Merge auto-render ops with the op just before it.

This ensures that auto-render is considered as part of a batch edit,
thus preventing situations where ctrl-z appears to have no effect.

Fixes: #852

Author: obsgolem

crates/koharu-app/bin/pipeline.rs

@@ -229,6 +229,7 @@ async fn run() -> Result<()> {
             text_node_ids: None,
             reading_order: None,
             region: None,
+            merge_with_previous_op: false,
         },
     };
 

crates/koharu-app/src/history.rs

@@ -86,6 +86,25 @@ impl History {
         Ok(self.epoch)
     }
 
+    /// Does the same as apply, but merges the op with the previous undo entry so they undo together.
+    pub fn apply_merge_up(&mut self, scene: &mut Scene, mut op: Op) -> Result<u64> {
+        op.apply(scene).context("apply op to scene")?;
+        self.epoch += 1;
+        self.write_frame(&op)?;
+
+        if let Some(back) = self.undo_stack.pop_back() {
+            self.push_undo(Op::Batch {
+                ops: vec![back, op],
+                label: "Merged undo entry".into(),
+            });
+        } else {
+            self.push_undo(op);
+        }
+
+        self.redo_stack.clear();
+        Ok(self.epoch)
+    }
+
     /// Undo the most recent op. Applies its inverse, records the inverse in
     /// the log, and moves the original onto the redo stack. Returns the new
     /// epoch + the inverse op that was just applied (so the RPC layer can
@@ -94,6 +113,7 @@ impl History {
         let Some(original) = self.undo_stack.pop_back() else {
             return Ok(None);
         };
+
         let mut inverse = original.inverse();
         inverse.apply(scene).context("apply inverse op")?;
         self.epoch += 1;

crates/koharu-app/src/pipeline/engine.rs

@@ -63,6 +63,9 @@ pub struct PipelineRunOptions {
     /// and process just that one block. Other engines ignore it.
     pub region: Option<Region>,
     pub reading_order: Option<ReadingOrder>,
+    /// If enabled, merge any ops generated by this with the entry above it, ensuring that they undo as a batch.
+    /// Used for implementing auto-render so that the render doesn't get a separate undo entry.
+    pub merge_with_previous_op: bool,
 }
 
 // ---------------------------------------------------------------------------

crates/koharu-app/src/pipeline/mod.rs

@@ -242,7 +242,14 @@ pub async fn run(
                 ops,
                 label: format!("{}: page {}", info.id, page_id),
             };
-            if let Err(err) = session.apply(batch) {
+
+            let apply_res = if spec.options.merge_with_previous_op {
+                session.apply_merge_up(batch)
+            } else {
+                session.apply(batch)
+            };
+
+            if let Err(err) = apply_res {
                 report_step_failure(
                     info.id,
                     page_id,

crates/koharu-app/src/session.rs

@@ -130,6 +130,13 @@ impl ProjectSession {
         history.apply(&mut scene, op)
     }
 
+    /// Apply an op, merges with the op immediately before if possible.
+    pub fn apply_merge_up(&self, op: Op) -> Result<u64> {
+        let mut history = self.history.lock();
+        let mut scene = self.scene.write();
+        history.apply_merge_up(&mut scene, op)
+    }
+
     pub fn undo(&self) -> Result<Option<(u64, Op)>> {
         let mut history = self.history.lock();
         let mut scene = self.scene.write();

crates/koharu-rpc/src/mcp/mod.rs

@@ -98,6 +98,7 @@ pub struct StartPipelineInput {
     pub system_prompt: Option<String>,
     pub default_font: Option<String>,
     pub reading_order: Option<ReadingOrder>,
+    pub merge_with_previous_op: bool,
 }
 
 #[derive(Debug, Clone, Serialize, schemars::JsonSchema)]
@@ -192,6 +193,7 @@ impl KoharuServer {
                 text_node_ids: input.text_node_ids,
                 reading_order: input.reading_order,
                 region: None,
+                merge_with_previous_op: input.merge_with_previous_op,
             },
         };
         let job_id = Uuid::new_v4().to_string();

crates/koharu-rpc/src/routes/pipelines.rs

@@ -50,6 +50,10 @@ pub struct StartPipelineRequest {
     pub default_font: Option<String>,
     #[serde(default)]
     pub reading_order: Option<ReadingOrder>,
+    /// If enabled, merge any ops generated by this with the entry above it, ensuring that they undo as a batch.
+    /// Used for implementing auto-render so that the render doesn't get a separate undo entry.
+    #[serde(default)]
+    pub merge_with_previous_op: bool,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
@@ -88,6 +92,7 @@ async fn start_pipeline(
             text_node_ids: req.text_node_ids,
             region: req.region,
             reading_order: req.reading_order,
+            merge_with_previous_op: req.merge_with_previous_op,
         },
     };
 

ui/lib/api/schemas/startPipelineRequest.ts

@@ -1,32 +1,36 @@
 /**
- * Generated by orval v8.8.1 🍺
+ * Generated by orval v8.19.0 🍺
  * Do not edit manually.
- * OpenAPI spec version: 0.0.1
  */
-import type { NodeId } from './nodeId'
-import type { PageId } from './pageId'
-import type { ReadingOrder } from './readingOrder'
-import type { Region } from './region'
+import type { NodeId } from './nodeId';
+import type { PageId } from './pageId';
+import type { ReadingOrder } from './readingOrder';
+import type { Region } from './region';
 
 export interface StartPipelineRequest {
   /** @nullable */
-  defaultFont?: string | null
+  defaultFont?: string | null;
   /**
-   * `None` → whole project, `Some(pages)` → just those pages.
-   * @nullable
-   */
-  pages?: PageId[] | null
-  readingOrder?: null | ReadingOrder
-  region?: null | Region
+     * If enabled, merge any ops generated by this with the entry above it, ensuring that they undo as a batch.
+     * Used for implementing auto-render so that the render doesn't get a separate undo entry.
+     */
+  mergeWithPreviousOp?: boolean;
+  /**
+     * `None` → whole project, `Some(pages)` → just those pages.
+     * @nullable
+     */
+  pages?: PageId[] | null;
+  readingOrder?: null | ReadingOrder;
+  region?: null | Region;
   /** Engine ids (`inventory::submit!` ids) to run in order. */
-  steps: string[]
+  steps: string[];
   /** @nullable */
-  systemPrompt?: string | null
+  systemPrompt?: string | null;
   /** @nullable */
-  targetLanguage?: string | null
+  targetLanguage?: string | null;
   /**
-   * Optional text-node ids for engines that can operate on individual blocks.
-   * @nullable
-   */
-  textNodeIds?: NodeId[] | null
+     * Optional text-node ids for engines that can operate on individual blocks.
+     * @nullable
+     */
+  textNodeIds?: NodeId[] | null;
 }