diff --git a/graphify/__main__.py b/graphify/__main__.py
index 596d8fe..2a03087 100644
--- a/graphify/__main__.py
+++ b/graphify/__main__.py
@@ -14,6 +14,10 @@ try:
 except Exception:
     __version__ = "unknown"
 
+# Output directory — override with GRAPHIFY_OUT env var for worktrees or shared-output setups.
+# Accepts a relative name ("graphify-out-feature") or an absolute path ("/shared/graphify-out").
+_GRAPHIFY_OUT = os.environ.get("GRAPHIFY_OUT", "graphify-out")
+
 
 def _check_skill_version(skill_dst: Path) -> None:
     """Warn if the installed skill is from an older graphify version."""
@@ -553,7 +557,12 @@ def _antigravity_install(project_dir: Path) -> None:
     rules_path = project_dir / _ANTIGRAVITY_RULES_PATH
     rules_path.parent.mkdir(parents=True, exist_ok=True)
     if rules_path.exists():
-        print(f"graphify rule already exists at {rules_path} (no change)")
+        existing = rules_path.read_text(encoding="utf-8")
+        if _ANTIGRAVITY_RULES.strip() != existing.strip():
+            rules_path.write_text(_ANTIGRAVITY_RULES, encoding="utf-8")
+            print(f"graphify rule updated at {rules_path.resolve()}")
+        else:
+            print(f"graphify rule already up to date at {rules_path.resolve()}")
     else:
         rules_path.write_text(_ANTIGRAVITY_RULES, encoding="utf-8")
         print(f"graphify rule written to {rules_path.resolve()}")
@@ -562,7 +571,12 @@ def _antigravity_install(project_dir: Path) -> None:
     wf_path = project_dir / _ANTIGRAVITY_WORKFLOW_PATH
     wf_path.parent.mkdir(parents=True, exist_ok=True)
     if wf_path.exists():
-        print(f"graphify workflow already exists at {wf_path} (no change)")
+        existing = wf_path.read_text(encoding="utf-8")
+        if _ANTIGRAVITY_WORKFLOW.strip() != existing.strip():
+            wf_path.write_text(_ANTIGRAVITY_WORKFLOW, encoding="utf-8")
+            print(f"graphify workflow updated at {wf_path.resolve()}")
+        else:
+            print(f"graphify workflow already up to date at {wf_path.resolve()}")
     else:
         wf_path.write_text(_ANTIGRAVITY_WORKFLOW, encoding="utf-8")
         print(f"graphify workflow written to {wf_path.resolve()}")
@@ -1539,7 +1553,7 @@ def main() -> None:
             watch_path = Path(argv[2])
         else:
             # Try to recover the scan root saved by the last full build
-            saved = Path("graphify-out/.graphify_root")
+            saved = Path(_GRAPHIFY_OUT) / ".graphify_root"
             if saved.exists():
                 watch_path = Path(saved.read_text(encoding="utf-8").strip())
             else:
@@ -1578,7 +1592,7 @@ def main() -> None:
         # showing top-K outbound edges per symbol.
         from typing import Optional as _Opt
         from graphify.tree_html import write_tree_html, DEFAULT_MAX_CHILDREN
-        graph_path = Path("graphify-out/graph.json")
+        graph_path = Path(_GRAPHIFY_OUT) / "graph.json"
         output_path: "_Opt[Path]" = None
         root: "_Opt[str]" = None
         max_children = DEFAULT_MAX_CHILDREN
@@ -1630,7 +1644,7 @@ def main() -> None:
         # graphify merge-graphs graph1.json graph2.json ... --out merged.json
         args = sys.argv[2:]
         graph_paths: list[Path] = []
-        out_path = Path("graphify-out/merged-graph.json")
+        out_path = Path(_GRAPHIFY_OUT) / "merged-graph.json"
         i = 0
         while i < len(args):
             if args[i] == "--out" and i + 1 < len(args):
diff --git a/graphify/cache.py b/graphify/cache.py
index 1dedcac..ef7582d 100644
--- a/graphify/cache.py
+++ b/graphify/cache.py
@@ -7,6 +7,11 @@ import os
 import tempfile
 from pathlib import Path
 
