diff --git a/backend/internal/service/openai_codex_transform.go b/backend/internal/service/openai_codex_transform.go
index edca90f1e9..220358f1e4 100644
--- a/backend/internal/service/openai_codex_transform.go
+++ b/backend/internal/service/openai_codex_transform.go
@@ -93,6 +93,8 @@ type codexOAuthTransformOptions struct {
 	SkipDefaultInstructions             bool
 	PreserveToolCallIDs                 bool
 	OmitPromotedSystemMessagesFromInput bool
+	// ResponsesLite selects where an injected hosted tool is declared.
+	ResponsesLite bool
 }
 
 const (
@@ -347,6 +349,12 @@ func applyCodexOAuthTransformWithOptions(reqBody map[string]any, opts codexOAuth
 		result.Modified = true
 	}
 
+	// Runs after input filtering so it sees the final replayed history. The
+	// compact endpoint has its own wire shape and is left untouched.
+	if !opts.IsCompact && ensureOpenAIOAuthWebSearchToolForHistory(reqBody, opts.ResponsesLite) {
+		result.Modified = true
+	}
+
 	return result
 }
 
diff --git a/backend/internal/service/openai_gateway_forward.go b/backend/internal/service/openai_gateway_forward.go
index 444b2c4db1..16df53310f 100644
--- a/backend/internal/service/openai_gateway_forward.go
+++ b/backend/internal/service/openai_gateway_forward.go
@@ -508,6 +508,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 				SkipDefaultInstructions:             true,
 				PreserveToolCallIDs:                 true,
 				OmitPromotedSystemMessagesFromInput: omitPromotedSystemMessages,
+				ResponsesLite:                       responsesLite,
 			})
 			ensureCodexOAuthInstructionsField(decoded)
 			markDecodedModified()
@@ -516,6 +517,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 				IsCodexCLI:                          isCodexCLI,
 				IsCompact:                           isCompactRequest,
 				OmitPromotedSystemMessagesFromInput: omitPromotedSystemMessages,
+				ResponsesLite:                       responsesLite,
 			})
 		}
 		if codexResult.Error != nil {
diff --git a/backend/internal/service/openai_gateway_passthrough.go b/backend/internal/service/openai_gateway_passthrough.go
index a24ae4a007..bf74b242d9 100644
--- a/backend/internal/service/openai_gateway_passthrough.go
+++ b/backend/internal/service/openai_gateway_passthrough.go
@@ -213,7 +213,10 @@ func (s *OpenAIGatewayService) forwardOpenAIPassthrough(
 	}
 	if account != nil && account.IsOpenAI() {
 		responsesLite := isOpenAIResponsesLiteHeader(c.GetHeader(responsesLiteHeader)) || isOpenAIResponsesLiteWebSocketPayload(body)
-		normalizedBody, normalized, normalizeErr := normalizeOpenAIResponsesWebSocketCompatibilityBody(body, account, responsesLite)
+		normalizedBody, normalized, normalizeErr := normalizeOpenAIResponsesCompatibilityBodyWithOptions(body, account, openAIResponsesCompatibilityOptions{
+			ResponsesLite: responsesLite,
+			Compact:       isOpenAIResponsesCompactPath(c),
+		})
 		if normalizeErr != nil {
 			return nil, fmt.Errorf("normalize passthrough Responses compatibility: %w", normalizeErr)
 		}
diff --git a/backend/internal/service/openai_gateway_request_body.go b/backend/internal/service/openai_gateway_request_body.go
index 663944e479..7ae18793e7 100644
--- a/backend/internal/service/openai_gateway_request_body.go
+++ b/backend/internal/service/openai_gateway_request_body.go
@@ -1430,6 +1430,18 @@ func normalizeOpenAIResponseFormatSchemasBody(body []byte) ([]byte, bool, error)
 }
 
 func normalizeOpenAIResponsesWebSocketCompatibilityBody(body []byte, account *Account, responsesLite bool) ([]byte, bool, error) {
+	return normalizeOpenAIResponsesCompatibilityBodyWithOptions(body, account, openAIResponsesCompatibilityOptions{ResponsesLite: responsesLite})
+}
+
+type openAIResponsesCompatibilityOptions struct {
+	ResponsesLite bool
+	// Compact marks the /responses/compact wire shape, which is left as-is
+	// by request-shape compatibility rewrites such as web_search history.
