diff --git a/conductor/tracks.md b/conductor/tracks.md
index 568c6f8..d8c1b45 100644
--- a/conductor/tracks.md
+++ b/conductor/tracks.md
@@ -56,7 +56,7 @@ This file tracks all major tracks for the project. Each track has its own detail
 11. [x] **Track: Track Progress Visualization**
     *Link: [./tracks/track_progress_viz_20260306/](./tracks/track_progress_viz_20260306/)*
 
-12. [ ] **Track: Manual Skeleton Context Injection**
+12. [~] **Track: Manual Skeleton Context Injection**
     *Link: [./tracks/manual_skeleton_injection_20260306/](./tracks/manual_skeleton_injection_20260306/)*
 
 13. [ ] **Track: On-Demand Definition Lookup**
diff --git a/conductor/tracks/manual_skeleton_injection_20260306/plan.md b/conductor/tracks/manual_skeleton_injection_20260306/plan.md
index 15d2b2b..9a2ed01 100644
--- a/conductor/tracks/manual_skeleton_injection_20260306/plan.md
+++ b/conductor/tracks/manual_skeleton_injection_20260306/plan.md
@@ -5,10 +5,10 @@
 ## Phase 1: UI Foundation
 Focus: Add file injection button and state
 
-- [ ] Task 1.1: Initialize MMA Environment
+- [x] Task 1.1: Initialize MMA Environment
     - Run `activate_skill mma-orchestrator` before starting
 
-- [ ] Task 1.2: Add injection state variables
+- [~] Task 1.2: Add injection state variables
     - WHERE: `src/gui_2.py` `App.__init__`
     - WHAT: State for injection UI
     - HOW:
diff --git a/src/app_controller.py b/src/app_controller.py
index c6b7664..62f5099 100644
--- a/src/app_controller.py
+++ b/src/app_controller.py
@@ -270,6 +270,11 @@ class AppController:
   self.prior_session_entries: List[Dict[str, Any]] = []
   self.test_hooks_enabled: bool = ("--enable-test-hooks" in sys.argv) or (os.environ.get("SLOP_TEST_HOOKS") == "1")
   self.ui_manual_approve: bool = False
+  # Injection state
+  self._inject_file_path: str = ""
+  self._inject_mode: str = "skeleton"
+  self._inject_preview: str = ""
+  self._show_inject_modal: bool = False
   self._settable_fields: Dict[str, str] = {
    'ai_input': 'ui_ai_input',
    'project_git_dir': 'ui_project_git_dir',
@@ -293,7 +298,10 @@ class AppController:
    'mma_active_tier': 'active_tier',
    'ui_new_track_name': 'ui_new_track_name',
    'ui_new_track_desc': 'ui_new_track_desc',
-   'manual_approve': 'ui_manual_approve'
+   'manual_approve': 'ui_manual_approve',
+   'inject_file_path': '_inject_file_path',
+   'inject_mode': '_inject_mode',
+   'show_inject_modal': '_show_inject_modal'
   }
   self._gettable_fields = dict(self._settable_fields)
   self._gettable_fields.update({
@@ -311,10 +319,40 @@ class AppController:
     'prior_session_indicator': 'prior_session_indicator',
     '_show_patch_modal': '_show_patch_modal',
     '_pending_patch_text': '_pending_patch_text',
-    '_pending_patch_files': '_pending_patch_files'
+    '_pending_patch_files': '_pending_patch_files',
+    '_inject_file_path': '_inject_file_path',
+    '_inject_mode': '_inject_mode',
+    '_inject_preview': '_inject_preview',
+    '_show_inject_modal': '_show_inject_modal'
    })
   self._init_actions()
 
