Merge #18: bedrock /btw chats fail from invalid toolConfig

Inject a stub toolConfig when the message history contains toolUse or
toolResult blocks but req.Tools is empty (e.g. the /btw side-chat sends
the frozen main transcript). Bedrock's Converse API otherwise rejects
the request with HTTP 400. Bedrock-only; other providers unaffected.

Co-authored-by: Raymond Gasper <raymondgasper@fastmail.com>

commit: 6938d13e9006201c24ea3240ab7884fdea5e49e8
author: patriceckhart · 4mo ago · 2026-06-08 15:25 UTC
merge of: 7eb8a65 + fec5ae0 · diff against the first parent
signature: unsigned
refs: tag: v0.2.20

2 files · +102 -0

M packages/provider/amazon_bedrock.go +33 -0


@@ -299,6 +299,24 @@ func bedrockModelSupportsCaching(modelID string) bool {
299	299		return strings.HasPrefix(modelID, "anthropic.claude-")
300	300		}
301	301
	302	+	// bedrockMessagesHaveToolBlocks reports whether any message in msgs
	303	+	// contains a toolUse or toolResult content block. Bedrock's Converse API
	304	+	// rejects the request with HTTP 400 if those block types are present but
	305	+	// toolConfig is absent.
	306	+	func bedrockMessagesHaveToolBlocks(msgs []bedrockMessage) bool {
	307	+	for _, m := range msgs {
	308	+	for _, c := range m.Content {
	309	+	if _, ok := c["toolUse"]; ok {
	310	+	return true
	311	+	}
	312	+	if _, ok := c["toolResult"]; ok {
	313	+	return true
	314	+	}
	315	+	}
	316	+	}
	317	+	return false
	318	+	}
	319	+
302	320		func (c bedrockClient) buildRequest(req Request) (bedrockRequest, error) {
303	321		out := &bedrockRequest{}
304	322

@@ -380,6 +398,21 @@ func (c bedrockClient) buildRequest(req Request) (bedrockRequest, error) {
380	398		tc.Tools = append(tc.Tools, ts)
381	399		}
382	400		out.ToolConfig = &tc
	401	+	} else if bedrockMessagesHaveToolBlocks(out.Messages) {
	402	+	// Bedrock requires toolConfig to be present whenever the message
	403	+	// history contains toolUse or toolResult content blocks, even if
	404	+	// the current request does not intend to call any tools (e.g. the
	405	+	// /btw side-chat sends the frozen main transcript which may include
	406	+	// prior tool turns). Inject a stub tool so the API accepts the
	407	+	// request; it will never be invoked since no tool_use stop reason
	408	+	// can be triggered when the real tool list is empty.
	409	+	var stub bedrockToolSpec
	410	+	stub.ToolSpec.Name = "_placeholder"
	411	+	stub.ToolSpec.Description = "placeholder required by Bedrock when tool history is present"
	412	+	stub.ToolSpec.InputSchema.JSON = json.RawMessage(`{"type":"object","properties":{}}`)
	413	+	out.ToolConfig = &struct {
	414	+	Tools []bedrockToolSpec `json:"tools"`
	415	+	}{Tools: []bedrockToolSpec{stub}}
383	416		}
384	417
385	418		if caching {


@@ -299,6 +299,24 @@ func bedrockModelSupportsCaching(modelID string) bool {
299	return strings.HasPrefix(modelID, "anthropic.claude-")	299		return strings.HasPrefix(modelID, "anthropic.claude-")
300	}	300		}
301		301
		302	+	// bedrockMessagesHaveToolBlocks reports whether any message in msgs
		303	+	// contains a toolUse or toolResult content block. Bedrock's Converse API
		304	+	// rejects the request with HTTP 400 if those block types are present but
		305	+	// toolConfig is absent.
		306	+	func bedrockMessagesHaveToolBlocks(msgs []bedrockMessage) bool {
		307	+	for _, m := range msgs {
		308	+	for _, c := range m.Content {
		309	+	if _, ok := c["toolUse"]; ok {
		310	+	return true
		311	+	}
		312	+	if _, ok := c["toolResult"]; ok {
		313	+	return true
		314	+	}
		315	+	}
		316	+	}
		317	+	return false
		318	+	}
		319	+
302	func (c bedrockClient) buildRequest(req Request) (bedrockRequest, error) {	320		func (c bedrockClient) buildRequest(req Request) (bedrockRequest, error) {
303	out := &bedrockRequest{}	321		out := &bedrockRequest{}
304		322

