# Patch Codex App Server Observability

> This skill should be used when ensuring Codex emits centralized observability logs (sse_lines.jsonl) while running in app-server mode, especially when used by the VS Code extension.

- Skill: `tankygranny05/patch-codex-app-server-observability` (Agent Skill)
- Install (CLI): `npx skillmds@latest add tankygranny05/patch-codex-app-server-observability`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tankygranny05/patch-codex-app-server-observability/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: tankygranny05 (https://skillmd.com/u/tankygranny05)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/tankygranny05/patch-codex-app-server-observability

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# Patch Codex App Server Observability
*[Created by Codex: 019be564-39d9-7b12-a4cf-fb7a7f1af223 2026-01-22]*

## Purpose
Enable or restore centralized observability (writes `sse_lines.jsonl`) for the long-lived `codex app-server` process used by VS Code.

## When to Use
- VS Code Codex “New Thread” works but subsequent turns stop producing events in `~/centralized-logs/codex/sse_lines.jsonl`.
- `codex app-server` runs fine but the process never opens `sse_lines.jsonl`.
- A regression between Codex versions removed app-server logging.
- The user sets `"chatgpt.cliExecutable"` to a custom `codex` binary and expects the same observability behavior as terminal runs.

## Workflow
1. Confirm which `codex` binary VS Code is running:
   - Check settings for `"chatgpt.cliExecutable"` in:
     - `~/Library/Application Support/Code/User/settings.json`
     - `<repo>/.vscode/settings.json`
   - Record the resolved path and `codex --version`.
   - If the path points to a local repo build, ask the user to confirm the intended repo/branch/commit.
2. Confirm the running app-server process and whether it is logging:
   - Find the VS Code-started PID (search for `codex app-server`).
   - Check whether the process has the log file open:
     - `lsof -p <pid> | rg 'sse_lines\\.jsonl|centralized-logs/codex'`
3. Choose the patch location (prefer least invasive):
   - Preferred (matches `codex-cli 0.77.0` behavior): initialize observability in the **root CLI** when launching `codex app-server` (no sub-subcommand).
   - Alternative: initialize observability inside the `codex-app-server` crate (requires a decision on how to choose/configure log dir).
4. Implement the root CLI patch:
   - In `codex-rs/cli/src/main.rs`, before launching the server:
     - resolve the effective log dir (root `--log-dir` if set, otherwise default via `observability::resolve_log_dir`)
     - call `observability::init(log_dir)`
   - Keep failure non-fatal (print a warning and continue).
   - Keep SIGTERM handler behavior consistent.
5. Build and validate:
   - `cargo build -p codex-cli --release`
   - Ensure VS Code points at the rebuilt binary if `"chatgpt.cliExecutable"` is set.
6. Restart VS Code to pick up the new binary:
   - VS Code keeps `codex app-server` alive; reload the window (or kill the app-server PID and let the extension respawn it).
7. Re-test:
   - Confirm `lsof` shows `sse_lines.jsonl` opened by the app-server process.
   - Run multiple turns in one thread; confirm the JSONL file continues to append across turns.

## Evidence to Include in RCA
- The exact `codex` path VS Code ran (bundled binary vs `"chatgpt.cliExecutable"` override).
- The `codex app-server` command line and PID.
- Whether `lsof` shows `sse_lines.jsonl` open.
- Any stderr warnings emitted when observability initialization fails.