feat: Plexum-openai-provider v0.1 — OpenAI codex CLI as backend

Plexum ProviderPlugin that wraps the local `codex` CLI binary
(OpenAI Codex CLI ≥ 0.135). Same CLI-driven pattern as
Plexum-gemini-provider and Plexum-anthropic-provider's contractor.

internal/runner/ (~200 LOC):
- Per Plexum turn, fork:
    codex exec [resume <thread_id>] \
      --skip-git-repo-check \
      --dangerously-bypass-approvals-and-sandbox \
      --json \
      [--model <m>] \
      "<last user msg>"
  in agent workspace, with stdin = /dev/null (codex would otherwise
  block waiting for additional input).
- Stream-parses JSONL events:
    thread.started        → save thread_id to .plexum-codex-session
    item.completed        → if type==agent_message, emit text_delta
    turn.completed        → capture usage (input/output/cached/reasoning)
    error / turn.failed   → emit canonical EventError
- Other event types (turn.started, item.started, reasoning, etc.)
  logged at debug, don't produce user-facing events for v1

cmd/plexum-openai-provider-plugin/ implements ProviderPluginWithAgent
(needs AgentContext.Workspace as cwd).

Model surface:
  default: ["codex"]  (no --model flag → CLI default; only thing
                       ChatGPT-account installs support)
  override via config.supported_models + config.model_args for
  API-key installs that want gpt-5 / o3 / etc.

HostConfig (all optional):
  binary           default "codex" (operator should set abs path for
                   systemd PATH)
  extra_args       appended before the prompt
  supported_models override the advertised model list
  model_args       map plexum id → CLI --model value

No api_key field — codex CLI handles auth via ~/.codex/ state
(ChatGPT login OR OPENAI_API_KEY env).

End-to-end verified against local install (ChatGPT login):

1. CLI turn 1:        "OpenAI built me."
2. CLI turn 2 (resume): "I said: 'OpenAI built me.'" (multi-turn ✓)
3. Fabric channel e2e: alice → cx agent → codex CLI → outbound REST →
   seq=23: "Use list comprehensions for concise, readable filtering and
            transformation of iterables."

Known: when daemon runs under systemd PATH doesn't include nvm/local
bin dirs; operator must set absolute binary path in config.json.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
h z
2026-05-31 20:44:42 +01:00
commit 33de696653
5 changed files with 473 additions and 0 deletions

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plexum-openai-provider-plugin
/plexum-openai-provider-plugin
*.tmp
dist/

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# Plexum-openai-provider
Plexum ProviderPlugin that wraps the local `codex` CLI binary (OpenAI
Codex CLI ≥ 0.135). Same CLI-driven pattern as `Plexum-gemini-provider`
and `Plexum-anthropic-provider`'s contractor mode.
## Status
**v0.1**: subprocess-per-turn, JSONL stream parsing, per-workspace
session continuity via `codex exec resume <thread_id>`. Single model
`codex` advertised by default; operator can override.
## Auth
No API key in this plugin's config. The `codex` CLI handles auth via
`~/.codex/` (ChatGPT login OR `OPENAI_API_KEY`). Run `codex login`
once (or set env) and this plugin just shells out.
## Install
```bash
cd ~/Plexum-openai-provider
./scripts/install.sh
```
Operator notes in `~/.plexum/plugins/plexum-openai-provider/config.json`:
```json
{
"binary": "/home/<you>/.local/bin/codex",
"extra_args": []
}
```
(absolute path is required when the daemon runs under systemd —
systemd doesn't inherit shell PATH).
Then `.plugins.allow += ["plexum-openai-provider"]` and:
```bash
plexum agent-add --model codex my-agent
systemctl --user restart plexum
plexum say --agent-id my-agent --session-id $(plexum new-session --agent-id my-agent) "hello"
```
## How it works
Per Plexum turn:
```
codex exec [resume <thread_id>] \
--skip-git-repo-check \
--dangerously-bypass-approvals-and-sandbox \
--json \
[--model <m>] \
"<last user message>"
```
cwd = `<agent workspace>`, stdin = `/dev/null` (codex would otherwise
hang waiting for additional input). Codex emits JSONL:
```jsonl
{"type":"thread.started","thread_id":"..."}
{"type":"turn.started"}
{"type":"item.completed","item":{"id":"...","type":"agent_message","text":"..."}}
{"type":"turn.completed","usage":{"input_tokens":...,...}}
```
`thread.started.thread_id` is captured into
`<workspace>/.plexum-codex-session` so the next turn passes
`exec resume <id>` instead of `exec`. `item.completed` of type
`agent_message` becomes `text_delta`; `turn.completed.usage` populates
the canonical Usage on `message_end`.
## ChatGPT account vs API key
ChatGPT-account installs only support the default model; explicit
`--model gpt-5-codex` etc. returns `400 invalid_request_error`. With
an API key install, operator can declare more model ids via
`config.supported_models` + `config.model_args`.
## License
Same as Plexum.

