Module isolation 

P14 — display filtering and the honest isolation matrix.

Three different things live here, and they are deliberately not the same thing:

1. --display <id> restricts capture and coordinate conversion to one monitor from DisplayInfo. That is real, works on all three platforms through [crate::backend::capture], and is the only part that changes what the agent can see.
2. --display virtual on Linux prints the Xvfb recipe and, with --exec, runs a prepared command with DISPLAY set. It never starts a server on its own.
3. macOS CGVirtualDisplay is probed behind the virtual-display feature and reported as experimental. It is system-visible, it is not a sandbox, and this build never creates one.

Nothing here starts a hypervisor, a compositor, or an X server. See docs/ISOLATION.md for what an operator can set up instead.

Structs

DisplayTarget

One monitor the rest of the action is confined to.

VirtualDisplayProbe

What the private macOS symbol probe found.

Enums

DisplaySelector

What --display selected.

Constants

VIRTUAL_SELECTOR

--display virtual: a separate X server, prepared by the operator.

XVFB_DISPLAY

Display the Xvfb recipe prepares, as DISPLAY=:99.

XVFB_GEOMETRY

Screen geometry the recipe asks Xvfb for.

Functions

display_target

Build the target for one monitor. A zero-sized monitor is not a target.

ensure_point_inside

Reject a point that the chosen monitor does not cover.

ensure_region_inside

Reject a region that is not fully covered by the chosen monitor.

exec_arguments

Split --exec arguments, dropping a leading -- separator.

exec_prepared

Replace this process with command, running inside the prepared environment. Never returns on success.

find

Find one monitor by id.

infeasible

Everything that is not built, with the reason. Keys and wording mirror docs/ISOLATION.md; the snapshot test in this module is what keeps them from drifting apart.

matrix

The JSON body of computer-use isolation.

parse_selector

Parse --display. virtual is matched exactly, case-insensitively.

platform

target_os as the short name this crate uses everywhere else.

point_inside

True when the virtual-desktop point is inside the monitor.

prepared_env

Environment overrides applied by --display virtual --exec.

probe

Run the macOS symbol probe. Cheap enough for isolation on every call.

region_inside

True when region fits entirely inside the monitor.

resolve

Resolve a numeric --display against the live display list.

virtual_display_compiled

True when this binary was built with --features virtual-display.

virtual_supported

True when this platform has a supported --display virtual recipe.

window_inside

True when the window rectangle is fully covered by the chosen monitor.

xvfb_command

The Xvfb command line the recipe documents and docs/ISOLATION.md repeats.

xvfb_recipe

The recipe as JSON: the exact commands and what this binary does with them.