schema

@runt/schema

LiveStore schema for Anode notebooks, defining events, tables, and types with conflict-free cell ordering and real-time collaboration support.

Usage

import { createCellBetween, events, schema, tables } from "jsr:@runt/schema";

// Create cells using the helper (recommended approach)
const createEvent = createCellBetween(
  {
    id: "cell-123",
    cellType: "code",
    createdBy: "my-runtime",
  },
  cellBefore, // CellReference | null
  cellAfter, // CellReference | null
);
store.commit(createEvent);

// Query tables
const cells = store.query(tables.cells.select().where({ cellType: "code" }));
const outputs = store.query(
  tables.outputs.select().where({ cellId: "cell-123" }),
);

Core Functions

createCellBetween

Primary helper for creating cells with proper fractional indexing. Internally uses events.cellCreated2.

createCellBetween(
  cellData: {
    id: string;
    cellType: CellType;
    createdBy: string;
  },
  cellBefore: CellReference | null,
  cellAfter: CellReference | null,
  jitterProvider?: JitterProvider
): ReturnType<typeof events.cellCreated2>

Examples:

// Insert at beginning
const event = createCellBetween(cellData, null, firstCell);

// Insert at end
const event = createCellBetween(cellData, lastCell, null);

// Insert between cells
const event = createCellBetween(cellData, cell1, cell2);

// Custom jitter for testing
const event = createCellBetween(cellData, null, null, mockJitterProvider);

moveCellBetween

Helper for repositioning existing cells with conflict-free ordering.

moveCellBetween(
  cellId: string,
  cellBefore: CellReference | null,
  cellAfter: CellReference | null,
  jitterProvider?: JitterProvider
): ReturnType<typeof events.cellMoved2>

Schema Structure

Events

Cell Lifecycle:

• cellCreated2 - Created via createCellBetween with fractional indexing
• cellUpdated - Content or metadata changes
• cellDeleted - Cell removal
• cellMoved2 - Position changes via moveCellBetween

Execution:

• executionRequested - Queued for execution
• executionStarted - Runtime begins processing
• executionCompleted - Finished with success/error state

Outputs:

• cellOutputAdded - Rich display data, stdout, stderr
• cellOutputsCleared - Remove all outputs for cell

Runtime Management:

• runtimeSessionStarted - New runtime connection
• runtimeSessionHeartbeat - Keep-alive signal
• runtimeSessionTerminated - Runtime disconnect

Tables

cells - Cell content and state

• id, cellType, source, fractionalIndex
• createdAt, updatedAt, createdBy
• executionCount, lastExecutedAt

outputs - Rich execution results

• cellId, outputType, data (MediaBundle)
• executionCount, createdAt

executionQueue - Pending executions

• cellId, status, requestedAt
• startedAt, sessionId

runtimeSessions - Active runtimes

• sessionId, runtimeType, startedAt
• lastHeartbeatAt, capabilities

notebook - Metadata

• id, title, createdAt, updatedAt

Key Types

type CellType = "code" | "markdown" | "ai";

interface CellData {
  id: string;
  cellType: CellType;
  source: string;
  fractionalIndex: string;
  createdBy: string;
  executionCount: number;
}

interface CellReference {
  id: string;
  fractionalIndex: string;
}

interface MediaBundle {
  [mimeType: string]: string;
  // e.g., "text/plain", "text/html", "image/png"
}

Fractional Indexing

Cell ordering uses fractional indices to avoid conflicts during concurrent edits:

// Indices are lexicographically ordered strings
"a" < "b" < "c" < "z";
"a0" < "a1" < "a2";
"aV" < "aW" < "aX";

// Always room to insert between any two indices
fractionalIndexBetween("a", "b"); // → "aV" (example)
fractionalIndexBetween("aV", "aW"); // → "aVV"

Important Constraints

Materializer Purity: All materializers must be deterministic functions. No Date(), Math.random(), or external state access. Use event data only.

Event Immutability: Once committed, events cannot be modified. Design schema changes carefully.

Cell Creation: Always use createCellBetween instead of direct events.cellCreated2 to ensure proper indexing.

Session Overlap: Runtime restarts create new sessionId values. Handle overlapping sessions during transitions.

Concurrent Safety: Fractional indices prevent ordering conflicts when multiple clients create cells simultaneously.

Development Notes

Dual Package Files:

• package.json - Local development syncing with Anode
• deno.json - JSR publishing and Deno runtime

Type Safety: All events and tables are fully typed. LiveStore enforces schema at runtime.

Testing: Use createTestJitterProvider() for deterministic fractional indices in tests.

Migration from Legacy Events

Before (deprecated):

store.commit(events.cellCreated({ cellId, cellType, source, position }));

After (current):

const event = createCellBetween(
  { id: cellId, cellType, createdBy: "runtime" },
  cellBefore,
  cellAfter,
);
store.commit(event);

The helper handles fractional indexing automatically and uses the current cellCreated2 event internally.