What version of Codex is running?

0.53

What subscription do you have?

plus

Which model were you using?

i dont know

What platform is your computer?

apple silicon

What issue are you seeing?

✅ Issue Title

Codex CLI should run brew update before brew upgrade (Brew cask update fails without sync)

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✅ Issue Body

Summary
When Codex is installed via Homebrew (brew install --cask codex), the built-in update flow can fail to detect available updates because it does not run brew update before attempting the upgrade. This results in a stale cask index and a misleading “latest version installed” message, even when a newer version exists.

This creates a user-experience and automation gap between Codex’s internal updater and Homebrew’s package state.

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Actual Behavior
• Codex reports a new version available (e.g., 0.55)
• Internal updater runs
• Brew reports “already latest”
• After manually running brew update, the upgrade succeeds

This leads to confusion, redundant retries, and friction in managed macOS environments.

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Proposed Solution
1. Detect Homebrew-installed Codex
2. Pre-execute:

brew update

3.	Then run:

brew upgrade --cask codex

4.	If Homebrew install detected, disable internal updater and display:

“You installed Codex via Homebrew — updating via Homebrew…
(tip: our updater doesn’t run brew update, so we’re doing that now)”

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Acceptance Criteria
• Brew-installed Codex always updates correctly
• No contradictory “latest version already installed” messages
• Robust behavior in corporate environments (MDM, read-only dirs, proxies)
• Idempotent, scripting-safe behavior

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Nice-to-Have
• codex doctor or --diagnostics mode
• --no-update flag for CI
• Proxy / offline fallback messaging

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Why it Matters
Reduces friction, improves trust in update UX, prevents user confusion, and aligns Codex with macOS package management best practices.

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✅ End of Issue

What steps can reproduce the bug?

Steps to Reproduce
1. Install Codex via Homebrew:

brew install --cask codex

2.	A new Codex version is released
3.	Launch Codex → update prompt appears
4.	Choose in-app update or run:

brew upgrade --cask codex

5.	Output incorrectly claims the newest version is already installed
6.	Run:

brew update && brew upgrade --cask codex

7.	Upgrade succeeds

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Environment
• macOS (Apple Silicon)
• Codex installed via Homebrew Cask
• Observed with v0.53 → v0.55 transition
• Brew version and taps up to date only after manual sync

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What is the expected behavior?

No response

Additional information

Expected Behavior
• When Codex detects a Homebrew cask installation, the CLI should either:
✅ automatically run brew update && brew upgrade --cask codex
or
✅ delegate update operations entirely to Homebrew with clear instructions
• Output should be deterministic and aligned with Brew’s actual package registry state