How does Atlas ensure code changes are safe?

Atlas ensures safety by drafting a plan in a read-only plan agent, asking for approval before switching to a build agent, and computing a unified diff for every file edit, surfacing it for approval before writing.

Does Atlas support local embeddings for code indexing?

Yes, Atlas can build its code index with local Ollama embeddings, keeping code off third-party servers.

What operating systems does Crush support as a single binary?

Crush ships as one static binary across macOS, Linux, Windows, the BSDs, and Android.

What is the pricing for Atlas and Crush?

Atlas offers a free core; users bring their own model keys. Crush's CLI is free, users bring their own keys, and Charm Hyper credits cost around $0.05 each with 100 free per month.

Atlas vs Crush: Terminal AI Coding Agents in 2026

In 2026, developers choosing between Atlas and Crush will find Atlas offers a terminal-native TUI with robust change review and permission-gated tool calls, while Crush, a source-available agent, excels with LSP integration and the ability to switch models mid-session without losing context.

Code Understanding and Context Management

Crush distinguishes itself in 2026 by integrating directly with Language Server Protocols (LSP), feeding real language-server context to its model instead of raw file text, and allowing model switching mid-session without losing conversation context. Atlas, conversely, indexes code by AST declarations using tree-sitter and employs Axis, its hybrid semantic and keyword code search, fused by reciprocal rank fusion.

Atlas employs a sophisticated approach to code understanding, indexing code by AST declarations using tree-sitter, which provides a structural understanding beyond simple line windows. For searching, Atlas uses Axis, its hybrid semantic and keyword retrieval system, fused by reciprocal rank fusion, to locate relevant code efficiently. Furthermore, Atlas can build its code index with local Ollama embeddings, ensuring that sensitive code remains off third-party servers. Crush, in contrast, leverages its LSP integration to feed real language-server context directly to the model, which can provide highly accurate, real-time contextual information. A key advantage for Crush is its ability to switch models mid-session without losing the conversation context, offering flexibility for developers who might experiment with different models or providers during a single coding task. Atlas also lets you switch the active model and provider on the fly with favorites and recents, but Crush's strength is preserving the full conversation context during this switch.

Change Review and Agent Safety

For developers in 2026, Atlas prioritizes safety by drafting a plan in a read-only plan agent and asking for approval before switching to a build agent, computing a unified diff for every file edit, and surfacing it for approval before writing. Crush, however, has no proprietary harness layer, meaning its output quality is entirely a function of the model you bring, without an explicit diff review step.

Atlas is designed with a strong emphasis on developer control and safety. Before any changes are applied, Atlas drafts a plan in a read-only plan agent and explicitly asks for user approval before switching to a build agent to execute the plan. Crucially, Atlas computes a unified diff for every file edit and surfaces it for approval, allowing developers to review and understand every proposed modification before writing. Atlas also snapshots file changes as git patches so edits can be diffed and rolled back if needed. Every Atlas tool call is permission-gated against allow, ask, and deny rules, providing granular control over the agent's actions. Crush, while a powerful agent, does not include a proprietary harness layer. This means that the quality and safety of its output are entirely a function of the model brought by the user, without the explicit, built-in planning, diffing, and approval steps that Atlas provides.

Licensing and Open Source Status

Crush operates under an FSL-1.1-MIT license, which includes a two-year commercial-compete restriction, meaning it is not considered OSI open source today in 2026. Atlas, on the other hand, offers a free core and allows users to bring their own model keys, providing a different approach to accessibility and commercial use.

The licensing models for Atlas and Crush present a clear distinction for developers in 2026. Crush is distributed as source-available software under the FSL-1.1-MIT license. This license includes a two-year commercial-compete restriction, which means it does not meet the criteria for OSI open source today. Developers considering Crush for commercial projects should be aware of this restriction. Atlas, on the other hand, offers a free core, allowing users to bring their own model keys. This model provides flexibility for developers to choose their preferred AI models and providers without additional licensing costs from Atlas itself, focusing on the agent's functionality rather than model provision.

