engine: GIS 65+ floor, clawback only with OAS, couple mixed-row footnote, FIRE retire age 40

site/engine/engine.js

@@ -77,11 +77,18 @@
   }
 
   /* ---- OAS recovery tax (clawback) ---- */
+  // s.3(1) ETA: recovery applies ONLY to years OAS is actually payable/received —
+  // a pre-OAS-start pensioner has no OAS to recover. Callers guard with oasGross > 0
+  // (2026-10 math fix: pre-65 withdrawals must not generate a "clawback" on OAS never paid).
+  // Recovery is capped at the OAS received (Math.min at call sites) → net OAS is never negative.
   function clawback(netIncome) {
     return 0.15 * Math.max(0, (netIncome || 0) - V('oasClawbackThreshold'));
   }
 
-  /* ---- GIS (SIMPLIFIED — stamp: simplified) ---- */
+  /* ---- GIS (SIMPLIFIED — stamp: simplified; PAYABLE ONLY AT AGE 65+) ---- */
+  // Source fact: Service Canada — you must be 65 or older to receive the GIS.
+  // The 65+ floor is enforced at the call sites: solve() gates gis() on a >= 65,
+  // projectCouple() zeroes gisSum when the merged row age < 65 (2026-10 math fix).
   // Only below ~$20k (single) / ~$26k (couple, both 65+) income ex-OAS.
   // gis = max(0, gisMax − 0.5 × max(0, incomeExOAS − 5000)) (first $5k employment exemption approximated).
   // Returns ANNUAL $, non-taxable.
@@ -174,6 +181,11 @@
     var o = {}, k;
     for (k in DEFAULTS) o[k] = DEFAULTS[k];
     for (k in (inp || {})) if (inp[k] !== undefined && inp[k] !== null) o[k] = inp[k];
+    // FIRE-safe guard (2026-10 math fix): a stale saved retireAge below the current age
+    // (52-year-old returning user with retireAge 40, what-if slider below current age)
+    // would "retire" this run years in the past → clamp to next birthday. Age-30 user
+    // planning to retire at 40 is untouched.
+    if (+o.retireAge < +o.age + 1) o.retireAge = +o.age + 1;
     return o;
   }
 
