Blast Radius

Blast Radius answers a practical question: if I change this service, what else should I check?

It starts at the service you select, then follows the lines connected to it. The result is based on your map, not live traffic or production monitoring.

The rule: Blast Radius follows connected map topology

Every line has a start and an end, stored as source → target.

For example:

Web app → API → Payments

If API is selected:

• Web app is incoming, also called upstream.
• Payments is outgoing, also called downstream.
• Blast Radius shows both sides in the same color. Incoming and outgoing are labels that help you read the arrows, not separate modes or colors.

The meaning of an arrow depends on your map. In a request map, upstream is often a caller and downstream is often a dependency. In an event map, upstream may be the producer and downstream the consumer.

The walk stops at the depth you choose, when there are no more connected lines, or at a boundary that you set.

A concrete map

In this example, the arrows describe request and data flow:

Browser → Web app ─┐
                    ├→ API gateway → Auth
Mobile app ─────────┘              └→ Payments → Postgres
                                             └→ Queue

Select API gateway in the example below:

• Direct services: Web app, Mobile app, Payments, and Auth.
• Transitive services: Browser, Postgres, and Queue.
• Affected services: every service reached within the selected depth.

Use the controls in the example to change the depth or add a boundary. Click a different node to see its connected services.

How to use Blast Radius

1. Open a map. Press B, choose Blast radius in the left toolbar, or press ⌘K and search for Toggle Blast Radius. On Windows and Linux, use Ctrl K.
2. Click the service you are about to change. This becomes the focus.
3. Start with All to see the full connected map. Use 1 hop or 2 hops for a smaller review.
4. Follow the orange lines. Strong lines are close to the focus. Softer lines are farther away.
5. Open Review services to see a compact list of affected services and their hop count. Use Block here or Allow past on a row to control that branch.
6. Use Block here when the highlight should stop at a service.
7. Use Fit impact if part of the result is off screen.
8. Use Pin focus if you want to edit another node or line without changing the focus.

Press B, click the left toolbar button, or choose Toggle Blast Radius from ⌘K again to exit.

Blast Radius is a temporary view. It does not save the focus, depth, color, boundaries, or pin state into the map.

What the controls mean

Color and distance

Blast Radius uses one color for the whole review:

• Orange is the default.
• Direct connections use the strongest color.
• Farther connections become softer, but stay visible.
• Lines outside the result stay muted and are not part of the impact count.
• Flow dots pause in Blast Radius so the impact path stays still while you review it.

Use the color swatch or picker in the panel to choose another accent. The same color is used for the focus, nodes, and highlighted lines.

The four node handles are only connection positions. They do not create four Blast Radius directions.

Depth

Depth is the number of lines Canopy may follow from the focus. It is not zoom:

• 1 hop: show only services directly connected to the focus.
• 2 hops: include one more layer.
• All: continue until there are no more reachable services or a boundary.

Boundaries

Use Block here when the highlight should stop at a service. This is useful when the next system is outside the part of the map you are reviewing, such as:

• another team's service;
• a queue or webhook reviewed separately;
• a shared platform service;
• a database or vendor boundary.

The boundary service stays highlighted. The lines after it stay visible in gray, but they are not counted or highlighted. Choose Allow past to remove the boundary. Use Clear to remove all boundaries.

Pin focus

Pinning keeps the current focus while you work on the map:

• Clicking another node opens it in the editor without changing the focus.
• Clicking a line still lets you change its style, label, arrows, or delete it.
• Review services and Fit impact continue to work.

Turn off Pin focus when you want to choose a new focus from the canvas.

Important edge-direction details

An invisible arrow still has a direction

Even when an edge has no visible arrowhead, it still has a stored start and end. Blast Radius can follow it from either endpoint, but other readers cannot tell the intended direction. Add an arrowhead when direction matters.

Two arrowheads do not create two edges

Choosing Both draws arrowheads at both ends, but it still creates one edge. For a real two-way relationship, create two edges:

service-a → service-b
service-b → service-a

This makes the relationship explicit in the map and in exports.

Labels explain the relationship

Use a label such as REST, webhook, reads, publishes, or owns to explain why a line exists. Labels do not change the result, but they make it easier to understand.

Reading the result in a real change review

Suppose you are changing Payments in the example:

• Direct impact includes API gateway, Postgres, and Queue.
• Transitive impact includes Web app, Mobile app, Browser, and Auth.
• The full result includes every service reached within the selected depth.

That gives you a practical review order:

1. Check direct neighbors first. They are closest to the change.
2. Check transitive services next. They may need tests or rollout coordination.
3. Open the affected-service list and confirm that the result matches the change you are planning.

What Blast Radius does not know

Blast Radius only knows what is represented in the map. It does not know:

• live request volume, latency, errors, or uptime;
• whether an edge is synchronous or asynchronous unless you label it;
• ownership, permissions, or team boundaries;
• whether two arrowheads should be treated as two graph paths;
• hidden dependencies that are not represented by edges.

For a useful result, add important handoffs as edges, keep their directions current, and label ambiguous connections.

Troubleshooting

Nothing is highlighted

The focus may have no connected lines, or the lines may be outside the selected depth. Try All, then check the lines connected to the focus.

The result is too large

Switch to 1 hop or 2 hops for a smaller review. Return to All when you want the full connected result.

A service appears on the wrong side

Blast Radius follows the stored start and end of each line. If a service appears on the wrong side, edit the line's direction or add the correct arrowhead. Changing the line shape does not change the relationship.

I need to edit while reviewing

Turn on Pin focus, then select the node or line. The bottom editing controls and right inspector remain available while the focus stays fixed.