docs: add sync-clone and commit-clean helpers

CONTRIBUTING.md

@@ -74,10 +74,26 @@ refactor!: rename ClientV1 to Client (BREAKING CHANGE)
 ```
 
 **Co-authors:** do not add `Co-authored-by:` trailers. Commits should list
-only the human author. Optional local hook:
+only the human author. Install hooks with:
 
 ```bash
-git config core.hooksPath .githooks
+make hooks
+```
+
+This enables lefthook (format/lint/conventional commits) and the tracked
+`.githooks/prepare-commit-msg` strip hook.
+
+**Cursor / IDE commits:** some editors inject `Co-authored-by: Cursor` via their
+own git hooks. Use:
+
+```bash
+./scripts/commit-clean.sh -m "fix(scope): your message"
+```
+
+**After a history rewrite:** reset stale local SHAs with:
+
+```bash
+./scripts/sync-clone.sh
 ```
 
 ## Pull request checklist

Makefile

@@ -115,6 +115,12 @@ clean: ## Remove build artefacts.
 help: ## Show this help.
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-15s\033[0m %s\n", $$1, $$2}'
 
-.PHONY: hooks
-hooks:
+.PHONY: hooks sync-clone
+hooks: ## Install git hooks (lefthook + tracked .githooks prepare-commit-msg).
+	@command -v lefthook >/dev/null 2>&1 || (echo "install: go install github.com/evilmartians/lefthook@latest" && exit 1)
 	git config core.hooksPath .githooks
+	lefthook install
+
+sync-clone: ## Hard-reset eyrie to origin/main (post history rewrite).
+	@chmod +x scripts/sync-clone.sh scripts/commit-clean.sh
+	@./scripts/sync-clone.sh

scripts/commit-clean.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# Commit without IDE-injected Co-authored-by trailers (Cursor, etc.).
+# Usage: ./scripts/commit-clean.sh [-m "message"] [other git commit args...]
+set -euo pipefail
+
+cd "$(git rev-parse --show-toplevel)"
+exec git -c core.hooksPath=/dev/null commit "$@"

scripts/sync-clone.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+# Hard-reset eyrie to origin/main. Use after a history rewrite or stale SHAs.
+set -euo pipefail
+
+cd "$(git rev-parse --show-toplevel)"
+
+echo "==> Fetching origin"
+git fetch origin
+
+echo "==> Resetting eyrie to origin/main"
+git checkout main
+git reset --hard origin/main
+
+echo "==> Done. eyrie: $(git rev-parse --short HEAD)"