[coneilen]

Summary

Fix the Windows live UIA gate's DPI192 connector-to-target drag cutoff without changing GraphCanvas, mouse routing, native edge forms, or #778 context-menu product behavior. The gate now freezes exact owned card geometry after Actual Size and drops within the target card's visible graph/client intersection instead of using an off-viewport full-card center.

Changes

• Add a strict connector drag snapshot decision that preserves exact source/target identities and order, owned process IDs, non-overlap, viewport intersection, physical-screen coordinates, and absence of a preexisting native form.
• Reconnect the UIA provider after Actual Size, cache immutable card ID/name/PID/bounds values, and derive the source connector from the exact outgoing side.
• Intersect the target card with the live graph and client screen rectangles before selecting the native drop point; retain the raw target center in evidence to prove the DPI192 cutoff.
• Send four held-button mouse-move samples before release while keeping the native Create or edit edge sheet and locked endpoint fields as the success identity.
• Add DPI192 behavioral coverage for the off-viewport target center plus wrong connector, wrong target, wrong process, logical/physical coordinate mixing, and false-positive preexisting-dialog negatives.

Test plan

RED: pwsh -NoProfile -File Tools\windows\Tests\ValidationRunner.Tests.ps1 -> Get-ConnectorDragSnapshotDecision was not recognized at the DPI192 connector case
GREEN: pwsh -NoProfile -File Tools\windows\Tests\ValidationRunner.Tests.ps1 -> UiScenario 166/166 and UiCaptureDriver 182/182 passed
REGRESSION: pwsh -NoProfile -File Tools\windows\validate.ps1 -Task hardening -> repeated-runs PASS 3/3

• Focused connector contract -> FOCUSED_CONNECTOR_DRAG_CONTRACT=PASS positive=1 cutoff=1 negatives=6 dpi=192.
• PowerShell parser checks for Tools\windows\uia-live-gate.ps1 and Tools\windows\Tests\ValidationRunner.Tests.ps1 -> passed.
• git diff --check and LF checks for both changed files -> passed.
• Original head 4e07b00c5a94df748b08e279ef371d7832f9c9a0 -> all GitHub checks completed successfully or were intentionally path-gated skipped, including Windows shell integration, three unit shards, packaging, Windows spikes, deterministic hardening on Windows 2022/2025, DCO, TDD evidence, and privacy scan.
• Rebased patch onto origin/main at 1219d228473238c168d0065def34d3baafc57b27; stable patch ID remained cc28f2557644a6bc85dd404f32e8b950d5f16a4f.
• pwsh -NoProfile -File Tools\windows\uia-live-gate.ps1 -Shell graphcode-windows\zig-out\bin\graphcode-windows.exe -Zmx D:\gcp-5c0\zmx\zig-out\bin\zmx.exe with TEMP=D:\t5c3 -> connector drag passed at DPI192 with exact locked source/target endpoints; the gate advanced to the later unrelated lane cards do not normalize to the shared 250x96 geometry cutoff before Windows parity: Context menus carry the macOS item set and grouping #778 context-menu coverage.
• Rebased live evidence: source [1229,853]; old target center [1759,853] outside the client/graph; corrected visible target [1584,853]; no preexisting dialog; coordinate space physical-screen.
• Rebased local head validated before push: e0353c490d2aa01cbc986d3da20e3a9384b3e24d.

Checklist

• I have read the Contributing Guidelines
• I have signed off my commits (git commit -s) per the DCO
• Tests pass locally (make test)
• Code follows the existing style (make check)
• I added the test/contract before the implementation and observed the intended RED failure