Surface workflow step logs in terminal output

[pmateusz]

Why

Some workflows need to report intermediate results, decisions, warnings, or produced values while they run. Today the supported step logger writes step-log events to the run log, but those events are ignored by the live tree, headless progress output, summaries, and /workflow status. From the user's perspective, the output is lost unless the workflow writes a separate file.

What

Make messages written through a step's logger.info, logger.warn, and logger.error APIs visible during execution and retrievable afterward.

Description

The event log should remain the source of truth. Rendering should subscribe to persisted step-log events and present them on an output surface appropriate to the current mode. Interactive mode may use a dedicated log area or transcript entries rather than adding arbitrary text to the compact progress tree. Headless json and print modes must write human-facing log lines to stderr because stdout is reserved for their machine-readable/answer contracts.

Direct console.log calls should not become the workflow logging API: they cannot be attributed reliably and can corrupt stdout protocols. The documented path should be the injected structured logger, including its level, step path, message, and optional data.

Acceptance criteria

• logger.info, logger.warn, and logger.error messages become visible during a run.
• Each rendered message identifies its workflow step or node path and preserves its severity.
• Optional structured data has a readable, bounded representation and remains intact in the stored event.
• Interactive output does not disrupt or permanently overwrite the progress view.
• Headless json and print modes emit step logs to stderr only; stdout remains unchanged.
• Historical step logs can be retrieved through /workflow status or another documented run-inspection command.
• Replaying or resuming a run does not print old log entries again as if they were new.
• Concurrent step logs remain attributable even when their arrival order is interleaved.
• Tests cover all severity levels, structured data, headless channel separation, and resume behavior.