Statement
P09 Time and continuity are part of the interface
The person experiences the wait before they know anything about our architecture.
Tension
Explanation
Slowness changes behavior: it causes repeated clicks, doubt, and abandonment. Losing progress forces people to reconstruct context and destroys trust very quickly.
Go deeper: Tension
Slowness changes behavior: it produces repeated clicks, hesitation, abandonment and errors. Loss of continuity forces people to rebuild context and destroys trust quickly.
Meaning
Explanation
Latency, availability, and preservation of work are properties of the experience. The person using the product does not distinguish between infrastructure and interface when something takes time or is lost.
Go deeper: Meaning
Latency, availability, synchronization and preservation of work are properties of the experience. The user does not distinguish between infrastructure and interface when a response is slow, an action is duplicated or progress is lost.
Consequence
Explanation
Critical interactions have explicit response budgets. If an operation may take time, honest progress is shown, and work is saved at a frequency proportional to the cost of losing it.
Go deeper: Consequence
Define response budgets for critical interactions.
Show honest progress and allow work to continue when an operation may take time.
Save work, context and state at a frequency proportionate to the cost of losing them.
Example
The content of this site arrives as text before any script runs; if a script fails, reading continues.
Counterexample
Blocking reading until an animation finishes or fonts and heavy resources are downloaded.
Sign of non-compliance. A button with no feedback for three seconds invites a second press. The resulting duplication looks like user error, but it originates in the system.
Decision test
These questions treat time and continuity as part of what is delivered.
Does the interface respond immediately even though the underlying process continues?
What does the person lose if the connection fails right now?
Does the product avoid duplicate actions and ambiguous states?
Source
Manifesto core v2.1, section PRINCIPLE 9 · P09. Download the core