How to Implement Always-On Mode Across Different AI Platforms (Claude, Codex, OpenCode)

Always-on mode automatically injects the i-have-adhd ruleset into every model response by checking for platform-specific flag files and prepending the processed SKILL.md content to system prompts via Node.js hooks and plugins.

The ayghri/i-have-adhd repository implements a cross-platform architecture to implement always-on mode across different AI platforms, ensuring consistent ADHD-friendly response formatting persists across Claude Code, GitHub Codex, and OpenCode sessions. This solution uses a unified ruleset source and platform-specific injection mechanisms to maintain behavior without manual prompting.

Core Architecture Components

The always-on system relies on three primary components that work consistently across all supported platforms.

The Opt-In Flag File

The opt-in flag is a zero-byte file that signals the user wants continuous ruleset application. The system checks for this file before injecting content:

• Claude Code and Codex: ~/.claude/.i-have-adhd-always (path overridable via CLAUDE_CONFIG_DIR environment variable)
• OpenCode: ~/.config/opencode/.i-have-adhd-always

These flag locations are defined in hooks/always-on.mjs, hooks/always-on.sh, and .opencode/plugins/i-have-adhd.mjs respectively.

The Canonical Ruleset

The canonical ruleset resides in skills/i-have-adhd/SKILL.md and serves as the single source of truth for ADHD-friendly response guidelines. All platform hooks read this file, remove any YAML front-matter using a standardized regular expression, and inject the remaining markdown content into the system prompt.

Hook Scripts and Plugins

Three distinct implementations handle the injection logic:

• Node.js Hook (hooks/always-on.mjs): Primary implementation for Claude Code and Codex, invoked by the SessionStart hook
• Shell Fallback (hooks/always-on.sh): POSIX-compatible fallback using awk for front-matter removal
• PowerShell Fallback (hooks/always-on.ps1): Windows-specific implementation for Claude Code/Codex
• OpenCode Plugin (.opencode/plugins/i-have-adhd.mjs): Per-turn injection system for OpenCode registered via opencode.json

Platform-Specific Implementation Details

Each AI platform integrates the always-on functionality through different hook mechanisms, though all use identical ruleset processing logic.

Claude Code and Codex SessionStart Hooks

For Claude Code and Codex, the system uses the SessionStart hook mechanism defined in hooks/hooks.json. The Node.js script (hooks/always-on.mjs) runs at session initiation, checking for the flag file at ~/.claude/.i-have-adhd-always. If present, it reads skills/i-have-adhd/SKILL.md, strips front-matter using the regex /^---[^\S\r\n]*\r?\n[\s\S]*?\r?\n---[^\S\r\n]*(?:\r?\n|$)/, and writes a header plus ruleset body to stdout. The platform automatically concatenates this output to the system prompt before the first model turn.

If Node.js is unavailable, the runtime falls back to hooks/always-on.sh on Unix/macOS or hooks/always-on.ps1 on Windows, which perform identical operations using native shell commands.

OpenCode Per-Turn Plugin Injection

OpenCode implements always-on mode through the plugin system. The .opencode/plugins/i-have-adhd.mjs file registers an experimental.chat.system.transform hook that executes on every turn rather than only at session start. When the flag file exists at ~/.config/opencode/.i-have-adhd-always, the plugin reads SKILL.md, applies the same front-matter stripping regex, and injects the combined header and ruleset into output.system.

Enabling Always-On Mode

Users opt-in by creating the appropriate flag file for their platform.

For Claude Code and Codex

Create the flag file in your Claude configuration directory:

mkdir -p ~/.claude
touch ~/.claude/.i-have-adhd-always

If you have set the CLAUDE_CONFIG_DIR environment variable, create the file at $CLAUDE_CONFIG_DIR/.i-have-adhd-always instead.

For OpenCode

Create the flag in the OpenCode configuration directory:

mkdir -p ~/.config/opencode
touch ~/.config/opencode/.i-have-adhd-always

Once created, the .opencode/plugins/i-have-adhd.mjs plugin will inject the ruleset on every subsequent turn.

