v2: add 12B model test (Model12BTest)

.gitignore

@@ -7,5 +7,6 @@ Package.resolved
 *.xcodeproj/
 *.xcworkspace/
 .DS_Store
+blobs/
 test_summary.md.runner
 .runner

Tests/01_Model/Model12BTest.swift

@@ -0,0 +1,55 @@
+import XCTest
+@testable import MarkBase
+
+final class Model12BTest: XCTestCase {
+
+    var engine: MarkBaseEngine!
+    var model: E4BModel!
+    let modelDir = "/Users/accusys/MarkBaseEngine/models/gemma-4-12b-it-4bit"
+    let maxCtx = 64
+
+    override func setUp() {
+        super.setUp()
+        guard FileManager.default.fileExists(atPath: modelDir + "/model.safetensors.index.json") else {
+            return
+        }
+        engine = try? MarkBaseEngine(autoCompile: true)
+        model = try? E4BModel(modelDir: modelDir, engine: engine, maxContextLength: maxCtx)
+    }
+
+    func testModelLoads() throws {
+        try XCTSkipIf(model == nil, "gemma-4-12b-it-4bit model not found")
+        XCTAssertNotNil(model)
+        XCTAssertEqual(model.hiddenSize, 3840)
+        XCTAssertEqual(model.numHiddenLayers, 48)
+        XCTAssertEqual(model.vocabSize, 262144)
+    }
+
+    func testBosTokenLogitsNoNaN() throws {
+        try XCTSkipIf(model == nil, "gemma-4-12b-it-4bit model not found")
+        let logits = try model.forward(tokenId: 2, position: 0)
+        XCTAssertEqual(logits.count, model.vocabSize)
+        let nanCount = logits.filter { $0.isNaN }.count
+        XCTAssertEqual(nanCount, 0, "No NaN values in logits")
+    }
+
+    func testLogitSoftcapping() throws {
+        try XCTSkipIf(model == nil, "gemma-4-12b-it-4bit model not found")
+        let logits = try model.forward(tokenId: 2, position: 0)
+        let softcap: Float = 30.0
+        for logit in logits {
+            XCTAssertLessThanOrEqual(abs(logit), softcap + 0.1,
+                                     "Logit \(logit) exceeds softcap \(softcap)")
+        }
+    }
+
+    func testMultipleTokensProduceDifferentLogits() throws {
+        try XCTSkipIf(model == nil, "gemma-4-12b-it-4bit model not found")
+        let tokens = [2, 100, 1000]
+        for (pos, tokenId) in tokens.enumerated() {
+            let logits = try model.forward(tokenId: tokenId, position: pos)
+            let nanCount = logits.filter { $0.isNaN }.count
+            XCTAssertEqual(nanCount, 0, "NaN for token=\(tokenId) pos=\(pos)")
+        }
+    }
+}