chore: migrate from opencode to trellis 0.5.0-rc.6

- Remove legacy .opencode/ directory and configuration
- Update .trellis/ to v0.5.0-rc.6 structure
- Refactor scripts: modularize common/, remove multi_agent/
- Add new common modules: git.py, io.py, log.py, types.py, etc.
- Update workflow.md and AGENTS.md
- Archive completed migration tasks

.trellis/scripts/common/task_queue.py

@@ -12,23 +12,32 @@ Provides:
 
 from __future__ import annotations
 
-import json
 from pathlib import Path
 
 from .paths import (
-    FILE_TASK_JSON,
     get_repo_root,
     get_developer,
     get_tasks_dir,
 )
+from .tasks import iter_active_tasks
 
 
-def _read_json_file(path: Path) -> dict | None:
-    """Read and parse a JSON file."""
-    try:
-        return json.loads(path.read_text(encoding="utf-8"))
-    except (FileNotFoundError, json.JSONDecodeError, OSError):
-        return None
+# =============================================================================
+# Internal helper
+# =============================================================================
+
+def _task_to_dict(t) -> dict:
+    """Convert TaskInfo to the dict format callers expect."""
+    return {
+        "priority": t.priority,
+        "id": t.raw.get("id", ""),
+        "title": t.title,
+        "status": t.status,
+        "assignee": t.assignee or "-",
+        "dir": t.dir_name,
+        "children": list(t.children),
+        "parent": t.parent,
+    }
 
 
 # =============================================================================
@@ -54,41 +63,10 @@ def list_tasks_by_status(
     tasks_dir = get_tasks_dir(repo_root)
     results = []
 
-    if not tasks_dir.is_dir():
-        return results
-
-    for d in tasks_dir.iterdir():
-        if not d.is_dir() or d.name == "archive":
+    for t in iter_active_tasks(tasks_dir):
+        if filter_status and t.status != filter_status:
             continue
-
-        task_json = d / FILE_TASK_JSON
-        if not task_json.is_file():
-            continue
-
-        data = _read_json_file(task_json)
-        if not data:
-            continue
-
-        task_id = data.get("id", "")
-        title = data.get("title") or data.get("name", "")
-        priority = data.get("priority", "P2")
-        status = data.get("status", "planning")
-        assignee = data.get("assignee", "-")
-
-        # Apply filter
-        if filter_status and status != filter_status:
-            continue
-
-        results.append({
-            "priority": priority,
-            "id": task_id,
-            "title": title,
-            "status": status,
-            "assignee": assignee,
-            "dir": d.name,
-            "children": data.get("children", []),
-            "parent": data.get("parent"),
-        })
+        results.append(_task_to_dict(t))
 
     return results
 
@@ -126,46 +104,12 @@ def list_tasks_by_assignee(
     tasks_dir = get_tasks_dir(repo_root)
     results = []
 
-    if not tasks_dir.is_dir():
-        return results
-
-    for d in tasks_dir.iterdir():
-        if not d.is_dir() or d.name == "archive":
+    for t in iter_active_tasks(tasks_dir):
+        if (t.assignee or "-") != assignee:
             continue
-
-        task_json = d / FILE_TASK_JSON
-        if not task_json.is_file():
+        if filter_status and t.status != filter_status:
             continue
-
-        data = _read_json_file(task_json)
-        if not data:
-            continue
-
-        task_assignee = data.get("assignee", "-")
-
-        # Apply assignee filter
-        if task_assignee != assignee:
-            continue
-
-        task_id = data.get("id", "")
-        title = data.get("title") or data.get("name", "")
-        priority = data.get("priority", "P2")
-        status = data.get("status", "planning")
-
-        # Apply status filter
-        if filter_status and status != filter_status:
-            continue
-
-        results.append({
-            "priority": priority,
-            "id": task_id,
-            "title": title,
-            "status": status,
-            "assignee": task_assignee,
-            "dir": d.name,
-            "children": data.get("children", []),
-            "parent": data.get("parent"),
-        })
+        results.append(_task_to_dict(t))
 
     return results
 
@@ -211,24 +155,9 @@ def get_task_stats(repo_root: Path | None = None) -> dict[str, int]:
     tasks_dir = get_tasks_dir(repo_root)
     stats = {"P0": 0, "P1": 0, "P2": 0, "P3": 0, "Total": 0}
 
-    if not tasks_dir.is_dir():
-        return stats
-
-    for d in tasks_dir.iterdir():
-        if not d.is_dir() or d.name == "archive":
-            continue
-
-        task_json = d / FILE_TASK_JSON
-        if not task_json.is_file():
-            continue
-
-        data = _read_json_file(task_json)
-        if not data:
-            continue
-
-        priority = data.get("priority", "P2")
-        if priority in stats:
-            stats[priority] += 1
+    for t in iter_active_tasks(tasks_dir):
+        if t.priority in stats:
+            stats[t.priority] += 1
         stats["Total"] += 1
 
     return stats