Add Jev browser agent loop example

[rgarcia]

summary

• add a custom Jev browser-agent loop that observes viewport-visible controls through BrowserExecutor and builds a bounded, operation-aware candidate space
• derive click, text, and select capabilities from each control's underlying DOM element so non-editable comboboxes are never offered to TYPE_TEXT
• use document-stable node identities and target-specific guards instead of remapping snapshot-scoped references after a full freshness observation
• keep navigation inside the loop and call the text resolver only after Jev selects a field or navigation operation
• execute ordinary interactions with direct browser primitives while retaining navigation-safe browser_act waits
• automatically open the live view in the default browser for interactive macOS runs
• suppress repeated state/action transitions and expose controls inside visible cross-origin frames

This remains a separate Browser Loop-backed approach from #97's local prototype and evaluation.

design

Jev receives the goal, viewport text, visible elements, current values, executable operations, and recent action history. It chooses one bounded operation and target. Code owns text generation, URL validation, target freshness, execution, and termination limits.

The viewport observer assigns stable element identities for the life of the document, excludes covered and offscreen controls, keeps transparent native controls that receive pointer input, and exposes scroll controls for the active scroll container. A stale target causes a fresh observation and policy decision without executing or remapping the previous choice.

validation

• npm run typecheck
• npm run check:lockfile
• npm test --workspace @onkernel/browser-loop — 441 passing
• example npm run typecheck && npm test — 17 passing
• controlled Google Flights flow for CVG → SFO on December 14, 2026:
  • ticket type is click-only while airport inputs support text entry
  • autocomplete suggestions remain directly clickable
  • the date picker exposes Done, scrolling reveals December 14, and the search reaches matching results
  • the results page exposes the Stops control and all four stop-filter radio choices, including Nonstop only
• controlled restaurant reservation flow:
  • repeated top/bottom scroll transitions are suppressed before a third execution
  • the loop selects the visible reservation link instead of continuing the cycle
  • the embedded reservation widget exposes date, time, party-size, and submit controls
• live Jev + Kernel browser coverage for navigation, forms, autocomplete, history, scrolling, waits, completion, stale decisions, no-progress detection, and password exclusion

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Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

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^{Reviewed by Cursor Bugbot for commit d924abe. Configure here.}