Expose tool/subagent execution metadata to the agent #23421

Summary

OpenCode appears to have session/history/event data, but it does not clearly expose execution metadata for tool calls and subagent runs to the active agent.

This makes it hard for the agent to answer questions like:

• did the task stop in the middle?
• is it still running or just slow?
• when was the last successful activity?
• did it fail, timeout, or get cancelled?

Why this matters

Today the agent can usually see:

• tool results
• success/failure at a high level
• returned content

But it often cannot reliably see structured metadata such as:

• start time
• end time
• duration
• last activity time
• running/completed/timed_out/cancelled state per tool/subagent

That leads to vague answers where the platform may know more internally, but the agent cannot reason over it.

Proposal

Expose minimal execution metadata for:

• tool calls
• subagent/task runs

Suggested fields:

• id
• kind (tool_call | subagent_run)
• name
• status (queued | running | succeeded | failed | cancelled | timed_out)
• started_at
• ended_at
• duration_ms
• last_activity_at
• parent_id
• error_summary

This does not need full raw tracing. A small structured timeline would already be enough for better agent reasoning.

Why agent-visible matters

A UI timeline would be useful, but agent-visible metadata is the more important gap.

If the agent can inspect execution metadata, it can:

• answer interruption questions precisely
• decide whether to retry or wait
• distinguish slow vs stuck
• explain failures more accurately
• summarize partial runs without guessing

Notes

This report is intentionally phrased as an exposure/observability gap, not a claim that OpenCode has no internal trace data.

From the public docs, I could verify:

• session/message/history APIs exist
• event streaming exists
• share sync includes conversation history and session metadata
• a session timeline concept exists in the UI/docs

What I could not find clearly documented was agent-accessible execution metadata for tool/subagent runs.