fix: add terminal font fallbacks

[janburzinski]

summary

• adds fallback font
• font quoting
• tests

[janburzinski]

fixes #2142

[greptile-apps]

Greptile Summary

This PR introduces terminal-font.ts, a small utility that normalises CSS font-family strings before they are handed to xterm: it splits comma-separated font lists while respecting quoted substrings, quotes each individual font name correctly, and appends a hardcoded set of terminal-safe fallbacks (Menlo, Monaco, Consolas, monospace). The new helper replaces all three previous raw-assignment sites in pty.ts and use-pty.ts.

• terminal-font.ts — new splitFontFamilies (quote-aware comma splitter), quoteFontFamily (generic-family passthrough + already-quoted detection + backslash/double-quote escaping), and buildTerminalFontFamily (combines split, quote, dedup, fallback-append steps).
• pty.ts — initial Terminal options now include fontFamily: buildTerminalFontFamily() so the fallback stack is active from construction.
• use-pty.ts — settings-load and terminal-font-changed event paths both now call buildTerminalFontFamily(customFontFamily) instead of assigning raw user strings.

Confidence Score: 5/5

Safe to merge — the change is well-scoped, fully unit-tested, and correctly handles all the CSS font-family edge cases that were flagged in earlier review threads.

The new font utility correctly splits comma-separated font lists (respecting quoted substrings), quotes individual names, escapes embedded double-quotes, deduplicates against the fallback list, and handles CSS generic families. All three call sites in pty.ts and use-pty.ts are updated consistently. The unit tests cover the full range of inputs including pre-quoted CSS lists, embedded quotes, generic families, and the no-argument path. No regressions were found on the changed code paths.

No files require special attention.

Important Files Changed

Filename	Overview
src/renderer/lib/pty/terminal-font.ts	New module implementing CSS-aware font-family quoting, comma-aware splitting (respecting quoted substrings), and fallback appending. Logic and edge cases are correctly handled; all test cases verify correctly.
src/renderer/lib/pty/terminal-font.test.ts	Comprehensive unit tests covering spaces, embedded quotes, comma-separated lists, pre-quoted CSS lists, generic families, and the no-argument fallback path.
src/renderer/lib/pty/pty.ts	Adds buildTerminalFontFamily() to the initial xterm Terminal options so the fallback stack is active from construction, before any user settings are loaded.
src/renderer/lib/pty/use-pty.ts	Both the settings-load path and the runtime font-change event path now route through buildTerminalFontFamily, ensuring fallbacks are always appended and font names are properly quoted.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[fontFamily string from user setting or event] --> B[buildTerminalFontFamily]
    B --> C{fontFamily provided?}
    C -- No --> D[TERMINAL_FONT_FALLBACKS only]
    C -- Yes --> E[splitFontFamilies]
    E --> F[Quote-aware comma split]
    F --> G[userFonts concat TERMINAL_FONT_FALLBACKS]
    D --> H[map quoteFontFamily over each name]
    G --> H
    H --> I{CSS generic family?}
    I -- Yes --> J[Return unquoted]
    I -- No --> K[Already quoted by regex?]
    K -- Yes --> L[Return as-is]
    K -- No --> M[Escape backslash and quotes then wrap in double quotes]
    J --> N[new Set deduplicate]
    L --> N
    M --> N
    N --> O[join with comma-space]
    O --> P[xterm fontFamily option]

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_{Reviews (2): Last reviewed commit: "fix: preserve terminal font family lists" | Re-trigger Greptile}

[janburzinski]

@greptileai