Portability and Deployment

Crush offers exceptional portability in 2026, shipping as one static binary that runs across macOS, Linux, Windows, the BSDs, and Android, simplifying deployment for a wide range of environments. Atlas also ships as a single self-contained binary and provides a terminal-native TUI that runs directly in your shell, focusing on a consistent terminal experience.

Both Atlas and Crush are designed for ease of deployment, shipping as single, self-contained binaries. Crush stands out for its broad cross-platform compatibility, available as one static binary across a wide array of operating systems including macOS, Linux, Windows, the BSDs, and Android. This extensive support makes Crush highly versatile for developers working in diverse environments or on embedded systems. Atlas also ships as a single self-contained binary and provides a terminal-native TUI that runs directly in your shell. This focus ensures a consistent and integrated experience within the developer's existing terminal workflow, offering a TUI theme system with a charcoal-and-blue default theme and many presets for customization.

Extensibility and Model Integration

Regarding extensibility, Crush supports Model Context Protocol (MCP) over stdio, HTTP, and SSE, complete with per-project configuration and permission allowlists, offering flexible integration options in 2026. Atlas also connects to Model Context Protocol servers, exposing their tools to the agent, and is further extensible through plugins that contribute tools and hook into agent lifecycle events.

Both terminal agents support the Model Context Protocol (MCP), but their approaches to extensibility differ. Crush implements MCP over stdio, HTTP, and SSE, offering flexible integration points for various systems, and includes per-project configuration and permission allowlists for fine-grained control over its interactions. Atlas also connects to Model Context Protocol servers and exposes their tools to the agent, allowing it to utilize external capabilities. Beyond MCP, Atlas is designed to be highly extensible through a robust plugin system. These plugins can contribute new tools and hook into various agent lifecycle events, enabling developers to customize and extend Atlas's functionality significantly to fit specific workflows or integrate with proprietary systems. Atlas also fans out work to subagents that can run in the foreground or in parallel background sessions, enhancing its operational flexibility.

How to choose

Choose SeaShell if

You need a terminal-native TUI with a robust change review process, including plans, unified diffs, and explicit approval steps.
You require permission-gated tool calls to control agent actions with allow, ask, and deny rules.
You want to build your code index with local Ollama embeddings, keeping code off third-party servers.
You value extensibility through plugins that contribute tools and hook into agent lifecycle events.
You need advanced code search capabilities like Axis, Atlas's hybrid semantic and keyword retrieval fused by reciprocal rank fusion.

Choose the alternative if

You prioritize deep language server integration (LSP) to feed real language-server context to the model.
You need to switch models mid-session without losing conversation context.
You require a single static binary that runs across a very broad range of operating systems, including Android and BSDs.
You are comfortable with a source-available license (FSL-1.1-MIT) that includes a two-year commercial-compete restriction.
Your workflow is purely local and does not require cloud agents, remote execution, or PR automation.

Frequently asked questions

What is the licensing model for Crush in 2026?: In 2026, Crush is source-available under an FSL-1.1-MIT license, which includes a two-year commercial-compete restriction, meaning it is not OSI open source today.
How does Atlas ensure code changes are safe?: Atlas ensures safety by drafting a plan in a read-only plan agent, asking for approval before switching to a build agent, and computing a unified diff for every file edit, surfacing it for approval before writing.
Can Crush switch AI models during a session?: Yes, Crush allows users to switch models mid-session without losing the conversation context.
Does Atlas support local embeddings for code indexing?: Yes, Atlas can build its code index with local Ollama embeddings, keeping code off third-party servers.
What operating systems does Crush support as a single binary?: Crush ships as one static binary across macOS, Linux, Windows, the BSDs, and Android.
How does Atlas handle tool calls?: Every Atlas tool call is permission-gated against allow, ask, and deny rules before it runs.
What is the pricing for Atlas and Crush?: Atlas offers a free core; users bring their own model keys. Crush's CLI is free, users bring their own keys, and Charm Hyper credits cost around $0.05 each with 100 free per month.

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Sources

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