JuliusBrussee/caveman · error

requires a value

Error message

%s requires a value

What it means

Value-taking stats options (--days, --provider, --model, --agent, --auth, --out) must be followed by exactly one non-empty value that is not another flag (proxy/cmd/caveman-proxy/stats.go:34). When the next token is missing, empty, starts with '--', or contains NUL/CR/LF characters, the parser rejects it with '<flag> requires a value'.

Solutions

1. Supply a non-empty value immediately after the flag
2. Quote values containing spaces or special characters
3. Check that any $VAR used as a value is actually set and non-empty
4. Reorder arguments so a value never sits where another flag is expected

Example fix

// before (empty expansion)
caveman-proxy stats --model $MODEL --report
// after
caveman-proxy stats --model "${MODEL:-claude-fable-5}" --report

opts = {"--days": "7", "--provider": "anthropic"}
for flag, val in opts.items():
    if not val or val.startswith("--") or "\n" in val:
        raise ValueError(f"{flag} requires a non-empty value")

When it happens

Trigger: 'stats --provider' at end of args; 'stats --model --days 7' (flag where a value should be); '--out ""'; a value containing a newline from a badly quoted shell variable.

Common situations: Forgetting the value after a flag; empty environment variable expansion ($MODEL unset leaves an empty token); quoting mistakes dropping the value; another flag accidentally placed in the value position.

Understand the failure class

Background: "no subcommand specified" and "... is required": CLI errors when a required argument is missing — this error's family across 13 libraries.

Related errors

• duplicate
• unknown stats report option
• requires a value
• --days must be an integer from 0 to 3660
• duplicate

AI-assisted analysis of JuliusBrussee/caveman@3ee70a1026 (2026-09-20). Data as JSON: /api/errors/c72893ad38aea8fb. Report an issue: GitHub.

Appendix: source

Thrown at proxy/cmd/caveman-proxy/stats.go:34

// (telemetry and session footers) keep their original schema and behavior.
func parseStatsReportOptions(args []string) (store.StatsReportOptions, bool, string, error) {
	opts := store.StatsReportOptions{Days: 30, Now: time.Now()}
	writeReport, out := false, ""
	seen := map[string]bool{}
	for i := 0; i < len(args); i++ {
		arg := args[i]
		if seen[arg] {
			return opts, false, "", fmt.Errorf("duplicate %s", arg)
		}
		seen[arg] = true
		switch arg {
		case "--report", "--json":
		case "--write-report":
			writeReport = true
		case "--days", "--provider", "--model", "--agent", "--auth", "--out":
			i++
			if i >= len(args) || args[i] == "" || strings.HasPrefix(args[i], "--") || strings.ContainsAny(args[i], "\x00\r\n") {
				return opts, false, "", fmt.Errorf("%s requires a value", arg)
			}
			value := args[i]
			switch arg {
			case "--days":
				days, err := strconv.Atoi(value)
				if err != nil || days < 0 || days > 3660 {
					return opts, false, "", fmt.Errorf("--days must be an integer from 0 to 3660")
				}
				opts.Days = days
			case "--provider":
				opts.Provider = value
			case "--model":
				opts.Model = value
			case "--agent":
				opts.Agent = value
			case "--auth":
				opts.AuthMode = value
			case "--out":

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