Codex

Codex is OpenAI’s terminal coding agent (codex-rs). Signet integrates with Codex through a generated Codex plugin bundle when the installed Codex CLI supports plugin marketplaces. The plugin declares Signet metadata, skills, and MCP configuration. Until Codex exposes plugin lifecycle hooks, Signet also installs compatibility hooks.json entries for session start, prompt submit, and session end. Older Codex versions fall back to direct hook and MCP config patching.

Files managed by Signet

File	Description
`~/.codex/.tmp/signet-plugin-marketplace`	Generated local marketplace containing the Signet plugin bundle
`~/.codex/config.toml`	Plugin marketplace/config registration, or compatibility `[mcp_servers.signet]` on older Codex installs
`~/.codex/hooks.json`	Compatibility lifecycle hooks — SessionStart, UserPromptSubmit, Stop
`~/.codex/skills`	Compatibility symlink to `$SIGNET_WORKSPACE/skills` when plugin support is unavailable

Generated Codex hook manifests contain only fields from Codex’s hook schema. Signet identifies its entries by their hook command when reinstalling or uninstalling, so unrelated hook groups remain untouched without private metadata inside Codex-owned configuration.

Native memory bridge

Signet indexes Codex-owned memory artifacts without rewriting them or turning them into Signet-authored memory rows. The daemon polls Codex memory files with content hashes under ~/.codex/memories/, including memory_summary.md, MEMORY.md, rollout summaries, skill memories, ad-hoc extension notes, and automation-local ~/.codex/automations/*/memory.md files. Matching content is indexed as codex_native_memory source artifacts with path, hash, line range, and rollout-id metadata when present. Removed native files are soft-deleted from active recall while preserving their artifact rows for lineage.

When Codex native memories are enabled, Signet’s Codex prompt hook reduces automatic injection of Codex-owned memory rows. Prompt-time context stays focused on high-value Signet material: cross-harness history, source-backed documents, ontology, explicit recalls, and accepted decisions. Explicit recall still uses daemon-side dedupe keyed by session_key, agent_id, and context_epoch.

How it works

signet setup --harness codex feature-detects codex plugin support.
On supported Codex installs, Signet writes a local plugin marketplace bundle and registers signet@signet-local in ~/.codex/config.toml.
While plugin lifecycle hooks are not available, Codex also reads compatibility hooks from ~/.codex/hooks.json.
On session start, Codex fires SessionStart → calls signet hook session-start -H codex --codex-json → Signet returns identity + memories as hookSpecificOutput.additionalContext with suppressOutput: true, injected into the model’s context window without printing the hook payload to the user transcript.
On every user prompt, Codex fires UserPromptSubmit → calls signet hook user-prompt-submit -H codex --codex-json → Signet returns bounded entity current-view context only when the prompt mentions a known entity or active alias. Empty matches return no additional context. This is blocking — Codex waits for the hook before sending to the model.
On session end, Codex fires Stop → calls signet hook session-end -H codex → Signet extracts memories from the transcript.
The MCP server exposes signet_recall, signet_source_search, signet_session_search, signet_save_note, and compatibility memory_* tools that Codex can invoke directly during sessions.

Codex SessionStart hook timeout defaults to 20 seconds: the Signet CLI waits up to SIGNET_SESSION_START_TIMEOUT (15000 ms by default) for the daemon, and the generated Codex hook config adds 5 seconds of harness grace. Codex UserPromptSubmit defaults to 7 seconds: SIGNET_PROMPT_SUBMIT_TIMEOUT (5000 ms by default) plus 2 seconds of harness grace. Rerun signet setup or signet connect codex after upgrading to rewrite an existing ~/.codex/hooks.json.

For a remote Signet daemon, pass --url and --api-key when installing the Codex connector:

signet api-key create --name "work laptop codex" --connector codex --agent-id <agent-name>
signet connect codex --url http://192.168.0.60:3850 --api-key sig_sk_...

Use --agent-id when creating the API key to bind the remote Codex install to one Signet agent. The key scope becomes the default agent for Codex hook/MCP requests, and requests for another agent are rejected by daemon auth scope.

Codex also has a native-plugin-oriented npm installer name for machines where you do not want to install the full Signet CLI first:

npx -y @signetai/codex-plugin install --url http://192.168.0.60:3850 --api-key sig_sk_...

When SIGNET_DAEMON_URL or --url is set, the Codex connector writes the plugin MCP URL, or compatibility [mcp_servers.signet] url = "<daemon>/mcp" when plugin support is unavailable, and bakes the same daemon URL into generated lifecycle hook commands. This keeps on-demand MCP tools and automatic lifecycle memory pointed at the same Signet instance. When an API key is provided, Codex MCP and lifecycle hook calls send it as bearer auth. The URL value must be the daemon origin only, for example http://192.168.0.60:3850 or https://signet.internal:3850, with no path, query string, fragment, or embedded credentials.

Codex matches the session-start, prompt-submit, and session-end path, but it does not currently expose the same compaction lifecycle fidelity as Claude Code or OpenCode.

Supported hooks

Hook	Supported
session-start	yes — identity + memories via `hookSpecificOutput.additionalContext`
user-prompt-submit	yes — entity current-view context via `hookSpecificOutput.additionalContext` when matched
session-end	yes — transcript extraction via `Stop` hook

MCP tools

When the Signet MCP server is registered, Codex gains access to these tools (namespaced as mcp__signet__*):

signet_recall — explicit Signet recall for cross-harness history and accepted decisions
signet_source_search — search source-backed Signet artifacts and docs
signet_session_search — search active or completed session transcripts
signet_save_note — write a small explicit note into Codex native memory extensions
memory_search, memory_store, session_search, and other legacy memory_* tools — compatibility aliases

MCP tools do not replace hooks. MCP gives Codex on-demand tools during a session; hooks provide automatic identity injection, prompt-time recall, and session-end extraction.

Extraction provider

Codex can be selected as the extraction provider in agent.yaml. When set, the pipeline uses the Codex CLI (similar to the claude-code provider) to run extraction and decision passes against Codex’s configured model rather than a local Ollama instance.

Prerequisites

Codex (codex-rs) installed and in PATH
Signet daemon running (signet daemon start)