Module flow 

Information-flow admission gate + tool-label loading (EPIC A / A3+A4).

car_verify::check_information_flow is a verified static check for data exfiltration and forbidden tool orderings, but it was never called by the runtime, and it needs per-tool labels (capability, confidentiality, trust, sink) that nothing produced. This module supplies both halves:

• A3 — labels: a built-in default label table for CAR’s commodity tools, plus a .car/tool-labels.json loader so a project can declare which tools are sinks, which produce confidential data, and what tool orderings are forbidden.
• A4 — the gate: InformationFlowGate, an crate::admission::AdmissionGate that runs check_information_flow → gate_flow on every admitted proposal, blocking exfiltration and escalating forbidden orderings to approval (which fails closed until A7 wires the approval transport).

Structs

FlowLoadError

Error raised while loading .car/tool-labels.json.

InformationFlowGate

An AdmissionGate that enforces information-flow safety: confidential data must not reach an exfiltration sink, and forbidden tool orderings are escalated to human approval.

ToolLabelConfig

The deserialized .car/tool-labels.json document: per-tool labels plus the flow policy (what counts as a hazard) and the gate policy (what to do about each hazard class). Every field defaults, so a partial file is valid.

Constants

NET_SEND

The capability that marks a tool as reaching the network.

Functions

builtin_tool_labels

Default information-flow labels for CAR’s built-in commodity tools.

load_tool_labels

Load tool labels for a project, merging .car/tool-labels.json with the built-in defaults.

tool_output_is_external

Whether a tool’s output should be treated as coming from outside the trust boundary (car#723).