feat(session): extend Attempt with tier, timing, and verdict fields

internal/session/session_test.go

@@ -61,3 +61,22 @@ func TestRead_EmptyWhenNoFile(t *testing.T) {
 	require.NoError(t, err)
 	assert.Empty(t, entries)
 }
+
+func TestAttemptRoundTrip(t *testing.T) {
+	a := session.Attempt{
+		Attempt:    1,
+		Model:      "ollama/devstral",
+		Tier:       "local",
+		DurationMs: 4200,
+		WarmStart:  true,
+		Verified:   false,
+		Verdict:    "escalate",
+		Feedback:   "missing line references",
+	}
+	data, err := json.Marshal(a)
+	require.NoError(t, err)
+
+	var got session.Attempt
+	require.NoError(t, json.Unmarshal(data, &got))
+	assert.Equal(t, a, got)
+}