Definition

Completion traversal is the offering's identification of the next-active transition by walking the nested transition structure at every transition's completion.

The two governing rules

When the user completes a transition, the offering walks the structure to find what's next. Two rules govern the walk. First, if there's a sibling sub-transition remaining within the same containing transition, that's the next-active one. Second, if no sibling-next remains at the current level, walk up the parent stack until reaching a containing transition that still has a sibling-next available.

The output is which transition is now active. Selecting affordances for that transition is separate work — affordance matching — that runs after completion traversal lands.

Whether the siblings are sequence-ordered varies. Some critical routes have a forced order (cook side 1, then cook side 2); others have independent siblings the user can engage in any order. Either way, the rule is the same: take the sibling-next within the containing transition first; only walk up if none remains.

Walking up the parent stack

The walk-up can extend through multiple levels. If the just-completed sub-transition's containing transition is itself exhausted, traversal continues up — that containing transition is now also complete, so the walk keeps moving up the stack until it hits a containing transition with remaining work, or until it reaches the root and the user's overall pursuit is genuinely complete.

In practice, sibling-nexts happen more often than long walks up. Most completed sub-transitions sit inside containing transitions that still have work, so the walk usually terminates one step up.

Composition with affordance matching

Completion traversal and affordance matching compose at every transition's completion. Completion traversal identifies what's next; affordance matching surfaces affordances for it. The two are sequential but structurally distinct, and their failure modes differ: a completion-traversal failure produces a dead end (no continuation surfaced at all); an affordance-matching failure surfaces a continuation but with poorly-fit affordances for it.

Completion traversal also stops short of engaging the next transition. Once identified, engaging the next transition — descending into its sub-structure, instantiating its completion criteria, selecting affordances at its first sub-transition — is separate work that happens after completion traversal lands.

Dead-end failures

The characteristic failure mode is the offering completing a transition and going silent. The nested structure has a continuation available — sibling-next within the containing transition, or sibling-next further up the parent stack — and the offering doesn't surface it. The user reaches their sought state and nothing happens next.

A specific high-cost instance is "first payoff, then dead end." The first successful route is where the user is forming their confidence in the offering's continued usefulness, and a dead end at that point misses the surfacing opportunity precisely when the user's evidence base is most favorable.

Example

A user signs up for a project management tool and creates their first task. That sub-transition is now complete. Inside the containing transition "set up the team's workflow," sibling-nexts are available — create a project to group tasks, invite a teammate, set a due date. Completion traversal walks the structure and identifies one of these as the next-active sub-transition. If the product instead returns the user to an empty dashboard with no surfacing of what's next, that's a completion-traversal failure: the structure had continuation available and the offering went silent.

See also

• Reachability
• Route efficacy