diff --git a/.yoi/tickets/00001KVNG9B9Z/artifacts/orchestration-plan.jsonl b/.yoi/tickets/00001KVNG9B9Z/artifacts/orchestration-plan.jsonl
new file mode 100644
index 00000000..2f9c99b0
--- /dev/null
+++ b/.yoi/tickets/00001KVNG9B9Z/artifacts/orchestration-plan.jsonl
@@ -0,0 +1 @@
+{"id":"orch-plan-20260621-163647-1","ticket_id":"00001KVNG9B9Z","kind":"accepted_plan","accepted_plan":{"summary":"Add left sidebar navigation skeleton to `web/workspace` static SPA with workspace header/settings placeholder, repositories/objectives/workers sections, objectives API read, workers placeholder/API boundary, responsive layout, and section-level error/empty states while avoiding backend authority changes.","branch":"impl/00001KVNG9B9Z-workspace-sidebar","worktree":"/home/hare/Projects/yoi/.worktree/00001KVNG9B9Z-workspace-sidebar","role_plan":"Orchestrator creates a dedicated child worktree and spawns a narrow-scope frontend Coder. Reviewer will be spawned read-only after Coder reports implementation commit(s). After approval, Orchestrator integrates into `orchestration`, resolving any conflict with Host/Worker work if it has merged, validates Deno/frontend/Nix as needed, records closure, and cleans only the child worktree/branch."},"author":"yoi-orchestrator","at":"2026-06-21T16:36:47Z"}
diff --git a/.yoi/tickets/00001KVNG9B9Z/item.md b/.yoi/tickets/00001KVNG9B9Z/item.md
index 261d2b2a..22562bbb 100644
--- a/.yoi/tickets/00001KVNG9B9Z/item.md
+++ b/.yoi/tickets/00001KVNG9B9Z/item.md
@@ -1,8 +1,8 @@
 ---
 title: 'Workspace web UI: add sidebar navigation panel'
-state: 'queued'
+state: 'inprogress'
 created_at: '2026-06-21T16:30:12Z'
-updated_at: '2026-06-21T16:35:06Z'
+updated_at: '2026-06-21T16:36:47Z'
 assignee: null
 queued_by: 'workspace-panel'
 queued_at: '2026-06-21T16:35:06Z'
diff --git a/.yoi/tickets/00001KVNG9B9Z/thread.md b/.yoi/tickets/00001KVNG9B9Z/thread.md
index d5a2fcf9..9b71b72e 100644
--- a/.yoi/tickets/00001KVNG9B9Z/thread.md
+++ b/.yoi/tickets/00001KVNG9B9Z/thread.md
@@ -30,4 +30,80 @@ Marked ready by `yoi ticket state`.
 Ticket を `workspace-panel` が queued にしました。
 
 
+---
+
+<!-- event: decision author: yoi-orchestrator at: 2026-06-21T16:36:30Z -->
+
+## Decision
+
+Routing decision: `implementation_ready_parallel_with_conflict_risk`
+
+Reason:
+- Ticket body は Workspace web UI に左 sidebar navigation panel を追加する UX skeleton として、header / repositories / objectives / workers sections、responsive behavior、section-level error handling、Deno validation まで具体化されている。
+- Relations are `related` only to `00001KVMFFYVX` and `00001KVNEKH9Q`; no blocking dependency is recorded。
+- `00001KVMFFYVX` is closed/integrated。
+- `00001KVNEKH9Q` is currently in review and touches Host/Worker API plus `web/workspace/src/routes/+page.svelte`; this creates merge-conflict risk but not an authority blocker. Ticket body explicitly allows Workers section to be placeholder before Host/Worker API exists and asks for component boundary that can later connect to that API。
+- Current queued Ticket is this Ticket only。
+- Orchestrator worktree is clean on `orchestration` at `d4de8e26`; target worktree / branch is not present。
+
+Evidence checked:
+- Ticket body via direct `item.md` read。
+- `relations.json`: related to `00001KVMFFYVX` and `00001KVNEKH9Q` only。
+- `TicketOrchestrationPlanQuery(00001KVNG9B9Z)`: no records。
+- `TicketList(state=queued)`: this Ticket is the only queued Ticket。
+- `00001KVNEKH9Q` current state is `inprogress` / reviewer running; no approval/merge yet。
+- Orchestrator git state / worktree list / branch list checked from `/home/hare/Projects/yoi/.worktree/orchestration` only。
+
+IntentPacket:
+
+Intent:
+- Add a left sidebar navigation skeleton to Workspace web SPA that surfaces Workspace / Repository / Objective / Worker navigation without adding deep editing or business authority。
+
+Binding decisions / invariants:
+- Frontend-only UI skeleton unless a minimal API read is already available; do not change backend authority without need。
+- Keep static SPA; no SSR or frontend lifecycle/business authority。
+- Objective section should read existing `/api/objectives` and display bounded title/state data。
+- Worker section should use a component/data boundary that can connect to Host/Worker API, but must safely show placeholder/empty/error if API is absent or in flux。
+- Do not expose Pod as primary UI/domain naming; use `workers`。
+- API failures are section-local and must not take down the whole page。
+- Avoid broad design-system churn; keep current skeleton style direction。
+- Be aware that `00001KVNEKH9Q` may merge Host/Worker UI/API changes concurrently; keep sidebar changes narrow and componentized to reduce conflict。
+
+Requirements / acceptance criteria:
+- Left sidebar is visible in Workspace web UI。
+- Sidebar header displays workspace name/label plus settings placeholder/icon/button。
+- Sections present: `repositories`, `objectives`, `workers`。
+- Objectives section fetches existing `/api/objectives` and displays title/state minimal info。
+- Workers section safely displays placeholder/empty/error if Host/Worker API is not yet integrated; if API is available in branch, it may use it through a component boundary。
+- Main content and sidebar layout are separated and responsive enough to avoid narrow-viewport breakage / horizontal overflow。
+- Section-level error/empty states are bounded。
+- Deno check/build passes。
+
+Implementation latitude:
+- Split Svelte components under `web/workspace/src/lib` if useful。
+- Keep repository section placeholder/local summary if no Repository API exists。
+- Use simple CSS layout; no full design system。
+- If concurrent `00001KVNEKH9Q` merge creates conflict, report rather than broad rewrite。
+
+Escalate if:
+- Implementing sidebar requires backend API redesign beyond minimal frontend skeleton。
+- Workers section cannot be safely decoupled from unmerged Host/Worker API。
+- Deno/Svelte tooling fails for reasons unrelated to this Ticket。
+- Merge conflict with `00001KVNEKH9Q` becomes non-trivial and requires orchestration sequencing。
+
+Validation plan:
+- `cd web/workspace && deno task check && deno task build`
+- `git diff --check`
+- `cargo run -p yoi -- ticket doctor`
+- `nix build .#yoi --no-link` preferred because Workspace frontend package surface is touched。
+- `cargo test -p yoi-workspace-server` only if backend code changes。
+
+---
+
+<!-- event: state_changed author: yoi-orchestrator at: 2026-06-21T16:36:37Z from: queued to: inprogress reason: human_authorized_unblocked_sidebar_ui_implementation field: state -->
+
+## State changed
+
+Human authorized queue routing from Workspace Dashboard. Ticket has concrete frontend acceptance criteria and no blocking relation; related Host/Worker API work is in review and creates merge-conflict risk but not an authority blocker. Orchestrator accepts implementation with narrow frontend scope.
+
 ---