[Juliusolsson05]

What changed

• removes Claude's unsafe short-prompt prompt + CR atomic PTY write;
• writes prompt bytes first for every text submission;
• waits until the prompt tail or collapsed-paste placeholder is visible in the active Claude composer;
• sends Enter only after that observable absorption boundary;
• keeps durable user/queue JSONL acceptance as the final success condition;
• allows even one-character prompts to use the shared absorption detector.

Why

Claude Code 2.1.209 can leave text visibly inserted in a long-lived PTY composer while swallowing the Enter coalesced into the same write. Paste journals showed repeated 20-second acceptance timeouts after prompt-and-enter-written, with the prompt still editable on screen.

Fresh PTY probes confirmed CR/LF remain valid key bytes, including while busy. The broken invariant was relying on an atomic text+Enter write without first proving that Claude had processed the text.

Verification

• real Electron/node-pty probes against Claude Code 2.1.209;
• idle CR/LF and bracketed-paste matrix;
• busy-session queue probe;
• 18 focused delivery and durable-acceptance tests pass.

Closes #531