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fix(backend): increase AG-UI event buffer size from 1MB to 10MB #964

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Merged
Gkrumbach07 merged 2 commits into from
Mar 20, 2026
Merged

fix(backend): increase AG-UI event buffer size from 1MB to 10MB #964

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e69b8f0
fix(backend): increase AG-UI event buffer size from 1MB to 10MB
Gkrumbach07 Mar 19, 2026
bb60b5d
fix(backend): align DeriveAgentStatus tail buffer with scanner max li…
Gkrumbach07 Mar 19, 2026
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9 changes: 5 additions & 4 deletions components/backend/websocket/agui_store.go
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Original file line number Diff line number Diff line change
Expand Up @@ -57,8 +57,8 @@ var StateBaseDir string

const (
// Scanner buffer sizes for reading JSONL files
scannerInitialBufferSize = 64 * 1024 // 64KB initial buffer
scannerMaxLineSize = 1024 * 1024 // 1MB max line size
scannerInitialBufferSize = 64 * 1024 // 64KB initial buffer
scannerMaxLineSize = 10 * 1024 * 1024 // 10MB max line size (increased from 1MB to support large MCP tool results)
)

// ─── Live event pipe (multi-client broadcast) ───────────────────────
Expand Down Expand Up @@ -219,8 +219,9 @@ func DeriveAgentStatus(sessionID string) string {
path := fmt.Sprintf("%s/sessions/%s/agui-events.jsonl", StateBaseDir, sessionID)

// Read only the tail of the file to avoid loading entire event log into memory.
// 64KB is sufficient for recent lifecycle events (scanning backwards).
const maxTailBytes = 64 * 1024
// Use 2x scannerMaxLineSize to ensure we can read at least one complete max-sized
// event line plus additional events for proper status derivation.
maxTailBytes := int64(scannerMaxLineSize * 2)

file, err := os.Open(path)
if err != nil {
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