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Limits and roadmap ​

What it cannot do ​

  • Generators and suspending await under the original engine, EngineAowl (the interpreter is a tree walker). The newer default engine, EngineAowlJs, does not share this limit — its Promise/async/await is real — but has not yet been measured against the WPT standing tracked on the Web Platform Tests page, which still reflects EngineAowl.
  • WASM support (not ported).
  • Worker threading. The architecture is decided — process-per-Worker, using the sandboxed-child-process mechanism now proven for isolated JS/DOM execution — but the Worker interface itself is not built yet.
  • WebAudio.
  • Full Canvas rasterization: EngineAowlJs tracks canvas state (transform, styles, path construction) but does not paint pixels.
  • SVG path-data parsing: SVG DOM geometry and attributes are bound, but the d attribute's path-data grammar is not parsed.
  • MediaSource/EME DRM. This is a permanent, deliberate exclusion, not a todo — see below.
  • Multi-node-selection editing (contentEditable/execCommand cover single-range bold/italic/insertText, not arbitrary multi-node selections).
  • Some deep CSS edge cases remain on the original engine's known list: :focus-visible, dir=auto, named-item access.
  • UTF-16 offsets in CharacterData methods for non-BMP text.
  • A native HTTP/TLS stack: fetch() under EngineAowlJs does real network I/O, but by shelling out to curl.exe, not a client built into the mod.
  • Speed comparable to a JIT browser: EngineAowlJs has a JIT tier, but it is currently disabled for this embedding after a real x86-64 codegen bug was found (functions crossing a 64-call hotness threshold were miscompiled, corrupting memory). Reported upstream; EngineAowlJs runs interpreter-only until it's fixed.

DRM: a permanent exclusion, not a gap ​

Titicaca will not integrate Google's proprietary Widevine CDM, in any form — not extracted from Chrome, not via the openwv shim, not via a clean-room reimplementation — for licensing and DMCA reasons. This means DRM-protected video will not play, including actual YouTube video playback, even on pages (like youtube.com itself) that otherwise load and run their scripts correctly under EngineAowlJs. Clearkey-only EME, i.e. non-DRM test content, already works through the existing MSE/FFmpeg pipeline and is unaffected by this exclusion.

Levers, biggest first ​

  1. Re-run the WPT standing against EngineAowlJs. The tracked score on the Web Platform Tests page still reflects the original engine; the new default engine has real async/await and a substantial DOM/CSS/Events/Shadow-DOM surface but has not been scored the same way yet.
  2. Fix the JIT codegen bug so EngineAowlJs can run with its optimizing tier enabled instead of interpreter-only.
  3. Binding shape. A large share of remaining failures are interface-conformance tests for objects that exist but lack members, or exist without an exposed interface (Navigator, History, Storage, Location).
  4. Request and Response, currently the weakest part of URL-adjacent tests, and a real HTTP/TLS client to replace the curl.exe shell-out.
  5. Worker threading, building the Worker interface on the already-proven sandboxed-process mechanism.
  6. Cross-realm constructors, for example DOMParser reached through a frame.
  7. Selectors long tail, as above.

What we will not do ​

We will not stub interfaces for features that do not exist just to raise a number. Feature detection on real pages would then lie.

Where the numbers come from ​

Every claim on this page is checked against the Web Platform Tests. Gaps are ranked by comparing our per-file pass counts with a reference browser's, not by guessing.