feat(watch): one active watcher per directory tree across sessions

.agents/plugins/marketplace.json

@@ -0,0 +1,20 @@
+{
+  "name": "Mixedbread-Grep",
+  "interface": {
+    "displayName": "Mixedbread"
+  },
+  "plugins": [
+    {
+      "name": "mgrep",
+      "source": {
+        "source": "local",
+        "path": "./plugins/mgrep"
+      },
+      "policy": {
+        "installation": "AVAILABLE",
+        "authentication": "ON_INSTALL"
+      },
+      "category": "Developer Tools"
+    }
+  ]
+}

README.md

@@ -108,6 +108,44 @@ These commands sign you in (if needed) and add Mixedbread `mgrep` support to the
 agent. After that you only have to start the agent in your project folder, thats
 it.
 
+### Codex
+
+With the Codex CLI installed, run:
+
+```bash
+mgrep install-codex
+```
+
+This authenticates with Mixedbread, adds the `Mixedbread-Grep` marketplace, and
+installs `mgrep@Mixedbread-Grep`. The plugin includes an MCP server with a
+read-only `search` tool and a short skill. The MCP server syncs the session's
+project directory in the background while Codex runs.
+
+A SessionStart hook adds search guidance on startup and resume, helping Codex
+choose semantic search for conceptual or cross-file questions and rg or grep for
+exact matches. On first start, Codex asks you to review the hook ("Hooks need
+review"); you can also review it with `/hooks`. This one-time review allows the
+hook to run. The hook only adds context; the MCP server owns background sync.
+
+Use MCP `search` for conceptual questions; `path` is optional and defaults to the
+session's project directory. Use rg or grep for exact strings, symbol names, and
+regexes. The MCP server runs `mgrep mcp --expose-tools`. Searches within the
+project wait for the watcher's initial sync. If the watcher cannot start, or the
+search path is outside the project, the first search syncs that root once.
+
+The plugin forwards `MXBAI_API_KEY` and `MXBAI_STORE` from Codex's environment.
+You can also authenticate with `mgrep login`. No API key is written into plugin
+configuration. To install from a local checkout or another Git URL, set
+`MGREP_CODEX_MARKETPLACE` before running `mgrep install-codex`.
+
+```bash
+mgrep uninstall-codex
+```
+
+Uninstall removes the plugin, its marketplace, and the legacy MCP registration.
+Both commands remove the old mgrep block from `$CODEX_HOME/AGENTS.md` and
+`~/.codex/AGENTS.md`, preserving surrounding instructions.
+
 ### More Agents Coming Soon
 
