Pre-flight: check ssh-add -l before asking user to load a key

Keys are often pre-loaded. Added explicit check-first guidance and
a note to use grep -i (case-insensitive) — a case-sensitive grep
will silently miss keys whose comments use different capitalisation.

CLAUDE.md

@@ -78,7 +78,7 @@ Hard-won lessons that apply across every project:
 - **Verify scripts should be environment-resilient.** Avoid needing sudo or special access. Test from the accessible side of a connection. Use `curl --resolve` to bypass DNS/proxy layers when testing direct connectivity.
 - **Automate repeated sequences.** If you run the same 3+ commands in sequence more than once, it should become a script.
 - **Reflect after milestones.** Don't just finish — review what happened, what went wrong, what can be improved. Write it down.
-- **Pre-flight before push.** Before any `git push`: derive the SSH alias from `git remote get-url origin`, confirm that key is loaded (`ssh-add -l`). Passphrase-protected keys must be `ssh-add`ed by the user — hand off, don't retry. If a push fails: commit locally, say so explicitly, note the recovery step in CONTEXT.md. Details: `claude/source-control.md`.
+- **Pre-flight before push.** Before any `git push`: derive the SSH alias from `git remote get-url origin`, then run `ssh-add -l` and inspect the full output — keys are often pre-loaded, so always check before asking the user to load one. Use `grep -i` (case-insensitive) when scanning for the relevant key name. Only ask if the key is genuinely absent. Passphrase-protected keys must be `ssh-add`ed by the user — hand off, don't retry. If a push fails: commit locally, say so explicitly, note the recovery step in CONTEXT.md. Details: `claude/source-control.md`.
 - **Everyday shell/edit footguns.** `grep` exits 1 on no match (breaks `set -e` chains); Edit `replace_all` matches substrings — make the old string unique. Full list: `claude/scripting-conventions.md`.
 
 ## Session End