Agents: First prompts and worker briefs can be lost during startup #27676

What happens

Starting a terminal agent or delegated worker can launch it empty and later paste the first prompt or task brief. Startup dialogs can consume that input, and long or shell-sensitive text may not arrive intact.

Expected

Carry the exact initial text through the current launch service using verified command-line delivery where possible and a safe fallback otherwise. Do not report a worker’s task as started until the agent supplies evidence.

Notes

Earlier attempts are in #24080 and #24081, closed because they were too far behind main; their descriptions have the diagnosis. On origin/main, src/shared/startup-line-prompt-carry.ts:25 retains the 512-byte typed-line budget, and src/main/runtime/rpc/methods/orchestration/worker/deliver-worker-dispatch-preamble.ts:107 still sends the brief after launch.