remove food from ambient energy forms, size solar sails to actual power needs

Biological Feed (food) was treated as an "ambient" energy source, so
range_fuel always reported the domain's ceiling regardless of how much
food was carried -- stopping to eat is a resupply, the same category as
refuelling a tank, not a genuinely external/inexhaustible source like
sun or wind. Removed "biological" from AMBIENT_ENERGY_FORMS; food now
uses the normal storage-mass-limited range formula like any fuel.

Solar Sail was still special-cased to a fixed footprint-derived mass
(100m^2 -> 5kg) regardless of what a domain's power/velocity target
actually needed -- the same "fixed reference instead of a requirement
floor" bug biological actuators had before last session's fix. Folded
it into the same general requirement-floor + joint-optimizer path:
declared footprint becomes a FLOOR (SAIL_AREAL_DENSITY_KG_PER_M2), not
a fixed value, so sail size scales with what's actually needed --
"enough panels to supply enough power for actuator impulse" is now
enforced the same way structural/mass-ceiling requirements already are,
instead of relying on a product-spec constant that happened to work or
not. No actuator type is special-cased for mass sizing anymore.

Confirmed the fix surfaces an honest result rather than hiding one: a
solar sail's declared 0.01 W/kg specific power can never reach
interplanetary_travel's 10 W/kg power_density floor at any sail size
(the ratio is capped by the sail's own power_density regardless of
scale), so it correctly still scores 0 there -- a real technology/domain
mismatch, not a sizing bug.

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

src/physcom/engine/pipeline.py

@@ -106,6 +106,16 @@ ENERGY_FORM_RELIABILITY: dict[str, float] = {
 # validated it against the platform's ceiling), so it's used as the point
 # estimate rather than an invented one.
 
+# Radiation-pressure actuators (solar sails) don't declare a "mass" at
+# all -- thrust scales with sail area, not carried mass -- so their
+# effective mass is derived from declared footprint via a thin deployable
+# sail film's areal density. Used the same way as BIOLOGICAL_OPERATOR_MASS_KG
+# below: converts the entity's declared footprint FLOOR into a mass floor,
+# not a fixed value -- above it, effective mass is a free, budget-competing
+# variable like any other actuator (bigger sail = more collected power),
+# sized by the same joint optimizer, not a one-off product spec.
+SAIL_AREAL_DENSITY_KG_PER_M2: float = 0.05
+
 # Human/animal actuators declare mass_min=0 (there's no minimum purchase
 # quantity for a rider the way there is for an engine), but treated as a
 # literal floor that lets the optimizer size a payload down toward 0kg of
@@ -187,13 +197,16 @@ def _solve_two_requirement_masses(
         return a_min, s_min
     return max(a, a_min), max(s, s_min)
 
-# Ambient energy forms (sun, wind, gravity, food) aren't a depletable
+# Ambient energy forms (sun, wind, gravity) aren't a depletable onboard
-# onboard store the way a fuel tank is -- "distance before running out"
+# store the way a fuel tank is -- "distance before running out" doesn't
-# doesn't apply (a sailboat doesn't run out of wind). Rather than
+# apply (a sailboat doesn't run out of wind). Rather than degenerate to 0
-# degenerate to 0 (mass_min=0, energy_density often undeclared entirely),
+# (mass_min=0, energy_density often undeclared entirely), range_fuel
-# range_fuel reports the domain's own declared ceiling for these: full
+# reports the domain's own declared ceiling for these: full marks is the
-# marks is the physically honest answer, not an error.
+# physically honest answer, not an error. Food is deliberately NOT here:
-AMBIENT_ENERGY_FORMS: set[str] = {"biological", "wind", "radiation_pressure", "gravitational"}
+# stopping to eat is a resupply, the same category as refuelling a tank,
+# not a genuinely external/inexhaustible power source -- Biological Feed
+# uses the normal storage-mass-limited range_fuel formula.
+AMBIENT_ENERGY_FORMS: set[str] = {"wind", "radiation_pressure", "gravitational"}
 
 # Resistive energy cost of travel, J per kg of vehicle per meter --
 # rolling resistance for ground vehicles, cruise-flight lift/drag for
@@ -931,13 +944,16 @@ class Pipeline:
         performance target (accel/thrust, or target_velocity/resistance)
         sets a FLOOR -- a rotorcraft that can't produce enough thrust to
         hover isn't a rotorcraft, regardless of how a smaller/cheaper
-        engine might score. Biological actuators (a rider's own body) get
+        engine might score. Biological actuators (a rider's own body) and
-        the same treatment with one addition: BIOLOGICAL_OPERATOR_MASS_KG
+        radiation-pressure actuators (a solar sail) get the same treatment
-        sets a floor under the floor -- at least one real operator, even if
+        with one addition: BIOLOGICAL_OPERATOR_MASS_KG / a footprint-derived
-        the performance-derived requirement would otherwise ask for less
+        floor (see SAIL_AREAL_DENSITY_KG_PER_M2) sets a floor under the
-        -- but above that, mass is a free variable exactly like a
+        floor -- at least one real operator, or the sail's own declared
-        mechanical actuator's; "bigger" here means more or bigger
+        minimum footprint, even if the performance-derived requirement
-        operators, not a fixed physiological constant. That floor also
+        would otherwise ask for less -- but above that, mass is a free
+        variable exactly like a mechanical actuator's; "bigger" means more
+        or bigger operators, or a bigger sail, not a fixed constant. That
+        floor also
         sets the smallest platform mass that could structurally carry it
         (CARGO_KG_PER_STRUCTURAL_KG again, applied to the platform
         carrying its own actuator+storage instead of cargo) -- below that,
@@ -970,16 +986,6 @@ class Pipeline:
                     return float(dep.value)
             return None
 
