fix(onboarding) [BRNS-DESK-026]: make terms and privacy reachable from sign-in and about

[sebastian-ssvlabs]

Summary

• The sign-in screen asserted "By continuing you agree to the Terms & Privacy Policy." as plain text — a consent gate whose terms could not be read from the product. grep -rniE "terms|privacy|tos|eula" src/ messages/ src-tauri/src/ found that sentence as the only legal string in the codebase: no anchor, no URL, no Settings entry, no About link, no menu or tray item. The only way to review what was being agreed to was to guess a URL in a browser.
• It was also hardcoded English, so a zh-CN user got English legal copy in an otherwise translated UI.
• Both links now open the published documents (https://mybrains.ai/terms, https://mybrains.ai/privacy — the app.mybrains.ai variants 404), the sentence is localized, and the same two links are reachable from the About modal after onboarding.
• Closes BRNS-DESK-026 (P2, effort S, onboarding / desktop / legal-compliance).

Mechanism

src/lib/legal-links.ts holds the two URLs once (now referenced from two surfaces) plus openLegalLink(e, url), which sends the click to the default browser via the existing plugin-shell idiom with a window.open fallback. It bails on e.defaultPrevented because +page.svelte already installs a document-level capture handler that opens every http(s) anchor externally — without that guard a link inside that tree would open twice.

src/lib/components/LegalConsent.svelte renders the sentence from a single template key with {terms} / {privacy} slots and splits on those slots, so a locale can reorder the links rather than being locked to English word order; the labels are separate keys. Real <a href> elements keep the muted palette but add underline + pointer, so they are keyboard-reachable and expose as links (previously AXLink count on that screen was 0). The sign-in screen's paragraph becomes <LegalConsent marginTop={loginErr ? 14 : 26} />, which keeps the visual spacing behaviour and keeps this out of the 15k-line +page.svelte.

New keys legal_consent / legal_terms / legal_privacy are added to both messages/en.json and messages/zh-CN.json with a real Chinese translation.

Overlap with sibling DESK PRs: the AboutModal edit is deliberately additive — one import line and one new <span> appended after the existing copyright line in the footer — so BRNS-DESK-017's rebrand of the version/copyright lines rebases cleanly. The locale additions sit in their own legal_* block between the setup_* and chat_* groups (same line position in both files) rather than at either end, to stay clear of 017/027/028/030. The sign-in screen change is a 7-line deletion replaced by one component tag, so PRs touching the connect/sign-in screen have minimal surface to conflict with.

Worth flagging separately: AboutModal.svelte is currently only mounted from src/routes/_opencovibe_layout.svelte.txt (the inert fork-reference copy), so nothing in the live app opens it today. The links now live in the right surface, but re-wiring that surface is out of scope here — if 017 does not restore it, post-onboarding reachability needs a follow-up (e.g. a Settings entry).

Verification

• npx prettier --check on all six changed files — clean
• npx eslint on the changed files — 0 errors; the 35 warnings are pre-existing no-unused-vars in +page.svelte / chat/+page.svelte, none in the new files
• node scripts/i18n-check.mjs — 0 errors, 18 warnings (all pre-existing); the three new keys align across locales and their {terms}/{privacy} placeholder sets match
• svelte-check — 0 errors, 129 pre-existing warnings; none in LegalConsent.svelte or legal-links.ts (the one hit in AboutModal.svelte is the pre-existing dialog-role tabindex warning on an untouched line). Needed npx svelte-kit sync first, since a fresh clone has no .svelte-kit — the blocker BRNS-DESK-016 documents
• Pre-commit hook (lint + svelte-check) passed without --no-verify
• grep -rn "By continuing you agree" --include='*.svelte' src/ → 0
• Not verified: no GUI run — the accessibility tree (AXLink count ≥ 2), the actual browser hand-off on click, and the zh-CN rendering were not observed in a running app. cargo was not run at all (no local Rust target); shell:allow-open was already granted in src-tauri/capabilities/default.json, so no capability change was needed.

[Chris-ssvlabs]

🟡 BRNS-DESK-026: acceptance requires the Terms/Privacy links to be reachable from About, but AboutModal is only mounted from src/routes/_opencovibe_layout.svelte.txt (an inert reference copy), so no post-onboarding surface in the live app can reach these links. Mount AboutModal from a live surface (e.g. a Settings/menu entry) or add the two links to an actually reachable surface.

[nir-ssvlabs]

Verified the part that would quietly reproduce the bug: both URLs serve. https://mybrains.ai/terms and /privacy return 200, and https://app.mybrains.ai/terms really does 404 — so the host choice is right and a consent link that leads nowhere isn't shipping in place of one that didn't exist.

The e.defaultPrevented bail is the detail I'd have expected to be missing: +page.svelte already installs a document-level capture handler that routes every http(s) anchor externally, so without that guard these two links would open twice. Splitting the sentence on {terms} / {privacy} slots rather than concatenating is also the right call for a localized legal string — a locale that needs different word order can have it.

Checked: both URLs and the 404 claim by request, the double-open guard against the existing capture handler, and that the new keys are present in both locales. Not read: the About-modal surface beyond its use of the shared constants.

Merge: ✅ into main.