sipeed/picoclaw · error

failed to decode serialized config: %w

Error message

failed to decode serialized config: %w

What it means

validateConfigDocument re-unmarshals the bytes it just produced (helpers.go:149-152). Failing here means the in-memory config serialized into something encoding/json cannot read back — practically an invariant break, since the data was marshaled moments earlier from the same structs. Not reachable through normal CLI usage.

Source

Thrown at cmd/picoclaw/internal/mcp/helpers.go:151

	}

	clone.Tools = cfg.Tools
	clone.Tools.MCP = cfg.Tools.MCP
	clone.Tools.MCP.Servers = make(map[string]config.MCPServerConfig, len(cfg.Tools.MCP.Servers))
	for name, server := range cfg.Tools.MCP.Servers {
		if server.Type != "" {
			server.Type = config.NormalizeMCPTransportType(server.Type)
		}
		clone.Tools.MCP.Servers[name] = server
	}

	return &clone
}

func validateConfigDocument(data []byte) error {
	var instance map[string]any
	if err := json.Unmarshal(data, &instance); err != nil {
		return fmt.Errorf("failed to decode serialized config: %w", err)
	}

	schema, err := loadMCPConfigSchema()
	if err != nil {
		return fmt.Errorf("failed to load MCP config schema: %w", err)
	}

	if err := schema.Validate(instance); err != nil {
		return fmt.Errorf("config validation failed: %w", err)
	}

	return nil
}

func loadMCPConfigSchema() (*jsonschema.Resolved, error) {
	mcpConfigSchemaOnce.Do(func() {
		var schema jsonschema.Schema
		if err := json.Unmarshal([]byte(mcpConfigSchemaJSON), &schema); err != nil {

View on GitHub (pinned to 49183d7e8d)

Solutions

1. Report upstream as a bug with the config contents; there is no user-level remediation
2. If you added a custom MarshalJSON, make it emit strict RFC 8259 JSON (no NaN/Infinity) and round-trip test it

if err := saveValidatedConfig(cfg); err != nil {
	if strings.Contains(err.Error(), "failed to decode serialized config") {
		// invariant break inside picoclaw itself — collect a bug report
		// with the config contents; no caller-side remediation exists
		return fmt.Errorf("internal picoclaw bug (config round-trip): %w", err)
	}
	return err
}

When it happens

Trigger: Custom MarshalJSON on a config type emitting invalid JSON (e.g. bare NaN/Infinity via hand-rolled marshaling); memory corruption. Plain encoding/json cannot produce this.

Common situations: Contributors adding custom marshalers to config types.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• failed to serialize config: %w
• marshal result: %w
• conversation not found for %s after ingest
• marshal request: %w
• parse response: %w

AI-assisted analysis of sipeed/picoclaw@49183d7e8d (2026-08-15). Data as JSON: /api/errors/f4a82bf8f53e5657. Report an issue: GitHub.