- Category
- AI Agents
- Rank
- No. 1526Tools index
Previous survey · No. 1504 ·
- Pricing
- Open Source
- Type
- TOOL
- Builder
- moeru-ai
- GitHub
- 72 stars
- Date
About
Yet another memory layer, inspired by cognitive science, designed for AI companion characters. Written in Rust.
What it does
Plast-Mem turns conversation streams into searchable long-term context. Workers divide messages into episodes, generate summaries and embeddings, then extract durable facts. Retrieval combines keyword search, vector similarity, rank fusion, and decay-based reranking before returning context formatted for a language model.
Why it's ranked here
The design is unusually explicit about memory lifecycle, from ingestion through segmentation, consolidation, retrieval, and review. The current implementation also exposes meaningful gaps: core functionality remains incomplete, surprise-based retention is not active, and some accepted API options have no effect. It is promising infrastructure, not a finished component.
What's good
Episodic and semantic records have distinct retention rules instead of sharing one vague memory model. PostgreSQL-backed jobs separate ingestion from expensive model work. Retrieval mixes lexical and semantic signals, while episodic results also account for modeled retrievability. Semantic facts preserve provenance and use invalidation rather than hard deletion.
Tradeoffs
Deployment requires PostgreSQL with ParadeDB plus compatible chat and embedding services. The server port is fixed. Semantic facts have no direct write interface. Graph retrieval is only future design work. Current episode creation sets surprise to zero, so the documented surprise-based stability boost is absent. The retrieval detail option is accepted but ignored by formatting.
How to use it well
Use it when building a self-hosted conversational agent that needs asynchronous memory extraction and hybrid recall. Treat the HTTP service as a memory subsystem beside your model orchestration, and validate its unfinished behavior before production use. It does not provide a graph memory system, a hosted service, or general agent orchestration.
Technical notes+
Cargo.toml defines a Rust 2024 workspace with ten members, Rust 1.91, Axum, SeaORM, Apalis PostgreSQL storage, FSRS, and OpenAI-compatible clients. src/main.rs connects to the database, applies migrations, initializes four job stores, then runs workers and the HTTP server concurrently. docs/ARCHITECTURE.md documents the queue-and-worker flows and notes that surprise is currently written as 0.0 and retrieval detail does not affect rendering. package.json defines a private pnpm workspace, while packages/plastmem/src/index.ts exports generated TypeScript request helpers and response types.
Observed
- License
- MIT
- Primary language
- Rust
- Packaging
- Single binary or Docker image
- Service interface
- HTTP API with an OpenAPI surface
- Client interface
- Generated TypeScript client package
- Runtime dependencies
- PostgreSQL with ParadeDB and OpenAI-compatible chat and embedding services
- Repository structure
- Rust workspace with ten members plus a private pnpm workspace
Read from README.md, Cargo.toml, package.json, src/main.rs, packages/plastmem/src/index.ts, packages/plastmem/src/client/index.ts, docs/TYPESCRIPT.md, docs/ENVIRONMENT.md, docs/ARCHITECTURE.md, docs/CHANGE_GUIDE.md, docs/todo/README.md, docs/architecture/fsrs.md, docs/todo/flashbulb_memory.md, docs/architecture/graph_memory.md, docs/architecture/segmentation.md.
What it can do
Store episodic memories for AI companion characters
Conversation events and interactions → Structured memory records
Retrieve contextually relevant memories
Current conversation context or query → Related past interactions and experiences
Form associative memory connections
Related concepts, events, or conversation topics → Linked memory pathways
Simulate memory decay and forgetting
Time-based parameters and memory importance weights → Updated memory strength and accessibility
Consolidate short-term memories into long-term storage
Recent interaction data and importance metrics → Persistent memory structures
Generate personality-consistent responses based on memory
Current conversation input and character profile → Contextually-aware AI companion responses
Tags
Tech Stack
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Editorially curated, with community endorsements as a secondary signal. Corrections welcome.
