refactor: zero-copy zen output buffer — replace write_output_bytes with from_output_vec

add_output_buffer_from_vec moves the Vec<u8> directly into the IoProxy
WriteVec cursor instead of copying via write_all. write_output_bytes deleted.

Author: lilith

imageflow_core/src/codecs/mod.rs

@@ -423,29 +423,4 @@ impl CodecInstanceContainer {
             )),
         }
     }
-
-    /// Write encoded bytes to the output buffer (for zen pipeline).
-    ///
-    /// Replaces the output IoProxy with one backed by the given bytes.
-    /// The buffer then works with `take_output_buffer()` and
-    /// `output_buffer_raw_parts()` as if an encoder had written it.
-    /// Write encoded bytes into the output buffer (for zen pipeline).
-    ///
-    /// The buffer must be in `Ready` state (freshly created via `add_output_buffer`).
-    /// After writing, `take_output_buffer()` and `output_buffer_raw_parts()` work
-    /// as if an encoder had written the bytes.
-    pub fn write_output_bytes(&mut self, bytes: &[u8]) -> Result<()> {
-        match &mut self.output_state {
-            OutputBufferState::Ready(ref mut io) => {
-                use std::io::Write;
-                io.write_all(bytes).map_err(|e| nerror!(ErrorKind::EncodingIoError, "{}", e))?;
-                Ok(())
-            }
-            _ => Err(nerror!(
-                ErrorKind::InvalidState,
-                "io_id {} output buffer not in Ready state for write_output_bytes",
-                self.io_id
-            )),
-        }
-    }
 }

imageflow_core/src/context.rs

@@ -614,6 +614,11 @@ impl Context {
         self.add_io(io, io_id, IoDirection::Out).map_err(|e| e.at(here!()))
     }
 
+    pub fn add_output_buffer_from_vec(&mut self, io_id: i32, bytes: Vec<u8>) -> Result<()> {
+        let io = IoProxy::from_output_vec(self, io_id, bytes).map_err(|e| e.at(here!()))?;
+        self.add_io(io, io_id, IoDirection::Out).map_err(|e| e.at(here!()))
+    }
+
     fn swap_dimensions_by_exif(&mut self, io_id: i32, image_info: &mut ImageInfo) -> Result<()> {
         let exif_maybe = self
             .get_codec(io_id)
@@ -750,9 +755,7 @@ impl Context {
                 let output =
                     crate::zen::zen_build(parsed, &self.security, &job_options).map_err(|e| e.at(here!()))?;
                 for (io_id, bytes) in output.output_buffers {
-                    let _ = self.add_output_buffer(io_id);
-                    let mut codec = self.get_codec(io_id).map_err(|e| e.at(here!()))?;
-                    codec.write_output_bytes(&bytes).map_err(|e| e.at(here!()))?;
+                    self.add_output_buffer_from_vec(io_id, bytes).map_err(|e| e.at(here!()))?;
                 }
                 self.store_zen_captured_bitmaps(output.captured_bitmaps)?;
                 return Ok(output.job_result);
@@ -878,10 +881,7 @@ impl Context {
 
         // Store encoded outputs in Context's output buffer system.
         for (io_id, bytes) in output.output_buffers {
-            // Add output buffer only if not already present (test infra may pre-add it).
-            let _ = self.add_output_buffer(io_id);
-            let mut codec = self.get_codec(io_id).map_err(|e| e.at(here!()))?;
-            codec.write_output_bytes(&bytes).map_err(|e| e.at(here!()))?;
+            self.add_output_buffer_from_vec(io_id, bytes).map_err(|e| e.at(here!()))?;
         }
 
         // Store captured bitmaps as v2 BitmapKeys for test compatibility.

imageflow_core/src/io.rs

@@ -201,6 +201,12 @@ impl IoProxy {
         Ok(IoProxy { path: None, io_id, backend: IoBackend::WriteVec(Cursor::new(Vec::new())) })
     }
 
+    /// Wrap an already-encoded `Vec<u8>` as an output buffer — zero copy.
+    pub fn from_output_vec(context: &Context, io_id: i32, bytes: Vec<u8>) -> Result<IoProxy> {
+        IoProxy::check_io_id(context, io_id)?;
+        Ok(IoProxy { path: None, io_id, backend: IoBackend::WriteVec(Cursor::new(bytes)) })
+    }
+
     pub fn read_vec(context: &Context, io_id: i32, bytes: Vec<u8>) -> Result<IoProxy> {
         IoProxy::check_io_id(context, io_id)?;
 

imageflow_core/src/json/endpoints/v1.rs

@@ -894,9 +894,7 @@ fn zen_build(context: &mut Context, parsed: Build001) -> Result<BuildV1Response>
 
     // Store encoded output in Context so take_output_buffer() works for C ABI.
     for (io_id, bytes) in output.output_buffers {
-        context.add_output_buffer(io_id).map_err(|e| e.at(here!()))?;
-        let mut codec = context.get_codec(io_id).map_err(|e| e.at(here!()))?;
-        codec.write_output_bytes(&bytes).map_err(|e| e.at(here!()))?;
+        context.add_output_buffer_from_vec(io_id, bytes).map_err(|e| e.at(here!()))?;
     }
 
     Ok(BuildV1Response { job_result: output.job_result })