 More agents (Cursor, Windsurf, etc.) are on the way—this section will grow as soon as each integration lands.
@@ -245,6 +283,20 @@ mgrep watch --max-file-size 1048576  # limit uploads to files under 1MB
 mgrep watch --max-file-count 5000  # limit sync to 5000 changed files or fewer
 ```
 
+#### Multiple sessions
+
+Watchers using the same store coordinate across sessions: the first started
+watcher owns each directory tree. Later sessions covered by it stand by without
+syncing or watching files, and take over when it exits. A parent started after a
+child watcher leaves that child's subtree to the child, then takes it over if
+the child exits.
+
+A folder containing `.mgreprc.yaml` or `.mgreprc.yml` is a configuration boundary:
+ancestor watchers always exclude it, so a session in that folder gets its own
+watcher. Boundaries are computed when a watcher becomes active, including on
+takeover; restart watchers after adding or removing local config files.
+Dry runs skip coordination.
+
 ## Mixedbread under the hood
 
 - Every file is pushed into a Mixedbread Store using the same SDK your apps get.

package.json

@@ -19,7 +19,7 @@
     "build": "tsc",
     "postbuild": "chmod +x dist/index.js && cp -r plugins dist/",
     "dev": "npx tsc && node dist/index.js",
-    "test": "bats test/test.bats --filter-tags !long-running",
+    "test": "bats test/ --filter-tags !long-running",
     "format": "biome check --write .",
     "format:check": "biome check .",
     "lint": "biome lint --check .",

plugins/mgrep/.codex-plugin/plugin.json

@@ -0,0 +1,17 @@
+{
+  "name": "mgrep",
+  "version": "0.1.13",
+  "description": "Search your local files using Mixedbread",
+  "author": {
+    "name": "Joel Dierkes"
+  },
+  "skills": "./codex/skills/",
+  "mcpServers": "./codex/mcp.json",
+  "hooks": "./codex/hooks.json",
+  "interface": {
+    "displayName": "mgrep",
+    "shortDescription": "Semantic search for your project files",
+    "developerName": "Mixedbread",
+    "category": "Developer Tools"
+  }
+}

plugins/mgrep/codex/hooks.json

@@ -0,0 +1,16 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "startup|resume",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 \"${CLAUDE_PLUGIN_ROOT:-$PLUGIN_ROOT}/codex/session_start.py\"",
+            "timeout": 5
+          }
+        ]
+      }
+    ]
+  }
+}

plugins/mgrep/codex/mcp.json

@@ -0,0 +1,9 @@
+{
+  "mcpServers": {
+    "mgrep": {
+      "command": "mgrep",
+      "args": ["mcp", "--expose-tools"],
+      "env_vars": ["MXBAI_API_KEY", "MXBAI_STORE"]
+    }
+  }
+}

plugins/mgrep/codex/session_start.py

@@ -0,0 +1,46 @@
+import json
+import os
+import sys
+from pathlib import Path
+
+
+def read_update_notice():
+    try:
+        cache_path = Path.home() / ".mgrep" / "update-check.json"
+        with open(cache_path, "r", encoding="utf-8") as handle:
+            cache = json.load(handle)
+        latest = cache.get("latestVersion")
+        if not isinstance(latest, str):
+            return ""
+        return f" An mgrep update is available (latest: {latest}). Tell the user to run `mgrep update` to upgrade."
+    except Exception:
+        return ""
+
+
+def main():
+    try:
+        payload = json.load(sys.stdin)
+    except (ValueError, OSError):
+        payload = {}
+    cwd = payload.get("cwd") if isinstance(payload, dict) else None
+    if not isinstance(cwd, str) or not cwd or "\0" in cwd:
+        cwd = os.getcwd()
+    cwd = os.path.abspath(cwd)
+    context = (
+        "mgrep semantic search is available through the `search` tool of the mgrep MCP server. "
+        "Use it for conceptual or cross-file questions where you don't know the exact identifier, "
+        "such as 'where is authentication handled'. "
+        f"It searches {cwd} by default. "
+        "Use rg or grep for exact strings, symbol names and regexes. "
+        "Both are fine; pick whichever fits the question."
+    )
+    print(json.dumps({
+        "hookSpecificOutput": {
+            "hookEventName": "SessionStart",
+            "additionalContext": context + read_update_notice(),
+        }
+    }))
+
+
+if __name__ == "__main__":
+    main()

plugins/mgrep/codex/skills/mgrep/SKILL.md

@@ -0,0 +1,28 @@
+---
+name: mgrep
+description: Semantic search for conceptual questions about project files, alongside rg and grep for exact matches.
+---
+
+Use the mgrep MCP server's `search` tool for conceptual or cross-file questions
+when you do not know the exact identifier, such as "where is authentication
+handled". Provide a natural-language `query`; `path` is optional and defaults
+to the session's project directory. Results contain file paths and line ranges;
+read only those ranges. The MCP server keeps the session's project directory synced.
+
+Use rg or grep for exact strings, symbol names, and regexes. Both approaches are
+fine; choose whichever fits the question.
+
+Outside MCP, use the CLI from your project directory:
+
+```bash
+mgrep search "how are failed uploads retried"
+mgrep search --sync "where is authentication handled" ./src
+mgrep search --web --answer "how does this API work"
+```
+
+Prefer the MCP tool inside Codex to avoid shell network approval prompts. The CLI
+works in a terminal or when MCP is unavailable. Set `web` and `answer` to true
+for an MCP web lookup. Use `maxCount` (CLI `-m`) to limit results.
+
+`content: true` and CLI `-c` include full matching content and can produce large
+output. Start with paths and line ranges, then read the relevant ranges.

plugins/mgrep/hooks/mgrep_watch_kill.py

@@ -50,7 +50,7 @@ def read_hook_input():
         sys.exit(0)
     debug_log(f"Killing mgrep watch process: {pid}")
     try:
-        os.kill(pid, signal.SIGKILL)
+        os.kill(pid, signal.SIGTERM)
         debug_log(f"Killed mgrep watch process: {pid}")
     except ProcessLookupError:
         debug_log(f"Process {pid} already exited")