Lanes & value types

Every wire carries a value. threadle distinguishes lanes (what kind of thing moves) and value types (what shape the text has).

Lanes

A lane is the color-coded category of an edge. It is derived from the node types at each end — you never set it by hand.

Lane	Carries	Typical wiring
text	A string	prompt → agent, agent → output, anything → knot
session	A reference to a real session	agent → session, session → context
context	A context payload	session → context, context → agent

Most of a workflow lives on the text lane. The session lane is what makes an agent continue a conversation instead of starting a new one; the context lane is how a distilled brief travels from one tool to another.

Value types

Within the text lane, a node may declare what kind of text it emits or expects:

Type	Accepts
`text`	Anything (the default)
`int`	`-12`, `0`, `42`
`float`	Any finite number
`bool`	`true`, `false`, `1`, `0`
`json`	Anything `JSON.parse` accepts

Who declares them:

Prompt nodes have a type selector — a prompt can be a typed primitive, not just prose.
Custom nodes declare input/output (or per-port types) in node.json.

Compatibility rules

A connection is allowed when the source’s type fits the target’s:

identical types always fit
anything fits text
int widens to float
everything else is refused

The check runs while you drag — an incompatible wire simply won’t attach, so you find out at design time.

Validation happens twice

Design-time refusal isn’t enough, because a node can lie about what it produces. So values are checked again at run time:

inbound text is validated against the target’s declared input type
a custom node’s stdout is validated against its declared output type

A node that declares int output and prints a paragraph fails loudly, with the offending text in the error, instead of poisoning every node downstream.

head-tail: output "count" declares int but not an int: "about twelve"

Multiple wires into one input

When several wires land on the same input, their texts are joined with blank lines before the node sees them — but only if that handle still has capacity. A full slot refuses another wire while you drag (same as a type mismatch). Built-ins like Delay are one-in / one-out; a ⋈ Knot is the intentional multi-in merge. Custom named ports default to one wire; raise maxConnections for fan-in.

For named ports, joining happens per port, so each port sees only its own wires.

Graph & wires — the execution model
Knot — explicit fan-in
Params & named ports — typed ports on custom nodes