AW5 — Audit subsystem invariants, ownership boundaries, and shortcut-free architecture

[joris97jansen]

Description

Perform a final architecture audit across all static engine subsystems.

This issue should verify that the work from AD through AV still respects Borrowser’s core principle: no shortcuts, no ad-hoc cross-subsystem ownership leaks, and browser-engine-shaped internals.

The goal is to catch architectural drift before release.

Requirements

• Audit CSS ownership:

  • property semantics;

  • selector/cascade/computed values;

  • invalidation impact.

• Audit HTML ownership:

  • parser/tokenizer/tree construction;

  • parser-created DOM;

  • form semantics.

• Audit Layout ownership:

  • geometry;

  • formatting contexts;

  • intrinsic sizing;

  • advanced layout algorithms;

  • fragments.

• Audit Paint/GFX ownership:

  • paint primitives;

  • visual effects;

  • paint ordering;

  • semantic visual output.

• Audit Browser/runtime ownership:

  • retained render state;

  • dirty state;

  • work planning;

  • environment state;

  • lifecycle orchestration.

• Audit Networking/storage ownership:

  • fetch/cache/cookie/storage boundaries;

  • hardening limits.

• Audit Accessibility ownership:

  • accessibility tree;

  • semantic mapping;

  • name/state/value computation.

• Audit Compositor ownership:

  • display lists;

  • damage;

  • compositor tree;

  • raster/presentation planning.

• Verify no subsystem parses raw CSS or HTML semantics outside its owner.

• Verify frame-local IDs are not treated as retained identities.

• Verify debug strings are not used as behavior inputs.

• Verify deterministic ordering for maps/sets/snapshots.

• Verify unsupported features are classified rather than silently faked.

• Add final architecture review checklist.

• Link unresolved architecture issues as release blockers.

Exit Criteria

• Final subsystem ownership audit is complete.

• Architecture checklist exists.

• Ownership leaks are fixed or tracked as release blockers.

• Shortcut/ad-hoc behavior is removed or documented as blocker.

• Determinism rules are verified.

• Unsupported feature behavior is audited.

• The issue is closeable when architecture review is clean.