Senior Frontend / Product Engineer

Real-time voice UX, source evidence and accessible web interfaces | FreelanceElchai Group | Bounded contract opportunity | Remote working by agreementElchai is developing New Pulse as the authenticated human interface to a governed business-assistant architecture. Selection and any paid work remain subject to approval. This is not an unpaid internship or an invitation to start work before a contract.Safe branch switching and simulated voice cancellationImplement one browser-side switch boundary: stop listening/speaking before issuing a context-switch request; discard late old-context audio/text/responses; render only the newly authorized context or a safe error state.This package excludes a whole frontend rewrite, live speech-provider setup, backend permissions and a new orchestration system.We agree the exact scope, baseline or input register, interfaces, tests, reviewer, fees and availability before work. For development, the assignment uses an isolated sandbox and synthetic data; internal owners retain architecture, security, independent QA and release authority. For research/commercial work, only authorized public-source research and synthetic exercises are included unless separately stated.Milestones and smaller deliverablesM0: Freeze switch and display contract (client readiness gate; no free candidate deliverable).M0.1: verify existing behavior/baseline. M0.2: agree fixture/events/design subset. M0.3: freeze tests and approve start.Required evidence: Baseline and manifest; state/event table; browser cases; no-duplication record; review slots.Pass condition: The client confirms the agreed package, necessary dependencies, named reviewer and permission to start. A quote or interview does not require unpaid implementation.M1: Implement only the switch boundary (8-12 focused execution hours).M1.1: fixtures and adapter, 2-4 h. M1.2: stop/cancel/event ordering, 4 h. M1.3: minimal view/error states, 2-4 h.Required evidence: Components and three checkpoint handovers; event traces; authorized/failed switch demo.Pass condition: Audio stops first and context changes only through the approved response; no old-context rendering.M2: Test races and accessibility (6-10 focused execution hours).M2.1: functional/denial tests, 2-4 h. M2.2: late-event/reconnect stress, 2-4 h. M2.3: focused keyboard/layout checks, 2 h.Required evidence: FE-01 to FE-08 results, browser traces, seeds, videos/screenshots where useful and defects.Pass condition: Required cases pass on the agreed browsers; no stale data/audio or access-boundary defect.M3: Independent demonstration and acceptance (2-6 focused execution hours).M3.1: independent rerun. M3.2: corrections/retest, 2-6 h. M3.3: freeze candidate and limits.Required evidence: Repeatable demo; reviewer result; rollback and cold-start record.Pass condition: Accepted exact component version; fixture-only limits recorded; no backend/full-platform claim.M4: Transfer and estimate next UI slice (2-4 focused documentation/reporting hours).M4.1: complete component/API handover. M4.2: actuals and next estimate.Required evidence: Setup/test commands, event contract, known gaps, actual work/wait and remaining interface tasks.Pass condition: Replacement reproduces the selected checks and can identify the next task; further work stays unapproved.The hour ranges are initial planning guides, not deadlines or accepted prices. Quote your own effort and fee by milestone, including documentation, correction assumptions and availability. Internal approval and review time is separate; waiting for those decisions is not concealed as development work.Verification focusDemonstrate stop-before-switch, stale audio/text suppression, denied/failed switches, reconnect races and keyboard/focus behavior. The proposed repeated test includes 50 listening-state switches and 50 speaking-state switches per run, plus delayed-event scenarios. This does not claim backend isolation or full-product accessibility certification.Handover at every checkpointDeliver editable files, the exact current version, setup/test commands or research method, interface/source definitions, known defects, accepted versus unfinished work and the next task. Another authorized contributor must be able to reproduce the checkpoint without relying on your private account or undocumented knowledge. Final handover includes a clean-start reproduction and measured hours/corrections. We do not request confidential material from former clients.Experience evidenceRelevant skills: Async JavaScript/TypeScript; real-time/WebSocket/audio interfaces; race cancellation; keyboard/focus and assistive technology testing; maintaining existing code.Provide two relevant shipped-work or redacted project examples and your precise contribution; answer this question: Show how you prevented a late response or decoded audio clip from rendering after a user changed context. Show how you tested the race.Include your proposed milestone fees, currency, availability, working-time overlap, assumptions, exclusions and any subcontracting. We do not request free test work.