--- tags: [dependency, task-template, destructive] endpoints: [POST /entity/, POST /entity/_batch, PUT /entity//, POST /entity//_search, GET /entity//, DELETE /entity//] phase: write scope: api measured: sandbox project written, 2 templates, 6 Shots, 16 Tasks and their edges made and deleted by the probe; 45.7 s, 116 calls verdict: A template apply erases an edge where a linked Task depends on a Task not linked to the template (root or not, other template, other Shot); it kept the edge with the outside Task downstream. --- # 109_template_apply_outside_edge **Q** On a template apply, which edges between a Task linked to the template T and a Task not linked to T does the apply delete? **Endpoint** `POST /entity/_batch ; PUT /entity/shots/ ; POST /entity/task_dependencies/_search ; GET /entity/task_dependencies/ ; DELETE /entity/task_dependencies/` **Docs claim** Silent. Probe 102 said "one end unlinked → kept"; probe 107 found `a on x` (claimed root upstream from an outside Task) erased and `x on b` (outside Task downstream) kept. **Actual** Template tt: a, b; edge b on a (finish-to-start-next-day), so a is the root. Template tt2: y. One Shot per case: hand-made a, b claimed to tt (`_batch` of `template_task` updates -> 200), one outside Task, one hand-made edge; then `PUT /entity/shots/ {"task_template": tt}` -> 200 in every case. | case | outside Task | edge | after the PUT | GET | retired | |---|---|---|---|---|---| | up_nonroot | x, same Shot, unlinked | b on x #4477 (b has a template upstream) | erased | 404 | 404 | | other_tpl | y, same Shot, `template_task` = tt2's y | a on y #4481 | erased | 404 | 404 | | other_shot | z, on another Shot, unlinked | a on z #4485 | erased | 404 | 404 | | ctl_down | w, same Shot, unlinked | w on b #4487 | kept | 200 | 404 | | ctl_up | v, same Shot, unlinked | a on v #4489 | erased | 404 | 404 | ``` every case, edges after the PUT: b on a (new), plus w on b in ctl_down only outside Tasks after the PUT: x, y, z, w, v all GET -> 200; y keeps template_task = tt2's y ctl_down control for the retired read: DELETE #4487 -> 204, then GET options[return_only]=retired -> 200 edges read after the claim, before the PUT: the hand-made edge only, in every case left clean: 0 Tasks, Shots, TaskTemplates zzprobe_109_*, 0 of the edges seen ``` Preconditions: none from an operator. Provisioned by the probe: both templates, the Shots, Tasks and edges, deleted by `_lib.Created`, failure included. **Teaches** - **Measured rule: an edge whose downstream end is a Task linked to T and whose upstream end is not linked to T is erased by the apply.** It held for a root (a) and a non-root (b), for an unlinked Task, a Task linked to another template, and a Task on another entity. The claim alone did not touch it; the `PUT task_template` did. - An edge whose upstream end is linked to T and whose downstream end is not (w on b) was kept, as in probes 101, 102 and 107. One case only. - Erased, not retired: 404 under `options[return_only]=retired`, where an edge the caller DELETEs reads 200 (control in this run; probe 101 too). No error, no row to recover. Read each linked Task's `upstream_tasks` before the apply and re-create the edges to keep. - Probe 102's "one end unlinked or linked to another template → kept" holds only for the downstream direction. - Not measured: an outside Task upstream of a Task the apply creates (no edge to that Task can exist before the apply makes it); an outside Task downstream of a root; outside edges on a re-apply of the same template.