[feat] persist dynamic tools in session rollout file (#10130)

Add dynamic tools to rollout file for persistence & read from rollout on
resume. Ran a real example and spotted the following in the rollout
file:
```
{"timestamp":"2026-01-29T01:27:57.468Z","type":"session_meta","payload":{"id":"019c075d-3f0b-77e3-894e-c1c159b04b1e","timestamp":"2026-01-29T01:27:57.451Z","...."dynamic_tools":[{"name":"demo_tool","description":"Demo dynamic tool","inputSchema":{"additionalProperties":false,"properties":{"city":{"type":"string"}},"required":["city"],"type":"object"}}],"git":{"commit_hash":"ebc573f15c01b8af158e060cfedd401f043e9dfa","branch":"dev/cc/dynamic-tools","repository_url":"https://github.com/openai/codex.git"}}}
```

codex-rs/protocol/src/protocol.rs

@@ -20,6 +20,7 @@ use crate::config_types::WindowsSandboxLevel;
 use crate::custom_prompts::CustomPrompt;
 use crate::dynamic_tools::DynamicToolCallRequest;
 use crate::dynamic_tools::DynamicToolResponse;
+use crate::dynamic_tools::DynamicToolSpec;
 use crate::items::TurnItem;
 use crate::message_history::HistoryEntry;
 use crate::models::BaseInstructions;
@@ -1513,6 +1514,22 @@ impl InitialHistory {
             }),
         }
     }
+
+    pub fn get_dynamic_tools(&self) -> Option<Vec<DynamicToolSpec>> {
+        match self {
+            InitialHistory::New => None,
+            InitialHistory::Resumed(resumed) => {
+                resumed.history.iter().find_map(|item| match item {
+                    RolloutItem::SessionMeta(meta_line) => meta_line.meta.dynamic_tools.clone(),
+                    _ => None,
+                })
+            }
+            InitialHistory::Forked(items) => items.iter().find_map(|item| match item {
+                RolloutItem::SessionMeta(meta_line) => meta_line.meta.dynamic_tools.clone(),
+                _ => None,
+            }),
+        }
+    }
 }
 
 fn session_cwd_from_items(items: &[RolloutItem]) -> Option<PathBuf> {
@@ -1599,6 +1616,8 @@ pub struct SessionMeta {
     /// but may be missing for older sessions. If not present, fall back to rendering the base_instructions
     /// from ModelsManager.
     pub base_instructions: Option<BaseInstructions>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub dynamic_tools: Option<Vec<DynamicToolSpec>>,
 }
 
 impl Default for SessionMeta {
@@ -1613,6 +1632,7 @@ impl Default for SessionMeta {
             source: SessionSource::default(),
             model_provider: None,
             base_instructions: None,
+            dynamic_tools: None,
         }
     }
 }