Claude Fable and Dome

1. 01

   Connect Anthropic

   The frontier tag is what keeps Fable to the pilot group. The migration agent never sees the Anthropic key.

   $ dome models add fable-51-anthropic \
     --provider anthropic \
     --model claude-fable-5-1 \
     --api-key "$ANTHROPIC_API_KEY" \
     --attributes '{"tier":"frontier"}' \
     --gateway prod-gateway

2. 02

   Connect Amazon Bedrock

   On Bedrock, Fable is us.anthropic.claude-fable-5-1. Enter it with your AWS keys and region in the dashboard, tagged tier: frontier.

3. 03

   Pool them for failover

   Each call in a long run is routed on its own, so an Anthropic failure mid-run moves the next call to Bedrock.

   $ dome models pool create claude-fable-5-1 \
     --failover-max all --gateway prod-gateway
    
   $ dome models pool member add claude-fable-5-1 fable-51-anthropic --priority 0
   $ dome models pool member add claude-fable-5-1 fable-51-bedrock --priority 1

4. 04

   Point your agent at the Gateway

   The migration agent keeps the Anthropic SDK and swaps in the Gateway URL and its own Dome key.

   import anthropic
    
   client = anthropic.Anthropic(base_url=GATEWAY_URL, api_key=DOME_AGENT_KEY)
   client.messages.create(
       model="claude-fable-5-1",
       max_tokens=8192,
       messages=[{"role": "user", "content": "Plan the migration of this service."}],
   )

5. 05

   Cap the spend

   The pool cap covers everyone on Fable. The agent cap stops one runaway run without touching the rest.

   $ dome quotas set --subject pool --pool claude-fable-5-1 \
     --unit provider_usd --limit 1000 --window monthly
    
   $ dome quotas set --subject agent --agent migration-agent \
     --dimension llm --unit tokens --limit 20000000 --window daily

Commands and rules tested against a Dome workspace on October 1, 2026. For anything about Claude Fable itself, see Anthropic's documentation.

forbid (principal, action == Dome::Action::"llm:invoke", resource is Dome::LLMModel)
when { resource has tier && resource.tier == "frontier" }
unless {
  principal has act_as &&
  principal.act_as.groups.contains("frontier-pilot")
};