LinkedChain

A Temporal, Node-Based Graph Data Structure for TypeScript.

📖 Introduction

LinkedChain is a sophisticated data structure designed for scenarios where history, lineage, and version control are distinct first-class citizens of your runtime state.

Unlike a traditional Doubly Linked List, every LinkedChain node behaves like a "Git Repo" for its own data. It tracks every change, allows for instant time-travel (undo/redo) to any past state, and supports branching timelines where a single object can fork into multiple independent futures.

Use Cases

• Simulation Engines: Track the history of every entity in a simulation.
• Game State Management: Implement "Save Scumming", Undo/Redo, or branching narrative paths effortlessly.
• Collaborative Editing: Manage document versions and diverging drafts.
• Audit Logging: Automatically keep a delta-compressed history of all critical data changes for compliance.

⚡ Quick Start

Installation

Install via your preferred package manager:

Bun

bun add linked-chain

NPM

npm install linked-chain

Impatient? Copy-Paste-Ready:

import LinkedChain from "linked-chain";

Basic Usage

// 1. Create a chain node
const node = new LinkedChain({
    data: { value: 100 },
    metadata: { title: "Initial State" }
});

// 2. Update it (Automatic History Tracking)
node.update({
    data: { value: 200 } // Changes are recorded as deltas
});

// 3. Time Travel
console.log(node.data()); // { value: 200 }
node.revert_to_history(0);
console.log(node.data()); // { value: 100 }

Type Safety (Generics)

LinkedChain is fully typed. You can define your own interfaces to ensure type safety across history and branching.

// Define your state shape
interface UserProfile {
    id: number;
    username: string;
    role: "admin" | "user";
}

// Pass the interface to the Generic
const userNode = new LinkedChain<UserProfile>({
    data: { id: 1, username: "neo", role: "user" }
});

// TypeScript enforces the shape!
userNode.update({
    // @ts-expect-error: 'god' is not assignable to type "admin" | "user"
    data: { role: "god" } 
});

🧠 Core Concepts

1. Proof of "Self-Awareness"

We label this data structure "self-aware" because it satisfies three criteria of computational reflexivity that standard nodes lack:

1. Temporal Proprioception: It knows not just what it is, but when it is. Unlike a dumb object that gets overwritten, a LinkedChain node retains a memory of every state it has ever held.
2. Lineage Cognition: It understands its relationship to the "Prime Timeline" (Origin) and can distinguish between its direct ancestors and distinct parallel branches (Progeny).
3. Autonomic Regulation: It manages its own history. You don't update a separate "HistoryManager" utility; you update the Node, and the Node itself calculates the delta and crystallizes the event in its memory.

2. Built-in Version Control (LinkedChainHistory)

Every node has access to a LinkedChainHistory engine.

• Timeline: A linear array of HistoryEntry objects.
• Delta Compression: To save memory, LinkedChain calculates the difference between the current state and the previous state. It stores only this delta.
• Checkpoints: Full state snapshots are taken periodically to speed up time travel operations.

3. Branching Logic

Just like Git, you can create a "Fork" of your data at any point in its history.

// Create a NEW, independent chain starting from History Index 2
const branch = node.branch_from_history(2);

The new branch is a separate object but retains the lineage of the original.

📚 Examples & Walkthroughs

We have provided a suite of heavily commented examples to demonstrate the power of LinkedChain.

| Example | Complexity | Description | | :--- | :--- | :--- | | Basic Usage | ⭐ | Learn the basics: Creating nodes, updating data, and inspecting the auto-generated history timeline. | | Branching Scenarios | ⭐⭐ | A "Git-like" document drafting system where you fork a draft from a previous version to explore an alternate ending. | | The Multiverse Simulator | ⭐⭐⭐ | A complex sci-fi simulation tracking multiple parallel civilizations. Demonstrates deep lineage analysis and searching across divergent graph branches. | | Chrono-Rogue (Game) | ⭐⭐⭐⭐ | A "Roguelike" game engine that detects player death, automatically scans history for the last safe save state, rewinds time, and alters player strategy to survive. |

🛠 API Reference

LinkedChain<T>

Constructor

new LinkedChain<T>(ingredients: LinkedChainIngredients<T>)

• data: Initial data payload.
• metadata: Initial metadata (title, id, description).
• parent / next / origin: Optional graph connections.

State Methods

• update(ingredients): Updates data/metadata and records a history entry.
• data(): Returns the current data payload.
• metadata(): Returns the current metadata.
• toJSON(): Serializes the current state (excludes history).

History Methods

• revert_to_history(index): Reverts the current state to a past point in time. This creates a new history entry representing the revert.
• branch_from_history(index): Returns a new LinkedChain instance starting from the state at index.
• history().timeline(): Returns the array of all history entries.

Graph Traversal

• ancestor_path(): Returns an array of all previous nodes (walking backwards).
• progeny_path(): Returns an array of all next nodes (walking forwards).
• iterate('next' | 'previous'): A Generator for lazy iteration.
• find(predicate): Searches the entire connected linear chain (up and down) for a node matching the predicate.
• has_circular_link(): Returns true if the chain loops on itself.

⚠️ Computed Limitations

While powerful, LinkedChain is currently in Alpha and has several known architectural limitations:

1. Shallow Delta Compression: The history engine uses shallow equality checks. If you update a deeply nested object, the delta will store the entire top-level property path rather than a recursive diff.
2. Memory Growth: The LinkedChainHistory timeline grows indefinitely. There is currently no "Garbage Collection" or "Squashing" mechanism to purge old history entries, so very long-running chains may consume significant memory.
3. Serialization: The .toJSON() method exports only the current node's state. It does not export the entire history timeline or the graph structure (relationships). You cannot yet JSON.stringify a chain and JSON.parse it back into a fully functional, time-traveling object.
4. Reference Integrity: JavaScript object references are preserved in memory. If you branch a chain, the new branch points to the same underlying data objects until they are modified. Mutating data outside of the .update() method (e.g., node.data().value = 5) breaks the history tracking.

🤝 Caring for the Code?

I am actively looking for contributors!

This project (and others in our portfolio) needs engineers who love graph theory, data structures, and TypeScript. If you're interested in:

• Implementing Deep Diffing for smarter deltas.
• Building a Serialization/Deserialization engine to save entire multiverses to disk.
• Optimizing memory usage with History Pruning.

Please open an issue or submit a PR. I am building a suite of advanced tools and would love your help.

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