@@ -380,6 +398,21 @@ func (c bedrockClient) buildRequest(req Request) (bedrockRequest, error) {
380	tc.Tools = append(tc.Tools, ts)	398		tc.Tools = append(tc.Tools, ts)
381	}	399		}
382	out.ToolConfig = &tc	400		out.ToolConfig = &tc
		401	+	} else if bedrockMessagesHaveToolBlocks(out.Messages) {
		402	+	// Bedrock requires toolConfig to be present whenever the message
		403	+	// history contains toolUse or toolResult content blocks, even if
		404	+	// the current request does not intend to call any tools (e.g. the
		405	+	// /btw side-chat sends the frozen main transcript which may include
		406	+	// prior tool turns). Inject a stub tool so the API accepts the
		407	+	// request; it will never be invoked since no tool_use stop reason
		408	+	// can be triggered when the real tool list is empty.
		409	+	var stub bedrockToolSpec
		410	+	stub.ToolSpec.Name = "_placeholder"
		411	+	stub.ToolSpec.Description = "placeholder required by Bedrock when tool history is present"
		412	+	stub.ToolSpec.InputSchema.JSON = json.RawMessage(`{"type":"object","properties":{}}`)
		413	+	out.ToolConfig = &struct {
		414	+	Tools []bedrockToolSpec `json:"tools"`
		415	+	}{Tools: []bedrockToolSpec{stub}}
383	}	416		}
384		417
385	if caching {	418		if caching {

M packages/provider/amazon_bedrock_test.go +69 -0


@@ -357,6 +357,75 @@ func TestBedrockBuildRequestCachingWireJSON(t *testing.T) {
357	357		}
358	358		}
359	359
	360	+	// TestBedrockBuildRequestBtwToolHistory reproduces the /btw HTTP 400 bug:
	361	+	// the side-chat sends no tools but the frozen main transcript contains
	362	+	// toolUse / toolResult blocks. Bedrock rejects such a request unless
	363	+	// toolConfig is present. buildRequest must inject a stub toolConfig.
	364	+	func TestBedrockBuildRequestBtwToolHistory(t *testing.T) {
	365	+	client := &bedrockClient{region: "us-east-1"}
	366	+	req, err := client.buildRequest(Request{
	367	+	Model: "amazon.nova-pro-v1:0",
	368	+	// No tools — simulates /btw side-chat.
	369	+	Messages: []Message{
	370	+	// Frozen main transcript: one tool call + result already happened.
	371	+	{Role: RoleAssistant, Content: []Content{
	372	+	ToolCallBlock{ID: "tc-1", Name: "bash", Arguments: json.RawMessage(`{"command":"ls"}`)},
	373	+	}},
	374	+	{Role: RoleTool, Content: []Content{
	375	+	ToolResultBlock{CallID: "tc-1", Content: []Content{TextBlock{Text: "file.go"}}},
	376	+	}},
	377	+	// Side-chat question appended by btwDialog.submit.
	378	+	{Role: RoleUser, Content: []Content{TextBlock{Text: "what does that file do?"}}},
	379	+	},
	380	+	})
	381	+	if err != nil {
	382	+	t.Fatal(err)
	383	+	}
	384	+	if req.ToolConfig == nil {
	385	+	t.Fatal("buildRequest should inject a stub toolConfig when history has tool blocks and req.Tools is empty, but ToolConfig is nil")
	386	+	}
	387	+	if len(req.ToolConfig.Tools) == 0 {
	388	+	t.Fatal("stub toolConfig should have at least one tool")
	389	+	}
	390	+	// The stub must have a valid name and a non-nil schema so Bedrock won't
	391	+	// reject it for a different reason.
	392	+	stub := req.ToolConfig.Tools[0]
	393	+	if stub.ToolSpec.Name == "" {
	394	+	t.Error("stub tool name must not be empty")
	395	+	}
	396	+	if stub.ToolSpec.InputSchema.JSON == nil {
	397	+	t.Error("stub tool schema must not be nil")
	398	+	}
	399	+	// Serialised wire payload must include toolConfig.
	400	+	b, err := json.Marshal(req)
	401	+	if err != nil {
	402	+	t.Fatal(err)
	403	+	}
	404	+	if !strings.Contains(string(b), `"toolConfig"`) {
	405	+	t.Errorf("serialised request missing toolConfig: %s", b)
	406	+	}
	407	+	}
	408	+
	409	+	// TestBedrockBuildRequestNoToolHistoryNoStub ensures that when there are
	410	+	// no tool blocks in the history and no tools in the request (ordinary
	411	+	// conversational call), we do NOT inject a toolConfig at all — the extra
	412	+	// field is unnecessary and some models may behave differently with it.
	413	+	func TestBedrockBuildRequestNoToolHistoryNoStub(t *testing.T) {
	414	+	client := &bedrockClient{region: "us-east-1"}
	415	+	req, err := client.buildRequest(Request{
	416	+	Model: "amazon.nova-pro-v1:0",
	417	+	Messages: []Message{
	418	+	{Role: RoleUser, Content: []Content{TextBlock{Text: "hello"}}},
	419	+	},
	420	+	})
	421	+	if err != nil {
	422	+	t.Fatal(err)
	423	+	}
	424	+	if req.ToolConfig != nil {
	425	+	t.Errorf("expected nil ToolConfig for plain conversation, got: %+v", req.ToolConfig)
	426	+	}
	427	+	}
	428	+
360	429		func TestBedrockBuildRequestSkipsEmptyToolMessages(t *testing.T) {
361	430		client := &bedrockClient{}
362	431		req, err := client.buildRequest(Request{Messages: []Message{


