worker: add internal worker runner

.yoi/tickets/00001KXRXAJFZ/item.md

@@ -1,8 +1,8 @@
 ---
 title: 'Internal Worker runnerを実装する'
-state: 'inprogress'
+state: 'closed'
 created_at: '2026-07-17T20:47:11Z'
-updated_at: '2026-07-17T20:47:48Z'
+updated_at: '2026-07-17T20:58:47Z'
 assignee: null
 queued_by: 'yoi ticket'
 queued_at: '2026-07-17T20:47:48Z'

.yoi/tickets/00001KXRXAJFZ/resolution.md

@@ -0,0 +1,9 @@
+Implemented reusable Worker-internal runner and migrated memory extract to use it.
+
+The new runner provides a Worker-owned path for isolated internal LLM jobs with caller-supplied prompt, input, limited tools, cache key, max turns, and usage capture. Memory extract now uses this runner while preserving the existing trigger and staging behavior.
+
+Validation passed:
+- `cargo fmt --check`
+- `cargo test -p memory`
+- `cargo test -p worker`
+- `nix build .#yoi`

.yoi/tickets/00001KXRXAJFZ/thread.md

@@ -22,4 +22,61 @@ Ticket を `yoi ticket` が queued にしました。
 State changed to `inprogress`.
 
 
+---
+
+<!-- event: implementation_report author: hare at: 2026-07-17T20:58:47Z -->
+
+## Implementation report
+
+Implemented reusable Worker-internal runner and migrated memory extract to use it.
+
+Changes:
+- Added `crates/worker/src/internal_worker.rs` with `InternalWorkerSpec`, `InternalWorkerRunResult`, `InternalWorkerRunError`, and `run_internal_worker`.
+- The runner owns isolated Engine creation, limited tool registration, cache key / max turns, usage capture, and foreground-history isolation by construction.
+- Updated memory extract path to run through the internal runner with only the extract tool surface supplied by the caller.
+- Kept existing extract behavior: post-run threshold trigger, transitional `write_extracted` path, and flat staging output.
+- Left persistence / Protocol exposure / session-explore feature for later Tickets.
+
+Validation:
+- `cargo fmt --check`
+- `cargo test -p memory`
+- `cargo test -p worker`
+- `nix build .#yoi`
+
+
+---
+
+<!-- event: state_changed author: "yoi ticket" at: 2026-07-17T20:58:47Z from: inprogress to: done reason: cli_state field: state -->
+
+## State changed
+
+State changed to `done`.
+
+
+---
+
+<!-- event: state_changed author: hare at: 2026-07-17T20:58:47Z from: done to: closed reason: closed field: state -->
+
+## State changed
+
+Ticket を closed にしました。
+
+
+---
+
+<!-- event: close author: hare at: 2026-07-17T20:58:47Z status: closed -->
+
+## 完了
+
+Implemented reusable Worker-internal runner and migrated memory extract to use it.
+
+The new runner provides a Worker-owned path for isolated internal LLM jobs with caller-supplied prompt, input, limited tools, cache key, max turns, and usage capture. Memory extract now uses this runner while preserving the existing trigger and staging behavior.
+
+Validation passed:
+- `cargo fmt --check`
+- `cargo test -p memory`
+- `cargo test -p worker`
+- `nix build .#yoi`
+
+
 ---