fix(mcp): release repeated stock reservations with their owner

docs/automatic-nesting.md

@@ -58,7 +58,7 @@ MCP `autonest_plate` requires an empty target. The stdio server serializes all t
 
 MCP `pack_plate` and `autonest_plate` report each requested drawing's newly placed count and remaining quantity, indexed by request; partial fulfillment is explicitly warned about. Per-sheet ratios are not enforced or required: an uneven sheet is acceptable if the remaining quantities are placed elsewhere in the nest. These two plate tools operate on a single selected plate and do not automatically finish a multi-sheet job; callers can use `autonest_job` for that. Duplicate request tokens and ambiguous drawing names are refused before placement. A zero-quantity pack request places zero parts for that drawing; negative quantities are rejected.
 
-`autonest_job(plateIndex, drawingNames, quantities, engine?, no_new_plates=false, sheets?)` is the whole-session completion path. Quantities are total targets across existing placed parts (physical plate quantity included) plus newly proposed sheets. Without `sheets`, the selected empty cutoff-free plate supplies stock size, spacing, quadrant, grain and cutting settings; other empty plates with equivalent persisted settings may be reused first, then additional matching plates are created as needed. `no_new_plates=true` caps physical stock by the number of existing matching empty plates, not the number of grouped output layouts or their old repeat quantities. Exact repeats still attach once with their total quantity; redundant empty entries remain unchanged and are omitted on save. Empty entries consumed by those physical copies are tracked in the live MCP session and cannot be offered again or filled by another nesting tool. Genuinely unused entries remain available. No automatic deletion of user plates occurs. No new layout entries are created in this mode. The request uses the independently validated `NestPipeline` and commits only when every requested quantity is met; invalid, incomplete, cancelled or unknown-engine proposals leave existing plates and counts unchanged. A no-placement solver result is not proof that geometry cannot fit. `pack_plate` and `autonest_plate` remain single-sheet operations.
+`autonest_job(plateIndex, drawingNames, quantities, engine?, no_new_plates=false, sheets?)` is the whole-session completion path. Quantities are total targets across existing placed parts (physical plate quantity included) plus newly proposed sheets. Without `sheets`, the selected empty cutoff-free plate supplies stock size, spacing, quadrant, grain and cutting settings; other empty plates with equivalent persisted settings may be reused first, then additional matching plates are created as needed. `no_new_plates=true` caps physical stock by the number of existing matching empty plates, not the number of grouped output layouts or their old repeat quantities. Exact repeats still attach once with their total quantity; redundant empty entries remain unchanged and are omitted on save. Empty entries consumed by those physical copies are reserved by their populated layout in the live MCP session and cannot be offered again or filled by another nesting tool while that owner remains populated. Clearing or removing the owner (including replacement by `load_nest`) releases only its surviving placeholders; clearing or deleting a placeholder does not release the owner's other copies or another layout's reservations. Genuinely unused entries remain available. No automatic deletion of user plates occurs. No new layout entries are created in this mode. The request uses the independently validated `NestPipeline` and commits only when every requested quantity is met; invalid, incomplete, cancelled or unknown-engine proposals leave existing plates and counts unchanged. A no-placement solver result is not proof that geometry cannot fit. `pack_plate` and `autonest_plate` remain single-sheet operations.
 
 For finite mixed-size inventory, supply `sheets` as an array, for example `{"plateIndex":0,"drawingNames":"large,small","quantities":"1,1","engine":"Rectangles","sheets":[{"width":60,"length":120,"quantity":1},{"width":48,"length":96,"quantity":2}]}`. Width and length have the same units and orientation as `create_plate`. Every row's positive integer `quantity` is the total physical sheets available for this solve, including any compatible pre-created empty plates; it is never a `Plate.Quantity` repeat multiplier or additional stock. The selected plate supplies common spacing, edge spacing, quadrant, grain and cutting settings, but is reused only if its size matches a chosen sheet. Other compatible empty sheets can be reused; occupied or cutoff-bearing sheets cannot. Only needed different-sized sheets are created. Duplicate size pairs, nonpositive or nonfinite dimensions, unusable work areas, nonpositive quantities, an empty list and excessive total inventory are refused before solving. `sheets` cannot be combined with `no_new_plates=true`. Omit `sheets` to retain the previous single-size behavior. Successful output reports `stock-0`, `stock-1`, etc. in input order with physical used/remaining counts, reused/created layout counts, plus committed session layout index to stock ID and per-drawing totals. Stock is request-local, not a persistent purchasing catalog. Unused empty templates may be omitted by the `.nest` writer on save.