@@ -357,6 +357,75 @@ func TestBedrockBuildRequestCachingWireJSON(t *testing.T) {
357	}	357		}
358	}	358		}
359		359
		360	+	// TestBedrockBuildRequestBtwToolHistory reproduces the /btw HTTP 400 bug:
		361	+	// the side-chat sends no tools but the frozen main transcript contains
		362	+	// toolUse / toolResult blocks. Bedrock rejects such a request unless
		363	+	// toolConfig is present. buildRequest must inject a stub toolConfig.
		364	+	func TestBedrockBuildRequestBtwToolHistory(t *testing.T) {
		365	+	client := &bedrockClient{region: "us-east-1"}
		366	+	req, err := client.buildRequest(Request{
		367	+	Model: "amazon.nova-pro-v1:0",
		368	+	// No tools — simulates /btw side-chat.
		369	+	Messages: []Message{
		370	+	// Frozen main transcript: one tool call + result already happened.
		371	+	{Role: RoleAssistant, Content: []Content{
		372	+	ToolCallBlock{ID: "tc-1", Name: "bash", Arguments: json.RawMessage(`{"command":"ls"}`)},
		373	+	}},
		374	+	{Role: RoleTool, Content: []Content{
		375	+	ToolResultBlock{CallID: "tc-1", Content: []Content{TextBlock{Text: "file.go"}}},
		376	+	}},
		377	+	// Side-chat question appended by btwDialog.submit.
		378	+	{Role: RoleUser, Content: []Content{TextBlock{Text: "what does that file do?"}}},
		379	+	},
		380	+	})
		381	+	if err != nil {
		382	+	t.Fatal(err)
		383	+	}
		384	+	if req.ToolConfig == nil {
		385	+	t.Fatal("buildRequest should inject a stub toolConfig when history has tool blocks and req.Tools is empty, but ToolConfig is nil")
		386	+	}
		387	+	if len(req.ToolConfig.Tools) == 0 {
		388	+	t.Fatal("stub toolConfig should have at least one tool")
		389	+	}
		390	+	// The stub must have a valid name and a non-nil schema so Bedrock won't
		391	+	// reject it for a different reason.
		392	+	stub := req.ToolConfig.Tools[0]
		393	+	if stub.ToolSpec.Name == "" {
		394	+	t.Error("stub tool name must not be empty")
		395	+	}
		396	+	if stub.ToolSpec.InputSchema.JSON == nil {
		397	+	t.Error("stub tool schema must not be nil")
		398	+	}
		399	+	// Serialised wire payload must include toolConfig.
		400	+	b, err := json.Marshal(req)
		401	+	if err != nil {
		402	+	t.Fatal(err)
		403	+	}
		404	+	if !strings.Contains(string(b), `"toolConfig"`) {
		405	+	t.Errorf("serialised request missing toolConfig: %s", b)
		406	+	}
		407	+	}
		408	+
		409	+	// TestBedrockBuildRequestNoToolHistoryNoStub ensures that when there are
		410	+	// no tool blocks in the history and no tools in the request (ordinary
		411	+	// conversational call), we do NOT inject a toolConfig at all — the extra
		412	+	// field is unnecessary and some models may behave differently with it.
		413	+	func TestBedrockBuildRequestNoToolHistoryNoStub(t *testing.T) {
		414	+	client := &bedrockClient{region: "us-east-1"}
		415	+	req, err := client.buildRequest(Request{
		416	+	Model: "amazon.nova-pro-v1:0",
		417	+	Messages: []Message{
		418	+	{Role: RoleUser, Content: []Content{TextBlock{Text: "hello"}}},
		419	+	},
		420	+	})
		421	+	if err != nil {
		422	+	t.Fatal(err)
		423	+	}
		424	+	if req.ToolConfig != nil {
		425	+	t.Errorf("expected nil ToolConfig for plain conversation, got: %+v", req.ToolConfig)
		426	+	}
		427	+	}
		428	+
360	func TestBedrockBuildRequestSkipsEmptyToolMessages(t *testing.T) {	429		func TestBedrockBuildRequestSkipsEmptyToolMessages(t *testing.T) {
361	client := &bedrockClient{}	430		client := &bedrockClient{}
362	req, err := client.buildRequest(Request{Messages: []Message{	431		req, err := client.buildRequest(Request{Messages: []Message{