+	Compact bool
+}
+
+func normalizeOpenAIResponsesCompatibilityBodyWithOptions(body []byte, account *Account, opts openAIResponsesCompatibilityOptions) ([]byte, bool, error) {
+	responsesLite := opts.ResponsesLite
 	if account == nil || !account.IsOpenAI() {
 		return body, false, nil
 	}
@@ -1494,6 +1506,14 @@ func normalizeOpenAIResponsesWebSocketCompatibilityBody(body []byte, account *Ac
 			normalized = next
 			changed = true
 		}
+		if !opts.Compact {
+			webSearchBody, webSearchChanged, err := ensureOpenAIOAuthWebSearchToolForHistoryBody(normalized, responsesLite)
+			if err != nil {
+				return body, false, fmt.Errorf("normalize websocket body: %w", err)
+			}
+			normalized = webSearchBody
+			changed = changed || webSearchChanged
+		}
 	}
 	needsOrphanCleanup := account != nil && account.IsOpenAIOAuthLike() &&
 		gjson.GetBytes(normalized, "input").IsArray()
diff --git a/backend/internal/service/openai_oauth_web_search_history.go b/backend/internal/service/openai_oauth_web_search_history.go
new file mode 100644
index 0000000000..6a68eb7195
--- /dev/null
+++ b/backend/internal/service/openai_oauth_web_search_history.go
@@ -0,0 +1,264 @@
+package service
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+// The ChatGPT internal Codex endpoint rejects a request whose input replays a
+// hosted web_search_call item unless the request also declares the web_search
+// tool; the stream then fails with "response protection is unavailable".
+// Codex's local context compaction sends the full history with tools:[], so
+// every compaction after a web search fails (#7927).
+//
+// Declare a cached-only web_search tool for such requests. Responses Lite
+// rejects hosted tools at the top level, so Lite requests carry it in an
+// input additional_tools item instead. When the caller declared no tools at
+// all, also pin tool_choice to "none" so the injected tool cannot be invoked
+// and the request keeps its no-tools semantics.
+
+const (
+	openAIWebSearchCallItemType      = "web_search_call"
+	openAIAdditionalToolsItemType    = "additional_tools"
+	openAICompactionTriggerItemType  = "compaction_trigger"
+	openAIAdditionalToolsDefaultRole = "developer"
+)
+
+var openAIWebSearchHistoryTool = map[string]any{
+	"type":                "web_search",
+	"external_web_access": false,
+}
+
+func isOpenAIWebSearchToolType(toolType string) bool {
+	return strings.HasPrefix(strings.TrimSpace(toolType), "web_search")
+}
+
+func openAIToolsContainWebSearch(rawTools any) bool {
+	tools, ok := rawTools.([]any)
+	if !ok {
+		return false
+	}
+	for _, rawTool := range tools {
+		tool, ok := rawTool.(map[string]any)
+		if ok && isOpenAIWebSearchToolType(firstNonEmptyString(tool["type"])) {
+			return true
+		}
+	}
+	return false
+}
+
+// shouldPinOpenAIWebSearchHistoryToolChoice reports whether tool_choice may be
+// forced to "none": only when the caller offered no tools, so the choice
+// cannot meaningfully be anything else.
+func shouldPinOpenAIWebSearchHistoryToolChoice(choice any) bool {
+	switch typed := choice.(type) {
+	case nil:
+		return true
+	case string:
+		normalized := strings.ToLower(strings.TrimSpace(typed))
+		return normalized == "" || normalized == "auto" || normalized == "none"
+	default:
+		return false
+	}
+}
+
+// openAIAdditionalToolsInsertIndex keeps a trailing compaction trigger last,
+// as required by the remote compaction v2 wire format.
