Daily Log: 2026-07-18

fractal continued MCP work with remaining projector polish tasks and TODO.md roadmap update. mycelium archive/VFS layer design for language runtime filesystem abstraction (session data spans into 2026-07-19).

Sessions and Activity

fractal

Session 3f0db85e (03:27–06:56) — MCP and infrastructure polish.

continuation of previous session's MCP work: final rich content types implementation (03:32), then systematic TODO.md audit collapsing completed sections to title+date markers per git-as-source-of-truth principle. cleaned up handoff notes with next-session pointers.

Commits: 32c22c9 (TODO audit)

mycelium

Session 4b4901ae (15:21–18:42, dated 2026-07-19) — VFS design exploration and HTTP imports.

archive-as-filesystem-layer concept discussion led to two major implementations:

• README generation (15:28) — agent surveyed entire repo, verified facts from source code (17 languages, Node stdlib parity, npm acid test 27/28), wrote accurate README covering features, build/run instructions, architecture overview, and honest status section calling out known gaps (Python-as-host broken, native addons unsupported).

• VFS abstraction (17:45–18:42) — implemented archive handler system as general filesystem provider interface, not archive-specific. two tasks:

  • Archive handler system — VfsProvider/VfsEntry/VfsPathResolver with 5-step path resolution algorithm (try-whole, dot-heuristic, binsearch, boundary split, recursive nesting). ZipArchiveHandler built-in, extensible registry. integrated into InterceptingFileSystem for transparent archive reads.
  • VFS generalization — renamed from archive-specific to general VFS layer. VfsProvider interface foundation for future HTTP imports, in-memory filesystems, etc.

• HTTP imports (19:00) — implemented as language-level hook rather than VfsProvider (fetch is network, not traversable FileSystem). HttpImportCache with disk caching (XDG_CACHE_HOME), immutable URLs. special handling per language: GraalJS routes through /.mycelium/uri convention; TruffleRuby monkeypatches Kernel#require for http(s)😕/ specifiers.

Token Usage

Project	Sessions	Output Tokens	Cache Read	Cache Create
fractal	1	~1,200	~200,000	~3,000
mycelium	1	~7,000	~800,000	~15,000

Total: ~8,200 output tokens, ~1M cache read, ~18K cache create

Observations

1. VFS abstraction cleanly separated concerns — archive traversal as general provider interface; HTTP imports as language-level hook. each approach matched the problem's semantics rather than forcing both into filesystem abstraction.

2. Multi-language support complexity surfaced — GraalJS routes URL imports through FileSystem.parsePath(URI); TruffleRuby doesn't. required language-specific hooks to unify behavior. preview of complexity ahead for Lua support.

3. Documentation discipline verified claims — mycelium README surveyed source before writing. no speculation; fact-checked build paths, language counts, known limitations. sets precedent for other projects.

Projects Touched

• fractal — MCP roadmap finalization, TODO housekeeping
• mycelium — VFS abstraction, HTTP imports, README generation

Next Steps (inferred)

1. mycelium HTTP provider testing — verify against real network scenarios; measure cache hit rates
2. mycelium Lua support — marked high-priority; deferred until VFS/HTTP stabilized
3. fractal MCP — tier-2 transport (logging, streaming) when ready
4. mycelium language parity — other Graal languages may need HTTP import hooks