feat(tasks): richer task generation with recursive decomposition (#420)

## Summary
- Enhanced LLM task generation prompt to populate complexity_score, estimated_hours, uncertainty_level, depends_on, files_to_modify
- Added recursive decomposition engine: classify → decompose → recurse (inspired by tinyagi/fractals)
- New Task fields: parent_id, lineage, is_leaf, hierarchical_id
- ASCII tree display: `cf tasks tree` shows hierarchy with status icons
- Status propagation: children done → parent auto-completes
- Lineage context injected into agent prompts via ContextPackager
- `cf tasks generate --recursive [--max-depth N]` flag
- Backward compatible: `cf tasks generate` (without --recursive) still works

## Validation
- Tests: 51 new tests, 2357 v2 tests passing (0 regressions)
- CI: All checks green (Backend Tests, Code Quality, Security)
- Demo: Tree display, rich metadata, backward compat verified

Closes #420

Author: frankbria

codeframe/cli/app.py

@@ -1547,6 +1547,18 @@ def tasks_generate(
         "--overwrite",
         help="Delete existing tasks before generating new ones",
     ),
+    recursive: bool = typer.Option(
+        False,
+        "--recursive", "-r",
+        help="Use recursive decomposition",
+    ),
+    max_depth: int = typer.Option(
+        3,
+        "--max-depth",
+        help="Maximum recursion depth (1-5)",
+        min=1,
+        max=5,
+    ),
 ) -> None:
     """Generate tasks from the PRD.
 
@@ -1555,6 +1567,7 @@ def tasks_generate(
 
     Use --overwrite to clear existing tasks first (useful for regeneration).
     Without --overwrite, new tasks are appended (useful for multi-PRD projects).
+    Use --recursive for recursive decomposition into a task tree.
     """
     from codeframe.core.workspace import get_workspace
     from codeframe.core import prd, tasks
@@ -1585,13 +1598,27 @@ def tasks_generate(
             from codeframe.cli.validators import require_anthropic_api_key
             require_anthropic_api_key()
 
-        if no_llm:
+        if recursive:
+            console.print(f"[dim]Using recursive decomposition (max depth: {max_depth})...[/dim]")
+
+            from codeframe.adapters.llm import get_provider
+            from codeframe.core.task_tree import generate_task_tree, flatten_task_tree
+
+            provider = get_provider()
+            tree = generate_task_tree(
+                provider,
+                prd_record.content,
+                lineage=[],
+                depth=0,
+                max_depth=max_depth,
+            )
+            created = flatten_task_tree(tree, workspace, prd_id=prd_record.id)
+        elif no_llm:
             console.print("[dim]Using simple extraction (--no-llm)[/dim]")
+            created = tasks.generate_from_prd(workspace, prd_record, use_llm=False)
         else:
             console.print("[dim]Using LLM for task generation...[/dim]")
-
-        # Generate tasks
-        created = tasks.generate_from_prd(workspace, prd_record, use_llm=not no_llm)
+            created = tasks.generate_from_prd(workspace, prd_record, use_llm=True)
 
         # Emit event
         emit_for_workspace(
@@ -1624,6 +1651,35 @@ def tasks_generate(
         raise typer.Exit(1)
 
 
+@tasks_app.command("tree")
+def tasks_tree(
+    repo_path: Optional[Path] = typer.Option(
+        None,
+        "--workspace", "-w",
+        help="Workspace path (defaults to current directory)",
+    ),
+) -> None:
+    """Display task hierarchy as tree."""
+    from codeframe.core.task_tree import display_task_tree
+    from codeframe.core.workspace import get_workspace
+
+    workspace_path = repo_path or Path.cwd()
+
+    try:
+        workspace = get_workspace(workspace_path)
+        output = display_task_tree(workspace)
+        if output:
+            typer.echo(output)
+        else:
+            typer.echo("No tasks found.")
+    except FileNotFoundError as e:
+        console.print(f"[red]Error:[/red] {e}")
+        raise typer.Exit(1)
+    except Exception as e:
+        console.print(f"[red]Error:[/red] {e}")
+        raise typer.Exit(1)
+
+
 @tasks_app.command("list")
 def tasks_list(
     status: Optional[str] = typer.Option(None, "--status", "-s", help="Filter by status"),

codeframe/core/context_packager.py

@@ -53,6 +53,18 @@ def build(
 
         prompt_parts = [context.to_prompt_context()]
 
+        # Add lineage context if available
+        if (
+            hasattr(context, "task")
+            and context.task
+            and hasattr(context.task, "lineage")
+            and context.task.lineage
+        ):
+            lineage_str = " \u2192 ".join(context.task.lineage)
+            prompt_parts.append(
+                f"\n## Task Lineage\nThis task is part of: {lineage_str}\n"
+            )
+
         if attempt > 0 and previous_errors:
             prompt_parts.append(self._build_retry_section(attempt, previous_errors))