From 775c71baab707a06bf9a3d9ac0692b95fbefdaed Mon Sep 17 00:00:00 2001
From: ugin <157204743+ugin-man@users.noreply.github.com>
Date: Tue, 8 Sep 2026 08:15:37 +0900
Subject: [PATCH] fix: preserve explicit solver failures at the iteration limit

---
 lib/BaseSolver.ts                       | 12 +++-
 tests/explicit-failure-at-limit.test.ts | 76 +++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 2 deletions(-)
 create mode 100644 tests/explicit-failure-at-limit.test.ts

diff --git a/lib/BaseSolver.ts b/lib/BaseSolver.ts
index e071bf8..b4f7da9 100644
--- a/lib/BaseSolver.ts
+++ b/lib/BaseSolver.ts
@@ -52,10 +52,18 @@ export class BaseSolver {
       this.failed = true
       throw e
     }
-    if (!this.solved && this.iterations >= this.MAX_ITERATIONS) {
+    if (
+      !this.solved &&
+      !this.failed &&
+      this.iterations >= this.MAX_ITERATIONS
+    ) {
       this.tryFinalAcceptance()
     }
-    if (!this.solved && this.iterations >= this.MAX_ITERATIONS) {
+    if (
+      !this.solved &&
+      !this.failed &&
+      this.iterations >= this.MAX_ITERATIONS
+    ) {
       this.error = `${this.getSolverName()} ran out of iterations`
       this.failed = true
     }
diff --git a/tests/explicit-failure-at-limit.test.ts b/tests/explicit-failure-at-limit.test.ts
new file mode 100644
index 0000000..edd0874
--- /dev/null
+++ b/tests/explicit-failure-at-limit.test.ts
@@ -0,0 +1,76 @@
+import { expect, test } from "bun:test"
+import { BaseSolver } from "../lib/BaseSolver"
+
+test("an explicit failure at the iteration limit keeps its error and skips acceptance", () => {
+  class FailedSolver extends BaseSolver {
+    override MAX_ITERATIONS = 1
+    acceptanceCalls = 0
+
+    override _step() {
+      this.error = "No feasible route"
+      this.failed = true
+    }
+
+    override tryFinalAcceptance() {
+      this.acceptanceCalls++
+      this.solved = true
+    }
+  }
+  const solver = new FailedSolver()
+  solver.solve()
+
+  expect(solver.failed).toBe(true)
+  expect(solver.solved).toBe(false)
+  expect(solver.acceptanceCalls).toBe(0)
+  expect(solver.error).toBe("No feasible route")
+})
+
+test("an explicit failure is not replaced by an iteration exhaustion error", () => {
+  class FailedSolver extends BaseSolver {
+    override MAX_ITERATIONS = 1
+
+    override _step() {
+      this.error = "Invalid geometry"
+      this.failed = true
+    }
+  }
+  const solver = new FailedSolver()
+  solver.solve()
+
+  expect(solver.error).toBe("Invalid geometry")
+  expect(solver.failed).toBe(true)
+  expect(solver.solved).toBe(false)
+})
+
+test("a failure reported by final acceptance keeps its specific error", () => {
+  class RejectedSolver extends BaseSolver {
+    override MAX_ITERATIONS = 1
+
+    override tryFinalAcceptance() {
+      this.error = "Candidate violates clearance"
+      this.failed = true
+    }
+  }
+  const solver = new RejectedSolver()
+  solver.solve()
+
+  expect(solver.error).toBe("Candidate violates clearance")
+  expect(solver.failed).toBe(true)
+  expect(solver.solved).toBe(false)
+})
+
+test("an unfinished solver can still accept a solution at the iteration limit", () => {
+  class AcceptedSolver extends BaseSolver {
+    override MAX_ITERATIONS = 1
+
+    override tryFinalAcceptance() {
+      this.solved = true
+    }
+  }
+  const solver = new AcceptedSolver()
+  solver.solve()
+
+  expect(solver.solved).toBe(true)
+  expect(solver.failed).toBe(false)
+  expect(solver.error).toBeNull()
+})