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OpenRouter is an aggregator that fronts hundreds of models behind one OpenAI-compatible API. Fabro ships a disabled openrouter provider entry with a curated model catalog, so you can opt in from settings.toml without changing Fabro code.

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Prerequisites

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Enable the provider

Add the provider override to ~/.fabro/settings.toml:
settings.toml
_version = 1

[llm.providers.openrouter]
enabled = true

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Configure credentials

For server-backed runs, store the key in the Fabro server vault: 
fabro provider login openrouter
# or
fabro secret set OPENROUTER_API_KEY sk-or-v1-...
Standalone local SDK/CLI runs can use an env-backed credential source explicitly: 
export OPENROUTER_API_KEY=sk-or-v1-...

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Included models

The built-in catalog curates frontier and open-weights models under vendor-namespaced IDs:
Fabro model IDNotes
anthropic/claude-opus-4-7Claude via OpenRouter, Anthropic-style cache billing
anthropic/claude-sonnet-4-6Provider default
anthropic/claude-haiku-4-5Provider small default
openai/gpt-5.4, openai/gpt-5.5
google/gemini-3.1-pro-preview, google/gemini-3.5-flash
deepseek/deepseek-v4-pro, deepseek/deepseek-v4-flash
moonshotai/kimi-k2.6, qwen/qwen3-coder, qwen/qwen3.6-flash
z-ai/glm-4.6, minimax/minimax-m2.7, xiaomi/mimo-v2.5-pro
nvidia/nemotron-3-super-120b-a12b, mistralai/devstral-2512
Any other OpenRouter model can be added as a settings model entry with provider = "openrouter" and the OpenRouter slug as api_id:
settings.toml
[llm.models."meta-llama/llama-4-maverick"]
provider = "openrouter"
display_name = "Llama 4 Maverick"
family = "llama-4"

[llm.models."meta-llama/llama-4-maverick".limits]
context_window = 1000000

[llm.models."meta-llama/llama-4-maverick".features]
tools = true
vision = false
reasoning = false

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Use OpenRouter models

fabro model list --provider openrouter
fabro model test --model anthropic/claude-sonnet-4-6
fabro run workflow.fabro --model deepseek/deepseek-v4-flash
In workflow stylesheets:
workflow.fabro
digraph Example {
    graph [
        model_stylesheet="
            * { model: anthropic/claude-sonnet-4-6; }
        "
    ]

    start [shape=Mdiamond, label="Start"]
    work  [label="Work", prompt="Use the configured OpenRouter model."]
    exit  [shape=Msquare, label="Exit"]

    start -> work -> exit
}

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Cost telemetry

Every OpenRouter response includes an inline usage.cost with authoritative USD billing. Fabro surfaces it as cost_usd with cost_source = "authoritative" on completion responses. Other providers populate the same fields from catalog price estimates with cost_source = "estimated". The catalog prices on OpenRouter model rows are best-effort estimates used only before the authoritative figure arrives (for example, mid-stream rollups).

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Provider routing

OpenRouter’s provider routing preferences pass through verbatim via provider_options.openrouter on API/SDK requests — the keys merge into the top level of the request body: 
{
  "model": "anthropic/claude-sonnet-4-6",
  "provider_options": {
    "openrouter": {
      "provider": { "sort": "throughput", "data_collection": "deny" },
      "models": ["anthropic/claude-sonnet-4.6", "deepseek/deepseek-v4-pro"]
    }
  }
}

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Attribution headers

Fabro does not send OpenRouter’s optional attribution headers (HTTP-Referer, X-Title) by default, so self-hosted installations stay anonymous on OpenRouter’s public app leaderboard. To opt in:
settings.toml
[llm.providers.openrouter.extra_headers]
"HTTP-Referer" = { literal = "https://your-site.example" }
"X-Title" = { literal = "Your App" }

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Troubleshooting

“No API key configured” — For server-backed runs, set the key with fabro provider login openrouter or fabro secret set OPENROUTER_API_KEY .... For standalone local usage, export OPENROUTER_API_KEY in the invoking shell. 402 / insufficient credits — OpenRouter requires prepaid credit; check your balance at openrouter.ai/credits. Unknown model — Confirm the model’s api_id matches an OpenRouter slug exactly (including the vendor prefix), then run fabro model test --model <fabro-model-id>.

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Further reading

Models

How Fabro routes model IDs, providers, and fallbacks.

Settings Configuration

Full reference for [llm.providers.<id>] and [llm.models.<id>].