Denial is not absence — detection learns the unverifiable answer 06 ruled for it

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

KanbanTests/HistoryStoreTests.swift

@@ -323,6 +323,36 @@ struct HistoryStoreAddGitTests {
         #expect(git.mode == .none, "a refused add-git changes nothing, mode included")
     }
 
+    @Test("Create refuses a board that a fresh detection reads unverifiable — a denied ancestor")
+    func createRefusesUnverifiable() throws {
+        // **The tightened guard** (06 ▸ Rules ▸ Detection): "only a genuinely clean `.none` reading
+        // proceeds" — a stale `.none` that has since become unverifiable is refused exactly like one
+        // that has since become repo-nested (`createRefusesAStaleModeNone` above).
+        let outer = try WriterFixture()
+        defer { outer.tearDown() }
+        let blocked = outer.root.appendingPathComponent("blocked", isDirectory: true)
+        let boardRoot = blocked.appendingPathComponent("board", isDirectory: true)
+        try FileManager.default.createDirectory(at: boardRoot, withIntermediateDirectories: true)
+        try Data(Item.board.utf8).write(to: boardRoot.appendingPathComponent("index.md"))
+
+        try FileManager.default.setAttributes([.posixPermissions: 0o000], ofItemAtPath: blocked.path)
+        defer { try? FileManager.default.setAttributes([.posixPermissions: 0o755], ofItemAtPath: blocked.path) }
+
+        #expect(BoardGitMode.detect(boardRoot: boardRoot) == .unverifiable, "the fixture is set up correctly")
+
+        let failure = GitRepository.create(at: boardRoot)
+        guard case .failure(let reason) = failure else {
+            Issue.record("initializing where detection cannot rule out a repository must be refused")
+            return
+        }
+        #expect(reason.operation == "Adding git to this board")
+        #expect(!reason.message.isEmpty)
+        #expect(
+            !FileManager.default.fileExists(atPath: boardRoot.appendingPathComponent(".git").path),
+            "no repository created on an unverifiable read"
+        )
+    }
+
     @Test("A failure answers at the form when it is up, and at the banner when it is not")
     @MainActor
     func aFailureAnswersAtTheFormOrTheBanner() async throws {