feat(delegate-task): session_break authoring field [v0.2.2]

Add the authoring side of the `session_break` marker whose consumer
side shipped in using-tasks v1.2.0. At delegation time the author can
now mark a task so that, after it closes, an autonomous runner pauses
instead of chaining the next task.

- Pre-flight gate 5->6 questions: new Q (item 5, after notify) —
  "Session-break после этой задачи? (domain-switch / milestone /
  heavy infra)". Yes -> set session_break in body; no -> omit
  (default unchanged).
- Template trailer gains optional `[**session_break:** true |
  "<hint>"]` with inline comment (same lowercase frontmatter key
  using-tasks reads).
- Usage-guidance block: three set-it cases + tie to using-tasks
  Task-completion step 6 / SESSION BOUNDARY line.
- What-NOT-to-do bullet: don't set it routinely (real-boundary
  marker, not a default).
- Wiki concept page concepts/delegate-task-session-break.md
  (links using-tasks-session-break) + index + log.

PATCH bump: additive optional field + one pre-flight question, no
existing behaviour changed. Markdown policy artifact — no test
surface (TDD N/A). Closes [session-break-delegate-task].

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.wiki/log.md

@@ -67,4 +67,5 @@ Parseable: `grep "^## \[" .wiki/log.md | tail -20`.
 ## [2026-05-25] decision | install-cross-platform extended to build scripts — `build.{ps1,sh}` get the symmetric `--prune` / `-Prune` flag (removes `dist/<name>.skill` where `<name>` is not in `skills/`). Bash delegation to `powershell.exe -File build.ps1` does NOT forward the flag — bash runs prune itself against the shared `dist/`. Both paths smoke-tested with fake stale .skill files against real dist/. Closes `[install-ps1-build-prune-followup]`.
 
 ## [2026-06-09] decision | delegate-task-negative-trigger-fp — `delegate-task` 0.2.0→0.2.1 (PATCH): fixed 5/5-consistent false-positive on «создать задачу себе». Root cause: self-task phrase shares stem «создать задачу» with the «создать задачу на агента» positive trigger; the abstract "Does NOT apply when doing the work yourself" carve-out can't beat a literal stem-match under the 1%-rule. Fix: made the negative literal + routed («создать задачу себе» / «task for myself» / «поставить себе задачу» → using-tasks) in description + body disambiguator («на агента»/«агенту» = delegate; «себе» = own board). Re-verified via fresh-context subagent trigger run: positives 5/5 (no regression), negative 4/5 → using-tasks (was 0/5); the 1 residual miss was an eval-harness artifact (forced skill-name-before-reasoning), not description ambiguity. Concept page written; reusable principle = put the exact colliding negative phrase with an explicit →sibling route, literal beats abstract.
+## [2026-06-09] decision | delegate-task-session-break — `delegate-task` 0.2.1→0.2.2 (PATCH): authoring side of the `session_break` marker (consumer = using-tasks v1.2.0). Added pre-flight Q6 (after notify): "Session-break после этой задачи? (domain-switch / milestone / heavy infra)"; if yes → set optional template field `session_break: true | "<hint>"` (trailer, next to weight/notify/allow_upgrade; same lowercase frontmatter key using-tasks reads). Usage guidance lists three set-it cases; What-NOT-to-do bullet warns against setting it routinely (it's a real-boundary marker, not a default). Wiki concept page concepts/delegate-task-session-break.md + index. Pairs with using-tasks-session-break.
 ## [2026-06-09] decision | using-tasks-session-break — `using-tasks` 1.1.0→1.2.0 (MINOR): added the `session_break` marker. Task author sets `session_break: true | "<hint>"` in task frontmatter (mirrored as `**Session break:**` on the local board); after the task closes 🟢, before `tasks_claim_next`, an autonomous agent prints the verbatim line `🔚 SESSION BOUNDARY — [slug] закрыта. Рекомендую завершить текущую сессию. Следующий трек: [value | "см. STATUS.md"]` and stops instead of chaining the next task. Absent → behaviour unchanged. Enforced in Task completion step 6 + Rules bullet + format docs. Marker not heuristic: the stop-point is an authoring choice, not a runner guess.