Recap

In the previous chapters, we explored:

Scheduler internals

Memory and graph management

Priority and layered scheduling

Time-slicing and cooperative scheduling

All of these mechanisms are essential for making a reactivity system work correctly internally.

But internal correctness alone is not enough.

For developers, the more important question is:

How do we observe, debug, and understand the system?

That is where DevTools and diagnostics become critical.

Inspecting Nodes

Why do we need inspect() ?

One of the most common debugging needs during development is:

“What is the current value of this signal or computed?”

If the only solution is console.log , debugging quickly becomes inconvenient and intrusive.

A proper inspection layer gives developers visibility without polluting application logic.

Feature Design

The inspector should provide:

Current value

Dependency relationships ( deps / subs )

Whether the node is:

stale

disposed

Implementation

// devtools.ts // type reused from…