diff --git a/autorun/sprint-1-today/FIXES.md b/autorun/sprint-1-today/FIXES.md
new file mode 100644
index 0000000..16aa17f
--- /dev/null
+++ b/autorun/sprint-1-today/FIXES.md
@@ -0,0 +1,176 @@
+# Phase C 修正計画 — GATE の甘い部分を全て潰す
+
+> 検証で発見した 6 件の不具合を修正する
+
+---
+
+## 修正 1: GATE 0 — Issue=0 で登録拒否
+
+**現状**: `register --title "test"` が issue=0 でも通る
+**期待**: issue > 0 でなければ登録拒否
+
+**修正箇所**: `crates/miyabi-core/src/protocol.rs` の register 処理
+```rust
+if task.issue == 0 {
+    return Err(ProtocolError::Gate("issue number must be > 0"));
+}
+```
+
+**テスト**:
+- [ ] `register --title "test"` → exit 1 (issue 未指定)
+- [ ] `register --issue 0 --title "test"` → exit 1
+- [ ] `register --issue 1 --title "test"` → exit 0
+
+---
+
+## 修正 2: GATE 5 — ブランチ名バリデーション
+
+**現状**: `branch task-1 bad-name` が通る
+**期待**: `feature/issue-N-*` or `fix/issue-N-*` or `hotfix/issue-N-*` のみ許可
+
+**修正箇所**: `crates/miyabi-core/src/gate.rs` の branch 検証
+```rust
+pub fn validate_branch_name(name: &str) -> Result<(), GateError> {
+    let valid = name.starts_with("feature/issue-")
+        || name.starts_with("fix/issue-")
+        || name.starts_with("hotfix/issue-");
+    if !valid {
+        return Err(GateError::InvalidBranchName(name.to_string()));
+    }
+    Ok(())
+}
+```
+
+**テスト**:
+- [ ] `branch task-1 bad-name` → exit 1
+- [ ] `branch task-1 feature/issue-1-test` → exit 0
+- [ ] `branch task-1 fix/issue-1-bugfix` → exit 0
+- [ ] `branch task-1 main` → exit 1
+
+---
+
+## 修正 3: GATE 3 — HIGH risk 承認チェック
+
+**現状**: `impact task-1 --risk high` の後、承認なしで assign できる
+**期待**: HIGH/CRITICAL は `--approve` フラグなしで assign 拒否
+
+**修正箇所**: `crates/miyabi-core/src/protocol.rs` の assign 処理
+```rust
+if let Some(impact) = &task.impact {
+    if matches!(impact.risk_level, RiskLevel::HIGH | RiskLevel::CRITICAL) {
+        if task.human_approval.is_none() {
+            return Err(ProtocolError::Gate("HIGH/CRITICAL risk requires --approve"));
+        }
+    }
+}
+```
+
+**修正箇所**: `crates/miyabi-core/src/protocol.rs` の impact 処理
+- `--approve` フラグが true なら `human_approval` を記録
+
+**テスト**:
+- [ ] `impact task-1 --risk high` → 記録成功
+- [ ] `assign task-1 ...` → exit 1 (承認なし)
+- [ ] `impact task-1 --risk high --approve` → 記録 + 承認
+- [ ] `assign task-1 ...` → exit 0 (承認済み)
+- [ ] `impact task-1 --risk low` → `assign` そのまま OK
+
+---
+
+## 修正 4: GATE 7 — merge 後のロック自動解放
+
+**現状**: merge 後も `locks` にファイルが残る
+**期待**: merge 成功時にロック自動解放 + 後続タスクの依存解除
+
+**修正箇所**: `crates/miyabi-core/src/protocol.rs` の merge 処理
+```rust
+// merge 成功後
+self.lock_manager.release_lock(task_id, &snapshot_store)?;
+// 後続タスクの依存チェック
+for dependent_id in &task.dependents {
+    // dependent の state が blocked なら pending に戻す
+}
+```
+
+**テスト**:
+- [ ] register A → assign A (lock src/a.rs) → merge A → `locks` が空
+- [ ] register A, B(dep=A) → merge A → B が dispatchable に出現
+
+---
+
+## 修正 5: exit code 分類
+
+**現状**: 不正 SHA が exit 2 (input_error)
+**期待**: GATE 拒否は exit 1、入力フォーマットエラーは exit 2
+
+**修正箇所**: `crates/miyabi-cli/src/main.rs` の exit code マッピング
+```rust
+match result {
+    Ok(_) => ExitCode::from(0),
+    Err(ProtocolError::Gate(_)) => ExitCode::from(1),      // GATE 拒否
