diff --git a/.agents/plugins/marketplace.json b/.agents/plugins/marketplace.json
new file mode 100644
index 0000000..58223a0
--- /dev/null
+++ b/.agents/plugins/marketplace.json
@@ -0,0 +1,20 @@
+{
+  "name": "mempalace",
+  "interface": {
+    "displayName": "MemPalace"
+  },
+  "plugins": [
+    {
+      "name": "mempalace",
+      "source": {
+        "source": "local",
+        "path": "./.codex-plugin"
+      },
+      "policy": {
+        "installation": "AVAILABLE",
+        "authentication": "NONE"
+      },
+      "category": "Coding"
+    }
+  ]
+}
diff --git a/.claude-plugin/.mcp.json b/.claude-plugin/.mcp.json
new file mode 100644
index 0000000..b1e81ed
--- /dev/null
+++ b/.claude-plugin/.mcp.json
@@ -0,0 +1,9 @@
+{
+  "mempalace": {
+    "command": "python3",
+    "args": [
+      "-m",
+      "mempalace.mcp_server"
+    ]
+  }
+}
diff --git a/.claude-plugin/plugin.json b/.claude-plugin/plugin.json
index 482e77a..488f6f3 100644
--- a/.claude-plugin/plugin.json
+++ b/.claude-plugin/plugin.json
@@ -7,7 +7,7 @@
   },
   "license": "MIT",
   "commands": [],
-  "mcp": {
+  "mcpServers": {
     "mempalace": {
       "command": "python3",
       "args": [
diff --git a/.codex-plugin/README.md b/.codex-plugin/README.md
new file mode 100644
index 0000000..a7ec1de
--- /dev/null
+++ b/.codex-plugin/README.md
@@ -0,0 +1,73 @@
+# MemPalace - Codex CLI Plugin
+
+Give your AI a persistent memory -- mine projects and conversations into a searchable palace backed by ChromaDB, with 19 MCP tools, auto-save hooks, and guided skills.
+
+## Prerequisites
+
+- Python 3.10+
+- Codex CLI installed and configured
+- `pip install mempalace`
+
+## Installation
+
+### Local Install
+
+1. Copy or symlink the `.codex-plugin` directory into your project root:
+
+```bash
+cp -r .codex-plugin /path/to/your/project/.codex-plugin
+```
+
+2. Verify the plugin is detected:
+
+```bash
+codex --plugins
+```
+
+3. Initialize your palace:
+
+```bash
+codex /init
+```
+
+### Git Install
+
+1. Clone the MemPalace repository:
+
+```bash
+git clone https://github.com/milla-jovovich/mempalace.git
+cd mempalace
+```
+
+2. Install the Python package:
+
+```bash
+pip install -e .
+```
+
+3. The `.codex-plugin` directory is already in the repo root. Codex CLI will detect it automatically when you run Codex from inside the repository.
+
+4. Initialize your palace:
+
+```bash
+codex /init
+```
+
+## Available Skills
+
+| Skill | Description |
+|-------|-------------|
+| `/help` | Show available commands and usage tips |
+| `/init` | Initialize a new memory palace |
+| `/search` | Semantic search across all mined memories |
+| `/mine` | Mine a project or conversation into your palace |
+| `/status` | Show palace status, room counts, and health |
+
+## Hooks
+
+The plugin includes an auto-save hook that runs on session stop, automatically preserving conversation context into your palace.
+
+## Support
+
+- Repository: https://github.com/milla-jovovich/mempalace
+- Issues: https://github.com/milla-jovovich/mempalace/issues
diff --git a/.codex-plugin/hooks.json b/.codex-plugin/hooks.json
new file mode 100644
index 0000000..1c235f2
--- /dev/null
+++ b/.codex-plugin/hooks.json
@@ -0,0 +1,37 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "./hooks/mempal-session-start-hook.sh"
+          }
+        ]
+      }
+    ],
+    "Stop": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "./hooks/mempal-stop-hook.sh"
+          }
+        ]
+      }
+    ],
+    "PreCompact": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "./hooks/mempal-precompact-hook.sh"
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/.codex-plugin/hooks/mempal-precompact-hook.sh b/.codex-plugin/hooks/mempal-precompact-hook.sh
new file mode 100644
index 0000000..46af49d
--- /dev/null
+++ b/.codex-plugin/hooks/mempal-precompact-hook.sh
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+PLUGIN_ROOT="${CODEX_PLUGIN_ROOT:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)}"
+
+# Capture stdin (hook input from Codex)
+INPUT_FILE=$(mktemp 2>/dev/null || echo "/tmp/mempal-precompact-hook-$$.json")
+cat > "$INPUT_FILE"
+
+# Pipe to Python CLI with codex harness
+cat "$INPUT_FILE" | python3 -m mempalace hook run --hook precompact --harness codex
+EXIT_CODE=$?
+
+# Cleanup
+rm -f "$INPUT_FILE" 2>/dev/null
+exit $EXIT_CODE
diff --git a/.codex-plugin/hooks/mempal-session-start-hook.sh b/.codex-plugin/hooks/mempal-session-start-hook.sh
new file mode 100644
index 0000000..7c7b5c2
--- /dev/null
+++ b/.codex-plugin/hooks/mempal-session-start-hook.sh
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+PLUGIN_ROOT="${CODEX_PLUGIN_ROOT:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)}"
+
+# Capture stdin (hook input from Codex)
+INPUT_FILE=$(mktemp 2>/dev/null || echo "/tmp/mempal-session-start-hook-$$.json")
+cat > "$INPUT_FILE"
+
+# Pipe to Python CLI with codex harness
+cat "$INPUT_FILE" | python3 -m mempalace hook run --hook session-start --harness codex
+EXIT_CODE=$?
+
+# Cleanup
+rm -f "$INPUT_FILE" 2>/dev/null
+exit $EXIT_CODE
diff --git a/.codex-plugin/hooks/mempal-stop-hook.sh b/.codex-plugin/hooks/mempal-stop-hook.sh
new file mode 100644
index 0000000..2d38932
