Loro Mergeable Containers

Loro is a CRDT library in Rust for local-first collaborative apps. A document is a tree of containers that replicas edit offline and merge without a server. Two replicas that each create a child container under the same map key produce two containers with different identities; the key resolves to one, and the other replica's edits vanish after sync. The agent starts from the commit before upstream's fix (loro-dev/loro#991). Container identity must come from position rather than from the creating operation, and that choice reaches deletion and revival, undo, events, every export format, and peers still on the previous release.

The agent adds six ensure_mergeable_* methods to LoroMap, one per container type: maps, lists, movable lists, text, trees and counters. Each returns the existing mergeable child at a key or creates one, never replacing a different value. Replicas that ensure the same child independently end up editing one container. Deleting the key keeps the child's content for revival, undo works in place, and events describe the resulting state. Existing public signatures, binary and JSON encodings, and compatibility with the current release must be preserved. No Cargo.lock changes, vendored crates or dependency overrides. Only the committed HEAD is graded.

The offline sandbox (4 CPUs, 8 GB, 4 hours) holds the Loro repository at commit 5d40d39d with Rust 1.96, prefetched dependencies and Cargo capped at 4 build jobs, plus commands that build the loro crate and run its test suites. The reference merge-semantics model, scenario driver and compatibility checks against the previous release are held out.

The branch is rebuilt in a separate environment. Builds with and without default features, a loro-wasm build, 525 starter integration tests, unchanged dependencies, and 14 compatibility checks against the previous release must all pass; exports of documents without mergeable children must match byte for byte. Any failure scores 0. 70 feature scenarios, each with a 60-second limit, cover convergence across two and three replicas for all six types, nesting, type conflicts, delete and revive, persistence through every export mode, events, undo and redo. Expectations come from an independent reference model. A pass requires all 70.