feat(home-b): Today feed-first parent home prototype with persistent conversational composer (synthetic data)

[obvious-autobuild]

Candidate B of the parent-home A/B comparison — DO NOT AUTO-MERGE. Candidate PRs are excluded from individual auto-merge until the product owner compares candidates. Candidate A lives on its own branch; do not rebase or merge this PR against it.

Why

The parent home needs an organizing experience, and the A/B comparison must test two coherent answers, not two feature sets. Candidate B's thesis: the feed is home — today's recorded events newest-first, with the whole month's history one navigation away — and capture is always one composer away, docked at the bottom of every screen. A parent taking over care should answer "what happened today?" before they answer "what do I want to record?".

What

A runnable Expo React Native prototype (Expo web export verified) of the Today feed-first parent home with a persistent conversational composer:

• Today feed home — newest-first events with provenance back to the raw source; month navigation (‹ September 2026 › day chips with counts) into the Sep 1–16 synthetic history; a "since you were away" catch-up block heads the feed.
• Persistent composer — voice button + text field docked on every screen; both channels feed the identical pipeline (raw transcript → deterministic extraction double → proposed events → review → publish).
• Review surface over the feed — interpreted draft cards (type, child, time, amount, audience) edit in place next to the raw source text, with re-run-extraction and remove; publishing lands events with provenance.
• Append-only corrections — post-publish corrections append lineage from the event's source view; the original stays intact.
• Fail-closed authorization — persona switcher (mom / dad / invited caregiver) demonstrates audience-scoped visibility; a non-member sees nothing.

Synthetic data only (Polanco Household, 22 deterministic utterances across Sep 1–16, 2026); in-memory store mirroring the Convex adapter semantics — no live Convex, no LLM. All stored shapes decode through the canonical Effect v4 schemas in packages/domain.

Task: todo_w3Y69OzH
Evidence & findings: https://app.obvious.ai/p/ai-dictation-powered-agent-companion-monorepo-BIp9UTWX/parent-home-candidate-b-today-feed-first-prototype-VwaZuiWP

How to Review

• packages/home-b/src/store.ts — the behavioral core (raw-before-events, captureId idempotency, review edits, audience controls, append-only lineage, read-only lookups).
• packages/home-b/src/ui/HomeBDemoApp.tsx — the candidate experience; the persistent composer is the load-bearing UX claim, so check it stays reachable in every state.
• packages/home-b/src/ui/theme.ts + apps/mobile/App.tsx — candidate-local tokens and the env-guarded mobile wiring (EXPO_PUBLIC_HOME_CANDIDATE=b); the Convex-backed shell path is otherwise untouched.
• Intentionally excluded: backend/convex changes, arena/extraction-card review UI, live device voice (simulated-transcript demo mode ships instead — documented in the evidence doc), and any cross-cutting shared-code change — the last are listed as shared-change requests in the evidence doc §8.

Test Evidence

• corepack pnpm turbo run typecheck test build → 18/18 tasks successful, 0 cached, at pushed HEAD 3b4b53b19b9c2c509e8c55f0a83d8bcab39682d8.
• packages/home-b Vitest suite 22/22: mixed-topic capture via both text and simulated-voice paths; pre-publish correction of type/child/time/amount/audience; publish → raw-preserved entry + provenance; post-publish append-only lineage (original intact); read-only lookups never write; fail-closed authorization (non-member sees nothing).
• Expo web export (464 modules) exercised in a browser: feed rendered and a mixed-topic utterance produced the three expected draft cards (Milo meal, Milo mood, Iris nap). Screenshots tc-1-today-feed.png, tc-2-review-after-send.png in the evidence artifact.

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Human author: Gilbert Polanco (gilbertpolanco42@gmail.com)

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