perf(demo): installed browser, one browser process, early OpenCV load

[abrichr]

What changed

• Installed browser first. Browser launches use the installed Chrome or Edge through Playwright's channel option. When neither exists, Flow downloads only Chromium's headless shell (218 MB on disk, against 576 to 587 MB for the full download in 2.0.0). Headed runs still get the full build. If a channel browser is present but won't start, auto falls back to Playwright's build. OPENADAPT_FLOW_BROWSER accepts auto, chrome, msedge, or bundled.
• One browser process per demo. The record run and both replays share one browser process. Each run still gets a fresh browser context, so no cookies, storage, or cache carry over. In 2.0.0, each close() took about 2.8 s.
• OpenCV and OCR load during browser start. On a fresh macOS environment, the first import cv2 takes 9 to 19 s while the system verifies OpenCV's 78 MB of bundled libraries. The demo now starts that load on a background thread before it starts the browser. The browser-process code moved to backends/_browser_process.py, which doesn't import OpenCV.
• Visible progress. On a terminal, the demo shows the current stage on one line that rewrites itself. The summary still has at most eight lines, and piped output is unchanged.
• README. The demo command is now uvx --python 3.12 --from 'openadapt-flow[browser]' openadapt-flow demo, with pip as the alternative.

Nothing in recording, compiling, gating, or verification changed. Both runs still really execute, and the second run still halts on the system-of-record read.

Measurements

MacBook Pro (12 cores), Python 3.12. Each run uses a new virtual environment. The machine was shared with other jobs (load average 8 to 43), so single runs vary by a few seconds. "Cold" means an empty pip or uv cache and an empty PLAYWRIGHT_BROWSERS_PATH. Baseline is the published 2.0.0 installed with pip. "New" is this branch's wheel installed with uv pip. Every run printed "Done and checked" for run 1 and "Stopped" for run 2.

Case	Install (s)	Demo (s)	Total (s)
Baseline warm	7.5 / 8.0 / 9.1	37.1 / 39.3 / 42.0	44.7 / 47.3 / 51.1
New warm	0.5 / 0.3 / 0.3	37.9 / 37.9 / 36.8	38.4 / 38.1 / 37.1
Baseline cold (577 MB download)	33.0 / 36.4 / 35.6	54.5 / 61.2 / 63.4	87.5 / 97.5 / 98.9
New cold (installed Chrome)	10.3 / 11.7 / 22.3	48.2 / 47.1 / 46.7	58.5 / 58.8 / 69.0
New cold, no Chrome (headless shell)	9.9	58.4	68.3

In a reused environment (native libraries already verified), the demo takes 19.7 to 22 s. First output appears at 0.5 s, and the first stage line at 1.6 s.

Where the time goes (fresh environment, new build)

Phase	Seconds
First import cv2 (macOS library verification)	12 to 19
Playwright driver and Chrome start	0.75 to 2.1
Recording	1.8 to 2.5
Compile (12 full-frame OCR passes)	4 to 8
Run 1	3 to 4
Run 2: the effect check waits its full 5 s timeout before it refutes	8 to 12

The remaining large costs are the OpenCV first load and OCR. Removing them means replacing the OCR stack, which needs the identity evidence rerun first. This PR doesn't do that.

Signed-off-by: Richard Abrich richard.abrich@mldsai.com

Same browser on every web path

CI found that replay, resume, bench, record, the attended service and generated MCP tools still launched Playwright's own Chromium, while PlaywrightBackend picked the installed Chrome. A project pinned under one browser then replayed under the other, and the qualification environment check halted the Desktop check-it practice run (tests/test_desktop_check_it_cli_mockmed.py). All of these paths now go through launch_chromium. tests/test_console.py now expects browser setup inside the Playwright context, still on the owner thread.

[abrichr]

Carried over into the monorepo as OpenAdaptAI/OpenAdapt#1189 (merged as e395969abee94bdd906beb7d277dc534b05c8e47). openadapt-flow now lives in OpenAdapt/packages/flow.