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Announce

Sub-agents report back via an announce step:
  • The announce step runs inside the sub-agent session (not the requester session).
  • Runs spawned with expectsCompletionMessage: false skip the announce step entirely; the run registry records their delivery as not required.
  • An exact ANNOUNCE_SKIP response suppresses announce output.
  • For completion-required runs, an exact child NO_REPLY response or no output is a missing deliverable handed to the requester/parent for visible representation or retry; it is not credited as silent delivery.
  • Optional, duplicate, already-visible, or otherwise non-required paths may use exact NO_REPLY for intentional silence.
By default, delivery depends on requester depth:
  • Top-level requester sessions use a follow-up agent call with external delivery (deliver=true).
  • Nested requester subagent sessions receive an internal follow-up injection (deliver=false) so the orchestrator can synthesize child results in-session.
  • If a nested requester subagent session is gone, OpenClaw falls back to that session’s requester when available.
For top-level requester sessions, completion-mode direct delivery first resolves any bound conversation/thread route and hook override, then fills missing channel-target fields from the requester session’s stored route. That keeps completions on the right chat/topic even when the completion origin only identifies the channel. When an override selects a different chat or topic, it does not inherit the previous route’s thread. An explicit thread from the binding or hook is preserved. Child completion aggregation is scoped to the current requester run when building nested completion findings, preventing stale prior-run child outputs from leaking into the current announce. Announce replies preserve thread/topic routing when available on channel adapters.

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Private parent completion

Set completionTarget: "parent" on sessions_spawn to return the result in a private turn of the original requester session. The parent can inspect the result, start another child, or reply NO_REPLY. OpenClaw does not automatically send the child result, parent final, or generated media to a channel. The parent can still choose to send a message through its permitted tools. This option supports hidden, native, one-shot runs only. It cannot be combined with ACP, collect: true, visible: true, thread: true, mode: "session", or expectsCompletionMessage: false. It does not change the default completion mode. Finished private results remain in the registry until the spawning parent turn settles. A normal parent finish releases each ready result for private review; sessions_yield hands the results to its existing child batch instead. A reset or removed parent does not transfer the result to another session. When a settled batch contains a private result, its combined review stays private; ordinary siblings retain their individual completion delivery. Waiting for the spawning parent turn does not consume a private result’s delivery retry window. A normal parent finish starts that window when it releases the result. After sessions_yield, the yielded batch owns delivery; individual child cleanup cannot expire or suspend that batch’s result. Use a build that supports this option throughout the run. Older builds cannot resume private completion handoffs and may discard them after a downgrade; existing session transcripts remain separate.

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Announce context

Announce context is normalized to a stable internal event block: The result is the child’s complete visible final answer for the completed run. OpenClaw preserves prompt-data escaping and stable order when it delivers several results together. It does not shorten an answer to fit the former announce projection limits. The bounded lifecycle snapshot remains separate from the complete answer sent to the parent. For nested work, descendant findings help the child form its answer. The child’s own final answer is what travels onward to its parent. If the child sends its final answer through the message tool and then returns NO_REPLY, that final answer remains authoritative. Completion delivery can read an existing registered archive when child cleanup finishes before the parent resumes. This does not add a post-cleanup retrieval feature. Terminal failed runs report failure status without replaying captured reply text. Tool/toolResult output is not promoted into child result text.

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Stats line

Default announce payloads include a stats line at the end (even when wrapped). Private parent completions omit mutable usage statistics so a retried handoff keeps the same input:
  • Runtime (e.g. runtime 5m12s).
  • Token usage (input/output/total).
  • Estimated cost when model pricing is configured (models.providers.*.models[].cost).
  • sessionKey, sessionId, and transcript path so the main agent can fetch history via sessions_history or inspect the file on disk.
Internal metadata is meant for orchestration only; user-facing replies should be rewritten in normal assistant voice.

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Why prefer sessions_history

sessions_history is the safer orchestration path for reading a child’s transcript from within an agent turn:
  • Redacts credential/token-like text even when general-purpose log redaction is disabled.
  • Truncates long text blocks (4000 chars per block) and drops thinking signatures, reasoning replay payloads, and inline image data.
  • Caps returned messages at 80 KB; older rows can be dropped or an oversized row replaced with [sessions_history omitted: message too large].
  • Use nextOffset when present to page backward through older transcript windows.
  • Returns structured history rather than /subagents log’s plain chat lines. Reasoning tags, <relevant-memories> / <relevant_memories> scaffolding, and tool-call XML can remain in message text: sessions_history does not apply the log command’s assistant prose sanitizer. See Session tools for the recall guarantees.
  • Raw on-disk transcript inspection is the fallback when you need the full byte-for-byte transcript.