@@ -233,8 +245,8 @@
         var taxable1 = pre + W;
         var opts1 = { pensionIncome: (a >= 65 && a >= psStart ? (p.pensionAnnual || 0) : 0) + (a >= 65 ? W : 0) };
         var t1 = tax(taxable1, p.province, a, opts1);
-        var c1 = clawback(taxable1);
-        var g = gis(taxable1 - oasGross, 'single');
+        var c1 = oasGross > 0 ? Math.min(clawback(taxable1), oasGross) : 0;   // clawback only in years OAS is received, capped at OAS paid
+        var g = a >= 65 ? gis(taxable1 - oasGross, 'single') : 0; // GIS payable only at 65+ (Service Canada)
         var cash1 = pre + W + g - t1.total - c1;
         var n = 0, t = 0, taxable = taxable1, tt = t1, cc = c1, opts = opts1;
         var rem = need - cash1;
@@ -244,13 +256,13 @@
           taxable = taxable1 + 0.5 * n;
           opts = { pensionIncome: opts1.pensionIncome };
           tt = tax(taxable, p.province, a, opts);
-          cc = clawback(taxable);
-          g = gis(taxable - oasGross, 'single');
+          cc = oasGross > 0 ? Math.min(clawback(taxable), oasGross) : 0;      // same rule: no OAS received → no clawback; capped at OAS paid
+          g = a >= 65 ? gis(taxable - oasGross, 'single') : 0;
           rem = need - (pre + W + g + n - tt.total - cc);
         }
         if (rem > 0 && tfsa > 0) {
           t = Math.min(tfsa, rem);
-          g = gis(taxable - oasGross, 'single');
+          g = a >= 65 ? gis(taxable - oasGross, 'single') : 0;   // 65+ floor (TFSA draw is non-taxable; guard kept uniform)
           rem = need - (pre + W + g + n + t - tt.total - cc);
         }
         var cash = pre + W + g + n + t - tt.total - cc;
@@ -348,25 +360,39 @@
         if (Math.abs(shift) > 1) {
           var tA = tax(ra.taxable - shift, p.province, yr, { pensionIncome: pa - shift });
           var tB = tax(rb.taxable + shift, p.province, yr, { pensionIncome: pb2 + shift });
-          var newTax = tA.total + tB.total, newClaw = clawback(ra.taxable - shift) + clawback(rb.taxable + shift);
+          var newTax = tA.total + tB.total;
+          // Splitting comparison uses the SAME clawback rule: only a partner receiving OAS
+          // this year can generate recovery tax (2026-10 math fix).
+          var newClaw = (ra.oasGross > 0 ? Math.min(clawback(ra.taxable - shift), ra.oasGross) : 0)
+                      + (rb.oasGross > 0 ? Math.min(clawback(rb.taxable + shift), rb.oasGross) : 0);
           if (newTax + newClaw < taxSum + clawSum) { taxSum = newTax; clawSum = newClaw; }
         }
       }
       row.tax = taxSum; row.oasClawback = clawSum;
-      // GIS: household rate when both 65+, else sum of singles
+      // GIS: household rate when both 65+, else sum of singles. GIS is payable ONLY at
+      // 65+ (Service Canada): a partner's single GIS term counts only at their own age ≥ 65.
       var incA = ra.taxable - ra.oasGross, incB = rb.taxable - rb.oasGross;
       var gisSum;
       if (ra.phase === 'draw' && rb.phase === 'draw' && ra.age >= 65 && rb.age >= 65) {
         gisSum = gis(incA + incB, 'couple');
       } else {
-        gisSum = (ra.phase === 'draw' ? gis(incA, 'single') : 0) + (rb.phase === 'draw' ? gis(incB, 'single') : 0);
+        gisSum = (ra.phase === 'draw' && ra.age >= 65 ? gis(incA, 'single') : 0)
+               + (rb.phase === 'draw' && rb.age >= 65 ? gis(incB, 'single') : 0);
       }
+      if (yr < 65) gisSum = 0;   // GIS requires age 65+ (Service Canada) — 2026-10 math fix
       row.gis = gisSum;
       var cash = ra.cash + rb.cash + (ra.gis + rb.gis ? gisSum - ra.gis - rb.gis : 0) + (taxSum ? (ra.tax + rb.tax - taxSum) : 0);
       cash = ra.cash + rb.cash - (ra.gis + rb.gis) + gisSum + (ra.tax + rb.tax) - taxSum;
       row.cash = Math.min(cash, row.need);
+      // Mixed window: retirement HAS begun (row labelled 'draw' from the FIRST retirement),
+      // but one partner is still accumulating at the pre-retirement rate. Honest summation,
+      // and the renderer footnotes these rows (†) so a growing Total + Withdraw > 0 is explained.
+      row.mixed = row.phase === 'draw' && (ra.phase === 'accum' || rb.phase === 'accum');
       row.unfunded = Math.max(0, row.need - cash);
-      if (row.phase === 'draw' && row.totalBal <= 0.5 && row.unfunded > 0.5 && depletionAge === null) depletionAge = yr;
+      // Depletion must not fire in a mixed window: the balance there is mostly the
+      // accum partner's pre-retirement money, not the drawing partner's. Count fully-drawing
+      // rows only — a missing partner row (phase 'none') counts as sole income (not accum).
+      if (row.phase === 'draw' && !row.mixed && row.totalBal <= 0.5 && row.unfunded > 0.5 && depletionAge === null) depletionAge = yr;
       totalTax += taxSum; totalClawback += clawSum;
       merged.push(row);
     }
@@ -445,6 +471,7 @@
     recommendations: recommendations,
     pensionStartAge: pensionStartAge,
     pensionBridgeAnnual: pensionBridgeAnnual,
+    fillDefaults: fillDefaults,
     defaults: DEFAULTS,
     constants: C
   };