The in-app browser was a one-way mirror. open_preview put a page in the pane
and read_preview read its text back, but nothing could touch it. A click meant
falling back to the browser_* tools, which drive a separate Chromium the user
cannot see — so "log into this and pull my invoices" happened in a different
browser from the one on screen, with none of the sessions the user is already
signed into.
Four pieces, and they only make sense together:
· an in-page engine that inventories what is interactable and performs the
verb, injected as source because it has to run inside the guest page;
· the preview.act.request bridge from the gateway into the pane;
· drive_preview, for acting: elements, click, type, scroll, press, and the
pane's own back/forward/reload;
· annotate_preview, for marking without acting.
Those last two started as one tool doing two unrelated jobs. Leaving a mark is
not an action — it outlives the turn that drew it — so it gets its own verb,
and the interaction verb gets a name that says what it does.
Gating is the existing surface rule: desktop_ui folds in on session
source: 'desktop', and the bridge refuses to act for a background session, so a
turn running behind the user's back cannot reach into the page they are working
in.
Two details worth a reviewer's attention. Typing assigns through the
prototype's value setter, because React shadows value with its own accessor and
ignores an input event whose value it believes it already wrote — a plain
el.value = … types into a field that snaps back on the next render. And
clicking replays the pointer/mouse pair before activation, because frameworks
bind to mousedown as often as to click.
