The decision in one minute
| Token | Role | Check |
|---|---|---|
| Runtime shape | DeepSeek Harness composes Cordis plugins into named profiles; Pi keeps a deliberately small terminal-agent core. | Decide whether profile composition or a minimal programmable core better fits the project. |
| Tools and permissions | DeepSeek Harness connects shell tools with approval and sandbox policies; Pi runs tools with the privileges of its host process. | Document the real host and sandbox boundary before either harness handles sensitive work. |
| Models and providers | Both can work across model providers, but configuration and authentication flows differ. | Verify the required provider and authentication method in the current official documentation. |
| Extension surface | DeepSeek Harness centers plugins, profiles, and Skills; Pi exposes TypeScript extensions, Skills, prompt templates, themes, and Pi packages. | Choose the extension contract your team can review, pin, and maintain. |
| Interface and sessions | DeepSeek Harness supports its workbench and Web UI; Pi centers a TUI and also exposes RPC, JSON event, and SDK integrations. | Test the exact interface and session lifecycle used in daily work. |
Permissions and isolation are the decisive difference
Pi is an agent harness, meaning the software loop that gives a model tools, context, and a session. Its current official repository states that Pi has no built-in permission system restricting filesystem, process, network, or credential access. By default it inherits the permissions and reachable resources of the process that launched it.
DeepSeek Harness can combine approval policy with a process sandbox. Its documented sandbox modes control declared filesystem effects, while network and process visibility may remain outside that vocabulary. Treat the reported enforcement level as evidence: partial enforcement is not equivalent to complete operating-system isolation.
Compare extension models before migrating
- DeepSeek Harness: plugins provide capabilities; profiles compose a reproducible set; Skills provide reusable task instructions.
- Pi: TypeScript extensions can add tools, commands, and events; Skills and prompt templates add reusable guidance; themes change the TUI; Pi packages distribute related resources.
- In both systems, review source, pin a version or immutable revision, record the granted capabilities, and test removal before trusting an extension.
Evaluate both with the same bounded task
- 01
Define one observable task
Use a disposable repository and a task with a clear expected diff, command output, and failure condition.
- 02
Record effective access
List writable paths, available commands, network reachability, environment variables, credentials, and approval behavior.
- 03
Test the session lifecycle
Restart, resume, branch or compact the session as supported, then confirm that decisions and artifacts remain understandable.
- 04
Trigger a safe failure
Deny or remove one expected capability and confirm that the harness stops clearly without silently broadening access.
- 05
Compare evidence, not impressions
Review the final diff, tests, logs, approvals, recovery path, and the maintenance cost of required extensions.
Choose by use case and ownership
- Prefer DeepSeek Harness when profile composition, plugin integration, Web UI workflows, and explicit approval or sandbox policy are central requirements.
- Prefer Pi when a small terminal core, direct TypeScript customization, RPC or SDK embedding, and team-owned isolation are the better fit.
- Neither choice removes the need for least privilege, source review, reversible changes, and independent verification.
Continue with a controlled evaluation
Read the primary documentation
Common questions
Before you make a change
Answers about formats, compatibility, evidence, and rollback.
What does this guide verify?
This guide covers: DeepSeek Harness architecture and permission model; Current Pi Agent Harness documentation and package namespace; Runtime isolation and use-case boundaries
What should I do first?
Choose by operating model, not by a feature-count headline. DeepSeek Harness is a plugin-first workbench with profiles and policy integration; Pi is a small terminal coding harness designed to be extended through TypeScript and packaged resources.
Which boundary matters most?
For stronger isolation, run Pi or its tools in a container or sandbox and verify what that boundary actually covers. The official project documents approaches such as a whole-process container and tool isolation. A prompt that asks the model to be careful is not an access-control boundary.
Continue learning
Continue from the verified evidence
Compare published artifacts or return to the installation documentation.