fix(cli): set TERM, COLORTERM, and LANG defaults for terminal pty sessions

[GeT-LeFt]

Problem

When the hub process is started via launchd (macOS), systemd, or Docker, the spawned terminal PTY sessions inherit a stripped-down environment that is missing critical terminal variables:

Variable	Missing behavior
TERM	Programs fall back to dumb mode — no colors, no cursor movement
COLORTERM	Shell prompts (e.g. Powerlevel10k) skip truecolor output
LANG	Non-ASCII glyphs (powerline symbols, emoji, CJK) render as replacement characters �

This makes the web terminal nearly unusable for anyone running common shell setups like oh-my-zsh or p10k.

Solution

Set sensible defaults in buildFilteredEnv() only when the variable is not already present, so explicit user overrides via the parent process are respected:

• TERM=xterm-256color
• COLORTERM=truecolor
• LANG=en_US.UTF-8

Testing

• Verified on macOS (launchd-managed) and Docker (Ubuntu) deployments
• Confirmed p10k prompt renders correctly with powerline glyphs and truecolor
• Confirmed existing TERM/LANG values from parent env are preserved (not overwritten)

Fixes #498

[github-actions]

Findings

• [Major] Hard-coded en_US.UTF-8 is not portable for Docker/systemd deployments. Minimal Debian-based images commonly do not have that locale generated, so each new PTY can start with locale: Cannot set LC_*... warnings and locale-dependent tools inherit an invalid locale. Evidence cli/src/terminal/TerminalManager.ts.
  Suggested fix:

  if (!env.LANG) {
      env.LANG = process.platform === 'darwin' ? 'en_US.UTF-8' : 'C.UTF-8'
  }

Summary
Review mode: initial
One portability regression found in the new terminal env defaults: the fallback locale at cli/src/terminal/TerminalManager.ts is not safe for minimal Debian-based Docker images, which this PR explicitly targets.

Testing

• Not run (automation)
• Add a unit test for buildFilteredEnv() that covers missing locale vars on Linux and preserves an existing LANG override.

HAPI Bot

[github-actions]

[MAJOR] en_US.UTF-8 is not generated in common minimal Debian-based Docker images, so this fallback can make every spawned PTY print locale: Cannot set LC_*... on startup and leaves locale-sensitive tools in an invalid locale state.

Suggested fix:

if (!env.LANG) {
    env.LANG = process.platform === 'darwin' ? 'en_US.UTF-8' : 'C.UTF-8'
}

[github-actions]

Findings

• [Major] Hard-coded en_US.UTF-8 is not portable for Docker/systemd deployments. Minimal Debian-based images commonly do not have that locale generated, so each new PTY can start with locale: Cannot set LC_*... warnings and locale-dependent tools inherit an invalid locale. Evidence cli/src/terminal/TerminalManager.ts:78.
  Suggested fix:

  if (!env.LANG) {
      env.LANG = process.platform === 'darwin' ? 'en_US.UTF-8' : 'C.UTF-8'
  }

Summary
Review mode: follow-up after new commits
The only commit after the prior HAPI Bot review is a CI retrigger, so the PR code diff is unchanged. The locale fallback issue remains on the latest head and still affects the Docker/systemd use case described by the PR.

Testing

• Not run (automation)
• Add a unit test for buildFilteredEnv() that covers missing locale vars on Linux and preserves an existing LANG override.

HAPI Bot

[github-actions]

[MAJOR] en_US.UTF-8 is not generated in common minimal Debian-based Docker images, so this fallback can make every spawned PTY print locale: Cannot set LC_*... on startup and leaves locale-sensitive tools in an invalid locale state.

Suggested fix:

if (!env.LANG) {
    env.LANG = process.platform === 'darwin' ? 'en_US.UTF-8' : 'C.UTF-8'
}

[github-actions]

Findings
No issues found in the modified lines.

Summary
Review mode: follow-up after new commits
The previous HAPI Bot finding about the non-portable Linux locale fallback is addressed by using C.UTF-8 off macOS. Residual risk: buildFilteredEnv() still has no direct unit coverage for preserving existing env values and applying defaults when TERM, COLORTERM, or LANG are missing.

Testing
Not run (automation; did not execute PR code). Suggested coverage: add a unit test for buildFilteredEnv() covering missing terminal env defaults and preservation of parent overrides.

HAPI Bot