+ def _update_inject_preview(self) -> None:
+  """Updates the preview content based on the selected file and injection mode."""
+  if not self._inject_file_path:
+   self._inject_preview = ""
+   return
+  target_path = self._inject_file_path
+  if not os.path.isabs(target_path):
+   target_path = os.path.join(self.ui_files_base_dir, target_path)
+  if not os.path.exists(target_path):
+   self._inject_preview = ""
+   return
+  try:
+   with open(target_path, "r", encoding="utf-8") as f:
+    content = f.read()
+   if self._inject_mode == "skeleton" and target_path.endswith(".py"):
+    parser = ASTParser("python")
+    preview = parser.get_skeleton(content)
+   else:
+    preview = content
+   lines = preview.splitlines()
+   if len(lines) > 500:
+    preview = "\n".join(lines[:500]) + "\n... (truncated)"
+   self._inject_preview = preview
+  except Exception as e:
+   self._inject_preview = f"Error reading file: {e}"
+
  @property
  def thinking_indicator(self) -> bool:
   return self.ai_status in ("sending...", "streaming...")
diff --git a/src/gui_2.py b/src/gui_2.py
index 7d2c867..ebb70f4 100644
--- a/src/gui_2.py
+++ b/src/gui_2.py
@@ -744,6 +744,42 @@ class App:
      else:
       imgui.input_text_multiline("##tv_c", self.text_viewer_content, imgui.ImVec2(-1, -1), imgui.InputTextFlags_.read_only)
     imgui.end()
+   # Inject File Modal
+   if getattr(self, "show_inject_modal", False):
+    imgui.open_popup("Inject File")
+    self.show_inject_modal = False
+   if imgui.begin_popup_modal("Inject File", None, imgui.WindowFlags_.always_auto_resize)[0]:
+    files = self.project.get('files', {}).get('paths', [])
+    imgui.text("Select File to Inject:")
+    imgui.begin_child("inject_file_list", imgui.ImVec2(0, 200), True)
+    for f_path in files:
+     is_selected = (self._inject_file_path == f_path)
+     if imgui.selectable(f_path, is_selected)[0]:
+      self._inject_file_path = f_path
+      self.controller._update_inject_preview()
+    imgui.end_child()
+    imgui.separator()
+    if imgui.radio_button("Skeleton", self._inject_mode == "skeleton"):
+     self._inject_mode = "skeleton"
+     self.controller._update_inject_preview()
+    imgui.same_line()
+    if imgui.radio_button("Full", self._inject_mode == "full"):
+     self._inject_mode = "full"
+     self.controller._update_inject_preview()
+    imgui.separator()
+    imgui.text("Preview:")
+    imgui.begin_child("inject_preview_area", imgui.ImVec2(600, 300), True)
+    imgui.text_unformatted(self._inject_preview)
+    imgui.end_child()
+    imgui.separator()
+    if imgui.button("Inject", imgui.ImVec2(120, 0)):
+     formatted = f"## File: {self._inject_file_path}\n```python\n{self._inject_preview}\n```\n"
+     self.ui_ai_input += formatted
+     imgui.close_current_popup()
+    imgui.same_line()
+    if imgui.button("Cancel", imgui.ImVec2(120, 0)):
+     imgui.close_current_popup()
+    imgui.end_popup()
   except Exception as e:
    print(f"ERROR in _gui_func: {e}")
    import traceback
@@ -1543,6 +1579,9 @@ class App:
   with self._send_thread_lock:
    if self.send_thread and self.send_thread.is_alive():
     send_busy = True
+  if imgui.button("Inject File"):
+   self.show_inject_modal = True
+  imgui.same_line()
   if (imgui.button("Gen + Send") or ctrl_enter) and not send_busy:
    self._handle_generate_send()
   imgui.same_line()
diff --git a/tests/test_skeleton_injection.py b/tests/test_skeleton_injection.py
new file mode 100644
index 0000000..8f05dfb
--- /dev/null
+++ b/tests/test_skeleton_injection.py
@@ -0,0 +1,63 @@
+import os
+import pytest
+from src.app_controller import AppController
+from pathlib import Path
+
+def test_skeleton_injection_state_variables():
+ ctrl = AppController()
+ assert hasattr(ctrl, "_inject_file_path")
+ assert hasattr(ctrl, "_inject_mode")
+ assert hasattr(ctrl, "_inject_preview")
+ assert hasattr(ctrl, "_show_inject_modal")
+ assert ctrl._inject_mode == "skeleton"
+ assert ctrl._inject_preview == ""
+ assert ctrl._show_inject_modal is False
+
+def test_update_inject_preview_skeleton(tmp_path):
+ ctrl = AppController()
+ mock_file = tmp_path / "mock.py"
+ # Use 1-space indent in the mock content too for consistency
+ content = '"""Module docstring"""\ndef foo():\n """Foo docstring"""\n print("hello")\n\nclass Bar:\n """Bar docstring"""\n def baz(self):\n  pass\n'
+ mock_file.write_text(content)
+ 
+ ctrl._inject_file_path = str(mock_file)
+ ctrl._inject_mode = "skeleton"
+ ctrl._update_inject_preview()
+ 
+ # Skeleton should contain signatures and docstrings but not bodies
+ assert "def foo():" in ctrl._inject_preview
+ assert "class Bar:" in ctrl._inject_preview
+ assert 'print("hello")' not in ctrl._inject_preview
+ assert "pass" not in ctrl._inject_preview
+ assert '"""Foo docstring"""' in ctrl._inject_preview
+
+def test_update_inject_preview_full(tmp_path):
+ ctrl = AppController()
+ mock_file = tmp_path / "mock.py"
+ content = "line 1\n" * 10
+ mock_file.write_text(content)
+ 
+ ctrl._inject_file_path = str(mock_file)
+ ctrl._inject_mode = "full"
+ ctrl._update_inject_preview()
+ 
+ assert ctrl._inject_preview.strip() == content.strip()
+
+def test_update_inject_preview_truncation(tmp_path):
+ ctrl = AppController()
+ mock_file = tmp_path / "large.py"
+ content = "\n".join([f"line {i}" for i in range(1000)])
+ mock_file.write_text(content)
+ 
+ ctrl._inject_file_path = str(mock_file)
+ ctrl._inject_mode = "full"
+ ctrl._update_inject_preview()
+ 
+ lines = ctrl._inject_preview.splitlines()
+ # It should be 500 lines + 1 for truncated message
+ assert len(lines) == 501
+ assert "... (truncated)" in lines[-1]
+ # The 500th line is "line 499" (starting from 0)
+ assert "line 499" in lines[499]
+ # The 501st line should be "line 500", but it should be replaced by truncation msg
+ assert "line 500" not in ctrl._inject_preview