The continuation entry must be findable on the target device
Aliases: Handoff icon · Continue on PC · continuation affordance · lock-screen suggestion
What it is
The state may already be ready to hand over, yet the target device shows no surface that means “pick this up.” People will not guess the leftmost Dock slot, a lock-screen suggestion, or a hidden command. Continuation-affordance discoverability is the requirement that the resume action appear on the device about to be used, in that device’s habitual launch places. Windows “Continue on PC” can send the phone’s current page to a computer; if the only cue lives in a phone notification and the desktop has no counterpart, the person who just sat down still has nothing to click. A buried entry is a continuation that never happened. This is not about what the state payload contains, and not about whether a failure names its cause.
Why it happens
A device switch resets attention. By the time someone reaches the target, the source screen is gone; a “sent to your PC” banner on the phone cannot help. Launch habits are stable: Mac users look at the Dock and Spotlight, iPad users at the shelf and the app switcher, Windows users at the taskbar and Start. The continuation entry has to occupy one of those existing slots to be read as the next thing to do. Burying it in settings, or celebrating success only on the source, demands a new search strategy—and the continuation window is often a few seconds, pocket to desk. Unstable placement (Dock one day, notification center the next) prevents learning “where to look,” so the next time people just reopen the app from scratch.
Studying it
Treat full state as already present on the target and manipulate only where and when the entry appears. Have people work halfway on device A, walk to device B, and continue without being told where to click.
Independent variables: surface (system dock, lock-screen suggestion, in-app menu, source-only toast), delay before the entry appears, overlap with that device’s habitual launch places. Dependent variables: time to first successful resume, rate of giving up or relaunching the app, ability to point to the entry afterwards.
Circling the control in the lab inflates findability. Closer to use: say only “continue that thing on the computer,” with no brand name or icon location. Diaries should code “I didn’t know I could continue” separately from “I knew but couldn’t get it to work”—the first is an entry problem, the second may be an unexplained failure.
Where it stops holding
People who switch daily between two fixed devices with an unchanged location for months build muscle memory; findability pressure drops. Managed PCs that lock Start and the taskbar may strip the system slot, leaving an in-app “open on another device” as the only surface. On a shared or public machine, a highly visible entry can leak someone else’s in-progress task to the next person. When source and target are far apart and continuation is not expected (office PC and home tablet), omitting the entry is reasonable; forcing a suggestion becomes noise.
Applying it
- Place the resume control in the target’s habitual launch slot: an end of the dock or taskbar, a system suggestion on the lock or desktop—not a one-shot banner on the source.
- Show the app icon and a short status (which mail, which article) so the person knows what will resume before clicking.
- Do not bury the same product’s entry at wildly different depths across systems; the surface can follow the platform, the depth should stay comparable.
- Verify by handing the target device to someone who has never heard of the feature, saying only “continue the phone thing on this computer.” Record whether they find the entry in two minutes and which surfaces they visit; move the control rather than adding explanatory copy.