diff --git a/.yoi/tickets/00001KX6Y6ZEA/item.md b/.yoi/tickets/00001KX6Y6ZEA/item.md
index 7e4eb2cf..b555d218 100644
--- a/.yoi/tickets/00001KX6Y6ZEA/item.md
+++ b/.yoi/tickets/00001KX6Y6ZEA/item.md
@@ -1,9 +1,9 @@
 ---
 title: 'Replace Worker workspace_root path with WorkspaceBackend'
-state: 'inprogress'
+state: 'closed'
 priority: 'P1'
 created_at: '2026-07-10T21:16:22Z'
-updated_at: '2026-07-11T01:07:06Z'
+updated_at: '2026-07-11T01:09:59Z'
 assignee: null
 queued_by: 'workspace-panel'
 queued_at: '2026-07-10T22:03:27Z'
diff --git a/.yoi/tickets/00001KX6Y6ZEA/resolution.md b/.yoi/tickets/00001KX6Y6ZEA/resolution.md
new file mode 100644
index 00000000..59e440d6
--- /dev/null
+++ b/.yoi/tickets/00001KX6Y6ZEA/resolution.md
@@ -0,0 +1,32 @@
+Worker workspace identity / WorkspaceBackend boundary を実装・レビュー・merge・検証した。
+
+実装内容:
+- Worker-held `workspace_root: PathBuf` identity を削除し、path-free `WorkerWorkspaceContext`, `WorkspaceId`, `WorkspaceClient` に置き換えた。
+- Worker は `workspace_context` と `filesystem_authority` を分離して保持し、local filesystem authority は `WorkerFilesystemAuthority::{None, Local(LocalWorkingDirectory)}` に閉じ込めた。
+- Worker constructors / restore / spawn paths を workspace context と filesystem authority の分離形に更新した。
+- Runtime 側に `RuntimeWorkspaceBackendRef` を追加し、host-owned local backend binding から narrow Worker workspace context を注入するようにした。
+- `workspace_id/client` が存在しても local filesystem authority を意味しないようにした。
+- no-filesystem Workers では memory/workflow local layouts を workspace path fallback せず unavailable/fail-closed にした。
+- legacy metadata `workspace_root` は compatibility/local filesystem hint として、`WorkerFilesystemAuthority::Local` 由来の場合だけ扱うようにした。
+- tests で path-free workspace identity/client と local cwd/root の分離、filesystem authority なしの workspace client、local path-returning Worker workspace accessor 不在、constructor/restore/spawn behavior を確認した。
+
+Review:
+- Reviewer approved with no blockers。
+- Evidence included path-free Worker context, no Worker `workspace_root()` accessor, Runtime/host backend materialization boundary, workspace-client-without-filesystem tests, fail-closed local workspace features, and legacy metadata confinement。
+- Non-blocking note: `set_active_with_workspace_context` preserves existing metadata fields when passed `None`; future no-workspace reuse of an existing Pod name may want explicit clearing semantics to avoid stale UI hints。
+
+Merge / validation:
+- Merge commit: `391f11fc merge: workspace backend worker context`。
+- Final validation passed:
+  - `rg -n 'workspace_root' crates/worker crates/worker-runtime crates/client crates/workspace-server || true`
+  - `rg -n 'worker\\.workspace_root|pub fn workspace_root|fn workspace_root' crates/worker crates/worker-runtime crates/client crates/workspace-server || true`
+  - `git diff --check`
+  - `cargo test -p worker --lib --tests`
+  - `cargo test -p worker-runtime --features ws-server,fs-store`
+  - `cargo test -p yoi-workspace-server --lib`
+  - `cargo check -p yoi`
+  - `cd web/workspace && deno task check`
+  - `cd web/workspace && deno task test`
+  - `yoi ticket doctor`
+  - `nix build .#yoi --no-link`
+- Validation log: `/run/user/1000/yoi/yoi-orchestrator/bash-output/workspace-backend-final-validation-1783732052.txt`
\ No newline at end of file
diff --git a/.yoi/tickets/00001KX6Y6ZEA/thread.md b/.yoi/tickets/00001KX6Y6ZEA/thread.md
index b22ade57..7128b463 100644
--- a/.yoi/tickets/00001KX6Y6ZEA/thread.md
+++ b/.yoi/tickets/00001KX6Y6ZEA/thread.md
@@ -303,3 +303,93 @@ Non-blocking notes:
 - `set_active_with_workspace_context` preserves existing metadata fields when passed `None`; acceptable for this Ticket as compatibility metadata, but future no-workspace reuse of an existing Pod name may want explicit clearing semantics to avoid stale UI hints。
 
 ---
+
+<!-- event: implementation_report author: orchestrator at: 2026-07-11T01:09:39Z -->
+
+## Implementation report
+
+Merge / final validation report:
+
+- Reviewer approved the implementation with no blockers。
+- Merged branch `work/00001KX6Y6ZEA-workspace-backend` into orchestration branch with merge commit `391f11fc merge: workspace backend worker context`。
+- Final validation was rerun in `/home/hare/Projects/yoi/.worktree/orchestration` after merge。
+
+Validation passed:
