Gutter Navigation

The central problem Navigator solves is the one the bus creates: a producer and its consumers never reference each other directly in the source. Trigger(LoginRequested) in an auth coordinator and ReactTo<LoginRequested> { … } in a navigation coordinator are joined only by the type they share, and the IDE’s standard Ctrl+Click lands on the class declaration, not on the other call site.

Gutter icons close that gap. Every SynapseLib call site gets a clickable marker in the editor gutter; clicking it opens a popup listing every connected counterpart (plus any interceptors affecting the call), and each entry in the popup jumps directly to its source.

The icons

Icons appear at every producer, consumer, and provider call site on every channel. Each icon’s popup lists the counterparts that share its type argument. The same glyphs you see in the editor gutter are reused in the tool window and in Mermaid exports, so a quick visual scan tells you which channel you’re looking at without reading the label.

Channel	Producer	Consumer / handler
State	Broadcast<T>	ListenFor<T>
Reaction	Trigger<A>	ReactTo<A>
Request	Request<Impulse, N>	@SynapseProvider class

A seventh glyph — — marks every Intercept<T>(…) registration, regardless of which channel it’s bound to.

Clicking a Broadcast<UserLoggedIn> icon shows every ListenFor<UserLoggedIn> in the project — whether it lives in a coordinator, a Node, or a provider. Clicking a ReactTo<LoginRequested> shows every Trigger that fires the impulse. Clicking a Request<FetchProduct, Product> jumps straight to the one @SynapseProvider class that handles it.

Supertype matching follows the same rules as the bus: a consumer registered for a marker interface shows up on every subtype’s gutter popup, and vice versa. This is how the TokenBearer and AnalyticsEvent patterns stay navigable — one consumer, many concrete producers, all cross-linked automatically.

Interceptor markers

Intercept<T>(…) call sites get their own gutter icon. The popup shows which producer and consumer call sites the interceptor is visible to, tagged with:

• Direction — whether the interceptor sits at the upstream or downstream point of its channel.
• Priority — the Int priority the interceptor was registered with, so you can see at a glance whether it’s before or after other interceptors on the same point.

For a Broadcast<T> or Trigger<T> site, the producer’s gutter popup also lists every interceptor whose type matches — including supertype matches — so you can see every piece of middleware that will see the value without jumping tabs.

Type declaration markers

A separate marker appears next to the declaration of any data class, sealed hierarchy, or interface that’s used as a Synapse channel type. It summarizes every hook on that type in a single popup:

BuyProduct            (Impulse)
  Triggers            3 (CartScreen, ProductRow, QuickBuySheet)
  ReactTo             1 (CartCoordinator)
  Interceptors        2 (TokenBearer upstream, Analytics upstream)

This is the view you want when you’re deciding whether to rename an impulse, change its fields, or break it into variants — you see every site that participates in the type’s traffic without having to grep.

Popup navigation

All the popups share the same shape: a grouped list of targets, each one a clickable entry that takes you to the source location on click. The groupings — “Listeners”, “Reactors”, “Providers”, “Interceptors (upstream)”, “Interceptors (downstream)” — are consistent across every icon, so the visual scan becomes routine very quickly.

When a call has no counterparts, the gutter icon still appears but renders in a muted style and its popup shows the unconnected status — the same condition the inspection surfaces as a warning, covered on the Inspections page.

Next

• Tool Window — the project-wide topology view