+func openAIAdditionalToolsInsertIndex(itemTypes []string) int {
+	if n := len(itemTypes); n > 0 && itemTypes[n-1] == openAICompactionTriggerItemType {
+		return n - 1
+	}
+	return len(itemTypes)
+}
+
+// ensureOpenAIOAuthWebSearchToolForHistory is the map variant used by the
+// Codex OAuth transform.
+func ensureOpenAIOAuthWebSearchToolForHistory(reqBody map[string]any, responsesLite bool) bool {
+	if reqBody == nil {
+		return false
+	}
+	input, ok := reqBody["input"].([]any)
+	if !ok {
+		return false
+	}
+	hasWebSearchCall := false
+	callerDeclaredTools := false
+	additionalToolsIndex := -1
+	itemTypes := make([]string, len(input))
+	for i, rawItem := range input {
+		item, ok := rawItem.(map[string]any)
+		if !ok {
+			continue
+		}
+		itemTypes[i] = strings.TrimSpace(firstNonEmptyString(item["type"]))
+		switch itemTypes[i] {
+		case openAIWebSearchCallItemType:
+			hasWebSearchCall = true
+		case openAIAdditionalToolsItemType:
+			if openAIToolsContainWebSearch(item["tools"]) {
+				return false
+			}
+			if tools, _ := item["tools"].([]any); len(tools) > 0 {
+				callerDeclaredTools = true
+			}
+			if additionalToolsIndex < 0 {
+				additionalToolsIndex = i
+			}
+		}
+	}
+	if !hasWebSearchCall || openAIToolsContainWebSearch(reqBody["tools"]) {
+		return false
+	}
+	tools, _ := reqBody["tools"].([]any)
+	callerDeclaredTools = callerDeclaredTools || len(tools) > 0
+
+	switch {
+	case !responsesLite:
+		reqBody["tools"] = append(tools, cloneOpenAIWebSearchHistoryTool())
+	case additionalToolsIndex >= 0:
+		// additionalToolsIndex is only recorded for map items.
+		item, _ := input[additionalToolsIndex].(map[string]any)
+		existing, _ := item["tools"].([]any)
+		item["tools"] = append(existing, cloneOpenAIWebSearchHistoryTool())
+	default:
+		at := openAIAdditionalToolsInsertIndex(itemTypes)
+		additional := map[string]any{
+			"type":  openAIAdditionalToolsItemType,
+			"role":  openAIAdditionalToolsDefaultRole,
+			"tools": []any{cloneOpenAIWebSearchHistoryTool()},
+		}
+		next := make([]any, 0, len(input)+1)
+		next = append(next, input[:at]...)
+		next = append(next, additional)
+		next = append(next, input[at:]...)
+		reqBody["input"] = next
+	}
+	if !callerDeclaredTools {
+		if choice, exists := reqBody["tool_choice"]; !exists || shouldPinOpenAIWebSearchHistoryToolChoice(choice) {
+			reqBody["tool_choice"] = "none"
+		}
+	}
+	return true
+}
+
+// ensureOpenAIOAuthWebSearchToolForHistoryBody is the raw-body variant used by
+// the passthrough and WebSocket paths; it avoids decoding the whole body.
