codex-monitor@breixopd: add Codex usage and Remote Control monitor

[breixopd]

Summary

Adds Codex Monitor, a Cinnamon panel applet for monitoring Codex usage, reset windows, sessions, updates, and Remote Control.

The applet provides:

• Compact five-hour and weekly usage meters in the panel
• Amber and red quota/reset warnings with explanatory status indicators
• Reset countdowns, banked-reset availability, expiry warnings, and confirmed redemption
• Responsive wide and compact dashboards
• Detailed quota and activity graphs with 24-hour, 7-day, and 30-day ranges
• Exact graph values and timestamps on pointer movement
• Active and recent Codex sessions, elapsed active-session time, and terminal resume actions
• An Open Codex action using the configured default terminal
• Remote Control status, pairing, connected-device inventory, refresh, stop, confirmed revocation, and guarded recovery from a verified stuck service
• Automatic update checks with the update action shown only when a newer stable Codex version is available

Implementation and privacy

The Cinnamon UI remains asynchronous. Codex communication and bounded processing are handled by a local Python helper.

• Communicates only with the locally installed Codex CLI, app-server, and local Unix control socket
• Does not read or copy Codex authentication files
• Does not expose a TCP listener or send usage history to another service
• Stores bounded history under the user's XDG state directory
• Uses fixed subprocess argument arrays with shell=False
• Requires confirmation for reset redemption, Remote stop/repair, device revocation, and Codex updates
• Validates ownership, process state, parentage, executable identity, and pidfd stability before repairing a stuck Remote process
• Recognizes sessions in other local Codex processes through bounded /proc metadata only when the process belongs to the same user and its resolved executable exactly matches the configured Codex executable
• Retains only canonical thread UUIDs, matching open session filenames under CODEX_HOME, and safe process start timestamps; session contents and process command lines are never read
• Treats Remote and connected-device capabilities as optional and degrades to clear unavailable or unsupported states
• Keeps live Remote validation read-only; tests never start or stop Remote, create pairing state, revoke devices, or record device identity

Codex Remote and app-server interfaces are still evolving, so those features are capability-detected and isolated from ordinary quota and session monitoring.

Compatibility

• Cinnamon 6.0, 6.2, 6.4, and 6.6 in metadata
• Live tested on Linux Mint with Cinnamon 6.6
• Python 3.10 or newer
• Requires an installed and authenticated Codex CLI

Validation

• Official validate-spice passed
• Official Cinnamon pattern check passed
• 258 Python tests passed
• 48 JavaScript model tests passed
• Ruff, source validation, JavaScript and shell syntax checks, and translation-template validation passed
• Bandit reported no medium or high-severity findings
• Full installed Cinnamon smoke matrix passed, including wide/compact layouts, all graph ranges and modes, pointer values, elapsed session states, updates, resets, and read-only Remote device discovery
• Live active-session detection was verified against two simultaneously running Codex sessions
• Release and Cinnamon Spices archives passed integrity and private/generated-file checks
• Screenshot uses isolated synthetic state rendered with the applet's real dashboard, popup wrapper, and styling; it contains no live account, session, quota, path, or device data
• Project CI passed independently on both dev and main

This pull request adds only codex-monitor@breixopd.

Author: @breixopd

[breixopd]

Closing this submission because the project is undergoing a substantial v2 redesign into a broader cross-platform provider and usage manager. If we decide to distribute through Cinnamon Spices later, I’ll submit a fresh, focused Cinnamon integration after the new architecture and packaging have completed testing.