give output-group eligibility one home

The rule that decides whether a group may be picked -- every item it yields
unlocked, the group judged whole because its items are produced together
(REQ-LOCK-OUTPUT-POOL) -- was written out inside rollOutputGroup, where nothing
outside the sim could reach it. It moves next to producesItem and
getProducibleItems in RecipesConfig.h, which is where the recipe-level queries
already shared between lib and ui live.

Deliberately narrow: the helper says whether a group is eligible, not whether
eligibility is asked about at all. rollOutputGroup keeps its own reason for not
asking when a recipe has a single group.

No behaviour change; the pool's end-to-end test still covers the rule and a
direct one now pins the judged-whole semantics.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ne3mejABZoLWKLh8fgpM3x

src/lib/config/RecipesConfig.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <algorithm>
+#include <functional>
 #include <optional>
 #include <string>
 #include <vector>
@@ -82,6 +83,24 @@ inline bool producesItem(const RecipeDef& recipe, const std::string& itemId)
     return false;
 }
 
+// True when every item this group yields is unlocked. A group is judged whole -- its
+// items are produced together, so one locked item disqualifies the group entirely, since
+// taking it would hand the player a locked item (REQ-LOCK-OUTPUT-POOL).
+//
+// This says whether a group is eligible, not whether eligibility is asked about at all:
+// that is the caller's, because the callers differ. A cycle picking its result does not
+// ask where there is only one group to pick (see ProductionSystem::rollOutputGroup).
+inline bool isOutputGroupUnlocked(
+    const RecipeOutputGroup& group,
+    const std::function<bool(const std::string&)>& isItemUnlocked)
+{
+    for (const RecipeOutput& out : group.items)
+    {
+        if (!isItemUnlocked(out.item)) { return false; }
+    }
+    return true;
+}
+
 struct RecipesConfig
 {
     std::vector<RecipeDef> recipes;

src/lib/sim/ProductionSystem.cpp

@@ -67,20 +67,13 @@ std::vector<Item> ProductionSystem::rollOutputGroup(const RecipeDef& recipe)
         return itemsOf(recipe.outputGroups.front());
     }
 
-    // Several groups: only those whose items are all unlocked can be picked, and a group
-    // holding any locked item is dropped whole, since its items come together
-    // (REQ-LOCK-OUTPUT-POOL). Weights are renormalized over what is left by
-    // discrete_distribution.
+    // Several groups: only the unlocked ones can be picked (REQ-LOCK-OUTPUT-POOL), and
+    // weights are renormalized over what is left by discrete_distribution.
     std::vector<const RecipeOutputGroup*> eligible;
     std::vector<double> weights;
     for (const RecipeOutputGroup& group : recipe.outputGroups)
     {
-        bool allUnlocked = true;
-        for (const RecipeOutput& out : group.items)
-        {
-            if (!m_isItemUnlocked(out.item)) { allUnlocked = false; break; }
-        }
-        if (!allUnlocked) { continue; }
+        if (!isOutputGroupUnlocked(group, m_isItemUnlocked)) { continue; }
         eligible.push_back(&group);
         weights.push_back(group.probability.value_or(1.0));
     }

src/test/BuildingTest.cpp

@@ -1110,6 +1110,27 @@ TEST_CASE("BuildingSystem: a group with a locked item is never picked", "[buildi
     REQUIRE(produced > 0);
 }
 
+TEST_CASE("a group is judged whole against the unlock state", "[building][unlock]")
+{
+    // The rule the pool applies, on its own (REQ-LOCK-OUTPUT-POOL): a group counts as
+    // unlocked only when every item it yields is, because its items are produced
+    // together and one of them being locked is enough to rule the group out.
+    RecipeOutputGroup group;
+    group.items.push_back(RecipeOutput{"voidsteel", 1});
+    group.items.push_back(RecipeOutput{"iron_ingot", 1});
+
+    const std::function<bool(const std::string&)> allUnlocked =
+        [](const std::string&) { return true; };
+    const std::function<bool(const std::string&)> voidsteelLocked =
+        [](const std::string& itemId) { return itemId != "voidsteel"; };
+
+    CHECK(isOutputGroupUnlocked(group, allUnlocked));
+    CHECK_FALSE(isOutputGroupUnlocked(group, voidsteelLocked));
+
+    // An empty group yields nothing to be locked out by, so nothing disqualifies it.
+    CHECK(isOutputGroupUnlocked(RecipeOutputGroup{}, voidsteelLocked));
+}
+
 TEST_CASE("BuildingSystem: reprocessing plant sizes one output buffer per possible roll",
           "[building]")
 {