+func ensureOpenAIOAuthWebSearchToolForHistoryBody(body []byte, responsesLite bool) ([]byte, bool, error) {
+	if len(body) == 0 || !bytes.Contains(body, []byte(openAIWebSearchCallItemType)) {
+		return body, false, nil
+	}
+	input := gjson.GetBytes(body, "input")
+	if !input.IsArray() {
+		return body, false, nil
+	}
+	items := input.Array()
+	hasWebSearchCall := false
+	callerDeclaredTools := false
+	additionalToolsIndex := -1
+	itemTypes := make([]string, len(items))
+	for i, item := range items {
+		itemTypes[i] = strings.TrimSpace(item.Get("type").String())
+		switch itemTypes[i] {
+		case openAIWebSearchCallItemType:
+			hasWebSearchCall = true
+		case openAIAdditionalToolsItemType:
+			itemTools := item.Get("tools")
+			if gjsonToolsContainWebSearch(itemTools) {
+				return body, false, nil
+			}
+			if itemTools.IsArray() && len(itemTools.Array()) > 0 {
+				callerDeclaredTools = true
+			}
+			if additionalToolsIndex < 0 {
+				additionalToolsIndex = i
+			}
+		}
+	}
+	if !hasWebSearchCall {
+		return body, false, nil
+	}
+	tools := gjson.GetBytes(body, "tools")
+	if gjsonToolsContainWebSearch(tools) {
+		return body, false, nil
+	}
+	topLevelTools := tools.IsArray() && len(tools.Array()) > 0
+	callerDeclaredTools = callerDeclaredTools || topLevelTools
+
+	var (
+		next []byte
+		err  error
+	)
+	switch {
+	case !responsesLite && topLevelTools:
+		next, err = sjson.SetBytes(body, "tools.-1", cloneOpenAIWebSearchHistoryTool())
+	case !responsesLite:
+		next, err = sjson.SetBytes(body, "tools", []any{cloneOpenAIWebSearchHistoryTool()})
+	case additionalToolsIndex >= 0 && items[additionalToolsIndex].Get("tools").IsArray():
+		next, err = sjson.SetBytes(body, fmt.Sprintf("input.%d.tools.-1", additionalToolsIndex), cloneOpenAIWebSearchHistoryTool())
+	case additionalToolsIndex >= 0:
+		next, err = sjson.SetBytes(body, fmt.Sprintf("input.%d.tools", additionalToolsIndex), []any{cloneOpenAIWebSearchHistoryTool()})
+	default:
+		next, err = insertOpenAIAdditionalToolsItemRaw(body, items, openAIAdditionalToolsInsertIndex(itemTypes))
+	}
+	if err != nil {
+		return body, false, fmt.Errorf("declare web_search tool for web_search_call history: %w", err)
+	}
+	if !callerDeclaredTools {
+		choice := gjson.GetBytes(next, "tool_choice")
+		if !choice.Exists() || choice.Type == gjson.Null || (choice.Type == gjson.String && shouldPinOpenAIWebSearchHistoryToolChoice(choice.String())) {
+			next, err = sjson.SetBytes(next, "tool_choice", "none")
+			if err != nil {
+				return body, false, fmt.Errorf("pin tool_choice for web_search_call history: %w", err)
+			}
+		}
+	}
+	return next, true, nil
+}
+
+func insertOpenAIAdditionalToolsItemRaw(body []byte, items []gjson.Result, at int) ([]byte, error) {
+	additional, err := marshalOpenAIUpstreamJSON(map[string]any{
+		"type":  openAIAdditionalToolsItemType,
+		"role":  openAIAdditionalToolsDefaultRole,
+		"tools": []any{cloneOpenAIWebSearchHistoryTool()},
+	})
+	if err != nil {
+		return nil, err
+	}
+	rawItems := make([][]byte, 0, len(items)+1)
+	for i, item := range items {
+		if i == at {
+			rawItems = append(rawItems, additional)
+		}
+		rawItems = append(rawItems, []byte(item.Raw))
+	}
+	if at >= len(items) {
+		rawItems = append(rawItems, additional)
+	}
+	raw := append([]byte{'['}, bytes.Join(rawItems, []byte{','})...)
+	raw = append(raw, ']')
+	return sjson.SetRawBytes(body, "input", raw)
+}
+
+func gjsonToolsContainWebSearch(tools gjson.Result) bool {
+	if !tools.IsArray() {
+		return false
+	}
+	for _, tool := range tools.Array() {
+		if isOpenAIWebSearchToolType(tool.Get("type").String()) {
+			return true
+		}
+	}
+	return false
+}
+
+func cloneOpenAIWebSearchHistoryTool() map[string]any {
+	tool := make(map[string]any, len(openAIWebSearchHistoryTool))
+	for key, value := range openAIWebSearchHistoryTool {
+		tool[key] = value
+	}
+	return tool
+}
diff --git a/backend/internal/service/openai_oauth_web_search_history_forward_test.go b/backend/internal/service/openai_oauth_web_search_history_forward_test.go
new file mode 100644
index 0000000000..9735f179ce
--- /dev/null
+++ b/backend/internal/service/openai_oauth_web_search_history_forward_test.go
@@ -0,0 +1,71 @@
+//go:build unit
+
+package service
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+// TestForward_OAuthWebSearchHistoryDeclaresTool drives the Codex compaction
+// shape (web_search_call history, tools:[]) through Forward and asserts the
+// body reaching chatgpt.com declares web_search (#7927): top-level for the
+// standard wire, input additional_tools for Responses Lite.
