fix: lazy-load sqlite bindings and add bun:sqlite support

[brittianwarner]

Summary

• Removes the eager top-level require("node:sqlite") in sqlite-bindings.ts that crashed on any runtime without node:sqlite (including Bun)
• Lazy-loads the SQLite module on first AgentOs.create() call with promise-cached loading
• Adds a full bun:sqlite adapter (BunDatabaseAdapter/BunStatementAdapter) that normalizes API differences to match the node:sqlite shape
• Auto-selects the right backend via runtime detection (process.versions.bun)

Related: rivet-dev/rivet#4550 — lazy-loads agent-os-core on the RivetKit side to prevent the same crash at the actor layer.

Changes

packages/core/src/sqlite-bindings.ts — Full refactor

• Removed the eager top-level require("node:sqlite") (the crash root cause)
• Added SqliteDatabase, SqliteStatement, SqliteModule interfaces for runtime-agnostic abstraction
• Added BunDatabaseAdapter / BunStatementAdapter with full API mapping:
  • db.location() maps from db.filename (normalizes :memory: to null)
  • stmt.run() passes through { changes, lastInsertRowid } directly
  • stmt.get() normalizes Bun's null-for-no-rows to undefined
  • stmt.iterate() uses native iterate() when available, falls back to all()
  • stmt.columns() maps columnNames string[] to [{ name }] objects
  • stmt.finalize() calls through to release native resources
  • setReadBigInts / setAllowBareNamedParameters / setAllowUnknownNamedParameters are documented no-ops
  • constants forwarded from bun:sqlite (e.g. SQLITE_FCNTL_PERSIST_WAL)
• Promise-cached module loading prevents race conditions on concurrent calls
• Explicit unsupported-runtime error for non-Node/non-Bun environments
• Improved error messages with running version, minimum requirements, open handle diagnostics, and contextual hints (ENOENT, EACCES, corrupt DB)
• JSDoc on all exported functions

packages/core/src/agent-os.ts — One line

• bindings: createSqliteBindings(kernel) to bindings: await createSqliteBindings(kernel) (already inside static async create())

packages/core/src/index.ts — New exports

• Exported SqliteModule, SqliteDatabase, SqliteStatement types for custom backends
• Exported createSqliteBindings and createSqliteBindingsFromModule

packages/core/tests/sqlite-bindings.test.ts — 55 tests across 6 suites

• Lazy loading (no eager import, caching, reset, concurrent safety)
• Runtime detection
• Bun adapter surface via mock (20 tests)
• Binding tree lifecycle, error diagnostics, VFS sync (20 tests)
• Real node:sqlite integration (CRUD, bigint, Uint8Array, transactions, VFS sync)
• Public API entry point (createSqliteBindings)

Documentation

• CLAUDE.md: Added SQLite runtime requirement to Dependencies, Bun adapter parity gaps to Known VM Limitations
• .agent/todo/remove-sqlite-bindings.md: Updated with current state and known adapter limitations
• .agent/notes/vm-friction.md: Created per project policy

Impact

• Bun users: @rivet-dev/agent-os-core imports cleanly. SQLite features work via bun:sqlite.
• Node users: Zero behavior change. node:sqlite loads lazily instead of eagerly.
• Other runtimes: Import succeeds. Clear error on AgentOs.create() if SQLite is needed.

Testing

• 55 new tests, 251+ total across 9 test files, 0 failures
• Two rounds of multi-agent code review (correctness, Bun compat, test quality, DX)
• Verified against latest bun:sqlite spec
• Zero new type errors vs baseline

[brittianwarner]

#4550