feat: make reasoning effort/summaries configurable (#1199)

Previous to this PR, we always set `reasoning` when making a request
using the Responses API:


d7245cbbc9/codex-rs/core/src/client.rs (L108-L111)

Though if you tried to use the Rust CLI with `--model gpt-4.1`, this
would fail with:

```shell
"Unsupported parameter: 'reasoning.effort' is not supported with this model."
```

We take a cue from the TypeScript CLI, which does a check on the model
name:


d7245cbbc9/codex-cli/src/utils/agent/agent-loop.ts (L786-L789)

This PR does a similar check, though also adds support for the following
config options:

```
model_reasoning_effort = "low" | "medium" | "high" | "none"
model_reasoning_summary = "auto" | "concise" | "detailed" | "none"
```

This way, if you have a model whose name happens to start with `"o"` (or
`"codex"`?), you can set these to `"none"` to explicitly disable
reasoning, if necessary. (That said, it seems unlikely anyone would use
the Responses API with non-OpenAI models, but we provide an escape
hatch, anyway.)

This PR also updates both the TUI and `codex exec` to show `reasoning
effort` and `reasoning summaries` in the header.

codex-rs/core/src/client.rs

@@ -18,12 +18,13 @@ use tracing::warn;
 
 use crate::chat_completions::AggregateStreamExt;
 use crate::chat_completions::stream_chat_completions;
-use crate::client_common::Payload;
 use crate::client_common::Prompt;
-use crate::client_common::Reasoning;
 use crate::client_common::ResponseEvent;
 use crate::client_common::ResponseStream;
-use crate::client_common::Summary;
+use crate::client_common::ResponsesApiRequest;
+use crate::client_common::create_reasoning_param_for_request;
+use crate::config_types::ReasoningEffort as ReasoningEffortConfig;
+use crate::config_types::ReasoningSummary as ReasoningSummaryConfig;
 use crate::error::CodexErr;
 use crate::error::EnvVarError;
 use crate::error::Result;
@@ -41,14 +42,23 @@ pub struct ModelClient {
     model: String,
     client: reqwest::Client,
     provider: ModelProviderInfo,
+    effort: ReasoningEffortConfig,
+    summary: ReasoningSummaryConfig,
 }
 
 impl ModelClient {
-    pub fn new(model: impl ToString, provider: ModelProviderInfo) -> Self {
+    pub fn new(
+        model: impl ToString,
+        provider: ModelProviderInfo,
+        effort: ReasoningEffortConfig,
+        summary: ReasoningSummaryConfig,
+    ) -> Self {
         Self {
             model: model.to_string(),
             client: reqwest::Client::new(),
             provider,
+            effort,
+            summary,
         }
     }
 
@@ -98,17 +108,15 @@ impl ModelClient {
 
         let full_instructions = prompt.get_full_instructions();
         let tools_json = create_tools_json_for_responses_api(prompt, &self.model)?;
-        let payload = Payload {
+        let reasoning = create_reasoning_param_for_request(&self.model, self.effort, self.summary);
+        let payload = ResponsesApiRequest {
             model: &self.model,
             instructions: &full_instructions,
             input: &prompt.input,
             tools: &tools_json,
             tool_choice: "auto",
             parallel_tool_calls: false,
-            reasoning: Some(Reasoning {
-                effort: "high",
-                summary: Some(Summary::Auto),
-            }),
+            reasoning,
             previous_response_id: prompt.prev_id.clone(),
             store: prompt.store,
             stream: true,