add git commit hook - auto-rebuilds graph after every commit

README.md

@@ -70,6 +70,8 @@ When the user types `/graphify`, invoke the Skill tool with `skill: "graphify"`
 /graphify explain "SwinTransformer"
 
 /graphify ./raw --watch            # auto-sync graph as files change (code: instant, docs: notifies you)
+
+graphify hook install              # post-commit git hook - rebuilds graph on every commit automatically
 /graphify ./raw --wiki             # build agent-crawlable wiki (index.md + article per community)
 /graphify ./raw --svg              # export graph.svg
 /graphify ./raw --graphml          # export graph.graphml (Gephi, yEd)
@@ -98,6 +100,8 @@ Works with any mix of file types:
 
 **Auto-sync** (`--watch`) - run in a background terminal and the graph updates itself as your codebase changes. Code file saves trigger an instant rebuild (AST only, no LLM). Doc/image changes notify you to run `--update` for the LLM re-pass. Useful for agentic workflows where multiple agents are writing code in parallel - the graph stays current between waves automatically.
 
+**Git commit hook** (`graphify hook install`) - installs a post-commit hook that rebuilds the graph after every commit. No background process needed. Triggers once per commit, works with any editor, safe to add alongside existing hooks.
+
 **Wiki** (`--wiki`) - Wikipedia-style markdown articles per community and god node, with an `index.md` entry point. Point any agent at `index.md` and it can navigate the knowledge base by reading files instead of parsing JSON.
 
 Every edge is tagged `EXTRACTED`, `INFERRED`, or `AMBIGUOUS` - you always know what was found vs guessed.

graphify/__main__.py

@@ -59,12 +59,27 @@ def main() -> None:
         print("Commands:")
         print("  install                 copy skill to ~/.claude/skills/ and register in CLAUDE.md")
         print("  benchmark [graph.json]  measure token reduction vs naive full-corpus approach")
+        print("  hook install            install post-commit git hook (auto-rebuilds graph on commit)")
+        print("  hook uninstall          remove post-commit git hook")
+        print("  hook status             check if hook is installed")
         print()
         return
 
     cmd = sys.argv[1]
     if cmd == "install":
         install()
+    elif cmd == "hook":
+        from graphify.hooks import install as hook_install, uninstall as hook_uninstall, status as hook_status
+        subcmd = sys.argv[2] if len(sys.argv) > 2 else ""
+        if subcmd == "install":
+            print(hook_install(Path(".")))
+        elif subcmd == "uninstall":
+            print(hook_uninstall(Path(".")))
+        elif subcmd == "status":
+            print(hook_status(Path(".")))
+        else:
+            print("Usage: graphify hook [install|uninstall|status]", file=sys.stderr)
+            sys.exit(1)
     elif cmd == "benchmark":
         from graphify.benchmark import run_benchmark, print_benchmark
         graph_path = sys.argv[2] if len(sys.argv) > 2 else "graphify-out/graph.json"

