fix(reasoning): persist canonical history for DeepSeek and web chat

pkg/memory/jsonl_test.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"strings"
 	"sync"
 	"testing"
 
@@ -155,6 +156,27 @@ func TestAddFullMessage_ToolCallID(t *testing.T) {
 	}
 }
 
+func TestAddFullMessage_DropsTransientAssistantThought(t *testing.T) {
+	store := newTestStore(t)
+	ctx := context.Background()
+
+	err := store.AddFullMessage(ctx, "transient-thought", providers.Message{
+		Role:             "assistant",
+		ReasoningContent: "internal chain of thought",
+	})
+	if err != nil {
+		t.Fatalf("AddFullMessage: %v", err)
+	}
+
+	history, err := store.GetHistory(ctx, "transient-thought")
+	if err != nil {
+		t.Fatalf("GetHistory: %v", err)
+	}
+	if len(history) != 0 {
+		t.Fatalf("expected transient thought to be discarded, got %d messages", len(history))
+	}
+}
+
 func TestGetHistory_EmptySession(t *testing.T) {
 	store := newTestStore(t)
 	ctx := context.Background()
@@ -243,6 +265,46 @@ func TestSetSummary_GetSummary(t *testing.T) {
 	}
 }
 
+func TestSetHistory_DropsTransientAssistantThought(t *testing.T) {
+	store := newTestStore(t)
+	ctx := context.Background()
+
+	newHistory := []providers.Message{
+		{Role: "user", Content: "hello"},
+		{Role: "assistant", ReasoningContent: "internal chain of thought"},
+		{Role: "assistant", Content: "visible answer", ReasoningContent: "visible thought"},
+	}
+
+	err := store.SetHistory(ctx, "replace", newHistory)
+	if err != nil {
+		t.Fatalf("SetHistory: %v", err)
+	}
+
+	history, err := store.GetHistory(ctx, "replace")
+	if err != nil {
+		t.Fatalf("GetHistory: %v", err)
+	}
+	if len(history) != 2 {
+		t.Fatalf("expected transient thought to be removed, got %d messages", len(history))
+	}
+	if history[0].Role != "user" || history[0].Content != "hello" {
+		t.Fatalf("history[0] = %+v, want user/hello", history[0])
+	}
+	if history[1].Role != "assistant" || history[1].Content != "visible answer" ||
+		history[1].ReasoningContent != "visible thought" {
+		t.Fatalf("history[1] = %+v, want assistant visible answer with reasoning", history[1])
+	}
+
+	data, err := os.ReadFile(store.jsonlPath("replace"))
+	if err != nil {
+		t.Fatalf("ReadFile(jsonl): %v", err)
+	}
+	lines := strings.Split(strings.TrimSpace(string(data)), "\n")
+	if len(lines) != 2 {
+		t.Fatalf("jsonl line count = %d, want 2", len(lines))
+	}
+}
+
 func TestSessionMetaScopeAndAliasesPersist(t *testing.T) {
 	store := newTestStore(t)
 	ctx := context.Background()