg_w3, cg_w4, ugs_w1, ugs_w2) -> dict:
+def _build_result(inputs: GoodwillInput, weights: ResolvedWeights) -> dict:
     """Execute all goodwill equations and return the full result payload."""
     G = compute_G(
         CR=inputs.CR, ES=inputs.ES, BT=inputs.BT, RG=inputs.RG,
         NCB=inputs.NCB, T=inputs.T,
-        w1=g_w1, w2=g_w2, w3=g_w3, w_t=g_w_t,
+        w1=weights.g_w1, w2=weights.g_w2, w3=weights.g_w3, w_t=weights.g_w_t,
     )
     CG = compute_CG(
         CS=inputs.CS, BR=inputs.BR, CA=inputs.CA, SS=inputs.SS,
         NCB_consumer=inputs.NCB_consumer,
-        w1=cg_w1, w2=cg_w2, w3=cg_w3, w4=cg_w4,
+        w1=weights.cg_w1, w2=weights.cg_w2, w3=weights.cg_w3, w4=weights.cg_w4,
     )
-    UGS = compute_UGS(G=G, CG=CG, T=inputs.T, w1=ugs_w1, w2=ugs_w2)
+    UGS = compute_UGS(G=G, CG=CG, T=inputs.T, w1=weights.ugs_w1, w2=weights.ugs_w2)
     return {
         "G": G,
         "CG": CG,
         "UGS": UGS,
         "G_terms": {
-            "CR_term": inputs.CR * g_w1,
-            "ES_term": inputs.ES * g_w2,
-            "BT_term": inputs.BT * g_w3,
-            "RG_term": inputs.RG * g_w_t,
+            "CR_term": inputs.CR * weights.g_w1,
+            "ES_term": inputs.ES * weights.g_w2,
+            "BT_term": inputs.BT * weights.g_w3,
+            "RG_term": inputs.RG * weights.g_w_t,
             "NCB_penalty": inputs.NCB,
             "T": inputs.T,
             "time_normalized": True,
         },
         "CG_terms": {
-            "CS_term": inputs.CS * cg_w1,
-            "BR_term": inputs.BR * cg_w2,
-            "CA_term": inputs.CA * cg_w3,
-            "SS_term": inputs.SS * cg_w4,
+            "CS_term": inputs.CS * weights.cg_w1,
+            "BR_term": inputs.BR * weights.cg_w2,
+            "CA_term": inputs.CA * weights.cg_w3,
+            "SS_term": inputs.SS * weights.cg_w4,
             "NCB_consumer_penalty": inputs.NCB_consumer,
             "time_normalized": False,
         },
         "UGS_terms": {
-            "G_term": G * ugs_w1,
-            "CG_term": CG * ugs_w2,
+            "G_term": G * weights.ugs_w1,
+            "CG_term": CG * weights.ugs_w2,
             "T": inputs.T,
             "time_normalized": True,
         },
         "weights_used": {
-            "g_w1": g_w1, "g_w2": g_w2, "g_w3": g_w3, "g_w_t": g_w_t,
-            "cg_w1": cg_w1, "cg_w2": cg_w2, "cg_w3": cg_w3, "cg_w4": cg_w4,
-            "ugs_w1": ugs_w1, "ugs_w2": ugs_w2,
+            "g_w1": weights.g_w1, "g_w2": weights.g_w2,
+            "g_w3": weights.g_w3, "g_w_t": weights.g_w_t,
+            "cg_w1": weights.cg_w1, "cg_w2": weights.cg_w2,
+            "cg_w3": weights.cg_w3, "cg_w4": weights.cg_w4,
+            "ugs_w1": weights.ugs_w1, "ugs_w2": weights.ugs_w2,
         },
     }
 
