diff --git a/.yoi/tickets/00001KW55B32Y/item.md b/.yoi/tickets/00001KW55B32Y/item.md
index 3d46b4f0..844a7976 100644
--- a/.yoi/tickets/00001KW55B32Y/item.md
+++ b/.yoi/tickets/00001KW55B32Y/item.md
@@ -1,8 +1,8 @@
 ---
 title: 'worker-runtimeにWorker実行Backend境界を追加する'
-state: 'inprogress'
+state: 'closed'
 created_at: '2026-06-27T18:26:46Z'
-updated_at: '2026-06-27T19:48:30Z'
+updated_at: '2026-06-27T19:49:46Z'
 assignee: null
 queued_by: 'workspace-panel'
 queued_at: '2026-06-27T19:06:28Z'
diff --git a/.yoi/tickets/00001KW55B32Y/resolution.md b/.yoi/tickets/00001KW55B32Y/resolution.md
new file mode 100644
index 00000000..2b2dcb1b
--- /dev/null
+++ b/.yoi/tickets/00001KW55B32Y/resolution.md
@@ -0,0 +1,28 @@
+`worker-runtime` に Worker execution backend 境界を追加し、reviewer approval 後に orchestration branch へ merge した。
+
+実装内容:
+- `WorkerExecutionBackend` trait / handle / context / status / result / operation / outcome を追加。
+- backend 未接続 Worker への input を typed `WorkerExecutionUnavailable` として拒否。
+- backend dispatch の busy / rejected / errored / unsupported を typed rejection として扱う。
+- backend から Runtime observation bus へ `protocol::Event` を publish する hook を追加。
+- stop / cancel unsupported の typed rejection を追加。
+- `WorkerSummary` / `WorkerDetail` に raw handle/path/credential を含まない execution status projection を追加。
+- Runtime が fake/providerless assistant response を生成しない境界を維持。
+- `can_stream_events` / `can_read_bounded_transcript` public capability は復活させていない。
+- `ws-server + fs-store` restore path で observation bus state を正しく初期化。
+
+Integrated commits:
+- `2d5971738478f832ba9a135601ea11dda60c565d feat: add worker execution backend boundary`
+- `761b60c85750d03c119733a088fb5073f9b37e9a fix: initialize restored worker observations`
+- merge: `0753e155 merge: worker runtime execution backend`
+
+Validation:
+- `cargo fmt --all --check`: success
+- `cargo test -p worker-runtime --features ws-server`: success
+- `cargo test -p worker-runtime --features "ws-server fs-store"`: success
+- `cargo test -p yoi-workspace-server`: success
+- `cargo check -p yoi`: success
+- `git diff --check`: success
+- `nix build .#yoi --no-link`: success
+
+Cleanup は child implementation worktree / branch と related role Pods のみを対象に実施する。
\ No newline at end of file
diff --git a/.yoi/tickets/00001KW55B32Y/thread.md b/.yoi/tickets/00001KW55B32Y/thread.md
index a8353ef7..6e77d98e 100644
--- a/.yoi/tickets/00001KW55B32Y/thread.md
+++ b/.yoi/tickets/00001KW55B32Y/thread.md
@@ -324,3 +324,97 @@ approve
 作業ツリーも clean のまま。
 
 ---
+
+<!-- event: implementation_report author: yoi-orchestrator at: 2026-06-27T19:49:30Z -->
+
+## Implementation report
+
+Merge / validation report:
+
+Implementation branch was integrated into the orchestration branch after reviewer approval.
+
+Integrated commits:
+- `2d5971738478f832ba9a135601ea11dda60c565d feat: add worker execution backend boundary`
+- `761b60c85750d03c119733a088fb5073f9b37e9a fix: initialize restored worker observations`
+
+Merge commit:
+- `0753e155 merge: worker runtime execution backend`
+
+Validation in orchestration worktree:
+- `cargo fmt --all --check`: success
+- `cargo test -p worker-runtime --features ws-server`: success
+- `cargo test -p worker-runtime --features "ws-server fs-store"`: success
+- `cargo test -p yoi-workspace-server`: success
+- `cargo check -p yoi`: success
+- `git diff --check`: success
+- `nix build .#yoi --no-link`: success
+
+Outcome:
+- `worker-runtime` now has an explicit Worker execution backend boundary.
+- Backend-unconnected Workers reject input rather than accepting it or producing fake/providerless assistant responses.
+- Connected backend dispatch and observation publish hooks are covered by focused tests.
+- `ws-server + fs-store` restore path initializes observation bus state and is validated.
+- Browser-facing projections continue not to expose raw backend handle/path/socket/session/credential internals or legacy public `can_stream_events` / `can_read_bounded_transcript` capabilities.
+
+---
+
+<!-- event: state_changed author: yoi-orchestrator at: 2026-06-27T19:49:36Z from: inprogress to: done reason: implementation_merged_and_validated field: state -->
+
+## State changed
+
+Reviewer approval後に implementation branch を orchestration branch へ merge し、要求された validation が成功したため done に遷移する。
+
+Validation:
+- `cargo fmt --all --check`: success
+- `cargo test -p worker-runtime --features ws-server`: success
+- `cargo test -p worker-runtime --features "ws-server fs-store"`: success
+- `cargo test -p yoi-workspace-server`: success
+- `cargo check -p yoi`: success
+- `git diff --check`: success
+- `nix build .#yoi --no-link`: success
+
+---
+
+<!-- event: state_changed author: hare at: 2026-06-27T19:49:46Z from: done to: closed reason: closed field: state -->
+
+## State changed
+
+Ticket を closed にしました。
+
+
+---
+
+<!-- event: close author: hare at: 2026-06-27T19:49:46Z status: closed -->
+
+## 完了
+
+`worker-runtime` に Worker execution backend 境界を追加し、reviewer approval 後に orchestration branch へ merge した。
+
+実装内容:
+- `WorkerExecutionBackend` trait / handle / context / status / result / operation / outcome を追加。
+- backend 未接続 Worker への input を typed `WorkerExecutionUnavailable` として拒否。
+- backend dispatch の busy / rejected / errored / unsupported を typed rejection として扱う。
+- backend から Runtime observation bus へ `protocol::Event` を publish する hook を追加。
+- stop / cancel unsupported の typed rejection を追加。
+- `WorkerSummary` / `WorkerDetail` に raw handle/path/credential を含まない execution status projection を追加。
+- Runtime が fake/providerless assistant response を生成しない境界を維持。
+- `can_stream_events` / `can_read_bounded_transcript` public capability は復活させていない。
+- `ws-server + fs-store` restore path で observation bus state を正しく初期化。
+
+Integrated commits:
+- `2d5971738478f832ba9a135601ea11dda60c565d feat: add worker execution backend boundary`
+- `761b60c85750d03c119733a088fb5073f9b37e9a fix: initialize restored worker observations`
+- merge: `0753e155 merge: worker runtime execution backend`
+
+Validation:
+- `cargo fmt --all --check`: success
+- `cargo test -p worker-runtime --features ws-server`: success
+- `cargo test -p worker-runtime --features "ws-server fs-store"`: success
+- `cargo test -p yoi-workspace-server`: success
+- `cargo check -p yoi`: success
+- `git diff --check`: success
+- `nix build .#yoi --no-link`: success
+
+Cleanup は child implementation worktree / branch と related role Pods のみを対象に実施する。
+
+---