hook: prefer-terraform-chdir (avoid cd+redirect gate); carry no-avoidable-cd + xargs wrapper

[joshuaLW]

Three follow-ups to the read-only permission-hook chain, all aimed at turning avoidable manual-approval prompts into analyzable commands that match an allowlist.

prefer-terraform-chdir (new PreToolUse/Bash handler)

A cd <dir> && terraform ... >log trips Claude Code's built-in "cd with an output redirect" gate — it can't resolve the redirect target against the post-cd working directory, so it forces a manual approval prompt.

This handler blocks that pattern and points at terraform's own -chdir=<dir> flag. With the cd gone the gate never fires, the redirect is harmless on its own, and the command can match a terraform allowlist and run with no prompt.

It's conservative:

• Only fires when every non-cd segment is terraform (or an inert passenger like echo/printf), so a cd that a later step genuinely needs (a script, a relative path, make, dbt) is left untouched.
• Requires an output redirection to be present — without one, cd <dir> && terraform ... doesn't trip the gate, so there's nothing to fix.
• Skips a cd whose target already equals the working directory, leaving that to strip-redundant-cd.

Includes a table row in the README and full block/allow/skip test coverage.

no-avoidable-cd and the xargs wrapper

These two commits were already on the branch (they post-date the last merge to master) and are carried along:

• no-avoidable-cd — nudges cd <repo> && git ... toward git -C <repo> ... / gh ... -R <owner/repo>, which avoids the "changes directory before running git" gate.
• auto-approve: treats xargs as a wrapper and recurses into the wrapped command.

Testing

go test ./... passes. The new handler was also verified end-to-end against the real chain with the motivating command (a terraform fmt/init/validate compound with a redirect on init); it blocks with the -chdir guidance and the concrete directory extracted from the cd.

🤖 Generated with Claude Code

[joshuaLW]

Heads-up on how the no-avoidable-cd handler carried in this PR relates to no-git-c (added in #4): they take opposite positions and are mutually exclusive by design.

• no-git-c blocks git -C <path> and steers to plain git …, on the premise that the command already runs in the working directory.
• no-avoidable-cd blocks cd <repo> && git … and steers to git -C <repo> (and gh … -R <owner/repo>).

The difference is whether the repo you want to act on is always the session's working directory. In a single-checkout setup, no-git-c's "just run plain git" is right. In a multi-worktree setup — several sibling checkouts of the same repo, where the agent frequently needs to operate on a tree that isn't the current working directory — git -C <path> is the correct target and dropping -C would silently run against the wrong tree. That's the workflow no-avoidable-cd is for.

So these two shouldn't live in the same hook chain. Suggested framing: keep both available but document them as an either/or — pick no-git-c for single-checkout, no-avoidable-cd for multi-worktree. Happy to add a note to the README table making that explicit, or to drop no-avoidable-cd from this PR and land only prefer-terraform-chdir + the xargs change if you'd rather not ship the opposing handler upstream. Your call.