@offlinesync/conflict

Conflict detection and resolution framework. Zero dependencies.

ConflictResolutionManager

import { ConflictResolutionManager, LastWriteWinsStrategy, FunctionStrategy } from '@offlinesync/conflict'

const manager = new ConflictResolutionManager({
  defaultStrategy: 'last-write-wins',
  strategies: {
    'last-write-wins': new LastWriteWinsStrategy(),
    'tasks': new FunctionStrategy(async (ctx) => ({
      outcome: 'resolved',
      data: { ...ctx.serverData, ...ctx.clientData },
    })),
  },
  onConflict: (ctx) => console.log(`Conflict on ${ctx.entityId}`),
})

const resolution = await manager.resolve('tasks', {
  entityId: 'task-1',
  collectionName: 'tasks',
  clientVersion: { revision: 2, data: { title: 'My task' } },
  serverVersion: { revision: 3, data: { title: 'Your task' } },
})

Method	Returns	Description
resolve(collectionName, context)	Promise<ConflictResolution>	Route and resolve a conflict
registerStrategy(name, strategy)	void	Register a named strategy

Built-in Strategies

Strategy	Description
ServerWinsStrategy	Always returns server-wins with server data
ClientWinsStrategy	Always returns client-wins with client data
LastWriteWinsStrategy	Compares updatedAt timestamps, picks newer
FieldMergeStrategy	Merges individual fields; server wins on collision
OperationAwareStrategy	Uses operation type for smarter resolution
ManualStrategy	Returns manual for app-level handling
FunctionStrategy	Wraps a user-provided resolver function

Types

Export	Description
ConflictContext	{ entityId, collectionName, clientVersion, serverVersion, clientData, serverData, operation }
ConflictResolution	`{ outcome: 'resolved'
ConflictResolver	(context: ConflictContext) => Promise<ConflictResolution>
BuiltInStrategyName	Union of built-in strategy name literals

Strategy Names

import { BUILT_IN_STRATEGY } from '@offlinesync/conflict'

BUILT_IN_STRATEGY.SERVER_WINS       // 'server-wins'
BUILT_IN_STRATEGY.CLIENT_WINS       // 'client-wins'
BUILT_IN_STRATEGY.LAST_WRITE_WINS   // 'last-write-wins'
BUILT_IN_STRATEGY.FIELD_MERGE       // 'field-merge'
BUILT_IN_STRATEGY.OPERATION_AWARE   // 'operation-aware'
BUILT_IN_STRATEGY.MANUAL            // 'manual'