Fix codex exec --profile handling (#14524)

PR #14005 introduced a regression whereby `codex exec --profile`
overrides were dropped when starting or resuming a thread. That causes
the thread to miss profile-scoped settings like
`model_instructions_file`.

This PR preserve the active profile in the thread start/resume config
overrides so the
app-server rebuild sees the same profile that exec resolved. 

Fixes #14515

codex-rs/core/tests/suite/cli_stream.rs

@@ -160,6 +160,75 @@ async fn exec_cli_applies_model_instructions_file() {
     );
 }
 
+/// Verify that `codex exec --profile ...` preserves the active profile when it
+/// starts the in-process app-server thread, so profile-scoped
+/// `model_instructions_file` is applied to the outbound request.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn exec_cli_profile_applies_model_instructions_file() {
+    skip_if_no_network!();
+
+    let server = MockServer::start().await;
+    let sse = concat!(
+        "data: {\"type\":\"response.created\",\"response\":{}}\n\n",
+        "data: {\"type\":\"response.completed\",\"response\":{\"id\":\"r1\"}}\n\n"
+    );
+    let resp_mock = core_test_support::responses::mount_sse_once(&server, sse.to_string()).await;
+
+    let custom = TempDir::new().unwrap();
+    let marker = "cli-profile-model-instructions-file-marker";
+    let custom_path = custom.path().join("instr.md");
+    std::fs::write(&custom_path, marker).unwrap();
+    let custom_path_str = custom_path.to_string_lossy().replace('\\', "/");
+
+    let provider_override = format!(
+        "model_providers.mock={{ name = \"mock\", base_url = \"{}/v1\", env_key = \"PATH\", wire_api = \"responses\" }}",
+        server.uri()
+    );
+
+    let home = TempDir::new().unwrap();
+    std::fs::write(
+        home.path().join("config.toml"),
+        format!("[profiles.default]\nmodel_instructions_file = \"{custom_path_str}\"\n",),
+    )
+    .unwrap();
+
+    let repo_root = repo_root();
+    let bin = codex_utils_cargo_bin::cargo_bin("codex").unwrap();
+    let mut cmd = AssertCommand::new(bin);
+    cmd.arg("exec")
+        .arg("--skip-git-repo-check")
+        .arg("--profile")
+        .arg("default")
+        .arg("-c")
+        .arg(&provider_override)
+        .arg("-c")
+        .arg("model_provider=\"mock\"")
+        .arg("-C")
+        .arg(&repo_root)
+        .arg("hello?\n");
+    cmd.env("CODEX_HOME", home.path())
+        .env("OPENAI_API_KEY", "dummy")
+        .env("OPENAI_BASE_URL", format!("{}/v1", server.uri()));
+
+    let output = cmd.output().unwrap();
+    println!("Status: {}", output.status);
+    println!("Stdout:\n{}", String::from_utf8_lossy(&output.stdout));
+    println!("Stderr:\n{}", String::from_utf8_lossy(&output.stderr));
+    assert!(output.status.success());
+
+    let request = resp_mock.single_request();
+    let body = request.body_json();
+    let instructions = body
+        .get("instructions")
+        .and_then(|v| v.as_str())
+        .unwrap_or_default()
+        .to_string();
+    assert!(
+        instructions.contains(marker),
+        "instructions did not contain profile marker; got: {instructions}"
+    );
+}
+
 /// Tests streaming responses through the CLI using a local SSE fixture file.
 /// This test:
 /// 1. Uses a pre-recorded SSE response fixture instead of a live server

codex-rs/exec/src/lib.rs

@@ -77,6 +77,7 @@ use codex_utils_oss::get_default_model_for_oss_provider;
 use event_processor_with_human_output::EventProcessorWithHumanOutput;
 use event_processor_with_jsonl_output::EventProcessorWithJsonOutput;
 use serde_json::Value;
+use std::collections::HashMap;
 use std::collections::HashSet;
 use std::collections::VecDeque;
 use std::io::IsTerminal;
@@ -914,6 +915,7 @@ fn thread_start_params_from_config(config: &Config) -> ThreadStartParams {
         cwd: Some(config.cwd.to_string_lossy().to_string()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         sandbox: sandbox_mode_from_policy(config.permissions.sandbox_policy.get()),
+        config: config_request_overrides_from_config(config),
         ephemeral: Some(config.ephemeral),
         ..ThreadStartParams::default()
     }
@@ -928,10 +930,18 @@ fn thread_resume_params_from_config(config: &Config, path: Option<PathBuf>) -> T
         cwd: Some(config.cwd.to_string_lossy().to_string()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         sandbox: sandbox_mode_from_policy(config.permissions.sandbox_policy.get()),
+        config: config_request_overrides_from_config(config),
         ..ThreadResumeParams::default()
     }
 }
 
+fn config_request_overrides_from_config(config: &Config) -> Option<HashMap<String, Value>> {
+    config
+        .active_profile
+        .as_ref()
+        .map(|profile| HashMap::from([("profile".to_string(), Value::String(profile.clone()))]))
+}
+
 async fn send_request_with_response<T>(
     client: &InProcessAppServerClient,
     request: ClientRequest,