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Coding AIs start building the moment you ask. This hook makes your AI decide first: until it has finished a Trillion decision in the current turn, it cannot edit a file inside a code project or save work with git commit. A reminder to decide first gets skipped; a refusal at the moment of the change holds every time.

What counts as deciding

A call to decide that comes back with a decision (the option chosen, the reason, the next step and how success will be measured), or
A call to export_decision on a case that is already decided, whose answer shows Status: Decided and a Decision section.

Opening a decision with start_decision or answering its questions does not count: those only work the method. A “turn” is everything since your last message, so each new request needs its own decision or an export of one already made. When a change is refused, your AI sees this message and can carry on by deciding:

Before changing files, finish a Trillion decision in this turn: answer its questions, call decide, or export an already decided case. Opening a case is not a decision.

Deciding never needs a file change, so a refused AI can always decide and continue.

What it checks and what it leaves alone

Checked	Left alone
Edits and new files inside any folder that is a git repository	Files outside a git repository
`git commit` run from the terminal	Other terminal commands
	Scratch folders you list as free, such as `/tmp`

A helper AI started by your AI (a subagent) is judged by its own conversation, so it needs its own decision.

Install

Claude Code
Codex

Add this to hooks.PreToolUse in ~/.claude/settings.json:

{
  "matcher": "Edit|Write|MultiEdit|NotebookEdit|Bash",
  "hooks": [{ "type": "command", "command": "node <hooks folder>/decide-before-building.mjs" }]
}

Add this to hooks.PreToolUse in ~/.codex/hooks.json:

{
  "matcher": "apply_patch|exec_command|shell|exec|Bash|Edit|Write",
  "hooks": [{ "type": "command", "command": "node <hooks folder>/decide-before-building.mjs", "timeoutSec": 10 }]
}

Codex skips a new or changed hook until you trust it. Open Codex’s hook review and approve it once.

Change what it checks

Everything the hook looks for lives in decide-before-building.json: which tools change files, which calls count as deciding, and which folders are free. To let your AI change files somewhere without deciding, add that folder to free_folders. To cover a new AI app’s file tool, add its name to file_tools.

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Decide before building

What counts as deciding

What it checks and what it leaves alone

Install

Change what it checks

​What counts as deciding

​What it checks and what it leaves alone

​Install

​Change what it checks

What counts as deciding

What it checks and what it leaves alone

Install

Change what it checks