+func TestForward_OAuthWebSearchHistoryDeclaresTool(t *testing.T) {
+	for _, tc := range []struct {
+		name        string
+		passthrough bool
+		lite        bool
+	}{
+		{"transform", false, false},
+		{"passthrough", true, false},
+		{"transform lite", false, true},
+		{"passthrough lite", true, true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			gin.SetMode(gin.TestMode)
+			s := newAstraOAuthSetup(t, tc.passthrough)
+			if tc.lite {
+				s.c.Request.Header.Set(responsesLiteHeader, "true")
+			}
+			inner := `{"id":"resp_test","model":"gpt-5.5","output":[],"usage":{"input_tokens":1,"output_tokens":1,"total_tokens":2}}`
+			s.upstream.resp = &http.Response{
+				StatusCode: http.StatusOK,
+				Header:     http.Header{"Content-Type": []string{"text/event-stream"}},
+				Body:       io.NopCloser(strings.NewReader(codexCompletedSSE(inner))),
+			}
+			body, err := sjson.SetRawBytes([]byte(openAIWebSearchHistoryCompactionBody), "input.-1", []byte(`{"type":"compaction_trigger"}`))
+			require.NoError(t, err)
+
+			result, err := s.svc.Forward(context.Background(), s.c, s.account, body)
+			require.NoError(t, err)
+			require.NotNil(t, result)
+			require.NotNil(t, s.upstream.lastReq)
+			require.Equal(t, astraProCodexResponsesURL, s.upstream.lastReq.URL.String())
+
+			forwarded := s.upstream.lastBody
+			require.Equal(t, "web_search_call", gjson.GetBytes(forwarded, "input.1.type").String())
+			require.Equal(t, "none", gjson.GetBytes(forwarded, "tool_choice").String())
+			items := gjson.GetBytes(forwarded, "input").Array()
+			require.Equal(t, "compaction_trigger", items[len(items)-1].Get("type").String())
+			if !tc.lite {
+				tools := gjson.GetBytes(forwarded, "tools").Array()
+				require.Len(t, tools, 1)
+				require.Equal(t, "web_search", tools[0].Get("type").String())
+				return
+			}
+			require.False(t, gjsonToolsContainWebSearch(gjson.GetBytes(forwarded, "tools")))
+			additional := items[len(items)-2]
+			require.Equal(t, "additional_tools", additional.Get("type").String())
+			require.Equal(t, "web_search", additional.Get("tools.0.type").String())
+		})
+	}
+}
diff --git a/backend/internal/service/openai_oauth_web_search_history_test.go b/backend/internal/service/openai_oauth_web_search_history_test.go
new file mode 100644
index 0000000000..19b7ef0cfe
--- /dev/null
+++ b/backend/internal/service/openai_oauth_web_search_history_test.go
@@ -0,0 +1,152 @@
+package service
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/tidwall/gjson"
+)
+
+// Codex local compaction replays hosted web_search_call history with tools:[];
+// ChatGPT then fails with "response protection is unavailable" (#7927).