--- /dev/null
+++ b/.codex-plugin/hooks/mempal-stop-hook.sh
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+PLUGIN_ROOT="${CODEX_PLUGIN_ROOT:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)}"
+
+# Capture stdin (hook input from Codex)
+INPUT_FILE=$(mktemp 2>/dev/null || echo "/tmp/mempal-stop-hook-$$.json")
+cat > "$INPUT_FILE"
+
+# Pipe to Python CLI with codex harness
+cat "$INPUT_FILE" | python3 -m mempalace hook run --hook stop --harness codex
+EXIT_CODE=$?
+
+# Cleanup
+rm -f "$INPUT_FILE" 2>/dev/null
+exit $EXIT_CODE
diff --git a/.codex-plugin/plugin.json b/.codex-plugin/plugin.json
new file mode 100644
index 0000000..f040014
--- /dev/null
+++ b/.codex-plugin/plugin.json
@@ -0,0 +1,35 @@
+{
+  "name": "mempalace",
+  "version": "3.0.0",
+  "description": "Give your AI a memory — mine projects and conversations into a searchable palace. 19 MCP tools, auto-save hooks, and guided setup.",
+  "author": { "name": "milla-jovovich" },
+  "homepage": "https://github.com/milla-jovovich/mempalace",
+  "repository": "https://github.com/milla-jovovich/mempalace",
+  "license": "MIT",
+  "keywords": ["memory", "ai", "rag", "mcp", "chromadb", "palace", "search"],
+  "skills": "./skills/",
+  "hooks": "./hooks.json",
+  "mcpServers": {
+    "mempalace": {
+      "command": "python3",
+      "args": ["-m", "mempalace.mcp_server"]
+    }
+  },
+  "interface": {
+    "displayName": "MemPalace",
+    "shortDescription": "AI memory system for Codex",
+    "longDescription": "Give your AI a persistent memory — mine projects and conversations into a searchable palace backed by ChromaDB, with 19 MCP tools, auto-save hooks, and guided skills.",
+    "developerName": "milla-jovovich",
+    "category": "Coding",
+    "capabilities": ["Interactive", "Read", "Write"],
+    "websiteURL": "https://github.com/milla-jovovich/mempalace",
+    "privacyPolicyURL": "https://github.com/milla-jovovich/mempalace",
+    "termsOfServiceURL": "https://github.com/milla-jovovich/mempalace",
+    "defaultPrompt": [
+      "Search my memories for recent decisions",
+      "Mine this project into my memory palace",
+      "Show my palace status and room counts"
+    ],
+    "brandColor": "#7C3AED"
+  }
+}
diff --git a/.codex-plugin/skills/help/SKILL.md b/.codex-plugin/skills/help/SKILL.md
new file mode 100644
index 0000000..d0e8f43
--- /dev/null
+++ b/.codex-plugin/skills/help/SKILL.md
@@ -0,0 +1,13 @@
+---
+name: help
+description: Show MemPalace help — available commands, usage tips, and getting started guidance.
+allowed-tools: Bash, Read
+---
+
+# MemPalace Help
+
+Run the following command and follow the returned instructions step by step:
+
+```bash
+mempalace instructions help
+```
diff --git a/.codex-plugin/skills/init/SKILL.md b/.codex-plugin/skills/init/SKILL.md
new file mode 100644
index 0000000..cc0e2f9
--- /dev/null
+++ b/.codex-plugin/skills/init/SKILL.md
@@ -0,0 +1,13 @@
+---
+name: init
+description: Initialize a new MemPalace — guided setup for your AI memory palace with ChromaDB backend.
+allowed-tools: Bash, Read, Write, Edit
+---
+
+# MemPalace Init
+
+Run the following command and follow the returned instructions step by step:
+
+```bash
+mempalace instructions init
+```
diff --git a/.codex-plugin/skills/mine/SKILL.md b/.codex-plugin/skills/mine/SKILL.md
new file mode 100644
index 0000000..1a94e29
--- /dev/null
+++ b/.codex-plugin/skills/mine/SKILL.md
@@ -0,0 +1,13 @@
+---
+name: mine
+description: Mine a project or conversation into your MemPalace — extract and store memories for later retrieval.
+allowed-tools: Bash, Read, Glob, Grep
+---
+
+# MemPalace Mine
+
+Run the following command and follow the returned instructions step by step:
+
+```bash
+mempalace instructions mine
+```
diff --git a/.codex-plugin/skills/search/SKILL.md b/.codex-plugin/skills/search/SKILL.md
new file mode 100644
index 0000000..4d5bf4b
--- /dev/null
+++ b/.codex-plugin/skills/search/SKILL.md
@@ -0,0 +1,13 @@
+---
+name: search
+description: Search your MemPalace — semantic search across all mined memories, projects, and conversations.
+allowed-tools: Bash, Read
+---
+
+# MemPalace Search
+
+Run the following command and follow the returned instructions step by step:
+
+```bash
+mempalace instructions search
+```
diff --git a/.codex-plugin/skills/status/SKILL.md b/.codex-plugin/skills/status/SKILL.md
new file mode 100644
index 0000000..617d3be
--- /dev/null
+++ b/.codex-plugin/skills/status/SKILL.md
@@ -0,0 +1,13 @@
+---
+name: status
+description: Show MemPalace status — room counts, storage usage, and palace health.
+allowed-tools: Bash, Read
+---
+
+# MemPalace Status
+
+Run the following command and follow the returned instructions step by step:
+
+```bash
+mempalace instructions status
+```
diff --git a/.github/workflows/bump-plugin-version.yml b/.github/workflows/bump-plugin-version.yml
index d91c026..43adc8b 100644
--- a/.github/workflows/bump-plugin-version.yml
+++ b/.github/workflows/bump-plugin-version.yml
@@ -32,11 +32,15 @@ jobs:
         run: |
           jq --arg v "${{ steps.version.outputs.version }}" '.plugins[0].version = $v' .claude-plugin/marketplace.json > tmp.json && mv tmp.json .claude-plugin/marketplace.json
 
