feat: scratchpad tool + fix Claude auth token expiry warning

- Add cortex/tools/scratch.py with scratch_read/write/append/clear tools
- Register all four scratch tools in the orchestrator tool registry
- Create inara/SCRATCH.md as the backing file (never distilled/archived)
- Fix auth.py: expiresAt reflects short-lived access token (~8h) not the
  1-year refresh token — suppress expiry warning when refreshToken is present

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/tools/__init__.py

@@ -23,6 +23,12 @@ from tools.files import file_read as _file_read
 from tools.system import claude_allow_dir as _claude_allow_dir
 from tools.tasks import task_list as _task_list, task_create as _task_create
 from tools.tasks import task_update as _task_update, task_complete as _task_complete
+from tools.scratch import (
+    scratch_read as _scratch_read,
+    scratch_write as _scratch_write,
+    scratch_append as _scratch_append,
+    scratch_clear as _scratch_clear,
+)
 
 
 # ---------------------------------------------------------------------------
@@ -179,6 +185,10 @@ _CALLABLES: dict[str, callable] = {
     "task_create": _task_create,
     "task_update": _task_update,
     "task_complete": _task_complete,
+    "scratch_read": _scratch_read,
+    "scratch_write": _scratch_write,
+    "scratch_append": _scratch_append,
+    "scratch_clear": _scratch_clear,
 }
 
 _claude_allow_dir_declaration = types.FunctionDeclaration(
@@ -305,6 +315,64 @@ _task_complete_declaration = types.FunctionDeclaration(
     ),
 )
 
+_scratch_read_declaration = types.FunctionDeclaration(
+    name="scratch_read",
+    description=(
+        "Read the full contents of the scratchpad. "
+        "Use this to recall working notes, mid-task context, or anything previously jotted down. "
+        "The scratchpad is transient — nothing here is distilled or archived."
+    ),
+    parameters=types.Schema(type=types.Type.OBJECT, properties={}),
+)
+
+_scratch_write_declaration = types.FunctionDeclaration(
+    name="scratch_write",
+    description=(
+        "Replace the entire scratchpad with new content. "
+        "Use this to set a clean working note, replacing whatever was there before. "
+        "For adding without replacing, use scratch_append instead."
+    ),
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "content": types.Schema(
+                type=types.Type.STRING,
+                description="The new scratchpad content (markdown supported)",
+            ),
+        },
+        required=["content"],
+    ),
+)
+
+_scratch_append_declaration = types.FunctionDeclaration(
+    name="scratch_append",
+    description=(
+        "Add a new section to the bottom of the scratchpad without replacing existing content. "
+        "Each section gets a timestamp heading unless you supply one."
+    ),
+    parameters=types.Schema(
+        type=types.Type.OBJECT,
+        properties={
+            "content": types.Schema(
+                type=types.Type.STRING,
+                description="The content to append (markdown supported)",
+            ),
+            "heading": types.Schema(
+                type=types.Type.STRING,
+                description="Optional section heading. Defaults to current UTC timestamp.",
+            ),
+        },
+        required=["content"],
+    ),
+)
+
+_scratch_clear_declaration = types.FunctionDeclaration(
+    name="scratch_clear",
+    description="Erase everything in the scratchpad. Use when the working notes are no longer needed.",
+    parameters=types.Schema(type=types.Type.OBJECT, properties={}),
+)
+
+
 # Gemini Tool object — pass this to GenerateContentConfig
 TOOL_DECLARATIONS = [
     types.Tool(function_declarations=[
@@ -318,6 +386,10 @@ TOOL_DECLARATIONS = [
         _task_create_declaration,
         _task_update_declaration,
         _task_complete_declaration,
+        _scratch_read_declaration,
+        _scratch_write_declaration,
+        _scratch_append_declaration,
+        _scratch_clear_declaration,
     ])
 ]