Stream apply_patch changes (#17862)

Adds new events for streaming apply_patch changes from responses api.
This is to enable clients to show progress during file writes.

Caveat: This does not work with apply_patch in function call mode, since
that required adding streaming json parsing.

codex-rs/protocol/src/protocol.rs

@@ -1546,6 +1546,9 @@ pub enum EventMsg {
     /// `ExecCommandBegin` so front‑ends can show progress indicators.
     PatchApplyBegin(PatchApplyBeginEvent),
 
+    /// Latest model-generated structured changes for an `apply_patch` call.
+    PatchApplyUpdated(PatchApplyUpdatedEvent),
+
     /// Notification that a patch application has finished.
     PatchApplyEnd(PatchApplyEndEvent),
 
@@ -3240,6 +3243,14 @@ pub struct PatchApplyBeginEvent {
     pub changes: HashMap<PathBuf, FileChange>,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
+pub struct PatchApplyUpdatedEvent {
+    /// Identifier for the originating `apply_patch` tool call.
+    pub call_id: String,
+    /// Structured file changes parsed from the model-generated patch input so far.
+    pub changes: HashMap<PathBuf, FileChange>,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
 pub struct PatchApplyEndEvent {
     /// Identifier for the PatchApplyBegin that finished.