+      - name: Sync codex plugin.json
+        run: |
+          jq --arg v "${{ steps.version.outputs.version }}" '.version = $v' .codex-plugin/plugin.json > tmp.json && mv tmp.json .codex-plugin/plugin.json
+
       - name: Commit and push
         run: |
           git config user.name "github-actions[bot]"
           git config user.email "github-actions[bot]@users.noreply.github.com"
-          git add mempalace/version.py .claude-plugin/plugin.json .claude-plugin/marketplace.json
+          git add mempalace/version.py .claude-plugin/plugin.json .claude-plugin/marketplace.json .codex-plugin/plugin.json
           if ! git diff --staged --quiet; then
             git commit -m "chore: bump version to ${{ steps.version.outputs.version }}"
             git push
diff --git a/mempalace/cli.py b/mempalace/cli.py
index 9d2465b..0a24abf 100644
--- a/mempalace/cli.py
+++ b/mempalace/cli.py
@@ -475,13 +475,13 @@ def main():
     p_hook_run.add_argument(
         "--hook",
         required=True,
-        choices=["stop", "precompact"],
+        choices=["session-start", "stop", "precompact"],
         help="Hook name to run",
     )
     p_hook_run.add_argument(
         "--harness",
         required=True,
-        choices=["claude-code"],
+        choices=["claude-code", "codex"],
         help="Harness type (determines stdin JSON format)",
     )
 