graphify/hooks.py

@@ -0,0 +1,118 @@
+# git hook integration - install/uninstall graphify post-commit hook
+from __future__ import annotations
+from pathlib import Path
+
+_HOOK_MARKER = "# graphify-hook"
+
+_HOOK_SCRIPT = """\
+#!/bin/bash
+# graphify-hook
+# Auto-rebuilds the knowledge graph after each commit (code files only, no LLM needed).
+# Installed by: graphify hook install
+
+CHANGED=$(git diff --name-only HEAD~1 HEAD 2>/dev/null || git diff --name-only HEAD 2>/dev/null)
+if [ -z "$CHANGED" ]; then
+    exit 0
+fi
+
+export GRAPHIFY_CHANGED="$CHANGED"
+python3 -c "
+import os, sys
+from pathlib import Path
+
+CODE_EXTS = {
+    '.py', '.ts', '.js', '.go', '.rs', '.java', '.cpp', '.c', '.rb', '.swift',
+    '.kt', '.cs', '.scala', '.php', '.cc', '.cxx', '.hpp', '.h', '.kts',
+}
+
+changed_raw = os.environ.get('GRAPHIFY_CHANGED', '')
+changed = [Path(f.strip()) for f in changed_raw.strip().splitlines() if f.strip()]
+code_changed = [f for f in changed if f.suffix.lower() in CODE_EXTS and f.exists()]
+
+if not code_changed:
+    sys.exit(0)
+
+print(f'[graphify hook] {len(code_changed)} code file(s) changed - rebuilding graph...')
+
+try:
+    from graphify.watch import _rebuild_code
+    _rebuild_code(Path('.'))
+except Exception as exc:
+    print(f'[graphify hook] Rebuild failed: {exc}')
+    sys.exit(0)
+"
+"""
+
+
+def _git_root(path: Path) -> Path | None:
+    """Walk up to find .git directory."""
+    current = path.resolve()
+    for parent in [current, *current.parents]:
+        if (parent / ".git").exists():
+            return parent
+    return None
+
+
+def install(path: Path = Path(".")) -> str:
+    """Install graphify post-commit hook in the nearest git repo.
+
+    Returns a message describing what was done.
+    """
+    root = _git_root(path)
+    if root is None:
+        raise RuntimeError(f"No git repository found at or above {path.resolve()}")
+
+    hooks_dir = root / ".git" / "hooks"
+    hooks_dir.mkdir(exist_ok=True)
+    hook_path = hooks_dir / "post-commit"
+
+    if hook_path.exists():
+        content = hook_path.read_text()
+        if _HOOK_MARKER in content:
+            return f"graphify hook already installed at {hook_path}"
+        # Append to existing hook
+        hook_path.write_text(content.rstrip() + "\n\n" + _HOOK_SCRIPT)
+        return f"graphify hook appended to existing post-commit hook at {hook_path}"
+
+    hook_path.write_text(_HOOK_SCRIPT)
+    hook_path.chmod(0o755)
+    return f"graphify hook installed at {hook_path}"
+
+
+def uninstall(path: Path = Path(".")) -> str:
+    """Remove graphify post-commit hook."""
+    root = _git_root(path)
+    if root is None:
+        raise RuntimeError(f"No git repository found at or above {path.resolve()}")
+
+    hook_path = root / ".git" / "hooks" / "post-commit"
+    if not hook_path.exists():
+        return "No post-commit hook found - nothing to remove."
+
+    content = hook_path.read_text()
+    if _HOOK_MARKER not in content:
+        return "graphify hook not found in post-commit - nothing to remove."
+
+    # Strip everything from our marker onwards
+    before = content.split(_HOOK_MARKER)[0].rstrip()
+    # 'before' is empty or just a shebang line if the whole file was ours
+    non_empty = [l for l in before.splitlines() if l.strip() and not l.startswith("#!")]
+    if not non_empty:
+        hook_path.unlink()
+        return f"Removed post-commit hook at {hook_path}"
+    else:
+        hook_path.write_text(before + "\n")
+        return f"graphify hook removed from {hook_path} (other hook content preserved)"
+
+
+def status(path: Path = Path(".")) -> str:
+    """Check if graphify hook is installed."""
+    root = _git_root(path)
+    if root is None:
+        return "Not in a git repository."
+    hook_path = root / ".git" / "hooks" / "post-commit"
+    if not hook_path.exists():
+        return "graphify hook: not installed"
+    if _HOOK_MARKER in hook_path.read_text():
+        return f"graphify hook: installed at {hook_path}"
+    return "graphify hook: not installed (post-commit exists but graphify hook not found)"

graphify/skill.md

@@ -1119,6 +1119,22 @@ For agentic workflows: run `--watch` in a background terminal. Code changes from
 
