[browser-use-demo] only_n_most_recent_images is ignored — screenshots accumulate unbounded

Summary

In browser-use-demo, the "keep only N most recent screenshots" feature is dead code. sampling_loop() accepts only_n_most_recent_images and the helper _maybe_filter_to_n_most_recent_images() exists, but the helper is never called and the parameter is never read. As a result every screenshot accumulates in the message history for the whole browser session, so context size and token cost grow without bound.

Where (on main, f37f168)

• browser_use_demo/loop.py:78 — sampling_loop(..., only_n_most_recent_images: int | None = None, ...) is declared but never used in the function body.
• browser_use_demo/loop.py:176 — _maybe_filter_to_n_most_recent_images() is defined but has zero call sites.
• browser_use_demo/streamlit.py:500 — the UI explicitly requests it: only_n_most_recent_images=3, # Keep only 3 most recent screenshots for context. The documented intent never takes effect.

Impact

Long browser sessions send the full history of screenshots on every step, inflating token usage and latency, and can push past context limits — exactly the behavior the parameter was meant to prevent.

For contrast

computer-use-demo/computer_use_demo/loop.py wires the same helper correctly (it's called inside the sampling loop). The browser demo appears to have dropped that call.

Note

There's a second, subtler problem: in this demo screenshots are nested inside tool_result blocks, but the helper only inspects top-level image blocks — so even once it's called it would need to descend into tool_result content to actually remove anything.

Related (computer-use-demo variants): #118, #266.