+# Output directory name — override with GRAPHIFY_OUT env var for worktrees or
+# shared-output setups. Accepts a relative name ("graphify-out-feature") or an
+# absolute path ("/shared/graphify-out").
+_GRAPHIFY_OUT = os.environ.get("GRAPHIFY_OUT", "graphify-out")
+
 
 def _body_content(content: bytes) -> bytes:
     """Strip YAML frontmatter from Markdown content, returning only the body."""
@@ -62,7 +67,9 @@ def cache_dir(root: Path = Path("."), kind: str = "ast") -> Path:
     kind is "ast" or "semantic". Separate subdirectories prevent semantic cache
     entries from overwriting AST cache entries for the same source_file (#582).
     """
-    d = Path(root).resolve() / "graphify-out" / "cache" / kind
+    _out = Path(_GRAPHIFY_OUT)
+    base = _out if _out.is_absolute() else Path(root).resolve() / _out
+    d = base / "cache" / kind
     d.mkdir(parents=True, exist_ok=True)
     return d
 
@@ -89,7 +96,7 @@ def load_cached(path: Path, root: Path = Path("."), kind: str = "ast") -> dict |
             return None
     # Migration fallback: check legacy flat cache/ dir for AST entries
     if kind == "ast":
-        legacy = Path(root).resolve() / "graphify-out" / "cache" / f"{h}.json"
+        legacy = Path(root).resolve() / _GRAPHIFY_OUT / "cache" / f"{h}.json"
         if legacy.exists():
             try:
                 return json.loads(legacy.read_text(encoding="utf-8"))
@@ -140,7 +147,7 @@ def save_cached(path: Path, result: dict, root: Path = Path("."), kind: str = "a
 
 def cached_files(root: Path = Path(".")) -> set[str]:
     """Return set of file hashes that have a valid cache entry (any kind)."""
-    base = Path(root).resolve() / "graphify-out" / "cache"
+    base = Path(root).resolve() / _GRAPHIFY_OUT / "cache"
     hashes: set[str] = set()
     # Legacy flat entries
     if base.is_dir():
@@ -155,7 +162,7 @@ def cached_files(root: Path = Path(".")) -> set[str]:
 
 def clear_cache(root: Path = Path(".")) -> None:
     """Delete all cache entries (ast/, semantic/, and legacy flat entries)."""
-    base = Path(root).resolve() / "graphify-out" / "cache"
+    base = Path(root).resolve() / _GRAPHIFY_OUT / "cache"
     # Legacy flat entries
     if base.is_dir():
         for f in base.glob("*.json"):
diff --git a/graphify/watch.py b/graphify/watch.py
index 1249685..88cc8c6 100644
--- a/graphify/watch.py
+++ b/graphify/watch.py
@@ -1,10 +1,13 @@
 # monitor a folder and auto-trigger --update when files change
 from __future__ import annotations
 import json
+import os
 import sys
 import time
 from pathlib import Path
 
+_GRAPHIFY_OUT = os.environ.get("GRAPHIFY_OUT", "graphify-out")
+
 
 from graphify.detect import CODE_EXTENSIONS, DOC_EXTENSIONS, PAPER_EXTENSIONS, IMAGE_EXTENSIONS
 
@@ -68,7 +71,7 @@ def _rebuild_code(watch_path: Path, *, follow_symlinks: bool = False, force: boo
         # Filter by node ID membership in the new AST output, not by file_type —
         # INFERRED/AMBIGUOUS nodes extracted from code files also carry file_type="code"
         # and would be wrongly dropped by a file_type-based filter.
-        out = watch_path / "graphify-out"
+        out = watch_path / _GRAPHIFY_OUT
         existing_graph = out / "graph.json"
         if existing_graph.exists():
             try:
@@ -159,7 +162,7 @@ def check_update(watch_path: Path) -> bool:
     re-extraction via `/graphify --update` — this function only signals
     that the update is needed.
     """
-    flag = Path(watch_path) / "graphify-out" / "needs_update"
+    flag = Path(watch_path) / _GRAPHIFY_OUT / "needs_update"
     if flag.exists():
         print(f"[graphify check-update] Pending non-code changes in {watch_path}.")
         print("[graphify check-update] Run `/graphify --update` to apply semantic re-extraction.")
@@ -168,7 +171,7 @@ def check_update(watch_path: Path) -> bool:
 
 def _notify_only(watch_path: Path) -> None:
     """Write a flag file and print a notification (fallback for non-code-only corpora)."""
-    flag = watch_path / "graphify-out" / "needs_update"
+    flag = watch_path / _GRAPHIFY_OUT / "needs_update"
     flag.parent.mkdir(parents=True, exist_ok=True)
     flag.write_text("1", encoding="utf-8")
     print(f"\n[graphify watch] New or changed files detected in {watch_path}")
@@ -213,7 +216,7 @@ def watch(watch_path: Path, debounce: float = 3.0) -> None:
                 return
             if any(part.startswith(".") for part in path.parts):
                 return
-            if "graphify-out" in path.parts:
+            if _GRAPHIFY_OUT in path.parts:
                 return
             last_trigger = time.monotonic()
             pending = True