can1357/oh-my-pi · warning · ArgumentError

At least one output ID is required

Error message

At least one output ID is required

What it means

`output(*ids)` requires at least one artifact ID to fetch; it raises ArgumentError immediately after validating the artifacts directory when `ids` is empty. Calling `output()` with no arguments is a caller bug — there is nothing to look up.

Source

Thrown at packages/coding-agent/src/eval/rb/prelude.rb:182

    end
    current
  end

  def output(*ids, format: "raw", query: nil, offset: nil, limit: nil)
    artifacts_dir = ENV["PI_ARTIFACTS_DIR"]
    if artifacts_dir.nil? || artifacts_dir.empty?
      session_file = ENV["PI_SESSION_FILE"]
      if session_file.nil? || session_file.empty?
        __omp_emit_status("output", "error" => "No session file available")
        raise "No session - output artifacts unavailable"
      end
      artifacts_dir = session_file.sub(/\.[^.]*\z/, "")
    end
    unless File.directory?(artifacts_dir)
      __omp_emit_status("output", "error" => "Artifacts directory not found", "path" => artifacts_dir)
      raise "No artifacts directory found: #{artifacts_dir}"
    end
    raise ArgumentError, "At least one output ID is required" if ids.empty?
    if query && (!offset.nil? || !limit.nil?)
      __omp_emit_status("output", "error" => "query cannot be combined with offset/limit")
      raise ArgumentError, "query cannot be combined with offset/limit"
    end

    results = []
    not_found = []
    ids.each do |output_id|
      path = File.join(artifacts_dir, "#{output_id}.md")
      unless File.exist?(path)
        not_found << output_id
        next
      end
      raw = File.read(path, encoding: Encoding::UTF_8)
      raw_lines = raw.split("\n", -1)
      total_lines = raw_lines.length
      selected = raw
      range_info = nil

View on GitHub (pinned to 9690622007)

Solutions

1. Check the ID list before calling: `raise "no outputs" if ids.empty?` or branch to a no-op / alternate summary path
2. If you have an Array, splat it and guard: `ids.empty? ? [] : output(*ids)`
3. If a single Array was passed positionally, splat it: `output(*list)` instead of `output(list)`

Example fix

// before
results = output(*collected_ids)
// after
results = collected_ids.empty? ? [] : output(*collected_ids)

raise ArgumentError, "no output ids collected" if ids.empty?
results = output(*ids)

begin
  results = output(*ids)
rescue ArgumentError => e
  raise unless e.message == "At least one output ID is required"
  results = []
end

When it happens

Trigger: `output()` called with no positional arguments — commonly the result of building the ID list dynamically (`output(*my_ids)` where `my_ids` is empty) or forwarding optional args from a wrapper without a default.

Common situations: A pipeline step collects sub-agent output IDs at runtime; if the earlier phase produced no outputs the splatted array is empty and `output(*ids)` hits this error. Also happens when refactoring `output("id")` into `output(ids)` (passing an Array as a single positional instead of splatting).

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• query cannot be combined with offset/limit
• tool.#{name}(...) expects a Hash of arguments (got #{positio
• No messages to continue from
• Cannot continue from message role: assistant
• Gemini Files API cannot delete a handle from another provide

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/d3eb6986960cc0e7. Report an issue: GitHub.