feat: expose objective_factors and objective_mode in web UI

The solver form gains an Objective section with a product/sum mode
select and per-resource factor inputs (E/B/S/C, zero = excluded).
The /solve handler parses both fields and forwards them to solve(),
falling back to solve.py defaults when omitted.

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

templates/solver.html

@@ -414,6 +414,47 @@
                 </div>
             </div>
 
+            <!-- Objective Section -->
+            <div class="form-section">
+                <h2>Objective</h2>
+                <p style="color: #666; font-size: 13px; margin-bottom: 15px;">
+                    Factor = exponent in product mode, weight in sum mode. A factor of 0 excludes that
+                    resource from the objective (it is not forced to zero). Negative factors are only
+                    allowed in sum mode. Factors are unaffected by the internal x10 resource scaling.
+                </p>
+                <div class="form-group">
+                    <label for="objective_mode">Mode</label>
+                    <select id="objective_mode" name="objective_mode">
+                        <option value="product" {% if objective_mode=="product" %}selected{% endif %}>Product
+                            (maximize E^a &times; B^b &times; ...)</option>
+                        <option value="sum" {% if objective_mode=="sum" %}selected{% endif %}>Sum
+                            (maximize a&middot;E + b&middot;B + ...)</option>
+                    </select>
+                </div>
+                <div class="resource-inputs">
+                    <div class="form-group">
+                        <label for="objective_factor_E">Electrum Factor</label>
+                        <input type="number" id="objective_factor_E" name="objective_factor_E"
+                            value="{{ objective_factors.get('E', 0) }}" step="1">
+                    </div>
+                    <div class="form-group">
+                        <label for="objective_factor_B">Brass Factor</label>
+                        <input type="number" id="objective_factor_B" name="objective_factor_B"
+                            value="{{ objective_factors.get('B', 0) }}" step="1">
+                    </div>
+                    <div class="form-group">
+                        <label for="objective_factor_S">Steel Factor</label>
+                        <input type="number" id="objective_factor_S" name="objective_factor_S"
+                            value="{{ objective_factors.get('S', 0) }}" step="1">
+                    </div>
+                    <div class="form-group">
+                        <label for="objective_factor_C">Capital Factor</label>
+                        <input type="number" id="objective_factor_C" name="objective_factor_C"
+                            value="{{ objective_factors.get('C', 0) }}" step="1">
+                    </div>
+                </div>
+            </div>
+
             <!-- Solver Settings Section -->
             <div class="form-section">
                 <h2>Solver Settings</h2>
@@ -699,6 +740,17 @@
                 data[input.name] = input.checked;
             });
 
+            // Collect objective mode and factors (only nonzero factors; missing = excluded)
+            data.objective_mode = document.getElementById('objective_mode').value;
+            const objectiveFactors = {};
+            ['E', 'B', 'S', 'C'].forEach(r => {
+                const factor = parseInt(document.getElementById(`objective_factor_${r}`).value);
+                if (factor) {
+                    objectiveFactors[r] = factor;
+                }
+            });
+            data.objective_factors = objectiveFactors;
+
             // Collect fixed action constraints
             const fixedActions = {};
             form.querySelectorAll('[id^="action-constraint-"]').forEach(row => {

web_solve.py

@@ -21,6 +21,8 @@ def index():
         actions=solve.ENABLED_ACTIONS,
         agents=solve.AGENT_AVAILABILITY,
         num_steps=solve.NUM_STEPS,
+        objective_factors=solve.OBJECTIVE_FACTORS,
+        objective_mode=solve.OBJECTIVE_MODE,
     )
 
 
@@ -138,6 +140,18 @@ def solve_handler():
                     city, step = int(city), int(step)
                     fixed_choices["governors"][(city, step, agent)] = enabled
 
+        # Parse objective (factor = exponent in "product" mode, weight in
+        # "sum" mode; missing keys = resource excluded). Factors are NOT x10
+        # scaled — they apply to the scaled resource totals and the report
+        # descales the objective. None falls back to solve.py's defaults.
+        objective_mode = data.get("objective_mode") or None
+        objective_factors = None
+        objective_factors_data = data.get("objective_factors")
+        if objective_factors_data is not None:
+            # All-zero dict passes through so solve()'s validation rejects it
+            # with a clear error instead of silently using the defaults.
+            objective_factors = {r: int(f) for r, f in objective_factors_data.items()}
+
         # Parse resource constraints
         resource_constraints = None
         resource_constraints_data = data.get("resource_constraints", [])
@@ -165,6 +179,8 @@ def solve_handler():
                 verbose=verbose,
                 fixed_choices=fixed_choices,
                 resource_constraints=resource_constraints,
+                objective_factors=objective_factors,
+                objective_mode=objective_mode,
             )
 
         output = output_buffer.getvalue()