[krisiasty]

Pull request

Summary

-install saved the symlink-resolved path of the running binary in the service definition. This project ships a Homebrew cask, which installs each version under <prefix>/Caskroom/ssh-agent-proxy/<version>/, links it into <prefix>/bin, and removes the old version on upgrade. After the first brew upgrade, the service therefore pointed at a binary that no longer existed and could not start until it was reinstalled. Formulas behave the same way under <prefix>/Cellar.

• When the resolved binary is inside a Homebrew Caskroom or Cellar directory, the service records the <prefix>/bin/<name> link instead, which Homebrew repoints on upgrade. The link is used only when it is verifiably the same file; otherwise the resolved path is kept as before.
• -start and -restart fail with a -reinstall hint when the recorded binary no longer exists, and print a warning when it differs from the binary being run. The installed definition, config path, and cache arguments are never rewritten implicitly; -reinstall remains the way to change them.
• -diag reports a missing installed binary as a failure with the same hint, and now shares the path comparison (service.SamePath, service.CurrentExecutable) with the lifecycle commands instead of keeping its own copy.
• README: documents which binary the service records, that brew upgrade takes effect at the next -restart, and the one-time -reinstall for services installed by earlier versions.

Closes #50.

User impact

New installs from Homebrew record /opt/homebrew/bin/ssh-agent-proxy (or the equivalent prefix), so upgrades take effect at the next restart without reinstalling. Existing installs still record the versioned Caskroom path and need one ssh-agent-proxy -reinstall from a build that includes this change. When the recorded binary is missing, -start and -restart now explain how to fix it instead of failing inside launchd or systemd.

Installations outside Homebrew are unchanged: they record the resolved binary path and need -reinstall after the binary is moved or replaced.

Validation

• Unit tests: cask and formula layouts map to the bin link; a missing link, a link to a different version, and a non-Homebrew path keep the resolved path; the program check accepts present, uninstalled, and unknown programs and rejects a removed one with a -reinstall hint; path comparison follows the Homebrew link and distinguishes versions; -diag fails on a missing installed binary; the -start/-restart check rejects a removed binary.
• Mutation checks in scratch copies: disabling the link mapping and removing the start/restart check each fail the corresponding tests.
• Read-only probe against the real local cask layout: the installed /opt/homebrew/Caskroom/ssh-agent-proxy/0.99.2/ssh-agent-proxy maps to /opt/homebrew/bin/ssh-agent-proxy, and a removed version path yields the reinstall error. A real brew upgrade was not run.
• SSH_AGENT_PROXY_REQUIRE_OPENSSH=1 go test -race ./....
• Native and Linux golangci-lint (0 issues), go vet ./... (also GOOS=linux), formatting, git diff --check, and CGO-disabled builds for darwin/linux × amd64/arm64.

Checklist

• Tests cover changed behavior.
• Documentation is updated when behavior or design changed.
• No credentials, private configuration, or identifying key metadata are included.
• go test -race ./... passes locally, or the reason it was not run is documented.

🤖 Generated with Claude Code