OpenTelemetry events (#2103)

### Title

## otel

Codex can emit [OpenTelemetry](https://opentelemetry.io/) **log events**
that
describe each run: outbound API requests, streamed responses, user
input,
tool-approval decisions, and the result of every tool invocation. Export
is
**disabled by default** so local runs remain self-contained. Opt in by
adding an
`[otel]` table and choosing an exporter.

```toml
[otel]
environment = "staging"   # defaults to "dev"
exporter = "none"          # defaults to "none"; set to otlp-http or otlp-grpc to send events
log_user_prompt = false    # defaults to false; redact prompt text unless explicitly enabled
```

Codex tags every exported event with `service.name = "codex-cli"`, the
CLI
version, and an `env` attribute so downstream collectors can distinguish
dev/staging/prod traffic. Only telemetry produced inside the
`codex_otel`
crate—the events listed below—is forwarded to the exporter.

### Event catalog

Every event shares a common set of metadata fields: `event.timestamp`,
`conversation.id`, `app.version`, `auth_mode` (when available),
`user.account_id` (when available), `terminal.type`, `model`, and
`slug`.

With OTEL enabled Codex emits the following event types (in addition to
the
metadata above):

- `codex.api_request`
  - `cf_ray` (optional)
  - `attempt`
  - `duration_ms`
  - `http.response.status_code` (optional)
  - `error.message` (failures)
- `codex.sse_event`
  - `event.kind`
  - `duration_ms`
  - `error.message` (failures)
  - `input_token_count` (completion only)
  - `output_token_count` (completion only)
  - `cached_token_count` (completion only, optional)
  - `reasoning_token_count` (completion only, optional)
  - `tool_token_count` (completion only)
- `codex.user_prompt`
  - `prompt_length`
  - `prompt` (redacted unless `log_user_prompt = true`)
- `codex.tool_decision`
  - `tool_name`
  - `call_id`
- `decision` (`approved`, `approved_for_session`, `denied`, or `abort`)
  - `source` (`config` or `user`)
- `codex.tool_result`
  - `tool_name`
  - `call_id`
  - `arguments`
  - `duration_ms` (execution time for the tool)
  - `success` (`"true"` or `"false"`)
  - `output`

### Choosing an exporter

Set `otel.exporter` to control where events go:

- `none` – leaves instrumentation active but skips exporting. This is
the
  default.
- `otlp-http` – posts OTLP log records to an OTLP/HTTP collector.
Specify the
  endpoint, protocol, and headers your collector expects:

  ```toml
  [otel]
  exporter = { otlp-http = {
    endpoint = "https://otel.example.com/v1/logs",
    protocol = "binary",
    headers = { "x-otlp-api-key" = "${OTLP_TOKEN}" }
  }}
  ```

- `otlp-grpc` – streams OTLP log records over gRPC. Provide the endpoint
and any
  metadata headers:

  ```toml
  [otel]
  exporter = { otlp-grpc = {
    endpoint = "https://otel.example.com:4317",
    headers = { "x-otlp-meta" = "abc123" }
  }}
  ```

If the exporter is `none` nothing is written anywhere; otherwise you
must run or point to your
own collector. All exporters run on a background batch worker that is
flushed on
shutdown.

If you build Codex from source the OTEL crate is still behind an `otel`
feature
flag; the official prebuilt binaries ship with the feature enabled. When
the
feature is disabled the telemetry hooks become no-ops so the CLI
continues to
function without the extra dependencies.

---------

Co-authored-by: Anton Panasenko <apanasenko@openai.com>

codex-rs/core/src/config.rs

@@ -1,8 +1,12 @@
 use crate::config_profile::ConfigProfile;
+use crate::config_types::DEFAULT_OTEL_ENVIRONMENT;
 use crate::config_types::History;
 use crate::config_types::McpServerConfig;
 use crate::config_types::McpServerTransportConfig;
 use crate::config_types::Notifications;
+use crate::config_types::OtelConfig;
+use crate::config_types::OtelConfigToml;
+use crate::config_types::OtelExporterKind;
 use crate::config_types::ReasoningSummaryFormat;
 use crate::config_types::SandboxWorkspaceWrite;
 use crate::config_types::ShellEnvironmentPolicy;
@@ -199,6 +203,9 @@ pub struct Config {
     /// All characters are inserted as they are received, and no buffering
     /// or placeholder replacement will occur for fast keypress bursts.
     pub disable_paste_burst: bool,
+
+    /// OTEL configuration (exporter type, endpoint, headers, etc.).
+    pub otel: crate::config_types::OtelConfig,
 }
 
 impl Config {
@@ -719,6 +726,9 @@ pub struct ConfigToml {
     /// All characters are inserted as they are received, and no buffering
     /// or placeholder replacement will occur for fast keypress bursts.
     pub disable_paste_burst: Option<bool>,
+
+    /// OTEL configuration.
+    pub otel: Option<crate::config_types::OtelConfigToml>,
 }
 
 impl From<ConfigToml> for UserSavedConfig {
@@ -1068,6 +1078,19 @@ impl Config {
                 .as_ref()
                 .map(|t| t.notifications.clone())
                 .unwrap_or_default(),
+            otel: {
+                let t: OtelConfigToml = cfg.otel.unwrap_or_default();
+                let log_user_prompt = t.log_user_prompt.unwrap_or(false);
+                let environment = t
+                    .environment
+                    .unwrap_or(DEFAULT_OTEL_ENVIRONMENT.to_string());
+                let exporter = t.exporter.unwrap_or(OtelExporterKind::None);
+                OtelConfig {
+                    log_user_prompt,
+                    environment,
+                    exporter,
+                }
+            },
         };
         Ok(config)
     }
@@ -1809,6 +1832,7 @@ model_verbosity = "high"
                 active_profile: Some("o3".to_string()),
                 disable_paste_burst: false,
                 tui_notifications: Default::default(),
+                otel: OtelConfig::default(),
             },
             o3_profile_config
         );
@@ -1868,6 +1892,7 @@ model_verbosity = "high"
             active_profile: Some("gpt3".to_string()),
             disable_paste_burst: false,
             tui_notifications: Default::default(),
+            otel: OtelConfig::default(),
         };
 
         assert_eq!(expected_gpt3_profile_config, gpt3_profile_config);
@@ -1942,6 +1967,7 @@ model_verbosity = "high"
             active_profile: Some("zdr".to_string()),
             disable_paste_burst: false,
             tui_notifications: Default::default(),
+            otel: OtelConfig::default(),
         };
 
         assert_eq!(expected_zdr_profile_config, zdr_profile_config);
@@ -2002,6 +2028,7 @@ model_verbosity = "high"
             active_profile: Some("gpt5".to_string()),
             disable_paste_burst: false,
             tui_notifications: Default::default(),
+            otel: OtelConfig::default(),
         };
 
         assert_eq!(expected_gpt5_profile_config, gpt5_profile_config);