diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..c849a23
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,4 @@
+# Keep hook entrypoints portable with Git autocrlf enabled.
+.githooks/pre-push text eol=lf
+scripts/hooks/*.sh text eol=lf
+scripts/install-hooks.sh text eol=lf
diff --git a/.githooks/pre-push b/.githooks/pre-push
new file mode 100755
index 0000000..92db22b
--- /dev/null
+++ b/.githooks/pre-push
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(git rev-parse --show-toplevel)"
+# Validate the pushed commit, never a different or partially edited checkout.
+head=$(git rev-parse HEAD)
+required=0
+updates=0
+paths=$(mktemp)
+trap 'rm -f "$paths"' EXIT
+while read -r local_ref local_oid remote_ref remote_oid extra || [[ -n ${local_ref:-}${local_oid:-}${remote_ref:-}${remote_oid:-}${extra:-} ]]; do
+  updates=1
+  if [[ -n ${extra:-} || ! $local_oid =~ ^[0-9a-f]+$ || ! $remote_oid =~ ^[0-9a-f]+$ || ${#local_oid} != ${#head} || ${#remote_oid} != ${#head} ]]; then
+    echo 'Invalid pre-push input; no checks skipped.' >&2; exit 1
+  fi
+  [[ $local_oid =~ ^0+$ ]] && continue
+  commit=$(git rev-parse --verify "$local_oid^{commit}")
+  if [[ $commit != "$head" ]]; then
+    echo 'Push only checked-out HEAD. Validate other refs in their own clean checkout.' >&2; exit 1
+  fi
+  if [[ $remote_oid =~ ^0+$ ]] || ! base=$(git rev-parse --verify "$remote_oid^{commit}" 2>/dev/null); then
+    required=1
+    continue
+  fi
+  git diff --no-ext-diff --name-only --no-renames -z "$base" "$commit" > "$paths"
+  # Empty/unknown ranges broaden to full automation checks.
+  [[ -s $paths ]] || required=1
+  while IFS= read -r -d '' path; do
+    required=1
+  done < "$paths"
+done
+[[ $updates == 1 ]] || required=1
+[[ $required == 1 ]] || exit 0
+checkout_status=$(git status --porcelain --untracked-files=normal)
+if [[ -n $checkout_status ]]; then
+  echo 'Automation checks require a clean checkout of pushed HEAD. No stashing or rewriting is performed.' >&2; exit 1
+fi
+exec bash scripts/hooks/check.sh
diff --git a/docs/local-checks.md b/docs/local-checks.md
new file mode 100644
index 0000000..28c90ab
--- /dev/null
+++ b/docs/local-checks.md
@@ -0,0 +1,17 @@
+# Opt-in local checks
+
+Owner must first choose a replacement for the GPUI dependency that points at the deleted BumpyClock/zed repository. Never fetch or recreate that repository. Then explicitly prepare the approved pinned gpui-component submodule and installed Rust toolchain/dependencies.
+
+## Installation and push contract
+
+Enable explicitly with `bash scripts/install-hooks.sh` using Bash/Git Bash. Windows-target repositories also provide `pwsh -NoProfile -File scripts/install-hooks.ps1`. Installer is idempotent and refuses to hide existing active hooks or replace custom core.hooksPath. Relative repository-local .githooks resolves within each linked worktree. It is never installed automatically.
+
+Every nondeleted ref must resolve to checked-out HEAD. Checks require a clean checkout including nonignored untracked files. No stash, rewriting, fetch or actual push occurs. New refs, unavailable bases, empty input/ranges, deletions, renames and shared changes broaden to full project checks. Multiple refs are consumed before one validation. Deleted refs alone skip. Other commits need their own clean checkout.
+
+## Commands and acceptance
+
+Prepared hook refuses the deleted dependency before Cargo can fetch it. After dependency ownership is resolved, it runs full `cargo fmt --all -- --check` and `cargo check --workspace --locked --offline`. Whole workspace is conservative until a passing baseline exists. No credentials or live provider accounts are touched.
+
+Application ref is main, not data-only tsq-sync. Deleted pinned GPUI origin and absent vendor submodule prevent real workspace acceptance. No dependency substitution is guessed.
+
+`python3 scripts/hooks/test-hooks.py` exercises executable hooks and installers in disposable Git repositories with stub project commands, including linked worktrees. No actual push. Harness evidence is separate from actual project/native acceptance. No under-nine-second promise, CI activation or affected-only optimization is claimed. No user hooks were installed during preparation.
