## MODIFIED Requirements

### Requirement: Pluggable dual-provider tool-calling abstraction
The system SHALL support at least two interchangeable LLM providers
(Anthropic native tool use and OpenAI function calling) for the AI
Planner's decision calls, selectable via configuration, with both providers
constrained to return exactly one tool call per request. Independently of
provider selection, the system SHALL support at least two transports for
making that decision call -- direct-to-provider (the tool-calling client
calls the provider's SDK itself, using locally configured credentials) and
cloud-proxy (the tool-calling client calls the Cloud Control Plane's
planner-decision endpoint, which calls the provider using cloud-held
credentials) -- selectable via configuration without requiring any change
to `AIPlanner`'s own decision logic.

#### Scenario: Provider selected via configuration
- **WHEN** the AI Planner is configured with a given provider identifier
- **THEN** it constructs and uses the tool-calling client for that provider
  without requiring any change to `AIPlanner`'s own decision logic

#### Scenario: Provider response resolves to a single decision
- **WHEN** either supported provider returns a response to a tool-calling
  request
- **THEN** the response is parsed into exactly one tool name and one
  arguments object, regardless of which provider produced it

#### Scenario: Transport selected via configuration
- **WHEN** the Host Agent is configured with a given transport (direct or
  cloud-proxy)
- **THEN** `AIPlanner` is constructed with the tool-calling client for that
  transport, and its own decision logic is unchanged regardless of which
  transport is in effect

#### Scenario: Cloud-proxy transport is the default
- **WHEN** no transport is explicitly configured
- **THEN** the AI Planner uses the cloud-proxy transport and the Cloud
  Control Plane's planner-decision endpoint

#### Scenario: Direct transport remains available by explicit configuration
- **WHEN** the Host Agent is configured with the direct transport
- **THEN** the AI Planner uses the direct-to-provider transport with locally
  configured credentials

#### Scenario: Cloud-proxy transport resolves a decision without a local provider client
- **WHEN** the Host Agent is configured with the cloud-proxy transport
- **THEN** its tool-calling client sends the decision request to the Cloud
  Control Plane's planner-decision endpoint instead of constructing a local
  Anthropic or OpenAI SDK client