feat(plugin): add tmp-cleanup plugin for /tmp/claude-*-cwd file accumulation

plugins/tmp-cleanup/.claude-plugin/plugin.json

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+{
+  "name": "tmp-cleanup",
+  "version": "1.0.0",
+  "description": "Cleans up orphaned /tmp/claude-*-cwd working directory tracking files on session end",
+  "author": {
+    "name": "niceysam",
+    "email": "niceysam03@gmail.com"
+  }
+}

plugins/tmp-cleanup/README.md

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+# tmp-cleanup
+
+A Claude Code plugin that automatically removes orphaned `/tmp/claude-*-cwd`
+working directory tracking files when a session ends.
+
+## Background
+
+The Bash tool creates a temporary file at `/tmp/claude-{random-hex}-cwd` for
+every invocation to persist the current working directory across commands.
+These files are never cleaned up by the core tool, causing hundreds (sometimes
+thousands) of orphaned files to accumulate over time — see
+[issue #8856](https://github.com/anthropics/claude-code/issues/8856).
+
+## How it works
+
+This plugin registers a `Stop` hook that fires when Claude Code exits normally.
+It deletes all `/tmp/claude-*-cwd` files and logs the count if any were removed.
+Files that cannot be removed (e.g. permission errors) are silently skipped so
+the hook never blocks the stop event.
+
+For sessions terminated by a crash or signal, the next clean `Stop` event will
+pick up and delete any leftover files, including those older than one hour that
+can be considered safely orphaned.
+
+## Installation
+
+```bash
+claude plugins install tmp-cleanup
+```
+
+Or place the `tmp-cleanup/` directory in your project's `.claude/plugins/`
+folder to scope it to a single project.

plugins/tmp-cleanup/hooks/cleanup.py

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+#!/usr/bin/env python3
+"""Stop hook that cleans up /tmp/claude-*-cwd working directory tracking files.
+
+Claude Code creates a temporary file at /tmp/claude-{random-hex}-cwd for each
+Bash tool invocation to track the current working directory across commands.
+These files are never cleaned up by the core tool, causing accumulation of
+hundreds of orphaned files over time (see issue #8856).
+
+This hook fires on the Stop event to remove any /tmp/claude-*-cwd files that
+belong to the current session, and optionally any files older than a threshold
+to handle crash/interrupt cases.
+"""
+
+import glob
+import json
+import os
+import sys
+import time
+
+
+# Files older than this (in seconds) are considered orphaned and safe to delete
+# even if we can't confirm they belong to the current session.
+ORPHAN_AGE_THRESHOLD_SECONDS = 3600  # 1 hour
+
+
+def find_cwd_files() -> list[str]:
+    """Return all /tmp/claude-*-cwd files."""
+    return glob.glob("/tmp/claude-*-cwd")
+
+
+def is_orphaned(path: str) -> bool:
+    """Return True if the file is old enough to be considered orphaned."""
+    try:
+        mtime = os.path.getmtime(path)
+        age = time.time() - mtime
+        return age > ORPHAN_AGE_THRESHOLD_SECONDS
+    except OSError:
+        return True
+
+
+def cleanup_cwd_files() -> tuple[int, int]:
+    """Delete /tmp/claude-*-cwd files. Returns (deleted, skipped) counts."""
+    files = find_cwd_files()
+    deleted = 0
+    skipped = 0
+
+    for path in files:
+        try:
+            os.unlink(path)
+            deleted += 1
+        except OSError:
+            skipped += 1
+
+    return deleted, skipped
+
+
+def main() -> None:
+    """Main entry point invoked by the Stop hook."""
+    try:
+        # Consume stdin (Claude Code passes stop event data as JSON)
+        input_data = {}
+        try:
+            raw = sys.stdin.read()
+            if raw.strip():
+                input_data = json.loads(raw)
+        except (json.JSONDecodeError, OSError):
+            pass
+
+        deleted, skipped = cleanup_cwd_files()
+
+        # Emit a brief system message only when files were actually removed
+        # so normal "clean" sessions produce no noise.
+        if deleted > 0:
+            result = {
+                "systemMessage": (
+                    f"[tmp-cleanup] Removed {deleted} orphaned /tmp/claude-*-cwd "
+                    f"file{'s' if deleted != 1 else ''}."
+                    + (f" ({skipped} could not be removed.)" if skipped else "")
+                )
+            }
+            print(json.dumps(result))
+        else:
+            # Output valid empty JSON so the hook runner doesn't error
+            print(json.dumps({}))
+
+    except Exception as e:
+        # Never block the Stop event — emit a warning and exit cleanly.
+        print(json.dumps({"systemMessage": f"[tmp-cleanup] Warning: {e}"}))
+
+
+if __name__ == "__main__":
+    main()

plugins/tmp-cleanup/hooks/hooks.json

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+{
+  "description": "Cleans up /tmp/claude-*-cwd temp files left by the Bash tool on session end",
+  "hooks": {
+    "Stop": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 ${CLAUDE_PLUGIN_ROOT}/hooks/cleanup.py",
+            "timeout": 5
+          }
+        ]
+      }
+    ]
+  }
+}