Recap the run's high-water mark: peak board synergy

JCA.board_synergy sums every owned pair once; the emplace hook that
already drives discovery keeps the maximum in G.GAME.jca_peak_synergy
(it can only rise when a joker arrives). The post-run recap shows it,
now also on runs that fielded no famous pair.

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

main.lua

@@ -844,8 +844,31 @@ end
 -- during the current run are also recorded in G.GAME.jca_run_combos (saved
 -- with the run) for end-of-run display.
 
+-- Total pairwise synergy across the current board: every owned pair scored
+-- once. The run's high-water mark is kept in G.GAME.jca_peak_synergy for the
+-- recap; it can only rise when a joker arrives, so the emplace hook that
+-- already drives discovery is the one place that needs to look.
+function JCA.board_synergy()
+    if not (G.jokers and G.jokers.cards) then return 0 end
+    local keys = {}
+    for _, c in ipairs(G.jokers.cards) do
+        if is_joker(c) then keys[#keys + 1] = c.config.center.key end
+    end
+    local sum = 0
+    for i = 1, #keys do
+        for j = i + 1, #keys do
+            sum = sum + JCA.score(keys[i], keys[j])
+        end
+    end
+    return sum
+end
+
 function JCA.check_discoveries()
     if not (G.jokers and G.jokers.cards) then return end
+    if G.GAME then
+        local s = JCA.board_synergy()
+        if s > (G.GAME.jca_peak_synergy or 0) then G.GAME.jca_peak_synergy = s end
+    end
     local keys = {}
     for _, c in ipairs(G.jokers.cards) do
         if is_joker(c) then keys[#keys + 1] = c.config.center.key end
@@ -943,28 +966,37 @@ end
 
 local function recap_row()
     local combos = G.GAME and G.GAME.jca_run_combos
-    if not combos or not next(combos) then return nil end
+    local peak = (G.GAME and G.GAME.jca_peak_synergy) or 0
     local names = {}
-    for pk in pairs(combos) do
+    for pk in pairs(combos or {}) do
         local a, b = pk:match('^(.-)|(.+)$')
         if a then names[#names + 1] = name_of(a) .. ' + ' .. name_of(b) end
     end
-    if #names == 0 then return nil end
+    if #names == 0 and peak <= 0 then return nil end
     table.sort(names)
-    local rows = {{n = G.UIT.R, config = {align = 'cm', padding = 0.03}, nodes = {
-        {n = G.UIT.T, config = {text = 'Combos fielded this run',
-            colour = G.C.GOLD, scale = 0.35, shadow = true}},
-    }}}
-    for i = 1, math.min(#names, 6) do
-        rows[#rows + 1] = {n = G.UIT.R, config = {align = 'cm', padding = 0.02}, nodes = {
-            {n = G.UIT.T, config = {text = names[i],
-                colour = G.C.WHITE, scale = 0.3, shadow = true}},
+    local rows = {}
+    if #names > 0 then
+        rows[#rows + 1] = {n = G.UIT.R, config = {align = 'cm', padding = 0.03}, nodes = {
+            {n = G.UIT.T, config = {text = 'Combos fielded this run',
+                colour = G.C.GOLD, scale = 0.35, shadow = true}},
         }}
+        for i = 1, math.min(#names, 6) do
+            rows[#rows + 1] = {n = G.UIT.R, config = {align = 'cm', padding = 0.02}, nodes = {
+                {n = G.UIT.T, config = {text = names[i],
+                    colour = G.C.WHITE, scale = 0.3, shadow = true}},
+            }}
+        end
+        if #names > 6 then
+            rows[#rows + 1] = {n = G.UIT.R, config = {align = 'cm', padding = 0.02}, nodes = {
+                {n = G.UIT.T, config = {text = '+' .. (#names - 6) .. ' more',
+                    colour = G.C.UI.TEXT_LIGHT, scale = 0.3}},
+            }}
+        end
     end
-    if #names > 6 then
+    if peak > 0 then
         rows[#rows + 1] = {n = G.UIT.R, config = {align = 'cm', padding = 0.02}, nodes = {
-            {n = G.UIT.T, config = {text = '+' .. (#names - 6) .. ' more',
-                colour = G.C.UI.TEXT_LIGHT, scale = 0.3}},
+            {n = G.UIT.T, config = {text = 'Peak board synergy: ' .. peak,
+                colour = G.C.GOLD, scale = 0.3, shadow = true}},
         }}
     end
     return {n = G.UIT.R, config = {align = 'cm', padding = 0.06}, nodes = rows}

test.lua

@@ -415,6 +415,28 @@ per[2].ability = {perishable = true, perish_tally = 0}
 eq(JCA.weakest_link(), per[2],
     'but a perished joker is the cut at any score - it will never work again')
 
+--------------------------------------------------------------------------------
+section('Engine: board synergy total and its run peak')
+--------------------------------------------------------------------------------
+
+-- Every owned pair scored once: Baron+Mime is the famous 6, the plain Joker
+-- adds only its generic +1 against Baron's xMult.
+field('j_baron', 'j_mime', 'j_joker')
+eq(JCA.board_synergy(), 7, 'board synergy sums every owned pair once')
+
+-- The peak rides the same emplace hook as discovery, and never goes down.
+-- Discovery state is snapshotted so this cannot leak into the UI tests.
+local saved_disc, saved_themes = JCA.config.discovered, JCA.config.themes_found
+JCA.config.discovered, JCA.config.themes_found = {}, {}
+G.GAME = {}
+JCA.check_discoveries()
+eq(G.GAME.jca_peak_synergy, 7, 'the emplace hook records the high-water mark')
+field('j_joker')
+JCA.check_discoveries()
+eq(G.GAME.jca_peak_synergy, 7, 'selling down does not lower the recorded peak')
+G.GAME = {}
+JCA.config.discovered, JCA.config.themes_found = saved_disc, saved_themes
+
 --------------------------------------------------------------------------------
 section('Engine: deck context counts base suits')
 --------------------------------------------------------------------------------