@@ -216,12 +264,11 @@ def export(
     ``format`` query parameter selects the output format (default: ``xlsx``).
     No additional computation beyond the standard equations is performed.
     """
-    g_w1, g_w2, g_w3, g_w_t, cg_w1, cg_w2, cg_w3, cg_w4, ugs_w1, ugs_w2 = (
-        _resolve_weights(inputs)
-    )
-    d = _build_result(inputs, g_w1, g_w2, g_w3, g_w_t,
-                      cg_w1, cg_w2, cg_w3, cg_w4, ugs_w1, ugs_w2)
+    weights = _resolve_weights(inputs)
+    d = _build_result(inputs, weights)
 
+    # 'format' is regex-validated to 'xlsx|csv' by the Query constraint, so the
+    # filename is safe to use directly in the Content-Disposition header.
     timestamp = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H%M%S")
     filename = f"goodwill_export_{timestamp}.{format}"
 
diff --git a/app/templates/dashboard.html b/app/templates/dashboard.html
index 833f753..8d4a912 100644
--- a/app/templates/dashboard.html
+++ b/app/templates/dashboard.html
@@ -145,20 +145,50 @@ <h3 style="font-size:.9rem;margin:.75rem 0 .4rem">UGS — Term Contributions</h3
 
   function buildTable(tableId, rows) {
     const t = document.getElementById(tableId);
-    t.innerHTML = '<tr><th>Term</th><th>Value</th><th>Note</th></tr>' +
-      rows.map(r => `<tr><td>${r[0]}</td><td>${r[1]}</td><td>${r[2]||''}</td></tr>`).join('');
+    while (t.firstChild) t.removeChild(t.firstChild);
+    const header = document.createElement('tr');
+    ['Term', 'Value', 'Note'].forEach(text => {
+      const th = document.createElement('th');
+      th.textContent = text;
+      header.appendChild(th);
+    });
+    t.appendChild(header);
+    rows.forEach(r => {
+      const tr = document.createElement('tr');
+      [r[0], r[1], r[2] || ''].forEach(text => {
+        const td = document.createElement('td');
+        td.textContent = text;
+        tr.appendChild(td);
+      });
+      t.appendChild(tr);
+    });
+  }
+
+  function _collectPayload() {
+    const fields = [
+      'CR', 'ES', 'BT', 'RG', 'NCB', 'CS', 'BR', 'CA', 'SS',
+      'NCB_consumer', 'T', 'g_w1', 'g_w2', 'g_w3', 'g_w_t',
+      'cg_w1', 'cg_w2', 'cg_w3', 'cg_w4', 'ugs_w1', 'ugs_w2',
+    ];
+    const payload = {};
+    for (const id of fields) {
+      const v = num(id);
+      if (isNaN(v)) {
+        return { error: `Field "${id}" is empty or not a valid number. Please enter a numeric value.` };
+      }
+      payload[id] = v;
+    }
+    return { payload };
   }
 
   async function exportFile(format) {
     document.getElementById('err').textContent = '';
-    const payload = {
-      CR: num('CR'), ES: num('ES'), BT: num('BT'), RG: num('RG'),
-      NCB: num('NCB'), CS: num('CS'), BR: num('BR'), CA: num('CA'),
-      SS: num('SS'), NCB_consumer: num('NCB_consumer'), T: num('T'),
-      g_w1: num('g_w1'), g_w2: num('g_w2'), g_w3: num('g_w3'), g_w_t: num('g_w_t'),
-      cg_w1: num('cg_w1'), cg_w2: num('cg_w2'), cg_w3: num('cg_w3'), cg_w4: num('cg_w4'),
-      ugs_w1: num('ugs_w1'), ugs_w2: num('ugs_w2'),
-    };
+    const result = _collectPayload();
+    if (result.error) {
+      document.getElementById('err').textContent = result.error;
+      return;
+    }
+    const payload = result.payload;
 
     let resp;
     try {
@@ -192,14 +222,12 @@ <h3 style="font-size:.9rem;margin:.75rem 0 .4rem">UGS — Term Contributions</h3
 