+const openAIWebSearchHistoryCompactionBody = `{"model":"gpt-5.5","instructions":"x","input":[{"type":"message","role":"user","content":[{"type":"input_text","text":"look it up"}]},{"type":"web_search_call","id":"ws_123","status":"completed","action":{"type":"search","query":"kwin inputmethod"}},{"type":"message","role":"assistant","content":[{"type":"output_text","text":"found"}]},{"type":"message","role":"user","content":[{"type":"input_text","text":"summarize"}]}],"tools":[],"tool_choice":"auto","parallel_tool_calls":false,"stream":true,"store":false}`
+
+func TestOAuthWebSearchHistoryToolAcrossPaths(t *testing.T) {
+	oauth := &Account{Platform: PlatformOpenAI, Type: AccountTypeOAuth}
+	transform := func(compact bool) func([]byte) ([]byte, bool, error) {
+		return func(b []byte) ([]byte, bool, error) {
+			var req map[string]any
+			if err := json.Unmarshal(b, &req); err != nil {
+				return nil, false, err
+			}
+			result := applyCodexOAuthTransform(req, true, compact)
+			out, err := json.Marshal(req)
+			return out, result.Modified, err
+		}
+	}
+	tests := []struct {
+		name      string
+		normalize func([]byte) ([]byte, bool, error)
+		inject    bool
+	}{
+		{"transformed OAuth", transform(false), true},
+		{"transformed OAuth compact", transform(true), false},
+		{"OAuth websocket", func(b []byte) ([]byte, bool, error) {
+			return normalizeOpenAIResponsesWebSocketCompatibilityBody(b, oauth, false)
+		}, true},
+		{"OAuth passthrough compact", func(b []byte) ([]byte, bool, error) {
+			return normalizeOpenAIResponsesCompatibilityBodyWithOptions(b, oauth, openAIResponsesCompatibilityOptions{Compact: true})
+		}, false},
+		{"API key websocket", func(b []byte) ([]byte, bool, error) {
+			return normalizeOpenAIResponsesWebSocketCompatibilityBody(b, &Account{Platform: PlatformOpenAI, Type: AccountTypeAPIKey}, false)
+		}, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			out, _, err := tt.normalize([]byte(openAIWebSearchHistoryCompactionBody))
+			require.NoError(t, err)
+			require.Equal(t, "web_search_call", gjson.GetBytes(out, "input.1.type").String())
+			if !tt.inject {
+				require.False(t, gjsonToolsContainWebSearch(gjson.GetBytes(out, "tools")))
+				return
+			}
+			tools := gjson.GetBytes(out, "tools").Array()
+			require.Len(t, tools, 1)
+			require.Equal(t, "web_search", tools[0].Get("type").String())
+			require.False(t, tools[0].Get("external_web_access").Bool())
+			require.True(t, tools[0].Get("external_web_access").Exists())
+			require.Equal(t, "none", gjson.GetBytes(out, "tool_choice").String())
+		})
+	}
+}
+
+func TestEnsureOpenAIOAuthWebSearchToolForHistory(t *testing.T) {
+	const (
+		user    = `{"type":"message","role":"user","content":[{"type":"input_text","text":"q"}]}`
+		search  = `{"type":"web_search_call","id":"ws_1","status":"completed","action":{"type":"search","query":"q"}}`
+		trigger = `{"type":"compaction_trigger"}`
+		history = `[` + user + `,` + search + `]`
+	)
+	tests := []struct {
+		name       string
+		body       string
+		lite       bool
+		changed    bool
+		toolsPath  string
+		toolCount  int
+		toolChoice string
+		itemTypes  []string
+	}{
+		{"tools absent", `{"input":` + history + `}`, false, true, "tools", 1, "none", nil},
+		{"tools null", `{"input":` + history + `,"tools":null,"tool_choice":null}`, false, true, "tools", 1, "none", nil},
+		{"explicit none kept", `{"input":` + history + `,"tools":[],"tool_choice":"none"}`, false, true, "tools", 1, "none", nil},
+		{"required not rewritten", `{"input":` + history + `,"tools":[],"tool_choice":"required"}`, false, true, "tools", 1, "required", nil},
+		{"caller tools keep choice", `{"input":` + history + `,"tools":[{"type":"function","name":"echo"}],"tool_choice":"auto"}`, false, true, "tools", 2, "auto", nil},
+		{"web_search already declared", `{"input":` + history + `,"tools":[{"type":"web_search"}]}`, false, false, "", 0, "", nil},