-        if ctx.actuator_energy_form == "radiation_pressure":
-            # thrust scales with sail area, not carried mass -- derive an
-            # effective mass from declared footprint and a thin-film areal
-            # density estimate rather than the (undeclared) mass attribute.
-            # No meaningful "bigger sail" mass slider here (area-driven,
-            # not budget-driven), so this stays its own case.
-            footprint = dep_value(ctx.actuator, "footprint", "range_min") or 0.0
-            actuator_mass = footprint * 0.05  # kg/m^2, thin deployable sail film
-            return actuator_mass, ctx.s_min, ctx.p_rep, True
-
         # Step 1: the required floor (same solve as before -- now a floor
         # for the search below, not the final answer).
         min_accel = dep_value(ctx.platform, "min_effective_accel", "range_min")
@@ -1026,6 +1032,13 @@ class Pipeline:
             # performance solve above would have asked for -- see the
             # BIOLOGICAL_OPERATOR_MASS_KG module comment.
             required_actuator = max(required_actuator, BIOLOGICAL_OPERATOR_MASS_KG[ctx.actuator_energy_form])
+        elif ctx.actuator_energy_form == "radiation_pressure":
+            # At least the entity's own declared minimum sail footprint,
+            # regardless of what the bare performance solve above would
+            # have asked for -- see the SAIL_AREAL_DENSITY_KG_PER_M2
+            # module comment.
+            footprint_floor = dep_value(ctx.actuator, "footprint", "range_min") or 0.0
+            required_actuator = max(required_actuator, footprint_floor * SAIL_AREAL_DENSITY_KG_PER_M2)
 
         if ctx.p_max is None:
             # No declared mass ceiling (e.g. Spaceship) -- no bounded
@@ -1296,20 +1309,19 @@ class Pipeline:
         minimum (platform is also ceiling-clamped to its declared max) --
         never silently allowed below what pass 1 would have rejected.
 
-        Returns None for combos with no free actuator mass to explore
+        Returns None only for combos with no declared platform mass
-        (radiation-pressure sails -- thrust is area-driven, not a mass
+        ceiling to bound a weight-class slider (e.g. Spaceship). Every
-        choice, see _decide_masses) or with no declared platform mass
+        actuator type gets sliders, including biological (rider/operator
-        ceiling to bound a weight-class slider. Biological actuators DO
+        mass, see BIOLOGICAL_OPERATOR_MASS_KG) and radiation-pressure
-        get sliders: rider/operator mass is a real, budget-competing
+        (effective sail mass derived from footprint, see
-        variable like any other actuator (see BIOLOGICAL_OPERATOR_MASS_KG).
+        SAIL_AREAL_DENSITY_KG_PER_M2) -- both are real, budget-competing
+        variables like any mechanical actuator's mass.
         """
         bounds_by_name = {mb.metric_name: mb for mb in domain.metric_bounds}
         units_by_name = {mb.metric_name: mb.unit for mb in domain.metric_bounds}
         ctx = self._physics_context(combo, bounds_by_name)
         if ctx is None or ctx.p_max is None:
             return None
-        if ctx.actuator_energy_form == "radiation_pressure":
-            return None
 
         cargo_capacity_kg = (ctx.p_min + ctx.a_min + ctx.s_min) * CARGO_KG_PER_STRUCTURAL_KG
         default_actuator, default_storage, default_platform, _feasible = self._decide_masses(

src/physcom_web/templates/results/_explore_result.html

@@ -1,8 +1,6 @@
 {% if explore_result is none %}
 <p class="empty">No free mass allocation to explore for this combination — its
-actuator's mass isn't a design choice (a footprint-derived quantity, like a
+platform has no declared mass ceiling to bound the sliders.</p>
-radiation-pressure sail), or the platform has no declared mass ceiling to
-bound the sliders.</p>
 {% else %}
 {% set r = explore_result %}
 <div class="optimize-summary">

src/physcom_web/templates/results/detail.html

@@ -155,7 +155,7 @@
       <output id="out_platform_mass">{{ "%.1f"|format(r.platform_mass) }}kg</output>
     </div>
     <div class="weight-slider-row">
-      <label for="actuator_mass">actuator (motor size, or operator count/size for muscle power)</label>
+      <label for="actuator_mass">actuator (motor/collector size, or operator count/size for muscle power)</label>
       <input type="range" min="{{ r.actuator_min }}" max="{{ r.actuator_slider_max }}" step="0.1"
              id="actuator_mass" name="actuator_mass" value="{{ r.actuator_mass }}"
              oninput="document.getElementById('out_actuator_mass').textContent = (+this.value).toFixed(1) + 'kg'">