Lanes & value types
Every wire carries a value. threadle distinguishes lanes (what kind of thing moves) and value types (what shape the text has).
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 → merge |
| 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
Section titled “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.
- ◇ Data nodes hold a typed value on the card, or coerce an inbound wire to that type at run time.
- Custom nodes declare
input/output(or per-port types) innode.json. - Output is 1-in / multi-out on the text lane (fan-out after a result).
Compatibility rules
Section titled “Compatibility rules”A connection is allowed when the source’s type fits the target’s:
- identical types always fit
- anything fits
text intwidens tofloat- 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
Section titled “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
Section titled “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 and ◇ Data are one-in / one-out. ⇤ Output allows fan-out. A ⋈ Merge 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.
Related
Section titled “Related”- Graph & wires. The execution model
- Merging. Explicit fan-in
- Params & named ports. Typed ports on custom nodes