+		{"web_search_preview declared", `{"input":` + history + `,"tools":[{"type":"web_search_preview"}]}`, false, false, "", 0, "", nil},
+		{"declared via additional_tools", `{"input":[{"type":"additional_tools","tools":[{"type":"web_search"}]},` + search + `]}`, false, false, "", 0, "", nil},
+		{"no web_search_call item", `{"input":[{"type":"message","role":"user","content":"web_search_call"}],"tools":[]}`, false, false, "", 0, "", nil},
+		{"string input", `{"input":"web_search_call"}`, false, false, "", 0, "", nil},
+		{"lite inserts before compaction trigger", `{"input":[` + user + `,` + search + `,` + trigger + `]}`, true, true, "input.2.tools", 1, "none",
+			[]string{"message", "web_search_call", "additional_tools", "compaction_trigger"}},
+		{"lite appends without trigger", `{"input":` + history + `,"tool_choice":"auto"}`, true, true, "input.2.tools", 1, "none",
+			[]string{"message", "web_search_call", "additional_tools"}},
+		{"lite extends caller additional_tools", `{"input":[{"type":"additional_tools","role":"developer","tools":[{"type":"function","name":"echo"}]},` + search + `,` + trigger + `],"tool_choice":"auto"}`, true, true, "input.0.tools", 2, "auto",
+			[]string{"additional_tools", "web_search_call", "compaction_trigger"}},
+		{"lite fills empty additional_tools", `{"input":[{"type":"additional_tools","role":"developer"},` + search + `]}`, true, true, "input.0.tools", 1, "none",
+			[]string{"additional_tools", "web_search_call"}},
+		{"lite keeps top-level tools untouched", `{"input":` + history + `,"tools":[{"type":"function","name":"echo"}]}`, true, true, "input.2.tools", 1, "",
+			[]string{"message", "web_search_call", "additional_tools"}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			out, changed, err := ensureOpenAIOAuthWebSearchToolForHistoryBody([]byte(tt.body), tt.lite)
+			require.NoError(t, err)
+			require.Equal(t, tt.changed, changed)
+			var req map[string]any
+			require.NoError(t, json.Unmarshal([]byte(tt.body), &req))
+			require.Equal(t, tt.changed, ensureOpenAIOAuthWebSearchToolForHistory(req, tt.lite))
+			if !tt.changed {
+				require.JSONEq(t, tt.body, string(out))
+				return
+			}
+			require.True(t, gjson.ValidBytes(out))
+			tools := gjson.GetBytes(out, tt.toolsPath).Array()
+			require.Len(t, tools, tt.toolCount)
+			require.Equal(t, "web_search", tools[len(tools)-1].Get("type").String())
+			require.Equal(t, tt.toolChoice, gjson.GetBytes(out, "tool_choice").String())
+			if tt.lite {
+				require.False(t, gjsonToolsContainWebSearch(gjson.GetBytes(out, "tools")), "Lite rejects top-level hosted tools")
+				var types []string
+				for _, item := range gjson.GetBytes(out, "input").Array() {
+					types = append(types, item.Get("type").String())
+				}
+				require.Equal(t, tt.itemTypes, types)
+			}
+
+			// The map variant used by the Codex transform must agree.
+			mapOut, err := json.Marshal(req)
+			require.NoError(t, err)
+			require.JSONEq(t, string(out), string(mapOut))
+		})
+	}
+}
+
+func TestEnsureOpenAIOAuthWebSearchToolForHistoryDoesNotShareToolMap(t *testing.T) {
+	first := map[string]any{"input": []any{map[string]any{"type": "web_search_call"}}}
+	second := map[string]any{"input": []any{map[string]any{"type": "web_search_call"}}}
+	require.True(t, ensureOpenAIOAuthWebSearchToolForHistory(first, false))
+	require.True(t, ensureOpenAIOAuthWebSearchToolForHistory(second, false))
+	firstTools, ok := first["tools"].([]any)
+	require.True(t, ok)
+	firstTool, ok := firstTools[0].(map[string]any)
+	require.True(t, ok)
+	firstTool["external_web_access"] = true
+	secondTools, ok := second["tools"].([]any)
+	require.True(t, ok)
+	secondTool, ok := secondTools[0].(map[string]any)
+	require.True(t, ok)
+	require.Equal(t, false, secondTool["external_web_access"])
+	require.Equal(t, false, openAIWebSearchHistoryTool["external_web_access"])
+}