+- `rg -n 'workspace_root' crates/worker crates/worker-runtime crates/client crates/workspace-server || true` with remaining hits limited to legacy metadata/local adapter/test contexts。
+- `rg -n 'worker\\.workspace_root|pub fn workspace_root|fn workspace_root' crates/worker crates/worker-runtime crates/client crates/workspace-server || true`; no Worker identity/accessor hits were found. The expected unrelated workspace-server project-record accessor remains outside Worker identity。
+- `git diff --check`
+- `cargo test -p worker --lib --tests`
+- `cargo test -p worker-runtime --features ws-server,fs-store`
+- `cargo test -p yoi-workspace-server --lib`
+- `cargo check -p yoi`
+- `cd web/workspace && deno task check`
+- `cd web/workspace && deno task test`
+- `yoi ticket doctor`
+- `nix build .#yoi --no-link`
+
+Validation log:
+- `/run/user/1000/yoi/yoi-orchestrator/bash-output/workspace-backend-final-validation-1783732052.txt`
+
+Reviewed/merged implementation commit:
+- `142b60e1 refactor: separate worker workspace identity`
+
+Non-blocking reviewer note:
+- `set_active_with_workspace_context` preserves existing metadata fields when passed `None`; acceptable for this Ticket as compatibility metadata, but future no-workspace reuse of an existing Pod name may want explicit clearing semantics to avoid stale UI hints。
+
+---
+
+<!-- event: state_changed author: orchestrator at: 2026-07-11T01:09:43Z from: inprogress to: done reason: implementation_validated field: state -->
+
+## State changed
+
+Implementation was reviewed, merged into orchestration branch, and final validation passed. Moving to done before closure.
+
+---
+
+<!-- event: state_changed author: hare at: 2026-07-11T01:09:59Z from: done to: closed reason: closed field: state -->
+
+## State changed
+
+Ticket を closed にしました。
+
+
+---
+
+<!-- event: close author: hare at: 2026-07-11T01:09:59Z status: closed -->
+
+## 完了
+
+Worker workspace identity / WorkspaceBackend boundary を実装・レビュー・merge・検証した。
+
+実装内容:
+- Worker-held `workspace_root: PathBuf` identity を削除し、path-free `WorkerWorkspaceContext`, `WorkspaceId`, `WorkspaceClient` に置き換えた。
+- Worker は `workspace_context` と `filesystem_authority` を分離して保持し、local filesystem authority は `WorkerFilesystemAuthority::{None, Local(LocalWorkingDirectory)}` に閉じ込めた。
+- Worker constructors / restore / spawn paths を workspace context と filesystem authority の分離形に更新した。
+- Runtime 側に `RuntimeWorkspaceBackendRef` を追加し、host-owned local backend binding から narrow Worker workspace context を注入するようにした。
+- `workspace_id/client` が存在しても local filesystem authority を意味しないようにした。
+- no-filesystem Workers では memory/workflow local layouts を workspace path fallback せず unavailable/fail-closed にした。
+- legacy metadata `workspace_root` は compatibility/local filesystem hint として、`WorkerFilesystemAuthority::Local` 由来の場合だけ扱うようにした。
+- tests で path-free workspace identity/client と local cwd/root の分離、filesystem authority なしの workspace client、local path-returning Worker workspace accessor 不在、constructor/restore/spawn behavior を確認した。
+
+Review:
+- Reviewer approved with no blockers。
+- Evidence included path-free Worker context, no Worker `workspace_root()` accessor, Runtime/host backend materialization boundary, workspace-client-without-filesystem tests, fail-closed local workspace features, and legacy metadata confinement。
+- Non-blocking note: `set_active_with_workspace_context` preserves existing metadata fields when passed `None`; future no-workspace reuse of an existing Pod name may want explicit clearing semantics to avoid stale UI hints。
+
+Merge / validation:
+- Merge commit: `391f11fc merge: workspace backend worker context`。
+- Final validation passed:
+  - `rg -n 'workspace_root' crates/worker crates/worker-runtime crates/client crates/workspace-server || true`
+  - `rg -n 'worker\\.workspace_root|pub fn workspace_root|fn workspace_root' crates/worker crates/worker-runtime crates/client crates/workspace-server || true`
+  - `git diff --check`
+  - `cargo test -p worker --lib --tests`
+  - `cargo test -p worker-runtime --features ws-server,fs-store`
+  - `cargo test -p yoi-workspace-server --lib`
+  - `cargo check -p yoi`
+  - `cd web/workspace && deno task check`
+  - `cd web/workspace && deno task test`
+  - `yoi ticket doctor`
+  - `nix build .#yoi --no-link`
+- Validation log: `/run/user/1000/yoi/yoi-orchestrator/bash-output/workspace-backend-final-validation-1783732052.txt`
+
+---