#Providers

A3S Code reads runtime configuration from ACL. A config source can be an .acl file path or an inline ACL string. JSON and legacy HCL configs are not part of the current config surface.

#Basic Shape

default_model = "provider/model-id"
max_parallel_tasks = 4
auto_parallel = false

providers "provider" {
  apiKey = env("PROVIDER_API_KEY")
  baseUrl = env("PROVIDER_BASE_URL")

  models "model-id" {
    name = "Human readable model name"
    tool_call = true
    limit = {
      context = 128000
      output = 4096
    }
  }
}

storage_backend = "file"
sessions_dir = ".a3s/sessions"

apiKey and api_key are accepted aliases. baseUrl and base_url are accepted aliases. Commit templates and non-secret defaults only; keep real API keys, private endpoints, and account-specific model names in the environment or in a secret manager.

#Provider Families

The built-in factory covers three paths:

The runtime does not hard-code model names. default_model and per-session model values are identifiers in the provider/model-id form that must match the provider blocks you define.

#Delegation Controls

agent_dirs = ["./.a3s/agents"]

auto_delegation {
  enabled                 = true
  auto_parallel           = false
  allow_manual_delegation = true
  min_confidence          = 0.72
  max_tasks               = 4
}

max_parallel_tasks limits bounded sibling fan-out. auto_delegation.enabled turns on automatic subagent delegation. The top-level auto_parallel = false overrides auto_delegation.auto_parallel and disables only automatic parallel child-agent fan-out; manual task and parallel_task remain available. When allow_manual_delegation = false, both model-visible child-agent tools are removed from the session tool surface.

#Storage

storage_backend = "memory"
storage_backend = "file"
sessions_dir = ".a3s/sessions"

Use memory storage for short-lived tests. Use storage_backend = "file" plus sessions_dir for resumable local sessions loaded from ACL. storage_url is parsed for custom storage metadata, but it does not create a file-backed session store by itself. SDK hosts can always pass sessionStore: new FileSessionStore(...) / opts.session_store = FileSessionStore(...) directly.

#Private Provider Checks

Real-provider smoke tests should point at a local, git-ignored ACL file through A3S_CONFIG_FILE. Do not copy provider values into commands, logs, docs, pull requests, or committed fixtures.

A3S_CONFIG_FILE=/path/to/local/config.acl \
  scripts/real_config_env_integration.sh

SDK parity is covered by a separate real-provider check:

A3S_CONFIG_FILE=/path/to/local/config.acl \
  scripts/sdk_real_config_env_integration.sh

Keep the provider evidence with the release or CI artifact, not in the public documentation. For the complete local API surface, see API Contract.