Metal AgentandClaude Opus 5
1556b87f37
main.rs held eleven `const … : u32` colours, and spikes/floem-shell held a byte-identical copy of the same eleven. Every one was a judgement call made once, and no user could change any of them without recompiling. lumbridge-theme takes a syntax theme's five anchors — background, foreground, comment, and the git added/deleted/modified colours where the theme has them — and derives the whole role set. The frame is the editor background pushed one logarithmic contrast step away from the content, so the work surface is the brightest thing on screen; a theme already at black lifts its surface instead of sinking its frame, which is why a pitch-black theme still shows a seam. Adapted from Buzz's adaptive-theme.ts (block/buzz, Apache-2.0) as a specification, not as copied code. The golden vectors were taken by running the original under Node — a research pass had supplied Python-derived vectors and claimed they reproduced it byte-exactly, and they did not: Python rounds half-to-even, JavaScript rounds half-up, they disagree on exactly one channel value of 22.5, and that decides whether the luminance bisection converges a step early. github-dark's chrome is #171a1d, not #191c20. Provenance colours are separate roles from state colours, with a test holding them pairwise distinct in every theme, because decision 0012 colours a usage reading by where its number came from and never by how alarming it is. This changed no pixels, and that was verified rather than asserted: the only difference between before-and-after screenshots is the digits of a process ID. The check earned its keep — the mechanical rename had rewritten three user-facing strings, turning the sidebar's "ATTENTION · 0" into "theme.attention · 0" and "+ ADD PANEL" into "+ ADD theme.surface". A literal-by-literal diff now confirms zero strings changed. The default theme pins its roles to the previous constants to make that true; the anchors underneath are real, and a test bounds how far the pure derivation sits from them. The terminal ANSI palette keeps its own table, so 29 colour literals remain in main.rs, all terminal. The catalog, its attribution, and the picker are separate work. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
4.7 KiB
0018: The interface palette is derived from a syntax theme's anchors
Status: accepted; the default theme reproduces the previous appearance exactly.
Lumbridge had eleven const … : u32 colours in main.rs and a byte-identical
copy of the same eleven in the Floem spike. Every one was a judgement call
someone made once, and there was no way for a user to change any of them without
recompiling.
The approach
A syntax theme has already answered the hard question — which background,
foreground, and comment colour work together — so the interface derives itself
from that answer instead of being invented beside it. Five anchors go in
(bg, fg, comment, and the git added/deleted/modified colours when the theme
has them) and a full role set comes out.
The core of it: the application frame is the editor background pushed one contrast step away from the content, so the frame recedes and the work surface is the brightest thing on screen. The step is logarithmic rather than fixed, because a separation that reads clearly against near-black is invisible against white. A theme already at black has no room below it, so the frame pins to black and the surface lifts instead — which is why a pitch-black theme still shows a seam between panel and frame.
Adapted from
Buzz's desktop/src/shared/theme/adaptive-theme.ts (block/buzz, Apache-2.0,
Copyright 2026 Block, Inc.), pinned in docs/RESEARCH_SNAPSHOTS.md. It is itself
a port of an earlier builderbot original, which is not in Research/ and whose
licence has not been verified; Block's Apache-2.0 grant covers what Block
distributes, which is what was read here.
No implementation code was copied. The algorithm was read as a specification and
reimplemented in Rust, and the golden vectors in derive.rs are what hold the
two together.
Those vectors were taken by running the original under Node, not by
re-deriving them. That distinction is not pedantry. A re-implementation in
Python reports #191c20 for github-dark's chrome; the real answer is #171a1d.
Python's round is banker's rounding and JavaScript's Math.round is half-up,
they disagree on exactly one channel value — 22.5 — and that one channel decides
whether the bisection's convergence test trips a step early. The first draft of
this work took the Python number on trust from a research pass that claimed to
have "reproduced it byte-exactly", and it was wrong. Anything claiming to
reproduce these must run the original.
Two consequences for the port: the arithmetic is f64 throughout, because
JavaScript numbers are f64 and f32 drifts the search; and mix quantises to
eight bits on every call, because the bisection searches over the space that
rounding produces.
The roles
Named for what they do, not for a container ladder: surface_active is the
selected panel and the hover fill, not "surface container highest". Nothing in
Lumbridge has to reason about how many containers deep it is.
The five provenance colours are separate fields from the state colours, and a test asserts they stay pairwise distinct in every theme. Decision 0012 says a usage value is coloured by where it came from and never by how alarming it is; a theme that collapsed two of them would silently defeat that, and once themes are user-editable the number of ways to do so multiplies.
Why the default theme carries overrides
RoleOverrides lets a theme pin a role instead of deriving it. Only
lumbridge-slate uses it, and only so this change is a zero-pixel one: the
commit should be reviewable as "colours now come from a palette", with no
appearance change smuggled inside it. That was verified by screenshot rather
than asserted — the only pixels that differ between the before and after builds
are the digits of a process ID, which changes per run.
The anchors underneath are real, and a test bounds how far the pure derivation lands from the pinned values, so the overrides are a starting position rather than a permanent exemption. A catalog theme setting them would be defeating the engine.
Not in this change
The terminal ANSI palette still has its own fixed table, so main.rs is not
yet free of colour literals — twenty-nine remain, all of them terminal. Per-theme
terminal palettes need the extraction pass that arrives with the catalog.
The catalog itself is one theme. The generator, the vendored theme files, and their attribution are a separate piece of work, as is the picker. What lands here is the engine and one first-party theme, which is what the sidebar and settings work needs in order to be built against roles rather than constants.
The Floem spike keeps its eleven constants. It is frozen under decision 0017 and is not maintained in parity.