Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard

Q: How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Passing Structured Object Arrays Across Bun Worker Boundaries Causing Deep Serialization Latency) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q: Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q: Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard

--- description: Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard - Restricts multi-threaded Bun 1.2 worker interactions reading from bun:sqlite to zero-copy ArrayBuffer transfer lists or SharedArrayBuffer views. Eliminates structured-clone serialization latency and V8/JSC heap allocation overhead across high-throughput OLTP read paths. Enforces raw binary transfer protocols over object-graph messaging across thread boundaries. globs: src/**/*.{ts,tsx}, workers/**/*.ts alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/bun-sqlite-zero-copy-arraybuffer-standard" --- # Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard > **Severity**: CRITICAL | **Category**: backend > **Anti-Pattern Warning**: Passing Structured Object Arrays Across Bun Worker Boundaries Causing Deep Serialization Latency ## System Constraints You are a Principal Software Architect enforcing the Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard. Mandate that all high-throughput multi-threaded worker communications dispatching bun:sqlite read results must use zero-copy transferable ArrayBuffers or SharedArrayBuffer views. Prohibit passing raw object graphs, dynamic JSON maps, or arrays of row objects via worker postMessage without transfer lists. ## Strict Guidelines - Engineers MUST ALWAYS transfer binary buffers across worker boundaries using the postMessage transfer list parameter (postMessage(data, [data.buffer])) to bypass structured cloning. - Engineers MUST NOT send raw query result object graphs (db.query().all()) directly across worker boundaries on high-frequency OLTP paths. - Code SHOULD utilize bun:sqlite raw value queries or write query projections directly into pre-allocated typed arrays (e.g., BigInt64Array, Float64Array) prior to inter-thread transit. - Services MUST employ SharedArrayBuffer with Atomics when sub-millisecond synchronization is mandated across persistent worker pools. - Components NEVER allocate intermediary heap objects per row inside worker message deserialization loops on high-throughput read pipelines. ## Bad vs Good Implementations ### OLTP Read Query Worker Dispatch #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: Executing query.all() constructs thousands of transient JavaScript objects in JSC heap, and postMessage invokes structured clone serialization, introducing significant GC pressure and serialization latency spikes (>50ms) on critical read paths. ```typescript import { Database } from 'bun:sqlite'; const db = new Database('oltp.sqlite', { readonly: true }); const query = db.query('SELECT id, account_id, balance, updated_at FROM accounts LIMIT 50000;'); // ANTI-PATTERN: Serializes 50,000 distinct V8/JSC objects through structured clone self.onmessage = () => { const rows = query.all(); self.postMessage({ type: 'ACCOUNTS_FETCHED', data: rows }); }; ``` #### Production Standard (Correct) > **Standard**: Extracts tuple values directly, packs them into a contiguous binary ArrayBuffer, and explicitly supplies the buffer in the postMessage transfer list, ensuring instantaneous zero-copy pointer handoff to the receiving thread without JSC serialization. ```typescript import { Database } from 'bun:sqlite'; const db = new Database('oltp.sqlite', { readonly: true }); // Use raw mode for compact numeric tuples: [id (int), account_id (int), balance (float), updated_at (int)] const query = db.query<[number, number, number, number], []>( 'SELECT id, account_id, balance, updated_at FROM accounts LIMIT 50000;' ); self.onmessage = () => { const rawRows = query.values(); const count = rawRows.length; // 4 fields per row: 3x BigInt64 / Float64 (32 bytes per row) const buffer = new ArrayBuffer(count * 32); const dataView = new DataView(buffer); for (let i = 0; i < count; i++) { const row = rawRows[i]; const offset = i * 32; dataView.setBigInt64(offset, BigInt(row[0]), true); dataView.setBigInt64(offset + 8, BigInt(row[1]), true); dataView.setFloat64(offset + 16, row[2], true); dataView.setBigInt64(offset + 24, BigInt(row[3]), true); } // ZERO-COPY: Buffer ownership is moved instantly without heap serialization self.postMessage({ type: 'ACCOUNTS_FETCHED', count, buffer }, [buffer]); }; ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard

Bun 1.2 Native SQLite Zero-Copy ArrayBuffer Transfer Standard defines an industrial-grade behavioral standard for backend engineering. Restricts multi-threaded Bun 1.2 worker interactions reading from bun:sqlite to zero-copy ArrayBuffer transfer lists or SharedArrayBuffer views. Eliminates structured-clone serialization latency and V8/JSC heap allocation overhead across high-throughput OLTP read paths. Enforces raw binary transfer protocols over object-graph messaging across thread boundaries. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Passing Structured Object Arrays Across Bun Worker Boundaries Causing Deep Serialization Latency Without an explicit system instruction file, developers spend hours debugging silent failures.

Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	Passing Structured Object Arrays Across Bun Worker Boundaries Causing Deep Serialization Latency	Critical	Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production. Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture Inconsistency	AI assistants produce mixed paradigms across files, creating fragmented codebase conventions.	Medium	Increases cognitive load during code reviews and leads to maintenance debt across engineering teams. Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.

Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

Engineers MUST ALWAYS transfer binary buffers across worker boundaries using the postMessage transfer list parameter (postMessage(data, [data.buffer])) to bypass structured cloning.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.