Blocks read earlier results through references. A connection determines when a block runs; a reference determines which value it reads.
Classify reads <start.input>. Reply reads <classify.content> after Classify finishes.
What an output is
Sim stores each block's result for the run. An output usually contains several named values; <classify.content> reads the content field from the block named Classify.
Different blocks produce different fields. An API returns its successful response body under data; a Function returns its value under result; a Table query returns rows and rowCount.
How a block references an output
Insert a connection tag into a supported input field, such as an Agent message or API request body. Type < to browse available references, or drag an output into the field.
A referenced output must exist when the receiving block runs. A connection from the source ensures that dependency; when several sources feed one block, it waits for their active paths. A block on an unselected branch produces no output.
For a known block that did not run, references resolve empty: usually an empty string, or null in Function code. An unknown name can remain unsubstituted, while an invalid field can fail resolution. Inspect the source output rather than assuming every reference failure has the same result.
See connection syntax for name normalization, nested fields, and arrays.
Data types
The output panel shows each value's type:
Files appear as metadata objects, including their name and URL. Table row cells are nested under each row's data. Check the actual output before choosing a path.
Use a Function block to reshape or convert a value, then reference its result downstream. Text fields stringify objects; Function code can use the referenced value as its original type.
Choose the workflow result
Block output and workflow output are different. A simple chain returns its last block's output. With several terminal branches, the last terminal block to finish supplies the default result, so its identity can vary between runs.
Join branches into one final block or add a Response block when a caller needs a deliberate result. Chat deployments and table workflow columns select the fields they consume. API selectedOutputs projects block values separately from the default result; synchronous v2 calls expose that projection in data.blockOutputs.
The v2 API returns the workflow result in data.output. A Response block does not replace that API's HTTP status, headers, or envelope.