diff --git a/mempalace/hooks_cli.py b/mempalace/hooks_cli.py
index 6e0ec0a..6b4bb0f 100644
--- a/mempalace/hooks_cli.py
+++ b/mempalace/hooks_cli.py
@@ -1,9 +1,9 @@
 """
-Hook logic for MemPalace — Python implementation of stop and precompact hooks.
+Hook logic for MemPalace — Python implementation of session-start, stop, and precompact hooks.
 
 Reads JSON from stdin, outputs JSON to stdout.
-Supported hooks: stop, precompact
-Supported harnesses: claude-code (extensible to cursor, gemini, etc.)
+Supported hooks: session-start, stop, precompact
+Supported harnesses: claude-code, codex (extensible to cursor, gemini, etc.)
 """
 
 import json
@@ -105,10 +105,20 @@ def _parse_claude_code_input(data: dict) -> dict:
     }
 
 
+def _parse_codex_input(data: dict) -> dict:
+    """Parse stdin JSON for the codex harness."""
+    return {
+        "session_id": _sanitize_session_id(str(data.get("session_id", "unknown"))),
+        "stop_hook_active": data.get("stop_hook_active", False),
+        "transcript_path": str(data.get("transcript_path", "")),
+    }
+
+
 def _parse_harness_input(data: dict, harness: str) -> dict:
     """Parse stdin JSON according to the harness type."""
     parsers = {
         "claude-code": _parse_claude_code_input,
+        "codex": _parse_codex_input,
     }
     parser = parsers.get(harness)
     if parser is None:
@@ -163,6 +173,20 @@ def hook_stop(data: dict, harness: str):
         _output({})
 
 
+def hook_session_start(data: dict, harness: str):
+    """Session start hook: initialize session tracking state."""
+    parsed = _parse_harness_input(data, harness)
+    session_id = parsed["session_id"]
+
+    _log(f"SESSION START for session {session_id}")
+
+    # Initialize session state directory
+    STATE_DIR.mkdir(parents=True, exist_ok=True)
+
+    # Pass through — no blocking on session start
+    _output({})
+
+
 def hook_precompact(data: dict, harness: str):
     """Precompact hook: always block with comprehensive save instruction."""
     parsed = _parse_harness_input(data, harness)
@@ -196,6 +220,7 @@ def run_hook(hook_name: str, harness: str):
         data = {}
 
     hooks = {
+        "session-start": hook_session_start,
         "stop": hook_stop,
         "precompact": hook_precompact,
     }