diff --git a/scripts/hooks/check.sh b/scripts/hooks/check.sh
new file mode 100755
index 0000000..bf2bada
--- /dev/null
+++ b/scripts/hooks/check.sh
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+set -euo pipefail
+command -v cargo >/dev/null || { echo 'Prepare the project Rust toolchain and locked dependencies first.' >&2; exit 1; }
+export RUSTUP_AUTO_INSTALL=0 CARGO_NET_OFFLINE=true
+[[ -f Cargo.lock ]] || { echo 'Missing Cargo.lock; restore the tracked lockfile.' >&2; exit 1; }
+if grep -q 'https://github.com/BumpyClock/zed' Cargo.toml; then
+  echo 'Pinned GPUI points at a deleted repository. Owner must choose a replacement; hook never fetches it.' >&2; exit 1
+fi
+[[ -f vendor/gpui-component/crates/ui/Cargo.toml ]] || { echo 'Prepare the pinned gpui-component submodule explicitly before pushing.' >&2; exit 1; }
+cargo fmt --all -- --check
+cargo check --workspace --locked --offline
diff --git a/scripts/hooks/test-hooks.py b/scripts/hooks/test-hooks.py
new file mode 100644
index 0000000..54c4a0b
--- /dev/null
+++ b/scripts/hooks/test-hooks.py
@@ -0,0 +1,168 @@
+#!/usr/bin/env python3
+"""Exercise executable hooks/installers in disposable Git repositories. No push."""
+import os
+import shutil
+import subprocess
+import tempfile
+import unittest
+from pathlib import Path
+
+SOURCE = Path(__file__).resolve().parents[2]
+
+
+class HookTests(unittest.TestCase):
+    def setUp(self):
+        self.temp = tempfile.TemporaryDirectory(prefix="hooks space ")
+        self.addCleanup(self.temp.cleanup)
+        self.root = Path(self.temp.name)
+        self.env = dict(os.environ, GIT_CONFIG_NOSYSTEM="1", GIT_CONFIG_GLOBAL=os.devnull)
+        self.run_command("git", "init", "-q")
+        shutil.copytree(SOURCE / ".githooks", self.root / ".githooks")
+        (self.root / "scripts/hooks").mkdir(parents=True)
+        shutil.copy2(SOURCE / "scripts/install-hooks.sh", self.root / "scripts/install-hooks.sh")
+        # Stub only the project payload. Range/clean-tree/installer code is real.
+        (self.root / "scripts/hooks/check.sh").write_text(
+            '#!/usr/bin/env bash\nprintf "checked\\n" >> "$HOOK_RECEIPT"\nexit "${HOOK_EXIT:-0}"\n')
+        self.env["HOOK_RECEIPT"] = str(self.root / ".git/receipt")
+        self.commit()
+        self.base = self.git("rev-parse", "HEAD").stdout.strip()
+
+    def run_command(self, *args, input=None, expected=0):
+        result = subprocess.run(args, cwd=self.root, env=self.env, input=input,
+                                text=True, capture_output=True)
+        if expected is not None:
+            self.assertEqual(result.returncode, expected, result.stdout + result.stderr)
+        return result
+
+    def git(self, *args, **kwargs):
+        return self.run_command("git", *args, **kwargs)
+
+    def commit(self):
+        self.git("add", ".")
+        self.git("-c", "user.name=Hook Fixture", "-c", "user.email=fixture@invalid",
+                 "-c", "commit.gpgsign=false", "-c", "core.hooksPath=/dev/null",
+                 "commit", "-qm", "fixture", "--allow-empty")
+
+    def update(self, path="source with spaces.go"):
+        (self.root / path).write_text("changed\n")
+        self.commit()
+        return self.git("rev-parse", "HEAD").stdout.strip()
+
+    def row(self, local=None, remote=None):
+        head = self.git("rev-parse", "HEAD").stdout.strip()
+        return f"refs/heads/test {local or head} refs/heads/test {remote or self.base}\n"
+
+    def hook(self, data=None, expected=0):
+        return self.run_command(str(self.root / ".githooks/pre-push"), "origin", "unused",
+                                input=self.row() if data is None else data, expected=expected)
+
+    def checked(self):
+        return (self.root / ".git/receipt").exists()
+
+    def test_changed_path_with_spaces_and_failure_propagation(self):
+        self.update()
+        self.env["HOOK_EXIT"] = "23"
+        self.hook(expected=23)
+        self.assertTrue(self.checked())
+
+    def test_new_branch_unknown_base_and_empty_input_broaden(self):
+        for data in (self.row(remote="0" * 40), self.row(remote="1" * 40), "", self.row()):
+            self.hook(data)
+            self.assertTrue(self.checked())
+            (self.root / ".git/receipt").unlink()
+
+    def test_deleting_ref_needs_no_project_tools(self):
+        self.hook(self.row(local="0" * 40))
+        self.assertFalse(self.checked())
+
+    def test_multiple_refs_cannot_hide_later_failure(self):
+        self.update()
+        self.env["HOOK_EXIT"] = "17"
+        self.hook(self.row(local="0" * 40) + self.row(), expected=17)
+        self.assertTrue(self.checked())
+
+    def test_last_record_without_newline_is_not_skipped(self):
+        self.update()
+        self.env["HOOK_EXIT"] = "19"
