feat(desktop): add configurable terminal font family (terminal.font_family in config.yaml)

[baoyu0]

Summary

Adds a new config option terminal.font_family that lets users customize the CSS font-family for the desktop app's embedded xterm.js terminal.

Problem

The embedded terminal font was hardcoded to:

JetBrains Mono, Cascadia Code, SF Mono, Menlo, Consolas, monospace

None of these are Nerd Fonts, so Nerd Font-only glyphs (like Starship prompt icons for the Windows logo) render as tofu/boxes. Users who have Nerd Fonts installed cannot configure the terminal to use them without patching the built desktop app JS.

Solution

Thread a new config value terminal.font_family from config.yaml through to the xterm.js Terminal constructor:

1. Python backend (hermes_cli/config.py): added "font_family": "" to the terminal section of DEFAULT_CONFIG
2. TypeScript types (types/hermes.ts): added font_family?: string to HermesConfig.terminal
3. Config hook (use-hermes-config.ts): reads config.terminal?.font_family and exposes it as terminalFontFamily
4. Component chain (desktop-controller.tsx -> persistent.tsx -> index.tsx -> use-terminal-session.ts): passes the value down to the Terminal constructor
5. Fallback: when the field is empty or unset, the original hardcoded default is preserved (backward compatible)

Usage

# config.yaml
terminal:
  font_family: "'CaskaydiaCoveNerdFont', 'JetBrains Mono', monospace"

After restarting the desktop app, Nerd Font icons in the embedded terminal will render correctly.

Files changed

• hermes_cli/config.py - added font_family default + documentation
• apps/desktop/src/types/hermes.ts - added type
• apps/desktop/src/app/session/hooks/use-hermes-config.ts - reads config value
• apps/desktop/src/app/desktop-controller.tsx - wires value to terminal
• apps/desktop/src/app/right-sidebar/terminal/persistent.tsx - passes through
• apps/desktop/src/app/right-sidebar/terminal/index.tsx - passes through
• apps/desktop/src/app/right-sidebar/terminal/use-terminal-session.ts - uses config value with fallback
• apps/desktop/src/app/settings/constants.ts - field label + description for Settings UI

Testing

• Verified config parsing: empty value falls back to built-in default
• Settings UI displays "Terminal Font" field with description
• The field supports arbitrary CSS font-family syntax (single font, font stacks, Nerd Font names)
• Non-empty value overrides the xterm fontFamily in the Terminal constructor
• No regressions: when font_family is unset or empty, behavior is identical to before
• Pre-existing TypeScript lint errors untouched (all are path-alias resolution issues in test/build context)

[teknium1]

Thanks for the focused configuration contribution. The need still exists: current main hardcodes the interactive xterm font at apps/desktop/src/app/right-sidebar/terminal/use-terminal-session.ts:504.

Problems

• The PR targets the old TerminalTab tree. Current main instead mounts TerminalWorkspace from persistent.tsx:136, which renders TerminalInstance in workspace.tsx:53-61; the changed terminal/index.tsx no longer exists. GitHub reports this PR as DIRTY.
• At commit 98191306, use-hermes-config.ts:31,69 initializes the font as '' and fills it asynchronously, but use-terminal-session.ts:658 does not depend on fontFamily. If xterm is created first, it keeps the fallback font.
• Current startup intentionally warms fonts before fitting and starting the PTY (use-terminal-session.ts:884-892); a custom family needs to participate in that path.

Suggested changes

• Adapt the plumbing to the current PersistentTerminal → TerminalWorkspace → TerminalInstance → useTerminalSession path.
• Add an update path that applies the resolved font, warms it, refits, and refreshes WebGL without restarting persistent terminals; cover delayed config resolution.
• Decide whether the same setting should apply to the agent-background xterm at use-agent-terminal.ts:44.

Automated hermes-sweeper review.

[teknium1]

terminalFontFamily starts as '' and is set only after the asynchronous config request resolves, while this xterm-construction effect does not depend on fontFamily (line 658). If the terminal mounts first, it remains on the fallback for the session. Add a dedicated font-update path that also refits and clears the WebGL atlas; simply recreating the persistent terminal on every config response would discard shell state.

[GottZ]

This was generated by AI during triage.

Summary

Three PRs address the hardcoded Desktop terminal font: #49592 adds the initial config plumbing, #70925 expands it into a profile-scoped picker with lifecycle handling and tests, and #76395 carries that broader implementation onto current main.

Related pull requests

• #49592 related — (+25/-8) — superseded by #76395: #49592 introduces terminal.font_family but targets the removed TerminalTab path and does not update an xterm instance when the asynchronously loaded font changes. Despite the keep_open review on #49592, #76395 implements the salvage path requested there through the current terminal hooks, including font warming and live updates.
• #70925 [closed] related — (+1078/-30) — superseded by #76395: #70925 provides the comprehensive picker, profile persistence, both interactive and agent-terminal integration, font warming, live repaint, documentation, and tests. Despite the keep_open review on #70925, the #76395 diff contains the same core implementation while resolving the review's duplicate-import and nullable-observer cleanup blockers; #70925 remains relevant as the source branch identified as salvaged in the #76395 PR body and as superseded by #76395 in the contributor discussion on #70925.
• #76395 [merged] related — (+1009/-30) — implemented reference: #76395 is the current-main implementation of configurable terminal fonts, covering both terminal surfaces, profile-scoped settings, safe fallback resolution, asynchronous warming, live repaint, config round-trip coverage, locales, and documentation. Its merged state makes it the reference that supersedes the two earlier proposals.

Duplicates

#70925 and #76395 are substantially the same end-to-end change, with #76395 carrying the implementation onto current main and resolving the documented review blockers. #49592 is the narrower configuration foundation whose intended behavior is subsumed by #76395.

Suggested consolidation

Close #49592 as duplicate of #76395: the chain is #49592 → #70925 → #76395, and the #76395 diff contains the current-tree implementation requested by the keep_open review on #49592. Keep #70925 closed as superseded by #76395; its keep_open review was appropriate before the duplicate imports and nullable-observer cleanup issue were addressed, but those fixes and the pending-font-preparation unmount test are present in #76395.

Cross-PR triage: Reviewed 3 pull requests and 0 issues in this complex. Each diff was read against this issue; Assessment working set: 116 kB of PR diffs, 8 kB of issue/PR text, 5 kB of discussion (10 comments), 0 verify verdicts. verdicts reflect diff content, not PR titles. Part of an automated triage batch.