Added saturation, vibrancy, and hue rotation controls to the composite pipeline — then immediately refactored compositeService to replace the 10+ positional parameters with an options object so adding the new controls wasn't a mess.
Finally cracked open the composite route and split it into focused pipeline stages. Also gated window.jwst debug globals behind dev-only builds, replaced hand-rolled caches with TTLCache, bounded polling retries, and surfaced the errors that frontend components were quietly swallowing.
Short day — cleaned up three processing-engine correctness bugs that had been sitting in the tech-debt queue (#1019, #1023, #969) and centralized the duplicate MAX_FITS_FILE_SIZE_BYTES constant that was defined in three places.
Docs day — added the 4+1 architecture view documentation and reorganized mkdocs nav around it, plus removed the dead per-channel feathering code that single-instrument composites no longer run.
Session cleanup day — added z-index and spacing tokens, killed dead CSS, capped the auto palette at blue so single-channel composites stop going purple, and patched the guided step-card styles that the token refactor accidentally deleted.