Disabling Always-On Mode

The system provides both temporary and permanent disable options.

Temporary Session Disabling

To disable always-on mode for the current session only, type the following in your conversation:

stop adhd mode

The injected header informs the model to respect the Persistence rule, disabling the ruleset for that specific session without removing the flag file.

Permanent Disabling

To permanently disable always-on mode, delete the flag file:

# For Claude Code and Codex

rm ~/.claude/.i-have-adhd-always

# For OpenCode

rm ~/.config/opencode/.i-have-adhd-always

Removing this file prevents the hooks from injecting the ruleset in future sessions.

Technical Implementation Details

The consistent behavior across platforms relies on standardized text processing.

Front-Matter Stripping Logic

All three environments share exactly the same regular expression to remove YAML front-matter from SKILL.md:

/^---[^\S\r\n]*\r?\n[\s\S]*?\r?\n---[^\S\r\n]*(?:\r?\n|$)/

This regex matches the opening --- delimiter, any content until the closing ---, and trailing whitespace, ensuring only the substantive ruleset content remains for injection.

Header Injection Format

The system prepends the following standardized header to the ruleset:

ADHD MODE ACTIVE (always-on). The ruleset below applies to every response.
"stop adhd mode" or "normal mode" turns it off for this session;
delete <flag-path> to turn always-on off for good.

The <flag-path> placeholder displays the actual file path (e.g., /home/user/.claude/.i-have-adhd-always), providing users with context-specific instructions for disabling the feature.

Summary

• Always-on mode uses flag files (~/.claude/.i-have-adhd-always or ~/.config/opencode/.i-have-adhd-always) to signal opt-in status across Claude Code, Codex, and OpenCode platforms.
• The canonical ruleset in skills/i-have-adhd/SKILL.md provides the single source of truth, with front-matter stripped using the regex /^---[^\S\r\n]*\r?\n[\s\S]*?\r?\n---[^\S\r\n]*(?:\r?\n|$)/ before injection.
• Claude Code and Codex use SessionStart hooks (hooks/always-on.mjs with shell fallbacks) defined in hooks/hooks.json to inject content once at session start.
• OpenCode uses the experimental.chat.system.transform hook in .opencode/plugins/i-have-adhd.mjs to inject rules on every turn.
• Users disable the feature temporarily by typing "stop adhd mode" or permanently by deleting the flag file.

Frequently Asked Questions

How does the system handle the SKILL.md file differently between Claude Code and OpenCode?

Both platforms process skills/i-have-adhd/SKILL.md identically using the same regular expression to strip YAML front-matter, but Claude Code and Codex inject the content once at session start via the SessionStart hook, while OpenCode injects it on every turn using the experimental.chat.system.transform hook. This ensures OpenCode maintains the ruleset even if the system prompt is modified mid-session.

Can I use the always-on feature if Node.js is not installed?

Yes. While hooks/always-on.mjs is the primary implementation for Claude Code and Codex, the hooks/hooks.json configuration specifies fallback scripts. If Node.js is unavailable, the runtime automatically uses hooks/always-on.sh on Unix/macOS or hooks/always-on.ps1 on Windows, both of which implement the same flag-checking and front-matter stripping logic using native shell commands.

What happens if I create the flag file while a session is already running?

For Claude Code and Codex, the SessionStart hook only executes when the session initializes, so creating the flag file mid-session will not activate always-on mode until you start a new session. For OpenCode, the .opencode/plugins/i-have-adhd.mjs plugin checks the flag file on every turn, so always-on mode activates immediately on the next interaction after you create ~/.config/opencode/.i-have-adhd-always.

Is the injected content identical across all three platforms?

Yes. According to the ayghri/i-have-adhd source code, all platforms use the same regex pattern and read from the same skills/i-have-adhd/SKILL.md file, ensuring the ADHD-friendly formatting rules remain consistent whether you are using Claude Code, Codex, or OpenCode.

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