   async function runCalculation() {
     document.getElementById('err').textContent = '';
-    const payload = {
-      CR: num('CR'), ES: num('ES'), BT: num('BT'), RG: num('RG'),
-      NCB: num('NCB'), CS: num('CS'), BR: num('BR'), CA: num('CA'),
-      SS: num('SS'), NCB_consumer: num('NCB_consumer'), T: num('T'),
-      g_w1: num('g_w1'), g_w2: num('g_w2'), g_w3: num('g_w3'), g_w_t: num('g_w_t'),
-      cg_w1: num('cg_w1'), cg_w2: num('cg_w2'), cg_w3: num('cg_w3'), cg_w4: num('cg_w4'),
-      ugs_w1: num('ugs_w1'), ugs_w2: num('ugs_w2'),
-    };
+    const result = _collectPayload();
+    if (result.error) {
+      document.getElementById('err').textContent = result.error;
+      return;
+    }
+    const payload = result.payload;
 
     let resp;
     try {
diff --git a/goodwill/__init__.py b/goodwill/__init__.py
index 0dca30d..6e0b95f 100644
--- a/goodwill/__init__.py
+++ b/goodwill/__init__.py
@@ -2,4 +2,6 @@
 
 from goodwill.metrics import compute_CG, compute_G, compute_UGS
 
-__all__ = ["compute_G", "compute_CG", "compute_UGS"]
+__version__ = "1.1.0"
+
+__all__ = ["compute_G", "compute_CG", "compute_UGS", "__version__"]
diff --git a/goodwill/metrics.py b/goodwill/metrics.py
index 70f4c74..f5c136f 100644
--- a/goodwill/metrics.py
+++ b/goodwill/metrics.py
@@ -149,7 +149,8 @@ def compute_G(
     Raises
     ------
     ValueError
-        If any metric input is outside [0, 100], or if T ≤ 0.
+        If any metric input is outside [0, 100], if T ≤ 0, or if any weight
+        is not a finite real number.
     """
     _validate_metric(CR, "CR")
     _validate_metric(ES, "ES")
@@ -157,6 +158,10 @@ def compute_G(
     _validate_metric(RG, "RG")
     _validate_metric(NCB, "NCB")
     _validate_T(T)
+    _validate_real_number(w1, "w1")
+    _validate_real_number(w2, "w2")
+    _validate_real_number(w3, "w3")
+    _validate_real_number(w_t, "w_t")
 
     return ((CR * w1) + (ES * w2) + (BT * w3) + (RG * w_t) - NCB) / T
 
@@ -213,13 +218,18 @@ def compute_CG(
     Raises
     ------
     ValueError
-        If any metric input is outside [0, 100].
+        If any metric input is outside [0, 100], or if any weight is not a
+        finite real number.
     """
     _validate_metric(CS, "CS")
     _validate_metric(BR, "BR")
     _validate_metric(CA, "CA")
     _validate_metric(SS, "SS")
     _validate_metric(NCB_consumer, "NCB_consumer")
+    _validate_real_number(w1, "w1")
+    _validate_real_number(w2, "w2")
+    _validate_real_number(w3, "w3")
+    _validate_real_number(w4, "w4")
 
     return (CS * w1) + (BR * w2) + (CA * w3) + (SS * w4) - NCB_consumer
 
@@ -264,8 +274,13 @@ def compute_UGS(
     Raises
     ------
     ValueError
-        If T ≤ 0.
+        If G or CG is not a finite real number, if T ≤ 0, or if any weight
+        is not a finite real number.
     """
+    _validate_real_number(G, "G")
+    _validate_real_number(CG, "CG")
     _validate_T(T)
+    _validate_real_number(w1, "w1")
+    _validate_real_number(w2, "w2")
 
     return ((G * w1) + (CG * w2)) / T
diff --git a/requirements.txt b/requirements.txt
index 2318e30..d0b7b60 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-fastapi>=0.100.0
-uvicorn>=0.23.0
-jinja2>=3.1.0
-openpyxl>=3.1.0
+fastapi>=0.100.0,<1.0
+uvicorn>=0.23.0,<1.0
+jinja2>=3.1.0,<4.0
+openpyxl>=3.1.0,<4.0