Summary

`rtk rewrite` returns exit code 3 ("ask rule matched") for read-only file-inspection commands like `ls`, `grep`, `find`, `wc`. These are non-destructive and should return exit 0 ("auto-allow") so the Claude Code hook can rewrite and auto-execute them without requiring user approval on every call.

Reproduction

Running against the standard `rtk-rewrite.sh` hook (`rtk-hook-version: 3`):

```bash $ rtk rewrite 'ls -la /tmp' rtk ls -la /tmp $ echo $? 3

$ rtk rewrite 'grep -n foo /tmp/x' rtk grep -n foo /tmp/x $ echo $? 3

$ rtk rewrite 'ls -la /tmp; echo done' rtk ls -la /tmp; echo done $ echo $? 3

$ rtk rewrite 'ls /tmp && echo ok' rtk ls /tmp && echo ok $ echo $? 3 ```

All four return exit 3. Per the hook protocol documented in `rtk-rewrite.sh`:

```

Exit code protocol for `rtk rewrite`:

0 + stdout Rewrite found, no deny/ask rule matched → auto-allow

1 No RTK equivalent → pass through unchanged

2 Deny rule matched → pass through

3 + stdout Ask rule matched → rewrite but let Claude Code prompt the user

```

Why this matters

Read-only commands don't warrant a user prompt. But more importantly, exit 3 has a silent-failure mode in permissive Claude Code Bash configurations (filed separately): when exit 3 is returned, the hook outputs `updatedInput` without `permissionDecision`, expecting Claude Code to prompt. In a session where Bash is auto-approved, no prompt is shown and the mutation is silently dropped — the original unrewritten command runs.

Because of this interaction, classifying `ls`/`grep`/`find`/`wc` as exit 3 means in many real-world Claude Code sessions, RTK provides ~0% savings on the very commands that should be its hot path.

Empirically on my setup, `rtk discover` reports across 30 days of Claude Code usage:

Command	Count
`grep -n`	60
`ls -la`	27
`find`	24
`tail -20`	11
`wc -l`	5

All listed as "already handled by RTK" — yet the corresponding session JSONLs show raw command output, not rewritten format, proving the hook never successfully mutated them.

Suggested fix

In `src/discover/registry.rs`, classify these as auto-allow (exit 0):

• `ls`, `ll`
• `grep`, `rg`
• `find`
• `wc`
• `cat`, `head`, `tail`
• `stat`, `file`

Keep exit 3 for commands that modify state: `rm`, `mv`, destructive `git`/`npm` operations, etc.

Environment

• rtk: 0.23.0+ (verified via `rtk verify`: 141/141 tests pass)
• Claude Code: current
• Platform: macOS Darwin 25.5.0
• Hook: `rtk-hook-version: 3`