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module git.hangman-lab.top/hzhang/Plexum-openai-provider
go 1.24.2
require git.hangman-lab.top/hzhang/Plexum-sdk-go v0.0.0
replace git.hangman-lab.top/hzhang/Plexum-sdk-go => ../Plexum-sdk-go

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// Package runner forks the OpenAI `codex` CLI per Plexum turn and
// translates its JSONL output into canonical TurnEvents.
//
// Each Stream call spawns one subprocess:
//
// codex exec --skip-git-repo-check --dangerously-bypass-approvals-and-sandbox --json [<prompt>]
// < /dev/null
//
// For multi-turn continuity:
//
// codex exec resume <thread_id> --skip-git-repo-check ... --json <prompt>
//
// in the agent's workspace dir. Codex emits a stream of JSONL events:
// {"type":"thread.started","thread_id":"..."}
// {"type":"turn.started"}
// {"type":"item.completed","item":{"id":"...","type":"agent_message","text":"..."}}
// {"type":"turn.completed","usage":{"input_tokens":..., ...}}
//
// Session continuity: per-workspace thread_id stored at
// <workspace>/.plexum-codex-session, used as the resume arg.
package runner
import (
"bufio"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"git.hangman-lab.top/hzhang/Plexum-sdk-go/canonical"
plugin "git.hangman-lab.top/hzhang/Plexum-sdk-go/plugin"
)
// SessionFile is the per-workspace filename storing the codex
// thread_id between turns.
const SessionFile = ".plexum-codex-session"
// Run is the ProviderPlugin Stream implementation.
func Run(
ctx context.Context,
host plugin.HostAPI,
agent plugin.AgentContext,
model string,
binary string,
extraArgs []string,
req canonical.TurnRequest,
) (<-chan canonical.TurnEvent, error) {
workspace := agent.Workspace
if workspace == "" {
return nil, errors.New("codex: agent workspace required (host must supply AgentContext)")
}
if err := os.MkdirAll(workspace, 0o755); err != nil {
return nil, fmt.Errorf("mkdir workspace: %w", err)
}
prompt := extractLastUserText(req.Messages)
if prompt == "" {
return nil, errors.New("codex: no user text in request messages")
}
resumeID := loadSessionID(workspace)
// Build the argv. `codex exec [resume <id>]` then flags then prompt.
args := []string{"exec"}
if resumeID != "" {
args = append(args, "resume", resumeID)
}
args = append(args,
"--skip-git-repo-check",
"--dangerously-bypass-approvals-and-sandbox",
"--json",
)
if model != "" {
args = append(args, "--model", model)
}
args = append(args, extraArgs...)
// Prompt is the last positional. Codex's exec/resume both accept
// it positionally; we pass via arg to avoid the stdin path.
args = append(args, prompt)
host.Log("info", "codex: spawning CLI", map[string]any{
"workspace": workspace, "model": model, "resume": resumeID,
"prompt_len": len(prompt),
})
cmd := exec.CommandContext(ctx, binary, args...)
cmd.Dir = workspace
cmd.Env = os.Environ()
cmd.Stdin = nil // detach from inherited stdin (codex would otherwise wait)
stdout, err := cmd.StdoutPipe()
if err != nil {
return nil, fmt.Errorf("stdout pipe: %w", err)
}
stderr, err := cmd.StderrPipe()
if err != nil {
return nil, fmt.Errorf("stderr pipe: %w", err)
}
if err := cmd.Start(); err != nil {
return nil, fmt.Errorf("codex: start: %w", err)
}
out := make(chan canonical.TurnEvent, 16)
go pumpEvents(ctx, host, cmd, stdout, stderr, workspace, out)
return out, nil
}
// pumpEvents drains stdout (JSONL), translates each line to a
// canonical TurnEvent, and closes the channel on subprocess exit.
func pumpEvents(
ctx context.Context,
host plugin.HostAPI,
cmd *exec.Cmd,
stdout io.Reader,
stderr io.Reader,
workspace string,
out chan<- canonical.TurnEvent,
) {
defer close(out)
// Drain stderr in a side goroutine — codex chatters informational
// stuff there ("Reading additional input from stdin..." etc.).
go func() {
sc := bufio.NewScanner(stderr)
for sc.Scan() {
host.Log("debug", "codex stderr: "+sc.Text(), nil)
}
}()
