The Trace Model

The Trace model

The unit of implementation is the Trace, a tracer-bullet work unit (The Pragmatic Programmer, AI Hero). A Trace claims one user story and a declared subset of its Gherkin scenarios: its Scenario Claim. It implements that claim through every layer in one pass. Each Trace leaves the system in a releasable state.

Skeleton, Spine, and later Traces

The first Trace of a Feature is the Skeleton: the happy path of the primary story, minimal, through every layer, at production quality. Each later Trace extends the Spine.

• An Extension Trace adds the next story.
• A Deepening Trace claims more scenarios of a story that already started.

The Scenario Claims of a story cover all its scenarios, with no overlap.

The Feature is canonical

The Feature body is the canonical source for all stories and their Gherkin. A Trace claims scenarios and never re-derives them.

The Trace Plan on the Feature is an aim, not a contract. After each Trace lands, wtf.refine re-aims the plan. An autonomous re-aim changes only the order. It can reorder entries, re-batch them, and move scenarios between them. A human approves each change to the set of scenarios that the plan delivers.

One stack per Feature

Each Feature delivers through one linear stack of Trace PRs. Each Trace starts its branch from the top of the stack. Thus no Trace waits for a merge. Traces that share no files build at the same time. Then they join the stack one after the other. See Delivery and stacks.

Domain-Driven Design

DDD is the foundation of WTF, not an add-on. Each issue, scenario, and PR uses the ubiquitous language of the project. The skills apply ddd-writing-rules.md each time they write. Actors are domain roles, never a generic "user" or "admin". Gherkin scenarios use the vocabulary from the VISION doc. Thus product, design, engineering, and QA share one model of the system.

As a result, the specs stay clear when the project grows. Agents write code against stable terms, not against synonyms that drift. A new contributor learns the domain, not a set of nicknames.

WTF uses the same discipline for its own terms. CONTEXT.md defines them: Trace, Skeleton, Extension Trace, Deepening Trace, Spine, Spine Position, Scenario Claim, and Re-aim.