TODO.md

Data-Oriented Optimisation Backlog

1. Stabilise process I/O buffers (watcher.odin:454-505)

   • Persist stdout/stderr byte slabs and OVERLAPPED structs inside ProcessIOState instead of reallocating them every poll tick.
   • Reset lengths/events instead of allocating to keep CPU caches hot and eliminate allocator churn.
   • Measure: expect fewer heap calls per second, steadier RSS, and lower latency in tight watch loops.

2. Batch decode directory notifications (watcher.odin:556-600)

   • Treat the ReadDirectoryChangesW block as a struct-of-arrays batch (actions, offsets, lengths, hashes).
   • UTF-8 convert and filter only the rows that survive extension checks to cut string work on ignored files.

3. Preparse build templates (watcher.odin:603-677)

   • Parse arg_info.build_template once into literal spans + placeholder descriptors.
   • Assemble commands via memcpy of literals plus direct insertion of dynamic spans (file/out/target), eliminating per-trigger splits and joins.

4. Hash-based filename filters (watcher.odin:570-589)

   • Replace repeated strings.has_suffix/contains calls with a small hashed table or bitset of skip/build extensions.
   • Express state as membership in these tables to keep the hot filtering path branch-light and cache-resident.