What does it mean that workflow composition?

Complex workflows are built by combining simpler workflows. The output of one becomes the input of another. Composition is the mechanism that turns a library of small, proven workflows into an infrastructure that handles arbitrarily complex work.

Example: You need to publish a blog post. Instead of running one massive, undifferentiated process called 'publish a blog post,' you chain five independent workflows: a research workflow that produces structured notes, an outlining workflow that accepts notes and produces a hierarchical structure, a drafting workflow that accepts an outline and produces a rough manuscript, an editing workflow that accepts a rough manuscript and produces a polished document, and a publishing workflow that accepts a polished document and produces a live page. Each workflow exists independently in your library. Each has been tested and refined on its own. The publishing pipeline is not a single complex workflow — it is a composition of five simple ones, and you can swap any one of them without touching the others.

Try this: Choose one complex process you perform regularly — something that takes more than an hour and involves multiple distinct phases. Decompose it into the smallest independent workflows you can identify. For each sub-workflow, write its input specification and its output specification. Then verify the chain: does the output of workflow A match the input specification of workflow B? Does the output of workflow B match the input specification of workflow C? Where there is a mismatch — where you have to mentally translate or manually reformat between stages — you have found a composition seam that needs repair. Fix the specifications so the chain flows without manual intervention at the boundaries.