[Feat] Add verified text input to the desktop agent

[QianCyrus]

What this enables

The desktop agent can now enter supplied text into a macOS application, click Save, and check that the file contains the expected text.

It can insert text at the current selection or replace a field's entire contents, including Chinese and multiple lines. After input, it reads the field again to confirm the result. An optional file check requires a fresh write and matching content before the task succeeds.

The implementation extends the existing desktop CLI, window environment, and Cua Driver adapter. Part of #15; RFC #26.

macOS results

Rerun on this branch with macOS 26.2 arm64 and Cua Driver 0.30.1:

Task	Action selection	Passed	Total time	Actions per trial
Enter Body and save in the native test app	Local Laya 0.3.20	3/3	27.3 s	4
Replace Chinese multiline text and save	Fixed action plan	1/1	4.9 s	2

Each successful trial checks the saved file independently. The Laya run uses no fixed plan, Jev, or chat-model calls. Episode time excludes model loading.

Tests

Added test_desktop_actions.py for text entry, replacement, readback, and saved-file verification.

Extended test_desktop_driver.py, test_agents_desktop.py, and test_desktop_env.py for window binding, native field identifiers, CLI configuration, dry runs, and stale or refused actions.

Core + dev suite: 515 passed, 41 skipped. Ruff, ty, lock check, package build, shell syntax, and CLI/MCP smoke passed.

How to run

Requires macOS, uv, the Swift command-line tools, and Cua Driver with Accessibility and Screen Recording permissions. These commands use the signed driver at /Applications/CuaDriver.app/Contents/MacOS/cua-driver. Run from the current project checkout. Close any older S1A document fixture before starting.

S1A_PROJECT_DIR="$(pwd -P)"
uv sync --project "$S1A_PROJECT_DIR" --extra dev --extra laya
bash "$S1A_PROJECT_DIR/evals/desktop/build_fixture.sh" /tmp/S1ADocumentFixture.app
export CUA_DRIVER_BIN=/Applications/CuaDriver.app/Contents/MacOS/cua-driver

Run a fixed input-and-save sequence to check execution:

uv run --project "$S1A_PROJECT_DIR" --no-sync s1a run desktop \
  --model rule --rethink off --episodes 1 \
  --app S1ADocumentFixture --app-path /tmp/S1ADocumentFixture.app \
  --window-title "S1A Document Fixture" --goal "Enter the text in Body and save it" --expect Saved \
  --text "Hello from the desktop agent." --text-target Body --text-mode replace \
  --verify-file /tmp/s1a-desktop-fixture.txt --clear Clear --plan 'type:Body,Save' --execute
cat /tmp/s1a-desktop-fixture.txt

To let local Laya select the actions instead, run:

S1A="$S1A_PROJECT_DIR/.venv/bin/s1a" \
  bash "$S1A_PROJECT_DIR/evals/desktop/run_local.sh" --episodes 3