Integrating with Claude Code¶

Claude Code is Anthropic's official CLI. It speaks the Anthropic Messages API, so it can be pointed at any Anthropic-compatible endpoint, including Continuum Router, via the ANTHROPIC_BASE_URL environment variable.

This guide walks through making Claude Code fully functional against a self-hosted LLM (vLLM, Ollama, llama.cpp, LM Studio, MLxcel, or any other OpenAI-compatible backend) served through Continuum Router, including the two features Claude Code ships that assume Anthropic's native backend: WebFetch and WebSearch.

What Claude Code expects¶

Claude Code is built for Anthropic's hosted API. Out of the box it hard-codes a handful of behaviors that need router-side translation when the upstream is a self-hosted model:

It talks to /v1/messages (Anthropic Messages format), not /v1/chat/completions.
It issues intermediate calls to a small haiku-class model (claude-haiku-4-5-20251001 at the time of writing) for WebFetch's summarizer and WebSearch's query extractor.
Its WebSearch feature sends Anthropic's native server tool (web_search_20250305) and expects the response to include server_tool_use + web_search_tool_result content blocks.

Continuum Router handles all three transparently when its web_search and model_aliases sections are configured; see Configure the router below.

Prerequisites¶

Before starting:

Continuum Router installed (see the Installation page).
At least one self-hosted, OpenAI-compatible LLM backend reachable by the router.
An API key for one search provider if you want WebSearch to work: Serper, Brave Search, or Exa.
Claude Code installed on your workstation.

Configure the router¶

Create a config.yaml that (a) defines your self-hosted backend, (b) enables web_search with a provider of your choice, and © declares model_aliases so Claude Code's hard-coded model names route to your backend.

server:
  bind_address: 0.0.0.0:8000

backends:
  - name: my-self-hosted
    type: vllm                  # or ollama | llamacpp | lmstudio | mlxcel | generic
    url: http://localhost:11434
    api_key: "${BACKEND_API_KEY}"
    models:
      - my-model

web_search:
  enabled: true
  provider: brave               # serper | brave | exa
  api_key: "${BRAVE_API_KEY}"

# Rewrite Claude Code's internal haiku / sonnet / opus calls so they
# reach your self-hosted model. Without this, WebFetch and WebSearch
# will fail with ModelNotFound.
model_aliases:
  haiku: my-model
  sonnet: my-model
  opus: my-model
  default: my-model

Start the router:

continuum-router --config config.yaml

Verify it is reachable:

curl http://localhost:8000/health
# {"status":"ok"}

Point Claude Code at the router¶

Claude Code reads two environment variables to choose an upstream Anthropic-compatible API:

ANTHROPIC_BASE_URL — the base URL the Anthropic SDK will hit. Point it at the router's Anthropic endpoint: http://localhost:8000/anthropic. (The /v1/messages suffix is appended by the SDK itself.)
ANTHROPIC_API_KEY — forwarded to the router as the x-api-key header. If your router's api_keys section is in permissive mode, any non-empty value works; otherwise use a key your router's api_keys store accepts.

Launch Claude Code with the variables set:

export ANTHROPIC_BASE_URL="http://localhost:8000/anthropic"
export ANTHROPIC_API_KEY="dev-key-anything-works-if-permissive"
claude

To pin the default model Claude Code uses for the main conversation turn (otherwise it defaults to a Claude sonnet model name which model_aliases will rewrite anyway), set one of:

export ANTHROPIC_MODEL="my-model"
# or start the session explicitly: `claude --model my-model`

Verify¶

Inside the Claude Code session, three quick checks cover every code path the router adds:

Main conversation turn¶

> Hi, what backend am I talking to?

The router's log should show one POST /anthropic/v1/messages forwarded to your backend, and the response should come from your self-hosted model.

WebFetch¶

> Summarize https://www.rust-lang.org/ in one sentence.

Claude Code fires off an intermediate call with model: claude-haiku-4-5-20251001. The router logs Rewrote request.model via model_aliases and forwards the call to your backend, which summarizes the fetched page.

WebSearch¶

> Use web search to find the latest Rust release.

Claude Code sends an intermediate request with an Anthropic server tool (web_search_20250305) forcing tool_choice. The router:

issues one backend turn to extract the query,
calls the configured search provider once,
returns an Anthropic-shaped response containing server_tool_use and web_search_tool_result content blocks.

The log shows the emulation path kicking in:

INFO  Anthropic web_search server-tool emulation (streaming): extracting query

Claude Code's WebSearch panel shows the ranked results.

Troubleshooting¶

`HTTP 422: missing field input_schema`¶

You are running a router version older than the web_search_20250305 support. Update the router; the fix relaxes AnthropicTool to accept both custom and server tool shapes.

`Model claude-haiku-4-5-20251001 not found`¶

model_aliases is not configured — Claude Code's intermediate haiku calls have nowhere to land. Add at least a default: entry mapping to your backend's model.

WebSearch returns zero results¶

Check the router log for web_search loop round complete:

If the loop is running but Brave / Serper / Exa returns HTTP 429, you are hitting the provider's rate limit. The provider's free tier may be capped at a low QPS; upgrade the plan or switch providers.
If you see Rewrote request.model followed by the emulation log line above but no results reach Claude Code, verify the provider's API key is valid.

Claude Code fails to connect¶

Check:

ANTHROPIC_BASE_URL ends in /anthropic (no trailing /v1/messages).
The router is reachable: curl $ANTHROPIC_BASE_URL/v1/messages -H 'content-type: application/json' -d '{"model":"my-model", "max_tokens":10,"messages":[{"role":"user","content":"hi"}]}'
If your router enforces API-key auth, ANTHROPIC_API_KEY is a key from its api_keys store.

What still does not work¶

Artifacts / attachments referencing Anthropic-hosted files by file_id — Claude Code's file-upload flow round-trips through the Anthropic Files API, which the router does not proxy. Paste content inline or upload via the router's own Files API (/v1/files).
Anthropic-side billing / rate-limit headers — Claude Code occasionally surfaces Anthropic-specific quota UI based on response headers the router does not emit.