feat(gui): Implement RAG context visualization in Discussion history

conductor/tracks/rag_support_20260308/plan.md

@@ -31,7 +31,7 @@
 - [x] Task: Implement the RAG Settings panel in `src/gui_2.py`. f57e2fe
     - [x] Add UI controls for choosing the RAG source, embedding model, and retrieval parameters. f57e2fe
     - [x] Add a "Rebuild Index" button and status progress bar. f57e2fe
-- [ ] Task: Implement retrieval visualization in the Discussion history.
+- [~] Task: Implement retrieval visualization in the Discussion history.
     - [ ] Display "Retrieved Context" blocks with expandable summaries.
     - [ ] Add "Source" buttons to each block that open the file at the specific chunk's location.
 - [ ] Task: Implement auto-start/indexing status indicators in the GUI.

src/gui_2.py

@@ -2710,6 +2710,26 @@ def hello():
       if read_mode:
        content = entry["content"]
        if content.strip():
+        if '## Retrieved Context' in content:
+         rag_match = re.search(r'## Retrieved Context\n\n([\s\S]*?)(?=\n\n#|\Z)', content)
+         if rag_match:
+          rag_section = rag_match.group(1)
+          if imgui.collapsing_header('Retrieved Context'):
+           chunks = re.finditer(r'### Chunk (\d+) \(Source: (.*?)\)\n([\s\S]*?)(?=\n### Chunk|\Z)', rag_section)
+           for chunk_match in chunks:
+            idx = chunk_match.group(1)
+            path = chunk_match.group(2)
+            chunk_content = chunk_match.group(3)
+            if imgui.collapsing_header(f'Chunk {idx}: {path}'):
+             if imgui.button(f'[Source]##rag_{i}_{idx}'):
+              res = mcp_client.read_file(path)
+              if res:
+               self.text_viewer_title = path
+               self.text_viewer_content = res
+               self.text_viewer_type = Path(path).suffix.lstrip('.') if Path(path).suffix else 'text'
+               self.show_text_viewer = True
+             imgui.text_unformatted(chunk_content)
+          content = content[:rag_match.start()] + content[rag_match.end():]
         pattern = re.compile(r"\[Definition: (.*?) from (.*?) \(line (\d+)\)\](\s+```[\s\S]*?```)?")
         matches = list(pattern.finditer(content))
         is_nerv = theme.is_nerv_active()