`src/middleware/permission.rs` — `PermissionMiddleware`

The pipeline’s enforcement point for the PermissionCheck decision type.

Key items

• Constructors: deny_all(), allow_all(), from_context() (honors ctx.permission); builders with_check(fn), with_ask_resolver(async fn).
• Types: PermissionCheckFn, AskResolverFn (args: prompt, tool name; true = allow).

Behavior notes

• Deny short-circuits the whole inner chain: soft error "Permission <reason> for tool 'x'", zero duration — tests pin that nothing inside executes.
• Ask without a resolver is denied (headless-safe): "permission required: <prompt>".
• Modify rewrites ctx.input then proceeds — the replacement is not re-validated against the tool’s schema.
• Install it outermost (or near) so denial happens before any other layer’s work.

Deep dive: Permissions.