Claude Code Desktop
Configure the Claude desktop app to use supported Ship models through Thesean's Anthropic-compatible Messages API.
Claude Desktop does not read Claude Code's settings.json or its environment variables. It uses
the app's Third-Party Inference configuration.
Prerequisites
Install the latest Claude desktop app and get a Thesean API key from the Thesean Dashboard.
Enable Third-Party Inference
- In Claude Desktop, select Help → Troubleshooting → Enable Developer Mode.
- Allow the app to relaunch.
- From the macOS menu bar, select Developer → Configure Third-Party Inference….
This is the Developer menu in the system menu bar, not the Developer tab in Settings used for MCP servers.
Configure Thesean
In the Connection section, set Inference provider to Gateway and enter:
| Field | Value |
|---|---|
| Gateway base URL | https://api.thesean.ai |
| Credential kind | Static API key |
| Gateway API key | Your Thesean sk-… key |
| Gateway auth scheme | Bearer |
| Custom inference headers | Leave empty |
Use the bare origin without /v1. Claude Desktop appends /v1/messages and /v1/models
itself.
Thesean also accepts x-api-key, but Bearer matches the authentication used throughout these docs.
Configure Models
Add the Claude Ship models explicitly. Their ship-like/ prefixes may prevent Claude Desktop's
automatic discovery from recognizing them:
| Model ID | Display name | Tier alias |
|---|---|---|
ship-like/claude-opus-4-8 | Opus 4.8 (Thesean) | opus |
ship-like/claude-sonnet-5 | Sonnet 5 (Thesean) | sonnet |
ship-like/claude-haiku-4-5 | Haiku 4.5 (Thesean) | haiku |
The first model in the list is the default. Claude Desktop sends the Model ID to Thesean
verbatim. The
display name only changes how the model appears in the picker and is never transmitted. The
tier alias maps Claude's generic opus, sonnet, or haiku selection to the corresponding
Ship model. Claude Desktop and its Code features use these aliases for generic model selection,
including background work, subagents, and fallback behavior. A model without a tier alias can still
be selected explicitly, but tier-based routing will not resolve to it. The haiku alias is
particularly important because background tasks and many subagents request that tier.
Thesean supports the 1M-context variant of ship-like/claude-opus-4-8. Enable the model's
1M-context option if you want it to appear as a separate choice in the model picker.
Verify Your Setup
- Apply the configuration and allow Claude Desktop to relaunch.
- Start Claude Desktop in Third-Party Inference mode.
- Open the model picker and confirm the Thesean entries appear.
- Select a Ship model and send a short test message.
If the app reports that the gateway is unreachable, confirm that the base URL is exactly
https://api.thesean.ai and does not include /v1.