llama: test key order preservation in schema_to_grammar (#8078)

This change adds a test to catch a regression in schema_to_grammar where
the order of keys in the JSON schema is not preserved in the generated
grammar, which is critical for step-by-step reasoning.

llama/grammar_test.go → llama/grammar/grammar_test.go

-package llama
+package grammar
 
 import (
 	"bufio"
 	"bytes"
 	"strings"
 	"testing"
+
+	"github.com/ollama/ollama/llama"
 )
 
 // https://github.com/ollama/ollama/issues/7978
@@ -17,20 +19,45 @@ const issue7978JSONSchema = `{
         "type": "object",
         "properties": {
           "explanation": { "type": "string" },
-	  "output": { "type": "string" }
+          "output": { "type": "string" },
+          "nested": {
+            "type": "object",
+            "properties": {
+              "deep": { "type": "string" }
+            }
+          }
         },
         "required": ["explanation", "output"],
         "additionalProperties": false
       }
     },
-    "final_answer": { "type": "string" }
+    "final_answer": { "type": "string" },
+    "01_numbered_key": { "type": "string" },
+    "numbers": {
+      "type": "array",
+      "items": { "type": "number" }
+    },
+    "booleans": {
+      "type": "array", 
+      "items": { "type": "boolean" }
+    },
+    "mixed": {
+      "type": "array",
+      "items": {
+        "oneOf": [
+          { "type": "string" },
+          { "type": "number" },
+          { "type": "boolean" }
+        ]
+      }
+    }
   },
   "required": ["steps", "final_answer"],
   "additionalProperties": false
 }`
 
 func TestIssue7978(t *testing.T) {
-	g := SchemaToGrammar([]byte(issue7978JSONSchema))
+	g := llama.SchemaToGrammar([]byte(issue7978JSONSchema))
 	if g == nil {
 		t.Fatal("failed to convert JSON schema to grammar")
 	}
@@ -38,16 +65,20 @@ func TestIssue7978(t *testing.T) {
 	t.Logf("grammar:\n%s", g)
 	t.Log()
 
-	var sawSteps bool
+	var got string
 	s := bufio.NewScanner(bytes.NewReader(g))
 	for s.Scan() {
-		line := s.Text()
-		if strings.Contains(line, "steps") {
-			sawSteps = true
+		line := strings.TrimSpace(s.Text())
+		step, _, _ := strings.Cut(line, " ::= ")
+		step = strings.TrimSpace(step)
+		if step == "root" {
+			got = line
 		}
-		if strings.Contains(line, "final-answer") && !sawSteps {
-			t.Error("expected 'steps' before 'final-answer'")
 	}
+
+	want := `root ::= "{" space steps-kv "," space final-answer-kv ( "," space ( 01-numbered-key-kv 01-numbered-key-rest | numbers-kv numbers-rest | booleans-kv booleans-rest | mixed-kv ) )? "}" space`
+	if got != want {
+		t.Errorf("root =\n%qwant:\n%q", got, want)
 	}
 }
 
@@ -64,7 +95,7 @@ func TestSchemaToGrammer(t *testing.T) {
 
 	for _, c := range cases {
 		t.Run("x", func(t *testing.T) {
-			g := SchemaToGrammar([]byte(c.schema))
+			g := llama.SchemaToGrammar([]byte(c.schema))
 			if c.prefix == nil && g != nil {
 				t.Fatalf("grammar = %v, want nil", g)
 			}