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Merged
dvyukov merged 1 commit into from
Jan 27, 2026
Merged

pkg/aflow: handle input token overflow for LLM tools #6696

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9 changes: 9 additions & 0 deletions pkg/aflow/execute.go
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,15 @@ func (err *modelQuotaError) Error() string {
return fmt.Sprintf("model %q is over daily quota", err.model)
}

func isTokenOverflowError(err error) bool {
var overflowErr *tokenOverflowError
return errors.As(err, &overflowErr)
}

type tokenOverflowError struct {
error
}

// QuotaResetTime returns the time when RPD quota will be reset
// for a quota overflow happened at time t.
func QuotaResetTime(t time.Time) time.Time {
Expand Down
52 changes: 42 additions & 10 deletions pkg/aflow/llm_agent.go
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Expand Up @@ -110,6 +110,11 @@ Note: if you already provided you final reply, you will need to provide it again
Or did you want to call some other tools, but did not actually do that?
`

const llmAnswerNow = `
Provide a best-effort answer to the original question with all of the information
you have so far without calling any more tools!
`

type llmOutputs struct {
tool Tool
provideOutputs func(*verifyContext, string, bool)
Expand Down Expand Up @@ -178,22 +183,43 @@ func (a *LLMAgent) executeOne(ctx *Context, candidate int) (string, map[string]a
func (a *LLMAgent) chat(ctx *Context, cfg *genai.GenerateContentConfig, tools map[string]Tool,
prompt string, candidate int) (string, map[string]any, error) {
var outputs map[string]any
answerNow := false
req := []*genai.Content{genai.NewContentFromText(prompt, genai.RoleUser)}
for {
reqSpan := &trajectory.Span{
span := &trajectory.Span{
Type: trajectory.SpanLLM,
Name: a.Name,
Model: ctx.modelName(a.Model),
}
if err := ctx.startSpan(reqSpan); err != nil {
if err := ctx.startSpan(span); err != nil {
return "", nil, err
}
resp, err := a.generateContent(ctx, cfg, req, candidate)
if err != nil {
return "", nil, ctx.finishSpan(reqSpan, err)
resp, respErr := a.generateContent(ctx, cfg, req, candidate)
if respErr != nil {
span.Error = respErr.Error()
if err := ctx.finishSpan(span, nil); err != nil {
return "", nil, err
}
// Input overflows maximum number of tokens.
// If this is an LLMTool, we remove the last tool reply,
// and replace it with an order to answer right now.
if isTokenOverflowError(respErr) &&
a.Reply == llmToolReply &&
len(req) >= 3 &&
!answerNow {
answerNow = true
cfg.ToolConfig = &genai.ToolConfig{
FunctionCallingConfig: &genai.FunctionCallingConfig{
Mode: genai.FunctionCallingConfigModeNone,
},
}
req[len(req)-1] = genai.NewContentFromText(llmAnswerNow, genai.RoleUser)
continue
}
return "", nil, respErr
}
reply, calls, respErr := a.parseResponse(resp, reqSpan)
if err := ctx.finishSpan(reqSpan, respErr); err != nil {
reply, calls, respErr := a.parseResponse(resp, span)
if err := ctx.finishSpan(span, respErr); err != nil {
return "", nil, err
}
req = append(req, resp.Candidates[0].Content)
Expand Down Expand Up @@ -361,13 +387,15 @@ func (a *LLMAgent) generateContent(ctx *Context, cfg *genai.GenerateContentConfi
for try := 0; ; try++ {
resp, err := a.generateContentCached(ctx, cfg, req, candidate)
var apiErr genai.APIError
if err != nil && try < 100 && errors.As(err, &apiErr) &&
apiErr.Code == http.StatusServiceUnavailable {
if err == nil || !errors.As(err, &apiErr) {
return resp, err
}
if try < 100 && apiErr.Code == http.StatusServiceUnavailable {
time.Sleep(backoff)
backoff = min(backoff+time.Second, 10*time.Second)
continue
}
if err != nil && errors.As(err, &apiErr) && apiErr.Code == http.StatusTooManyRequests &&
if apiErr.Code == http.StatusTooManyRequests &&
strings.Contains(apiErr.Message, "Quota exceeded for metric") {
if match := rePleaseRetry.FindStringSubmatch(apiErr.Message); match != nil {
sec, _ := strconv.Atoi(match[1])
Expand All @@ -378,6 +406,10 @@ func (a *LLMAgent) generateContent(ctx *Context, cfg *genai.GenerateContentConfi
return resp, &modelQuotaError{ctx.modelName(a.Model)}
}
}
if apiErr.Code == http.StatusBadRequest &&
strings.Contains(apiErr.Message, "The input token count exceeds the maximum") {
return resp, &tokenOverflowError{err}
}
return resp, err
}
}
Expand Down
20 changes: 18 additions & 2 deletions pkg/aflow/llm_tool_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
package aflow

import (
"net/http"
"strings"
"testing"

"github.com/stretchr/testify/assert"
Expand Down Expand Up @@ -40,7 +42,7 @@ func TestLLMTool(t *testing.T) {
NewFuncTool("researcher-tool", func(ctx *Context, state inputs, args toolArgs) (struct{}, error) {
// State passed all the way from the workflow inputs.
assert.Equal(t, state.Input, 42)
assert.True(t, args.Something == "subtool input 1" || args.Something == "subtool input 2",
assert.True(t, strings.HasPrefix(args.Something, "subtool input"),
"args.Something=%q", args.Something)
return struct{}{}, nil
}, "researcher-tool description"),
Expand Down Expand Up @@ -84,13 +86,27 @@ func TestLLMTool(t *testing.T) {
},
&genai.Part{
FunctionCall: &genai.FunctionCall{
ID: "id2",
ID: "id3",
Name: "researcher-tool",
Args: map[string]any{
"Something": "subtool input 2",
},
},
},
// Now model input token overflow.
&genai.Part{
FunctionCall: &genai.FunctionCall{
ID: "id4",
Name: "researcher-tool",
Args: map[string]any{
"Something": "subtool input 3",
},
},
},
genai.APIError{
Code: http.StatusBadRequest,
Message: "The input token count exceeds the maximum number of tokens allowed 1048576.",
},
genai.NewPartFromText("Still nothing."),
// Main returns result.
genai.NewPartFromText("YES"),
Expand Down
7 changes: 5 additions & 2 deletions pkg/aflow/runner_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ import (
"flag"
"os"
"path/filepath"
"slices"
"testing"
"time"

Expand All @@ -33,7 +34,7 @@ func testFlow[Inputs, Outputs any](t *testing.T, inputs map[string]any, result a
require.NoError(t, err)
type llmRequest struct {
Model string
Config *genai.GenerateContentConfig
Config genai.GenerateContentConfig
Request []*genai.Content
}
var requests []llmRequest
Expand All @@ -45,7 +46,9 @@ func testFlow[Inputs, Outputs any](t *testing.T, inputs map[string]any, result a
},
generateContent: func(model string, cfg *genai.GenerateContentConfig, req []*genai.Content) (
*genai.GenerateContentResponse, error) {
requests = append(requests, llmRequest{model, cfg, req})
// Copy config and req slices, so that future changes to these objects
// don't affect our stored requests.
requests = append(requests, llmRequest{model, *cfg, slices.Clone(req)})
require.NotEmpty(t, llmReplies, "unexpected LLM call")
reply := llmReplies[0]
llmReplies = llmReplies[1:]
Expand Down
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