JuliusBrussee/caveman · error

note exceeds 4096 bytes

Error message

note exceeds 4096 bytes

What it means

StartExperiment found the supplied note longer than 4096 bytes. Notes are bounded free-text metadata; the guard rejects oversized notes before persisting experiment state so storage stays bounded.

Source

Thrown at proxy/internal/store/learn_experiment.go:93

	Label      string                `json:"label"`
	SinkID     string                `json:"sink_id,omitempty"`
	FixKind    string                `json:"fix_kind,omitempty"`
	Arms       []ExperimentArmResult `json:"arms"`
	Verdict    string                `json:"verdict"`
	DeltaPct   *float64              `json:"median_session_tokens_delta_pct,omitempty"`
	SavedUSD   *float64              `json:"saved_usd_per_session,omitempty"`
	Currency   string                `json:"currency,omitempty"`
	Attributed LearnAttribution      `json:"attribution"`
	Caveats    []string              `json:"caveats"`
}

func (s *Store) StartExperiment(label, sinkID, fixKind, note string) (Experiment, error) {
	label = strings.TrimSpace(label)
	if label == "" || len(label) > 128 {
		return Experiment{}, fmt.Errorf("experiment label must be 1-128 bytes")
	}
	if len(note) > 4096 {
		return Experiment{}, fmt.Errorf("note exceeds 4096 bytes")
	}
	now := learnOutcomeClock().UTC().Format(time.RFC3339)
	result, err := s.db.Exec(`INSERT INTO experiments (label, sink_id, fix_kind, note, created_at)
		VALUES (?, ?, ?, ?, ?)`, label, sinkID, fixKind, note, now)
	if err != nil {
		return Experiment{}, fmt.Errorf("start experiment %q: %w", label, err)
	}
	id, err := result.LastInsertId()
	if err != nil {
		return Experiment{}, fmt.Errorf("read experiment id: %w", err)
	}
	if _, err := s.db.Exec(`INSERT INTO experiment_arms (experiment_id, arm, started_at)
		VALUES (?, ?, ?)`, id, experimentArmOn, now); err != nil {
		return Experiment{}, fmt.Errorf("open first arm: %w", err)
	}
	return s.LoadExperiment(label)
}

View on GitHub (pinned to 81536f57b3)

Solutions

1. Shorten the note to at most 4096 bytes
2. Move long context into a linked artifact instead of the note field
3. Truncate programmatically generated notes before submission

When it happens

Trigger: Thrown at proxy/internal/store/learn_experiment.go:93 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of JuliusBrussee/caveman@81536f57b3 (2026-08-27). Data as JSON: /api/errors/248344bcd7e4a1cd. Report an issue: GitHub.