--- tags: [task-template, dependency, batch, destructive, trap] endpoints: [POST /entity/_batch, POST /entity/, PUT /entity//, POST /entity//_search, GET /entity//, DELETE /entity//] phase: write scope: api measured: sandbox project written, 2 templates, 2 Shots, 18 Tasks and their edges made and deleted by the probe; 50.9 s, 125 calls verdict: An undo's write back to template A erases every edge whose downstream Task is A-linked and that A lacks, pre-merge edges included; recipe 022 DELETEs one such edge, 404s and rolls back. --- # 111_template_undo_outside_edge **Q** When the undo of a merge writes `task_template` back to the old template A (recipes 019, 022), which edges does that write erase: a re-created outside edge, a mixed edge, an edge between two A-linked Tasks that A lacks? **Endpoint** `POST /entity/_batch ; PUT /entity/shots/ ; POST /entity/task_dependencies ; POST /entity/task_dependencies/_search ; GET /entity/task_dependencies/ ; DELETE /entity//` **Docs claim** Silent. Probe 104 left mixed ends unmeasured; probe 109 measured the apply, not the undo. **Actual** A: comp, roto, lay; roto on comp. B: comp, lay, paint; lay on comp start-to-start 1, paint on lay. Twin Shots M, W made with A, plus unlinked x, y and hand edges comp on x, roto on x, roto on lay. Merge: recipe 020's batch (comp, lay claimed to B). Then by hand: R1 comp on x (re-created), R2 roto on paint, R3 y on lay. W undone by recipe 019's calls, edges read after each step; M by recipe 022's batch. | edge | kind | merge | W step 2, `task_template` A | M, retired read | |---|---|---|---|---| | roto on comp | A's own | kept, same id | **re-created, new id** | old id 404 / 404 | | comp on x | pre-merge, A-linked down, extra up | erased | (already gone) | 404 / 404 | | roto on x | pre-merge, roto never claimed, extra up | kept | **erased** | 404 / 404 | | roto on lay | pre-merge, both A-linked, A lacks | kept | **erased** | 404 / 404 | | lay on comp | B's, both back on A, A lacks | made | erased | (probe 104) | | R1 comp on x | re-created after merge, down back on A | made by hand | **erased** | 404 / 404 | | R2 roto on paint | A-linked down, merge-made up | made by hand | erased | 404 / 404 | | paint on lay | B's, merge-made down, up back on A | made | kept | retired with paint | | R3 y on lay | extra down, up back on A | made by hand | kept | DELETEd by the batch: 404 / 200 | ``` W step 1 claims back to A -> 200, 200; edges unchanged W step 2 PUT Shot task_template=A -> 200; edges: paint on lay, roto on comp #4615 (new), y on lay W step 3 DELETE paint 204, y on lay 204, roto on comp #4615 204 (not in the snapshot's ids) -> no edge M recipe 022 batch as written, edge DELETEs [comp on x #4607, y on lay #4609] -> 404 "Entity of type [TaskDependency] with id=4607 does not exist." edge ids unchanged M same batch, edges whose downstream end goes back to an A task left out: DELETE [y on lay] -> 200 edges after: roto on comp #4626 (new id). M, W: task_template A, comp/lay/roto on A, x, y none left clean: 0 Shots, Tasks (Shot and template), TaskDependency rows, templates zzprobe_111_* ``` The first run gave the same table (the probe then read 71.8 s, 158 calls, before its call count was cut). Preconditions: none from an operator. Provisioned by the probe: both templates, the Shots, Tasks and edges, deleted by `_lib.Created` (edges retire with their Tasks), failure included. **Teaches** - **The write back to A applies probe 109's rule: every edge whose downstream Task is A-linked and that A lacks is erased**, whatever the upstream end: extra (R1, roto on x), merge-made (R2), or A-linked (roto on lay). Pre-merge edges the merge kept (roto on x, roto on lay) are lost by the undo. Edges with only the upstream end on A (paint on lay, y on lay) are kept. - Recipe 022 DELETEs every non-snapshot edge unless both ends go back to A, so a re-created outside edge (R1) 404s the batch and nothing lands. Leave out every edge whose downstream end goes back to an A task. - **A's own roto on comp was re-created with a new id** on both Shots; probe 104, where roto had no other upstream edge, kept the id. Recipe 019's step 3 sweep then deleted it, leaving W with no edge at all. Which hand edge causes the re-create: not measured. - Re-create the lost pre-merge edges from a snapshot of ends, type and offset (recipe 016). Doing that inside the undo batch: not measured.