fix(tui): fall back to readable ANSI-16 palettes on basic-color terminals

[map-c]

Related Issue

Resolve #2671

Problem

See linked issue. On 16-color terminals (TERM=xterm, tput colors = 8/16), chalk only supports ANSI-16 (level 1), and chalk.hex() quantizes aggressively: mid grays below #808080 collapse to black (SGR 30 — invisible on dark backgrounds) and desaturated hues collapse to white. Several dark-theme tokens became unreadable (textMuted, border, diffGutter → black) or lost their hue (diffRemovedStrong, shellMode → white; diffAddedStrong → cyan).

What changed

• Added basicDarkColors / basicLightColors fallback palettes in src/tui/theme/colors.ts. Every value was verified against chalk's level-1 rgb→ansi16 conversion: dark neutrals land on SGR 37/97 (never black), and state/role tokens keep their intended hue (primary → bright blue, diff strong → bright green/red, shellMode → bright magenta). Light-theme tokens that quantized to the wrong hue (success → black, warning/roleUser → red, shellMode → bright blue) are corrected to green/yellow/magenta.
• Added isBasicColorTerminal() (chalk.level === 1) in detect.ts; level 0 needs no fallback (no color at all) and FORCE_COLOR=2/3 intentionally overrides TERM detection.
• Built-in palette resolution (getColorPalette / getColorPaletteSync / auto-theme tracking) now goes through getBuiltInPaletteForTerminal, which swaps in the basic variants only on level-1 terminals. Custom themes always load as written.
• Hue hierarchy is intentionally flatter in the basic palettes — 16 colors cannot express four neutral shades — readability takes priority.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: c755faa

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@moonshot-ai/kimi-code	Patch

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[chatgpt-codex-connector]

Preserve light-theme identity for ANSI-16 palettes

When chalk.level === 1, this returns basicLightColors rather than lightColors, but both applyThemeChoice in commands/config.ts and applyReloadedTuiConfig in commands/reload.ts still infer the current resolved theme using currentTheme.palette === lightColors. Consequently, selecting auto from an explicit light theme—or reloading while auto has resolved light—initially applies the dark palette; on terminals that do not answer the subsequent theme-report queries, it remains dark indefinitely. Recognize basicLightColors in that inference or track the resolved theme independently of palette object identity.

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[map-c]

Addressed in c755faa: added inferBuiltInResolvedTheme(), which recognizes all four built-in palette identities (dark/light plus both ANSI-16 basic variants) and returns null for custom-theme palettes. Both call sites (applyThemeChoice in config.ts, applyReloadedTuiConfig in reload.ts) now use it with a ?? 'dark' fallback, preserving the previous semantics for custom themes. Covered by a new test including the basic variants and a custom-palette negative case.