getTerminalBackgroundColor() always returns "dark" due to double color normalization

`getTerminalBackgroundColor()` always returns "dark" due to double color normalization

Affected versions

v1.4.4 through v1.4.6 (introduced by #22297)

Description

The refactoring in #22297 moved getTerminalBackgroundColor() from an inline function in app.tsx to Terminal.getTerminalBackgroundColor() in terminal.ts. The new implementation uses RGBA.fromInts() to parse the terminal's background color, but the mode() helper still divides by 255 — a leftover from the old code where r, g, b were raw 0–255 integers.

RGBA.fromInts() already normalizes to the 0.0–1.0 range internally:

// @opentui/core RGBA.ts
static fromInts(r: number, g: number, b: number, a: number = 255) {
    return new RGBA(new Float32Array([r / 255, g / 255, b / 255, a / 255]))
}

But mode() divides by 255 again:

// packages/opencode/src/cli/cmd/tui/util/terminal.ts
function mode(bg: RGBA | null): "dark" | "light" {
    if (!bg) return "dark"
    const luminance = (0.299 * bg.r + 0.587 * bg.g + 0.114 * bg.b) / 255
    //                                                               ^^^
    return luminance > 0.5 ? "light" : "dark"
}

The maximum possible luminance (for pure white #ffffff) is 1.0 / 255 ≈ 0.004, which can never exceed 0.5. The function returns "dark" for every terminal background color.

Impact

Any theme with dark/light variants (gruvbox, catppuccin, nord, etc.) always selects the dark palette, even on a light terminal. The system theme is unaffected because it works directly with raw RGBA values and never calls mode().

Steps to reproduce

Use a terminal with a light background
Set theme to gruvbox (or any theme with light/dark variants)
Run opencode on v1.4.4+
Observe the dark variant is selected instead of light

Fix

Remove the / 255 from the luminance calculation in mode():

function mode(bg: RGBA | null): "dark" | "light" {
    if (!bg) return "dark"
    const luminance = 0.299 * bg.r + 0.587 * bg.g + 0.114 * bg.b
    return luminance > 0.5 ? "light" : "dark"
}

Related: #20926 — the inverse of this bug. In v1.3.13 the detection was stuck on light; #22297 refactored the detection logic to fix that, but introduced the double-normalization which now makes it stuck on dark.

fix: remove double normalization in terminal background detection

i could downgrade to 1.4.3 to get around this, but now i have this problem even on those older versions

You can still clone and cherry-pick this. But gosh this is annoying, hopefully it'll get fixed soon in a release

Closing this: the code this PR fixes was removed in v1.14.19 by #23188, which replaced the custom getTerminalBackgroundColor() / mode() helper with renderer.waitForThemeMode() from @opentui/core. The double normalization bug no longer exists because the entire code path was deleted, not because someone fixed the / 255. Note that the new detection approach has its own set of issues for some users (see #20926), but that's a different problem.

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getTerminalBackgroundColor() always returns "dark" due to double color normalization #22615