# ReversibilityTier

**Kind:** Type

**Source:** [`atloria-monorepo/libs/agent-core/src/session/permission-gate.ts`](https://github.com/sherkety/atloria/blob/main/atloria-monorepo/libs/agent-core/src/session/permission-gate.ts#L17)

Permission Gate — Bash Command Reversibility Classification

Classifies bash commands into reversibility tiers before execution.
Inspired by Claude Code's blast-radius awareness.

Tiers:
 T0 — Read-only: cat, ls, grep, git log — zero side effects
 T1 — Reversible: mkdir, npm install, git add — easy to undo
 T2 — Hard-to-reverse: git push, npm publish — requires effort to undo
 T3 — Irreversible: rm -rf, DROP TABLE, DELETE without WHERE — blocked

Consumers:
 - bash.tool.ts: annotates outputs with tier, hard-blocks T3

## Definition

```ts
'T0' | 'T1' | 'T2' | 'T3'
```