personas = ["CFOs", "CTOs", "heads of ops", ...]   # the user-provided list
dimensions = dict(format_category="social", format_width=1080, format_height=1080)
window = bootstrap_response.get("concurrency_cap", 3)   # use the bootstrap value; fall back to 3 if unknown

def build_prompt(persona):
    return f"""
      LinkedIn ad for our automation tool, tailored to {persona}.
      Lead with the single pain point this persona feels most acutely
      and the one metric they measure success on. Bold typography, clean
      layout, one CTA.
    """

in_flight = {}          # persona -> task handle
done = {}               # persona -> terminal status
queue = list(personas)  # to-do

# 1. Seed the window
while len(in_flight) < window and queue:
    p = queue.pop(0)
    in_flight[p] = start_design_task(prompt=build_prompt(p), **dimensions)
    # tell the user immediately — canvas_url is in the queued response
    post(f"Started {p}: {in_flight[p]['canvas_url']}")

# 2. Drain + refill
while in_flight:
    # poll the whole pool in one call — cheaper than N get_task_status calls.
    # This is a pre-filter only: a task absent from the "running" list is NOT
    # necessarily terminal — it may still be "queued" (hasn't started yet) or
    # briefly missing from this page. Confirm with get_task_status before
    # ever removing a slot; never trust absence-from-pool by itself.
    pool = list_tasks(status="running", limit=window * 2)
    pool_ids = {t["task_id"] for t in pool["tasks"]}

    for persona, handle in list(in_flight.items()):
        if handle["task_id"] in pool_ids:
            continue   # confirmed still running

        # Not in the running pool — could be terminal, or still "queued".
        # is_terminal is the only thing allowed to free this slot.
        s = get_task_status(task_id=handle["task_id"])
        if not s.get("is_terminal"):
            continue   # e.g. still queued — leave the slot occupied

        done[persona] = s
        del in_flight[persona]
        post_done(persona, s)   # deliver this one as it finishes

        if queue:
            p = queue.pop(0)
            in_flight[p] = start_design_task(prompt=build_prompt(p), **dimensions)
            post(f"Started {p}: {in_flight[p]['canvas_url']}")

    sleep(3)   # respect retry_after_seconds from any poll

source_id = "cvs_…"               # the flyer canvas the user pointed at
resellers = [...]                  # 5 items, each with optional brand_kit_id for per-client rebrand
window = 3

queue = list(resellers)
in_flight = {}

def build_prompt(reseller):
    return f"""
      Customize this flyer for {reseller['name']}:
        - replace the headline price with {reseller['price']}
        - update the contact strip with {reseller['phone']} / {reseller['email']}
    """

while len(in_flight) < window and queue:
    r = queue.pop(0)
    in_flight[r["name"]] = start_design_task(
      template_canvas_id=source_id,
      prompt=build_prompt(r),
      brand_kit_id=r.get("brand_kit_id"),   # per-client brand if rebranding; omit for same-brand fill
      canvas_name=f"Flyer — {r['name']}",
      # wait defaults to False on start_design_task — handle returned immediately
    )
    post(f"Started {r['name']}: {in_flight[r['name']]['canvas_url']}")

# Same drain + refill loop as Pattern A