Claude Sonnet 5 — actual visible response Recorded: 2026-10-21 This is one unmodified model response, with its complete input. Multiple question excerpts from this response are not separate runs. Recommendations and code sketches were not executed or benchmarked. ORIGINAL INPUT Answer the three independent questions below in one reply, using headings Q1, Q2 and Q3. Keep the whole reply under 650 words. Give concrete decisions, reasons and checks rather than general introductions. Do not browse, call tools, delegate, run code, generate media or change models. Use the supplied reference facts and general programming reasoning. Distinguish documented facts, your recommendations and untested behavior. Do not claim that you tested anything. Do not invent current prices, license terms, benchmarks or product features. Reference facts checked on 20 October 2026: - BlockNote provides a React block editor with ready-made UI. Its documentation recommends native BlockNote JSON for durable, lossless document storage. - Tiptap is a headless editor framework and also offers UI components. It supports JSON export and restore. Its documentation explains that a JSON snapshot alone is not enough to merge Yjs changes. - Linear's 18 August 2026 engineering article describes a large-scale delta-sync read problem. Its new path indexes sync-action metadata in turbopuffer, filters relevant actions, then retrieves surviving payloads from Postgres. This is one product's engineering account, not evidence that every small application needs that architecture. References: https://www.blocknotejs.org/docs https://www.blocknotejs.org/docs/foundations/supported-formats https://tiptap.dev/docs/editor/getting-started/overview https://tiptap.dev/docs/guides/output-json-html https://linear.app/now/rebuilding-delta-sync-read-path Q1: How should I prevent duplicate animation loops and input listeners when restarting a small HTML canvas brick-breaker game? Give a minimal lifecycle pattern, list the game state that must reset, and provide four checks that expose restart bugs. Do not produce a complete game or claim the pattern has been run. Q2: How should a small React team choose between BlockNote and Tiptap for a Notion-style first version with paragraphs, headings, lists and reliable save-and-reload? Give a conditional initial choice, separate editor functionality from storage and permissions we must implement, and identify what must be verified before adding collaboration or comments. Q3: For an online-first issue tracker with occasional disconnects and concurrent edits, when should a small team use server-first optimistic updates rather than local-first sync? Explain retry idempotency, conflict handling, reload recovery and server-side authorization. Identify which scaling problems in Linear's August 2026 delta-sync article do not, by themselves, justify copying its architecture. VISIBLE RESPONSE Q1 — restarting a canvas brick-breaker Recommendation (untested): make one object the sole owner of both the loop and the listeners, and give every start a new generation id. start(): if already running, call stop() first. Create AbortController; attach all key/pointer listeners with {signal: controller.signal}. Record rafId = requestAnimationFrame(tick). stop(): cancelAnimationFrame(rafId), rafId = null, controller.abort(), controller = null, set running = false. tick(now): first line — if (id !== currentId) return; This kills any late frame from a previous run. visibilitychange → pause; resume must not create a second loop. State to reset: rafId, abort controller, running/paused flags, key-down set, paddle and ball position + velocity, brick grid, score/lives/level, timers and delta accumulator, previous timestamp, overlay text, any pending timeouts. Four checks: Call start() three times, count tick invocations for one second in a debug counter — expect one loop's worth, not three. Hold an arrow key, restart, keep holding: paddle speed per frame must be unchanged (duplicate listeners double it). After stop(), log inside tick; nothing should fire. Also confirm you can't remove listeners twice / leak handlers. Restart mid-game: lives, score, brick count and ball velocity must equal a fresh load, not carry the old run. Q2 — BlockNote vs Tiptap Documented: BlockNote ships a React block editor with ready-made UI and recommends native BlockNote JSON for durable storage. Tiptap is headless (with UI components available) and supports JSON export/restore. Conditional first choice: If the goal is a Notion-looking v1 shipped fast, pick BlockNote and persist its native JSON — least code between "list of blocks" and a working editor. Pick Tiptap instead if you need a custom schema, tight bundle or extension control, or your team already knows ProseMirror; budget for building the UI. Separate from the editor: the editor gives you JSON in/out and editing behaviour. You still must implement: a save API with debounce and a visible save/error state, schema versioning plus a migration path for old documents, a concurrency field (version or updatedAt), validation when parsing stored JSON, and permissions enforced on the server — per-document ACLs, never the client's word. Comments are your own model too. Verify before collaboration or comments: does a save→reload round-trip preserve everything (unknown nodes, marks, nesting)? What happens on two simultaneous saves — last-write-wins silently loses a document? And Tiptap's docs note a JSON snapshot alone is insufficient to merge Yjs changes, so test concurrent edits before promising collaboration. For comments, prove comment anchors survive insertions above them. Q3 — server-first vs local-first Use server-first optimistic updates while the server is authoritative, most issues have one editor at a time, conflicts are rare, documents are small, and offline means a brief blip. Move to local-first when users genuinely work offline for long stretches or several people edit the same issue simultaneously. Idempotency: client generates a mutation id; retries carry it and the server returns the stored result instead of applying twice. Set-field writes are naturally idempotent; increments and comments need the id. Conflicts: version/If-Match on write; on rejection, refetch and reapply or show the conflict — never blind-overwrite. Reload recovery: persist pending mutations locally and replay them on load; otherwise an optimistic edit vanishes silently. Authorization: check every mutation server-side against resolved state; a rejected optimistic update must roll back with a message. Linear's article describes a read-path scaling problem — indexing sync-action metadata to filter before fetching payloads. Its drivers are large action volumes and read fan-out; small teams don't have those. Don't copy the turbopuffer index or split metadata/payload stores until you measure that bottleneck.