assistant/docs/backlog.md

Vela Phased Backlog

This backlog is the implementation plan translated into phased, actionable work. It should be updated whenever implementation changes scope, ordering, or done criteria.

Phase 1 — Foundation and Contracts

Goal

Establish the boundaries, protocol, and state model for the system before integrating providers.

Backlog Items

• define repository structure for vela-ui and vela-gateway
• define the WebSocket event contract used by the UI and gateway via shared package
• define the session state machine and interrupt semantics
• define provider adapter interfaces for STT, LLM, TTS, and tools
• document error handling and cancellation behavior

Exit Criteria

• protocol and state machine are documented
• UI and gateway responsibilities are explicit
• interrupt behavior is defined for every active phase
• provider boundaries are clear enough to implement mocks first

Phase 2 — Vertical Slice Skeleton

Goal

Prove the end-to-end interaction model with mocked or stubbed providers.

Backlog Items

• bootstrap vela-ui as a runnable SvelteKit app in the Yarn workspace
• bootstrap vela-gateway as a runnable Fastify app in the Yarn workspace
• create a minimal UI with mic control, state indicator, transcript, and response text
• create a gateway WebSocket session skeleton
• implement mocked STT flow for partial and final transcript events
• implement mocked LLM response streaming
• implement stubbed audio playback or placeholder TTS output
• implement interrupt handling across the mocked pipeline

Exit Criteria

• one client can complete a voice turn through the real UI↔gateway contract
• transcript appears in the UI
• assistant text appears progressively or in structured steps
• audio playback or stubbed playback is visible to the user
• interrupt stops the active response and resets state cleanly

Phase 3 — Real STT Integration

Goal

Replace the mocked transcription layer with a real streaming STT provider.

Backlog Items

• integrate whisper.cpp behind the STT adapter
• support partial and final transcript delivery
• handle audio format conversion if browser capture format differs
• handle late transcript events after cancellation
• expose recoverable error handling for STT failures

Exit Criteria

• live mic audio produces usable transcripts
• partial and final results reach the UI
• cancellation prevents late transcript results from corrupting session state
• STT failure paths are visible and recoverable

Phase 4 — Ollama Streaming and Tool Calling

Goal

Replace the mocked reasoning layer with real LLM orchestration.

Backlog Items

• integrate Ollama behind the LLM adapter
• stream assistant text deltas to the UI
• define and validate tool-calling schema
• reject invalid or unsafe tool calls
• support interrupt during active thinking

Exit Criteria

• assistant responses stream from Ollama
• invalid tool requests fail safely
• cancellation stops active model work
• the LLM cannot directly execute external actions

Phase 5 — Tool Layer

Goal

Introduce useful tools in increasing order of operational risk.

Backlog Items

• implement SearXNG search adapter
• normalize search results for LLM consumption
• implement Home Assistant read actions
• implement Home Assistant write actions gated by confirmation
• implement clarification flow for ambiguous tool requests

Exit Criteria

• web search works end-to-end
• Home Assistant read queries work for approved entities
• Home Assistant write actions require explicit confirmation
• ambiguous actions do not execute automatically

Phase 6 — Kokoro TTS

Goal

Convert assistant text responses into spoken output.

Backlog Items

• integrate Kokoro behind the TTS adapter
• support streamed audio when practical
• add a temporary fallback for full-response playback if streaming is not ready
• stop or suppress playback correctly on interrupt

Exit Criteria

• spoken output plays in the UI
• interrupt stops or suppresses playback reliably
• any non-streaming fallback is explicitly documented as temporary

Phase 7 — Resilience and Performance

Goal

Make the system robust enough for routine use on the target hardware.

Backlog Items

• handle disconnect and reconnect cleanly
• add bounded timeouts for STT, LLM, tool, and TTS calls
• measure latency by pipeline stage
• improve buffering and recovery paths for flaky network dependencies
• validate behavior under cancellation and partial failure

Exit Criteria

• common network and provider failures do not leave sessions stuck
• latency is measurable at each major stage
• user-visible recovery paths exist for expected failure modes

Phase 8 — Productization and Secondary Surfaces

Goal

Polish the system after the core voice loop is reliable.

Backlog Items

• add PWA installability and UX polish
• implement /history
• implement /settings
• implement /admin
• document operational settings and maintenance guidance

Exit Criteria

• the app is installable as a PWA
• secondary screens exist without degrading the core voice loop
• supporting docs reflect the implemented behavior

Ongoing Documentation Tasks

• update docs whenever implementation changes the protocol, architecture, integrations, deployment, or backlog order
• mark completed backlog items or split phases into smaller slices as work progresses
• keep root README.md as the entrypoint and keep detailed technical docs in docs/

Current Progress Notes

• apps/vela-ui now boots as a minimal SvelteKit app with a starter page
• apps/vela-gateway now boots as a minimal Fastify app with / and /health endpoints
• apps/vela-protocol now provides the shared WebSocket event contract for the UI and gateway
• backend framework choice is now concrete: Fastify