emit := func(ev canonical.TurnEvent) {
select {
case out <- ev:
case <-ctx.Done():
}
}
emit(canonical.TurnEvent{Type: canonical.EventMessageStart})
scanner := bufio.NewScanner(stdout)
scanner.Buffer(make([]byte, 64*1024), 4*1024*1024)
var (
usage canonical.Usage
hadError bool
errMsg string
)
for scanner.Scan() {
line := scanner.Bytes()
if len(line) == 0 {
continue
}
var head struct {
Type string `json:"type"`
}
if err := json.Unmarshal(line, &head); err != nil {
host.Log("warn", "codex: unparseable JSONL line",
map[string]any{"err": err.Error(), "line": string(line)})
continue
}
switch head.Type {
case "thread.started":
var ev struct {
ThreadID string `json:"thread_id"`
}
_ = json.Unmarshal(line, &ev)
if ev.ThreadID != "" {
saveSessionID(workspace, ev.ThreadID, host)
}
case "turn.started":
// nothing user-facing
case "item.started":
// codex announces an item; we wait for completed.
case "item.completed":
var ev struct {
Item struct {
ID string `json:"id"`
Type string `json:"type"`
Text string `json:"text"`
} `json:"item"`
}
if err := json.Unmarshal(line, &ev); err != nil {
continue
}
// "agent_message" is the assistant's text reply.
// Other item types (reasoning_summary, tool_use, etc.)
// surface as logs for now.
if ev.Item.Type == "agent_message" && ev.Item.Text != "" {
emit(canonical.TurnEvent{
Type: canonical.EventTextDelta, Text: ev.Item.Text,
})
} else if ev.Item.Type != "" {
host.Log("debug", "codex item",
map[string]any{"type": ev.Item.Type, "id": ev.Item.ID})
}
case "turn.completed":
var ev struct {
Usage struct {
InputTokens int `json:"input_tokens"`
CachedInputTokens int `json:"cached_input_tokens"`
OutputTokens int `json:"output_tokens"`
ReasoningTokens int `json:"reasoning_output_tokens"`
} `json:"usage"`
}
if err := json.Unmarshal(line, &ev); err == nil {
usage.InputTokens = ev.Usage.InputTokens
usage.OutputTokens = ev.Usage.OutputTokens
usage.CacheReadTokens = ev.Usage.CachedInputTokens
usage.ThinkingTokens = ev.Usage.ReasoningTokens
}
case "error", "turn.failed":
var ev struct {
Message string `json:"message"`
Error struct {
Message string `json:"message"`
} `json:"error"`
}
_ = json.Unmarshal(line, &ev)
hadError = true
errMsg = ev.Message
if errMsg == "" {
errMsg = ev.Error.Message
}
emit(canonical.TurnEvent{
Type: canonical.EventError,
Error: &canonical.ErrorInfo{Code: head.Type, Message: errMsg},
})
default:
host.Log("debug", "codex unknown event",
map[string]any{"type": head.Type, "line": truncate(string(line), 200)})
}
}
if serr := scanner.Err(); serr != nil {
host.Log("warn", "codex scanner", map[string]any{"err": serr.Error()})
}
werr := cmd.Wait()
stopReason := canonical.StopEndTurn
if hadError || werr != nil {
stopReason = canonical.StopReason("error")
}
emit(canonical.TurnEvent{
Type: canonical.EventMessageEnd, StopReason: stopReason, Usage: &usage,
})
}
// ---- helpers ----
func extractLastUserText(msgs []canonical.Message) string {
for i := len(msgs) - 1; i >= 0; i-- {
m := msgs[i]
if m.Role != canonical.RoleUser {
continue
}
var parts []string
for _, b := range m.Content {
if t, ok := b.(*canonical.TextBlock); ok {
parts = append(parts, t.Text)
}
}
if len(parts) > 0 {
out := parts[0]
for _, p := range parts[1:] {
out += "\n" + p
}
return out
}
}
return ""
}
func loadSessionID(workspace string) string {
raw, err := os.ReadFile(filepath.Join(workspace, SessionFile))
if err != nil {
return ""
}
// Trim possible trailing newline.
s := string(raw)
for len(s) > 0 && (s[len(s)-1] == '\n' || s[len(s)-1] == '\r' || s[len(s)-1] == ' ') {
s = s[:len(s)-1]
}
return s
}
func saveSessionID(workspace, id string, host plugin.HostAPI) {
path := filepath.Join(workspace, SessionFile)
if err := os.WriteFile(path, []byte(id), 0o600); err != nil {
host.Log("warn", "codex: save session id failed",
map[string]any{"err": err.Error(), "path": path})
}
}
func truncate(s string, n int) string {
if len(s) <= n {
return s
}
return s[:n] + "…"
}