 ---
 
+## For git commit hook
+
+Install a post-commit hook that auto-rebuilds the graph after every commit. No background process needed - triggers once per commit, works with any editor.
+
+```bash
+graphify hook install    # install
+graphify hook uninstall  # remove
+graphify hook status     # check
+```
+
+After every `git commit`, the hook detects which code files changed (via `git diff HEAD~1`), re-runs AST extraction on those files, and rebuilds `graph.json` and `GRAPH_REPORT.md`. Doc/image changes are ignored by the hook - run `/graphify --update` manually for those.
+
+If a post-commit hook already exists, graphify appends to it rather than replacing it.
+
+---
+
 ## Honesty Rules
 
 - Never invent an edge. If unsure, use AMBIGUOUS.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "graphifyy"
-version = "0.1.9"
+version = "0.1.10"
 description = "Claude Code skill - turn any folder of code, docs, papers, images, or tweets into a queryable knowledge graph"
 readme = "README.md"
 license = { text = "MIT" }

skills/graphify/skill.md

@@ -1119,6 +1119,22 @@ For agentic workflows: run `--watch` in a background terminal. Code changes from
 
 ---
 
+## For git commit hook
+
+Install a post-commit hook that auto-rebuilds the graph after every commit. No background process needed - triggers once per commit, works with any editor.
+
+```bash
+graphify hook install    # install
+graphify hook uninstall  # remove
+graphify hook status     # check
+```
+
+After every `git commit`, the hook detects which code files changed (via `git diff HEAD~1`), re-runs AST extraction on those files, and rebuilds `graph.json` and `GRAPH_REPORT.md`. Doc/image changes are ignored by the hook - run `/graphify --update` manually for those.
+
+If a post-commit hook already exists, graphify appends to it rather than replacing it.
+
+---
+
 ## Honesty Rules
 
 - Never invent an edge. If unsure, use AMBIGUOUS.

tests/test_hooks.py

@@ -0,0 +1,80 @@
+"""Tests for hooks.py - git hook install/uninstall."""
+import subprocess
+from pathlib import Path
+import pytest
+from graphify.hooks import install, uninstall, status, _HOOK_MARKER
+
+
+def _make_git_repo(tmp_path: Path) -> Path:
+    subprocess.run(["git", "init", str(tmp_path)], check=True, capture_output=True)
+    return tmp_path
+
+
+def test_install_creates_hook(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    result = install(repo)
+    hook = repo / ".git" / "hooks" / "post-commit"
+    assert hook.exists()
+    assert _HOOK_MARKER in hook.read_text()
+    assert "installed" in result
+
+
+def test_install_is_executable(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    install(repo)
+    hook = repo / ".git" / "hooks" / "post-commit"
+    assert hook.stat().st_mode & 0o111  # executable bit set
+
+
+def test_install_idempotent(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    install(repo)
+    result = install(repo)
+    assert "already installed" in result
+    # marker appears only once
+    hook = repo / ".git" / "hooks" / "post-commit"
+    assert hook.read_text().count(_HOOK_MARKER) == 1
+
+
+def test_install_appends_to_existing_hook(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    hook = repo / ".git" / "hooks" / "post-commit"
+    hook.write_text("#!/bin/bash\necho existing\n")
+    hook.chmod(0o755)
+    install(repo)
+    content = hook.read_text()
+    assert "existing" in content
+    assert _HOOK_MARKER in content
+
+
+def test_uninstall_removes_hook(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    install(repo)
+    result = uninstall(repo)
+    hook = repo / ".git" / "hooks" / "post-commit"
+    assert not hook.exists()
+    assert "Removed" in result
+
+
+def test_uninstall_no_hook(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    result = uninstall(repo)
+    assert "nothing to remove" in result
+
+
+def test_status_installed(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    install(repo)
+    result = status(repo)
+    assert "installed" in result
+
+
+def test_status_not_installed(tmp_path):
+    repo = _make_git_repo(tmp_path)
+    result = status(repo)
+    assert "not installed" in result
+
+
+def test_no_git_repo_raises(tmp_path):
+    with pytest.raises(RuntimeError, match="No git repository"):
+        install(tmp_path / "not_a_repo")