+        self.hook(self.row(local="0" * 40) + self.row().rstrip("\n"), expected=19)
+        self.assertTrue(self.checked())
+
+    def test_git_status_failure_is_not_green(self):
+        self.update()
+        real_git = shutil.which("git")
+        tools = self.root / ".git/tools"
+        tools.mkdir()
+        stub = tools / "git"
+        stub.write_text(f'#!/bin/sh\nif [ "$1" = status ]; then exit 42; fi\nexec "{real_git}" "$@"\n')
+        stub.chmod(0o755)
+        self.env["PATH"] = str(tools) + os.pathsep + self.env["PATH"]
+        self.hook(expected=42)
+        self.assertFalse(self.checked())
+
+    def test_non_head_and_malformed_input_fail(self):
+        self.update()
+        self.hook(self.row(local=self.base), expected=1)
+        self.hook("malformed\n", expected=1)
+        self.assertFalse(self.checked())
+
+    def test_dirty_checkout_refused_without_rewriting(self):
+        self.update()
+        target = self.root / "untracked.txt"
+        target.write_text("preserve me")
+        self.hook(expected=1)
+        self.assertEqual(target.read_text(), "preserve me")
+        self.assertFalse(self.checked())
+
+    def test_rename_and_deletion_not_skipped(self):
+        self.update()
+        self.git("mv", "source with spaces.go", "renamed.go")
+        self.commit()
+        self.hook()
+        self.assertTrue(self.checked())
+        (self.root / ".git/receipt").unlink()
+        self.git("rm", "renamed.go")
+        self.commit()
+        self.hook()
+        self.assertTrue(self.checked())
+
+    def test_installer_idempotent_and_preserves_active_hook(self):
+        active = self.root / ".git/hooks/pre-commit"
+        active.write_text("#!/bin/sh\nexit 7\n")
+        active.chmod(0o755)
+        self.run_command("bash", "scripts/install-hooks.sh", expected=1)
+        self.assertEqual(active.read_text(), "#!/bin/sh\nexit 7\n")
+        active.unlink()
+        self.run_command("bash", "scripts/install-hooks.sh")
+        self.run_command("bash", "scripts/install-hooks.sh")
+        self.assertEqual(self.git("config", "--get", "core.hooksPath").stdout.strip(), ".githooks")
+
+    def test_installer_preserves_custom_configuration(self):
+        self.git("config", "core.hooksPath", "custom hooks")
+        self.run_command("bash", "scripts/install-hooks.sh", expected=1)
+        self.assertEqual(self.git("config", "--get", "core.hooksPath").stdout.strip(), "custom hooks")
+
+    def test_linked_worktree_installer_resolves_its_own_checkout(self):
+        with tempfile.TemporaryDirectory(prefix="linked hooks ") as directory:
+            linked = Path(directory) / "checkout"
+            self.git("worktree", "add", "--detach", str(linked), "HEAD")
+            result = subprocess.run(["bash", "scripts/install-hooks.sh"], cwd=linked,
+                                    env=self.env, capture_output=True, text=True)
+            self.assertEqual(result.returncode, 0, result.stderr)
+            result = subprocess.run([str(linked / ".githooks/pre-push")], cwd=linked,
+                                    env=self.env, input="", capture_output=True, text=True)
+            self.assertEqual(result.returncode, 0, result.stderr)
+            self.assertTrue(self.checked())
+
+    def test_content_only_skip_and_instruction_fallback(self):
+        if not (SOURCE / "package.json").exists() or 'personal-assistant' not in (SOURCE / "package.json").read_text():
+            self.skipTest("PersonalAssistant content policy only")
+        self.update("notes.md")
+        self.hook()
+        self.assertFalse(self.checked())
+        self.update("AGENTS.md")
+        self.hook()
+        self.assertTrue(self.checked())
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/scripts/install-hooks.sh b/scripts/install-hooks.sh
new file mode 100755
index 0000000..0d2afc3
--- /dev/null
+++ b/scripts/install-hooks.sh
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(git rev-parse --show-toplevel)"
+current=$(git config --get core.hooksPath || true)
+if [[ -n $current && $current != .githooks ]]; then
+  echo 'Refusing to replace existing core.hooksPath. Reconcile existing hooks explicitly.' >&2; exit 1
+fi
+if [[ -z $current ]]; then
+  hooks=$(git rev-parse --git-path hooks)
+  for hook in "$hooks"/*; do
+    [[ $hook == *.sample || ! -x $hook || -d $hook ]] && continue
+    echo 'Refusing to hide existing active hooks. Reconcile them explicitly.' >&2; exit 1
+  done
+fi
+[[ -x .githooks/pre-push ]] || { echo 'Missing executable .githooks/pre-push.' >&2; exit 1; }
+# Relative hooksPath resolves within each worktree, not the installer checkout.
+git config --local core.hooksPath .githooks
+echo 'Opt-in hooks enabled for this repository. No tools installed.'