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fix: prevent infinite loop in performAgentChain on repeating tool calls #178

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fix: prevent infinite loop in performAgentChain on repeating tool calls #178

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4a86e5e
fix: add iteration cap and repeating escalation to performAgentChain
mason5052 Mar 6, 2026
917b371
fix: address review feedback on iteration cap and repeating escalation
mason5052 Mar 6, 2026
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26 changes: 20 additions & 6 deletions backend/pkg/providers/performer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -26,11 +26,13 @@ import (
)

const (
maxRetriesToCallSimpleChain = 3
maxRetriesToCallAgentChain = 3
maxRetriesToCallFunction = 3
maxReflectorCallsPerChain = 3
delayBetweenRetries = 5 * time.Second
maxRetriesToCallSimpleChain = 3
maxRetriesToCallAgentChain = 3
maxRetriesToCallFunction = 3
maxReflectorCallsPerChain = 3
maxAgentChainIterations = 100
maxSoftDetectionsBeforeAbort = 4
delayBetweenRetries = 5 * time.Second
Comment on lines +33 to +35
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Copilot AI Mar 6, 2026

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The constant name maxRepeatingDetectionsBeforeErr is a bit ambiguous because the code escalates on the Nth repeating detection (via the -1 in the threshold math), not after N detections. Consider renaming it to something like “...ToAbort/ToError” or adjusting the condition so the name matches the behavior.

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@mason5052 mason5052 Mar 6, 2026

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Good point on the naming ambiguity. Renamed to maxSoftDetectionsBeforeAbort = 4 and removed the -1 from the condition. Now the math is straightforward: RepeatingToolCallThreshold(3) + maxSoftDetectionsBeforeAbort(4) = 7, and the name accurately describes the behavior (4 soft detection responses before abort). Fixed in 917b371.

)

type callResult struct {
Expand Down Expand Up @@ -91,7 +93,13 @@ func (fp *flowProvider) performAgentChain(
groupID := fmt.Sprintf("flow-%d", fp.flowID)
toolTypeMapping := tools.GetToolTypeMapping()

for {
for iteration := 0; ; iteration++ {
if iteration >= maxAgentChainIterations {
msg := fmt.Sprintf("agent chain exceeded maximum iterations (%d)", maxAgentChainIterations)
logger.WithField("iteration", iteration).Error(msg)
return errors.New(msg)
}

result, err := fp.callWithRetries(ctx, chain, optAgentType, executor)
if err != nil {
logger.WithError(err).Error("failed to call agent chain")
Expand Down Expand Up @@ -256,6 +264,12 @@ func (fp *flowProvider) execToolCall(
})

if detector.detect(toolCall) {
if len(detector.funcCalls) >= RepeatingToolCallThreshold+maxSoftDetectionsBeforeAbort {
errMsg := fmt.Sprintf("tool '%s' repeated %d times consecutively, aborting chain", funcName, len(detector.funcCalls))
logger.WithField("repeat_count", len(detector.funcCalls)).Error(errMsg)
return "", errors.New(errMsg)
}

response := fmt.Sprintf("tool call '%s' is repeating, please try another tool", funcName)

_, observation := obs.Observer.NewObservation(ctx)
Expand Down