v0.1.1127 Aug 2026·DevTools

DevTools Debugger: real `debugger;` breakpoints at the VM

The DevTools protocol grows a Debugger domain. Until now the engine's CDP subset could inspect and drive the page (Runtime, DOM, CSS, accessibility) but had no debugger at all. It now has a real one for the breakpoint that needs no source-line bookkeeping: the `debugger;` statement. When the domain is enabled, hitting a `debugger;` captures the actual pause state from the running engine - the current function name and the live scope chain, every local and block variable with its real value at that instant - reachable through the CDP Debugger methods and a small native bridge. It is an honest slice: there is still no WebSocket event transport (a pause is polled, not pushed), no line-number breakpoints (that needs source-to-bytecode mapping) and no stepping - but the pause it reports is real VM state, not a mock, and `debugger;` is now a zero-cost no-op when the domain is off. DevTools moves 20 to 22; overall holds at 51 (the full debugger floor - transport, line breakpoints, stepping - is not yet done).

Parity with the reference browser

74overall, as of v0.1.343

Web APIs / DOM surface42

Security architecture66

GPU / graphics acceleration68

DevTools / extensions72

Networking85

Media85

Accessibility85

Real-world site compatibility99

HTML parsing100

CSS parsing + selectors100

Layout: block / flex / grid / tables / writing-modes100

Paint + visual100

JavaScript language100

JavaScript performance (JIT)100

HTML parsing100

What changed 3 changes

DevTools	A real `debugger;` breakpoint: the statement is now parsed and compiled to a VM instruction that, when the Debugger domain is enabled, captures the current call frame name and the live scope chain (each Env frame up to the function boundary) with every variable's actual value at the pause - deterministic (scope keys sorted). Bare `debugger` only: `debugger.x` / `{debugger: 1}` stay ordinary identifiers, and `debugger;` is a zero-cost no-op when the domain is off.
DevTools	Exposed two ways: the CDP `Debugger.enable` / `Debugger.disable` / `Debugger.resume` / `Debugger.getPausedState` methods (a polled paused-state subset, since there is no WebSocket event transport yet), and a `__debug_*` native bridge (enable, paused, hits, resume) the tests and tooling drive directly.
DevTools	Honest scope: DevTools 20 -> 22 for a real Debugger-domain slice, but overall HOLDS at 51 because the full named floor is not done - no WebSocket CDP transport, no source-line breakpoints (needs a line-to-bytecode map), no single-stepping. 5 property tests (frame + scope capture, disabled no-op, resume, hit counting, property-name safety, CDP parity), conformance gate 6375/6375 with native-JIT and no-nanbox green.