feat(v4.4.0): Tasks, Sub-items & Dependencies

- Add is_task flag on collections (toggle-task API)
- New page_dependencies table with auto_shift config (blocks/blocked_by/related)
- API: GET/POST/DELETE page dependencies
- API: POST auto-shift dates based on blocking dependencies (skip_weekends option)
- 5 new tests (171 total)

app/db.py

@@ -515,6 +515,27 @@ def init_db():
         """)
         conn.commit()
 
+        # v4.4.0: Tasks & Dependencies
+        # Add is_task flag to collections
+        try:
+            conn.execute("ALTER TABLE collections ADD COLUMN is_task BOOLEAN NOT NULL DEFAULT 0")
+        except sqlite3.OperationalError:
+            pass
+
+        # Dependencies table: bloque/bloqué par with auto-shift config
+        conn.execute("""
+            CREATE TABLE IF NOT EXISTS page_dependencies (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                page_id INTEGER NOT NULL REFERENCES collection_pages(id) ON DELETE CASCADE,
+                dependency_id INTEGER NOT NULL REFERENCES collection_pages(id) ON DELETE CASCADE,
+                dependency_type TEXT NOT NULL DEFAULT 'blocks',
+                auto_shift TEXT DEFAULT 'overlap',
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                UNIQUE(page_id, dependency_id, dependency_type)
+            )
+        """)
+        conn.commit()
+
 
 @contextmanager
 def get_conn():

app/routers/collections.py

@@ -1010,6 +1010,161 @@ async def create_inline_database(request: Request):
     }
 
