We left a counter running.
Then came back.

We downloaded the official Apple silicon binary for Herdr 0.9.5 and matched its published SHA-256. A temporary configuration and a named proof session kept the experiment separate from personal sessions. The panes used a non-login shell. No account, plugin, model or remote host was connected.

The program below writes its process ID and a sequence number to heartbeat.jsonl. That file lets us observe progress while no client is attached. It also prints the same values in the terminal.

import os, time, pathlib
p = pathlib.Path("heartbeat.jsonl")
i = 0
while True:
    i += 1
    with p.open("a") as f:
        f.write(f"{os.getpid()} {i}\n")
    print("heartbeat", os.getpid(), i, flush=True)
    time.sleep(0.25)

Download the original heartbeat program · Observed results as JSON

1. Create an empty test directory, save the heartbeat program there, and start a new named session: herdr --session exit-practice. Use a name that is not already in use.
2. Inside the pane, change to that directory and run python3 -u heartbeat.py. Leave it a moment to write a few lines.
3. Press Ctrl+B, release, then q. From your ordinary shell, read the last line of heartbeat.jsonl twice with a short gap. A larger counter under the same PID is evidence of ongoing progress.
4. Run herdr --session exit-practice again. Observe the continuing output. Press Ctrl+C to stop this test program.
5. For the restart comparison, run the test program again, add a second empty pane, and detach. Save anything else before stopping the test session with herdr session stop exit-practice.
6. Open herdr --session exit-practice again. Compare the layout and directory with the heartbeat file. Our file did not keep growing. Finish by stopping this disposable session.

Use only the test session and directory you created. The sample appends to its local file until interrupted; remove your test files when you no longer need them. Your PIDs and line counts will differ.

We did not reboot, sleep the computer, test a broken network, connect through SSH, upgrade with live handoff, enable pane-history replay, or resume an AI conversation. We did not test Windows or Linux. A program may catch Ctrl+C differently, require its own cleanup, or finish unsuccessfully while you are detached.

The general distinctions match Herdr’s documentation; the exact numbers and drawings come from our own controlled run. Herdr can change these behaviors in later releases. Check your installed version with herdr --version.

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