remove and restore a dependency

DELETE on the TaskDependency row retires it, and revive brings back the same row with its dependency_type and offset_days. A delete request inside _batch retires it the same way (probe 103, recipe 021). A remove on upstream_tasks or downstream_tasks erases the row, and nothing brings it back (probe 095).

Call

import json
import sys

sys.path.insert(0, "src")                       # or PYTHONPATH=src
from sg_groundtruth.client import FPT
from sg_groundtruth.env import load

c = FPT.from_env(load("."))
ARR = {"Content-Type": "application/vnd+shotgun.api3_array+json"}


def fail(r):
    raise SystemExit(json.dumps(r.json()["errors"], indent=2))


def edge_id(downstream_id, upstream_id):
    """The row id for one edge. `task` is the downstream Task, `dependent_task` the upstream (probe 085)."""
    r = c.post("/entity/task_dependencies/_search", headers=ARR, json={
        "filters": [["task", "is", {"type": "Task", "id": downstream_id}],
                    ["dependent_task", "is", {"type": "Task", "id": upstream_id}]],
        "fields": ["dependency_type", "offset_days"]})
    if not r.ok:
        fail(r)
    rows = r.json()["data"]
    return rows[0]["id"] if rows else None


def remove_edge(row_id):
    """Retire the row. Keep the id: it is the undo."""
    r = c.delete(f"/entity/task_dependencies/{row_id}")
    if r.status_code != 204:
        fail(r)


def restore_edge(row_id):
    """Revive the same row: same id, type and offset. The downstream Task reschedules at once."""
    r = c.post(f"/entity/task_dependencies/{row_id}", params={"revive": 1})
    if not r.ok:
        fail(r)    # 400 "... non-unique value for a unique index: sgcu_task_dependencies" if the pair was re-linked
    return r.json()["meta"]["did_revive"]


row = edge_id(47339, 47337)
remove_edge(row)
print(restore_edge(row))

Response

edge_id -> 3764   (finish-to-start-next-day, offset_days 2)
DELETE /entity/task_dependencies/3764 -> 204
  g 03-11..03-12 held; upstream moved to end 03-13; g does not follow
POST /entity/task_dependencies/3764?revive=1 -> 200 {"did_revive": true}
  row 3764 (finish-to-start-next-day, 2); g 03-18..03-19, placed from the upstream's current end

Notes

• The revived edge places the Task from the upstream's current dates, not the dates it had when the edge was removed. An undo that wants those dates writes them after the revive; the start_date write pins the Task (probe 093).
• A pinned downstream Task keeps its dates through both calls. Its dependency_violation reads false while the edge is retired and true again after revive if it is still placed too early.
• If something re-linked the same pair in between, revive is a 400 on the unique index. Delete the new row first, or keep it and drop the undo entry.
• A remove through the multi_entity fields has no undo: re-create the row with its type and offset (recipe 016), which gets a new id.