Element selection from the local preview should preserve the visual target
the user picked and send the confirmed request directly to chat. The
screenshot now captures the visible viewport before drawing the marker, and
the selection event sends a model-facing prompt while the chat UI shows only
the annotated image and compact element label.
Constraint: No issue number was provided for this task.
Constraint: Keep the preview-agent protocol shape unchanged.
Rejected: Prefill the composer with the selection note | it keeps the old extra confirmation step and exposes implementation text in the input.
Rejected: Full-document annotation coordinates | body-relative captures drift from the viewport selection users see.
Confidence: high
Scope-risk: moderate
Directive: Do not route confirmed preview selections back through composer prefill without rechecking the Codex-style direct-send flow.
Tested: cd desktop && bun run test --run src/preview-agent/screenshot.test.ts src/lib/previewEvents.test.ts src/lib/selectionComposer.test.ts src/components/chat/AttachmentGallery.test.tsx src/stores/chatStore.test.ts
Tested: cd desktop && bun run lint
Tested: cd desktop && bun run build:preview-agent
Tested: bun run check:desktop
Tested: git diff --check
Not-tested: Real Tauri webview click-through smoke; in-app Browser automation timed out while local Vite HTTP smoke returned 200.
圈选标注截图作为引用承载元素位置；输入框文字只放用户修改意见+具体改动(人话)，
不再写 selector/nthPath/computedStyles/页面URL/「请在源码中落地」。沿用进输入框+手动发送。
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