 
+# ── v4.4.0: Tasks & Dependencies ──
+
+
+@router.put("/{collection_id}/toggle-task/api")
+async def toggle_task(request: Request, collection_id: int):
+    """API: toggle is_task flag on a collection (Turn into Tasks)."""
+    with get_conn() as conn:
+        coll = conn.execute("SELECT id, is_task FROM collections WHERE id=?", (collection_id,)).fetchone()
+        if not coll:
+            raise HTTPException(status_code=404, detail="Collection not found")
+        new_val = 0 if coll["is_task"] else 1
+        conn.execute("UPDATE collections SET is_task=?, updated_at=CURRENT_TIMESTAMP WHERE id=?", (new_val, collection_id))
+        conn.commit()
+    return {"collection_id": collection_id, "is_task": bool(new_val), "mode": "tasks" if new_val else "standard"}
+
+
+@router.get("/{collection_id}/pages/{page_id}/dependencies/api")
+async def list_page_dependencies(request: Request, collection_id: int, page_id: int):
+    """API: list dependencies for a page (blocks, blocked_by, related)."""
+    with get_conn() as conn:
+        rows = conn.execute(
+            "SELECT * FROM page_dependencies WHERE page_id=? ORDER BY created_at",
+            (page_id,),
+        ).fetchall()
+        deps = []
+        for r in rows:
+            d = dict(r)
+            dep_page = conn.execute(
+                "SELECT id, title FROM collection_pages WHERE id=?", (r["dependency_id"],)
+            ).fetchone()
+            if dep_page:
+                d["dependency_title"] = dep_page["title"]
+            deps.append(d)
+    return {"dependencies": deps}
+
+
+@router.post("/{collection_id}/pages/{page_id}/dependencies/api")
+async def add_page_dependency(request: Request, collection_id: int, page_id: int):
+    """API: add a dependency (blocks/blocked_by/related) between two pages."""
+    try:
+        body = await request.json()
+    except Exception:
+        body = {}
+    dependency_id = body.get("dependency_id")
+    if not dependency_id:
+        raise HTTPException(status_code=400, detail="dependency_id is required")
+    dep_type = body.get("dependency_type", "blocks")
+    auto_shift = body.get("auto_shift", "overlap")
+
+    with get_conn() as conn:
+        for pid in (page_id, dependency_id):
+            if not conn.execute("SELECT id FROM collection_pages WHERE id=?", (pid,)).fetchone():
+                raise HTTPException(status_code=404, detail=f"Page {pid} not found")
+        try:
+            cur = conn.execute(
+                "INSERT INTO page_dependencies (page_id, dependency_id, dependency_type, auto_shift) VALUES (?,?,?,?)",
+                (page_id, dependency_id, dep_type, auto_shift),
+            )
+            conn.commit()
+        except sqlite3.IntegrityError:
+            raise HTTPException(status_code=409, detail="This dependency already exists")
+    return {"id": cur.lastrowid, "page_id": page_id, "dependency_id": dependency_id, "status": "added"}
+
+
+@router.delete("/{collection_id}/pages/{page_id}/dependencies/{dep_id}/api")
+async def remove_page_dependency(request: Request, collection_id: int, page_id: int, dep_id: int):
+    """API: remove a dependency."""
+    with get_conn() as conn:
+        existing = conn.execute(
+            "SELECT * FROM page_dependencies WHERE id=? AND page_id=?", (dep_id, page_id)
+        ).fetchone()
+        if not existing:
+            raise HTTPException(status_code=404, detail="Dependency not found")
+        conn.execute("DELETE FROM page_dependencies WHERE id=?", (dep_id,))
+        conn.commit()
+    return {"id": dep_id, "status": "removed"}
+
+
+@router.post("/{collection_id}/pages/{page_id}/auto-shift/api")
+async def auto_shift_dates(request: Request, collection_id: int, page_id: int):
+    """API: auto-shift dates based on blocking dependencies."""
+    from datetime import date as dt_date, timedelta
+
+    try:
+        body = await request.json()
+    except Exception:
+        body = {}
+    skip_weekends = body.get("skip_weekends", False)
+
+    with get_conn() as conn:
+        page = conn.execute("SELECT property_values_json FROM collection_pages WHERE id=?", (page_id,)).fetchone()
+        if not page:
+            raise HTTPException(status_code=404, detail="Page not found")
+
+        # Get all blocking dependencies
+        deps = conn.execute(
+            "SELECT * FROM page_dependencies WHERE page_id=? AND dependency_type='blocks'",
+            (page_id,),
+        ).fetchall()
+
+        shifted = False
+        new_start = None
+        for dep in deps:
+            dep_page = conn.execute(
+                "SELECT title, property_values_json FROM collection_pages WHERE id=?",
+                (dep["dependency_id"],),
+            ).fetchone()
+            if not dep_page:
+                continue
+            dep_props = json.loads(dep_page["property_values_json"])
+            # Find the latest end date among blockers
+            for v in dep_props.values():
+                if isinstance(v, str) and v.startswith("20"):
+                    end_date = v.split("...")[-1].split("→")[-1].strip()[:10]
+                    try:
+                        ed = dt_date.fromisoformat(end_date)
+                        if new_start is None or ed >= new_start:
+                            new_start = ed + timedelta(days=1)
+                        shifted = True
+                    except ValueError:
+                        continue
+
+        if not shifted:
+            return {"page_id": page_id, "shifted": False, "message": "No blocking dependencies with dates found"}
+
+        # Skip weekends if requested
+        if skip_weekends and new_start:
+            while new_start.weekday() >= 5:  # 5=Sat, 6=Sun
+                new_start = new_start + timedelta(days=1)
+
+        # Update the page's date properties
+        props = json.loads(page["property_values_json"])
+        for k, v in list(props.items()):
+            if isinstance(v, str) and v.startswith("20"):
+                old_parts = v.split("...")
+                old_end = old_parts[-1] if len(old_parts) > 1 else old_parts[0]
+                try:
+                    old_start_d = dt_date.fromisoformat(old_parts[0][:10])
+                    old_end_d = dt_date.fromisoformat(old_end[:10])
+                    duration = (old_end_d - old_start_d).days
+                    new_end = new_start + timedelta(days=max(duration, 0))
+                    props[k] = f"{new_start.isoformat()}...{new_end.isoformat()}"
+                except ValueError:
+                    props[k] = new_start.isoformat()
+                break
+
+        conn.execute(
+            "UPDATE collection_pages SET property_values_json=?, updated_at=CURRENT_TIMESTAMP WHERE id=?",
+            (json.dumps(props), page_id),
+        )
+        conn.commit()
+
+    return {"page_id": page_id, "shifted": True, "new_start": new_start.isoformat(), "skip_weekends": skip_weekends}
+
+
 # ── {collection_id} wildcards (LAST — catches everything else) ──