[iFurySt]

Large lists can exhaust a snapshot's node budget before later dialog buttons are visited. This change prioritizes visible controls and ordinary UI regions across macOS AX, Windows UIA and Linux AT-SPI, then renders the selected graph in its original order with valid action indexes and ancestor paths.

The default 1200-node limit stays unchanged. Candidate discovery is separately bounded, duplicate references and cycles cannot bypass it, and truncated snapshots carry an explicit notice. macOS respects AXVisibleChildren; Linux supplements SHOWING with viewport geometry; Windows batches UIA properties per snapshot to avoid the 30-second timeout found by the real WPF test.

Validation:

• macOS: signed native MCP with a real 2000-file NSOpenPanel at 1200/40 nodes, actual indexed Cancel, all 12 sheet/panel scenarios, and 423 Swift tests (9 skipped, zero failures). The old runtime loses Cancel at 40 nodes. The existing 300-control AppKit output matches main and live actions work.
• Linux: real GTK/AT-SPI with 2000 rows, both budgets, footer clicks and newly visible last row after scrolling; hidden-detail, action read-back, JS and selective-observation regressions pass. Old main loses the footer at the default 1200-node budget. Python 39 tests and Linux Go tests pass.
• Windows: real WPF/UIA/native MCP with 2000 items, both budgets, footer clicks and newly visible last item; existing observation, scroll, DPI and physical-input regressions pass. The sample snapshots took 9.3s/5.4s within the unchanged timeout. Production PowerShell traversal and Go tests pass.
• Node: 54 tests pass; repository documentation and action-pinning checks pass.

Reproducible commands and limits: docs/tree-budget.md. A slow provider's individual API call is still outside the candidate-count bound; extremely small budgets cannot guarantee every control.

Final-head Windows CI passed. Its first attempt timed out while starting the pre-existing WPF fixture, before native MCP was launched; the unchanged commit passed on retry.

[iFurySt]

LGTM. Thanks!