---
name: git-commit-signing
description: "Commits sign in-sandbox via ssh-agent (allowAllUnixSockets + inlined pubkey); local verify shows sig=N without an allowedSignersFile but the commit IS signed."
metadata:
  node_type: memory
  type: feedback
  originSessionId: a223254b-6bee-435f-ac39-e3cedf064893
---

Lyra's git is configured to SSH-sign commits (`commit.gpgsign=true`, `gpg.format=ssh`). The sandbox masks `~/.ssh/*` (read-denied; the files appear as char devices backed by `/dev/null`), so git cannot read a file-based `user.signingkey` and ssh-keygen cannot read the private key directly. Signing in-sandbox therefore requires routing through ssh-agent over the agent's unix socket.

**Working setup (as of 2026-06-02):**

1. NixOS / home-manager runs an ssh-agent so `/run/user/1000/ssh-agent` exists and `SSH_AUTH_SOCK` is exported into the sandbox env.
2. `~/.claude/settings.json` has `sandbox.network.allowAllUnixSockets: true` to let the sandbox `connect()` to that socket. On Linux/WSL2 this is the ONLY available switch — the per-path `sandbox.network.allowUnixSockets` array is macOS-only because the seccomp filter cannot inspect socket paths. Tradeoff: every unix socket on the host (including `/var/run/docker.sock` if present, DBus, etc.) becomes reachable from sandboxed commands.
3. `user.signingkey` set to the inlined pubkey: `git config --global user.signingkey "key::$(cat ~/.ssh/id_ed25519.pub)"`. Must run with DOUBLE quotes outside the sandbox so `$(...)` expands; single quotes or running it from inside the sandbox stores literal garbage (`cat ~/.ssh/id_ed25519.pub` reads `/dev/null` in-sandbox).

**Why:** removes the per-commit `! git commit ...` friction; private key stays in the agent, never enters the sandbox.

**How to apply:** Commit normally with `git commit`. If signing fails with `Couldn't load public key`, check (a) `git config --get user.signingkey` starts with `key::ssh-ed25519 AAAA...` (not literal `$(...)`), (b) `ssh-add -l` from in-sandbox lists keys (if it says "Operation not permitted", the sandbox config didn't take effect — restart Claude Code), (c) the ssh-agent on the host actually has the key loaded (`ssh-add -l` outside the sandbox). Do NOT use `--no-gpg-sign` to bypass — the repo's `ReleaseWorkflow-Commit` check enforces signed commits.

**Verifying — the recurring trap:** `git log --show-signature` and the `%G?` format both report `N` and print `error: gpg.ssh.allowedSignersFile needs to be configured and exist for ssh signature verification`. This does NOT mean the commit is unsigned — it means git has no local allowed-signers file to check it against. The signature is present. Confirm the real state with `git cat-file commit <ref> | grep -i '^gpgsig'`: an `-----BEGIN SSH SIGNATURE-----` block means signed. So `N` here is cosmetic, not a signing failure — do not "fix" it by re-committing. To make local verification actually pass, set `gpg.ssh.allowedSignersFile` to a file mapping the signer to the pubkey (a line like `emma.thorpe@cloud.com ssh-ed25519 AAAA...`); Gitea/CI verifies server-side regardless.

Related: [[git-network-ops]], [[git-conventions]].