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#!/usr/bin/env bash
# Plexum-openai-provider installer.
#
# Builds + installs the plugin under ~/.plexum/plugins/. Plugin wraps
# the local `codex` CLI; auth lives in the CLI's own ~/.codex/ state.
set -euo pipefail
REPO="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
PROFILE_DIR="${HOME}/.plexum"
while [[ $# -gt 0 ]]; do
case "$1" in
--profile) PROFILE_DIR="$2"; shift 2 ;;
-h|--help) sed -n '2,/^set -euo/p' "$0" | sed -n '/^#/p' | sed 's/^# \{0,1\}//'; exit 0 ;;
*) echo "unknown flag: $1" >&2; exit 2 ;;
esac
done
log() { printf '\033[1;34m[openai-install]\033[0m %s\n' "$*"; }
command -v go >/dev/null || { echo "go not found on PATH" >&2; exit 1; }
command -v codex >/dev/null || log "WARN: codex CLI not on PATH yet — operator must install + 'codex login' before first turn"
PLUGIN_DIR="${PROFILE_DIR}/plugins/plexum-openai-provider"
mkdir -p "${PLUGIN_DIR}"
cd "${REPO}"
VERSION="$(git describe --tags --always 2>/dev/null || echo dev)"
LDFLAGS="-X main.Version=${VERSION}"
log "building plexum-openai-provider-plugin (v=${VERSION})"
CGO_ENABLED=0 go build -ldflags="${LDFLAGS}" \
-o "${PLUGIN_DIR}/plexum-openai-provider-plugin" \
./cmd/plexum-openai-provider-plugin
cat > "${PLUGIN_DIR}/manifest.json" <<'EOF'
{
"name": "plexum-openai-provider",
"version": "0.1.0",
"activation": "lazy",
"executable": "plexum-openai-provider-plugin",
"contracts": {
"provider": {
"models": ["codex"]
}
}
}
EOF
cat <<EOF
[openai-install] done.
plugin binary: ${PLUGIN_DIR}/plexum-openai-provider-plugin
manifest: ${PLUGIN_DIR}/manifest.json
models: codex (CLI default — ChatGPT login restricts model selection;
add others via config.supported_models if on API key)
Optional config: ${PLUGIN_DIR}/config.json
{
"binary": "codex", // absolute path required under systemd
"extra_args": [],
"supported_models": ["codex"],
"model_args": {"gpt-5": "gpt-5"} // map plexum id → --model value
}
No api_key needed — codex CLI handles auth via ~/.codex/ state.
Next steps:
1. .plugins.allow += ["plexum-openai-provider"] in ${PROFILE_DIR}/plexum.json
2. plexum agent-add --model codex <agent-id>
3. systemctl --user restart plexum
EOF