Callback notification not delivered on agent completion

[c-h-]

Problem

When launching a coding agent with --callback-session and --callback-agent, the completion callback is not reliably delivered to the target OpenClaw session.

Reproduction

agentctl launch claude-code \
  --worktree ~/personal/orgloop \
  --branch fix/issue-140-lane-support \
  --callback-session "agent:personal:mattermost:channel:6hmcskm5jbyqpcu77qaa41nw8c" \
  --callback-agent personal \
  -p "..."

Agent completed successfully (session 7c4bbcb5, PR created at OrgLoop/orgloop#141), but the callback event was never received by the target OpenClaw session. The orchestrating agent had to manually check agentctl list and gh pr list to discover the work was done.

Expected

On agent completion, a callback event should be delivered to the specified session so the orchestrator knows the work is done without polling.

Observed

• Agent ran to completion (~15 min)
• PR was created successfully
• Session 7c4bbcb5 disappeared from agentctl list -a (possibly cleaned up)
• No callback event was received by the target session
• Orchestrator only discovered completion when the user asked "still running?"

Impact

Without reliable callbacks, the orchestrator can't know when work is done, leading to either constant polling (wasteful) or missed completions (bad UX).