execlisted

One `pd-implementer` per task, fresh context each time. Fresh context is not tidiness: a worker that has already failed twice carries both failures into the third attempt, and that is where drift starts. ## Preconditions `pdkit state <issue>` says `plan-approved`. Implementing an unapproved plan means the requirements can still move under the code. ## Once, before the first task ``` pdkit task sync --issue <n> ``` Reads the `Owns` sets out of the task files into the state record, which is what the pre-write hook enforces. Skip it and the hook has nothing to enforce: it allows every write and says so, which is a worse failure than a refusal because it looks like nothing happened. ## Per task 1. `pdkit task start --issue <n> --task T1` in the working tree the task runs in. From here until `task stop`, writes outside `T1`'s files are refused and completing the task requires its receipt. 2. Give the worker the task, its `Owns` list, its `Done when` command, and the frozen interfaces. Nothing else — not the whole plan, not the issue thread. 3. The worker touches **only** the files in `Owns`. Anything else is a planning error to report, not a boundary to cross. 4. `pdkit receipt write --issue <n> --task T1` runs the `Done when` command and records what it printed. 5. Commit: conventional subject, one `Signed-off-by`. Squash with `git reset --soft <base> && git commit`, never `rebase -i`. 6. `pdkit task stop`. Tasks that share no files may run in parallel.