COLLECTION

Omoikane

2026.10.10

After implementing Omoikane’s DOM and exception notifications, we ended up investigating copying and garbage‑collection lifetimes as well.

This article provides a detailed overview of the DOM manipulation, HTML parsing, sanitizer, and exception/Promise‑rejection notifications added in Omoikane’s PR #1322. It traces the garbage‑collection lifetime issue that arose in Boa’s Promise.finally, examines iframe navigation and document ownership, discusses copy reduction, local measurements and the final CI run, and outlines the remaining challenges.

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2026.10.08

WeakMap and Generational Garbage Collection

This article explains the issue that occurred in the Rust‑based JavaScript engine Boa, where references via ephemerons were incorrectly reclaimed by the generational garbage collector. It covers the conditions for retaining WeakMap values, the calculation of fixed points, the recording of writes from older parents to younger children, the reasons references were lost after a major GC, and the regression tests that tracked the problem.

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2026.09.30

The object returned by Boa’s getter was collected by the garbage collector while the inline cache was being updated.

Investigating the SIGSEGV that occurred in Omoikane’s WPT revealed that the new object returned by Boa’s getter in the Rust‑based JavaScript engine was being reclaimed during the inline‑cache update before it could be placed in a VM register. We are isolating the issue with the JIT, verifying it with Valgrind, and tracking the root fix along with regression tests.

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2026.09.29

Since generating realms with Omoikane was slow, I looked into Boa’s scope lookup and lexical analysis.

Each time we created a JavaScript realm with Omoikane, it parsed and compiled a roughly 1.1 MB DOM bootstrap. I’ll document how we shifted from a caching approach to improving Boa’s scope lookup and lexical analysis in the Rust‑based JavaScript engine, along with the actual measurements from the test profile.

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2026.09.29

As AI-driven development progressed, the 30‑minute CI wait became increasingly burdensome, so I revisited the validation of Omoikane.

While the amount of work keeps growing with AI‑based development, the Rust‑based Omoikane’s CI suffers from long wait times for each pull request. This is a record of re‑examining document‑change detection, Rust caching, WPT setup, and sequential pushes based on actual measurements.

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2026.09.27

Tracing with Omoikane how a URL fragment becomes the CSS :target

Which element a URL’s #fragment points to, and how that influences the CSS :target selector and the results of querySelector. Using the HTML and Selectors specifications as guides, we follow Omoikane’s implementation and tests.

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2026.09.26

Fixed the origin‑boundary bypass that was present in the internal host function of Omoikane.

We identified pathways from the internal host function visible on the Omoikane page that could reach DOM, cookies, or storage of a different origin. This covers bootstrap isolation, origin verification on the Rust side, and related processing and testing.

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2026.09.25

JavaScript Realms as Seen Through Omoikane’s iframe Implementation

What aspects of an iframe are isolated by a JavaScript Realm? This outlines the boundaries that became apparent while implementing the child Document’s execution environment, WindowProxy, navigation, and asynchronous processing in Omoikane.

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2026.09.25

A SIGSEGV occurred after garbage collection because the iterator function passed to Boa’s Array.from was not properly retained.

We investigated a garbage‑collection reference‑retention bug in Boa, the Rust‑based JavaScript engine, that was discovered in Omoikane’s Acid3 test. This covers the lifetime of the temporary iterator function obtained by Array.from, the reproduction test, and the fix along with its verification results.

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2026.09.23

I advanced browser compatibility for cookies and scrolling in Omoikane.

In my custom browser Omoikane, I implemented features such as integration between document.cookie and HTTP communication, the Page Visibility API, event listeners, and CSS Scroll Snap. I summarized the process of connecting these APIs to the DOM, network, and the host’s state.

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