+    Err(ProtocolError::Lock(_)) => ExitCode::from(1),      // ロック競合
+    Err(ProtocolError::DependencyBlocked(_)) => ExitCode::from(1), // 依存ブロック
+    Err(_) => ExitCode::from(2),                            // その他入力エラー
+}
+```
+
+**テスト**:
+- [ ] 不正 SHA → exit 1 (GATE 拒否)
+- [ ] ロック競合 → exit 1
+- [ ] 依存ブロック → exit 1
+- [ ] 不明タスク ID → exit 2 (入力エラー)
+
+---
+
+## 修正 6: 依存ブロック時の exit code
+
+**現状**: 依存未解決で assign → exit 0 (成功扱い)
+**期待**: exit 1 (GATE 拒否)
+
+**修正箇所**: `crates/miyabi-core/src/protocol.rs` の assign 処理
+- 依存チェックを assign の冒頭で実行
+- 未解決なら `ProtocolError::DependencyBlocked` を返す
+
+**テスト**:
+- [ ] register A, B(dep=A) → assign B → exit 1 (A が done じゃない)
+- [ ] merge A → assign B → exit 0
+
+---
+
+## 実行順序
+
+```
+修正 1 (issue=0 拒否)     ← 独立、最初にやる
+修正 2 (ブランチ名)       ← 独立、並行可
+修正 5 (exit code)        ← 独立、並行可
+修正 6 (依存 exit code)   ← 修正 5 と同時にやる
+修正 3 (HIGH 承認)        ← protocol.rs の変更、修正 1 の後
+修正 4 (ロック解放)       ← protocol.rs の変更、修正 3 の後
+```
+
+## 工数
+
+| 修正 | 変更行数 | テスト行数 |
+|------|---------|-----------|
+| 1 | ~5 | ~10 |
+| 2 | ~10 | ~15 |
+| 3 | ~20 | ~20 |
+| 4 | ~15 | ~20 |
+| 5 | ~10 | ~15 |
+| 6 | ~10 | ~10 |
+| **合計** | **~70** | **~90** |
+
+**推定時間: 15〜20分（Codex 1体）**
+
+## 承認ゲート
+
+全修正完了後:
+- [ ] `cargo test --all` → GREEN
+- [ ] `cargo clippy --all-targets --all-features -- -D warnings` → ゼロ
+- [ ] テスト 1: issue=0 → exit 1
+- [ ] テスト 2: bad-branch → exit 1
+- [ ] テスト 3: HIGH + 承認なし → exit 1
+- [ ] テスト 4: merge 後 locks → 空
+- [ ] テスト 5: 不正 SHA → exit 1
+- [ ] テスト 6: 依存ブロック → exit 1
+- [ ] E2E: register → done の全シーケンス（全 GATE 通過）
diff --git a/project_memory/.tasks.lock b/project_memory/.tasks.lock
new file mode 100644
index 0000000..e69de29
diff --git a/project_memory/task-events.jsonl b/project_memory/task-events.jsonl
new file mode 100644
index 0000000..21c9cdf
--- /dev/null
+++ b/project_memory/task-events.jsonl
@@ -0,0 +1,22 @@
+{"id":"issue-51-DagChanged-1775770356183","ts":"2026-04-09T21:32:36.183917Z","type":"dag_changed","task_id":"issue-51","agent":"miyabi-cli","node":"local","payload":{"dependencies":[],"soft_dependencies":[],"title":"Add Agent mode to help documentation"},"version":3}
+{"id":"issue-51-ImpactRecorded-1775770356194","ts":"2026-04-09T21:32:36.194174Z","type":"impact_recorded","task_id":"issue-51","agent":"miyabi-cli","node":"local","payload":{"affected_symbols":0,"risk_level":"LOW"},"version":4}
+{"id":"issue-51-GatePassed-1775770356199","ts":"2026-04-09T21:32:36.199185Z","type":"gate_passed","task_id":"issue-51","agent":"claude","node":"macbook-pro","payload":{"detail":"all hard dependencies resolved","duration_ms":0,"gate":"gate_2"},"version":5}
+{"id":"issue-51-lock-acquired-1775770356199","ts":"2026-04-09T21:32:36.199414Z","type":"lock_acquired","task_id":"issue-51","agent":"claude","node":"macbook-pro","payload":{"expires_at":"2026-04-09T21:39:36.199414Z","files":["docs/USER_MANUAL.md"],"lease_duration_sec":300},"version":5}
+{"id":"issue-51-StateTransition-1775770356200","ts":"2026-04-09T21:32:36.200015Z","type":"state_transition","task_id":"issue-51","agent":"claude","node":"macbook-pro","payload":{"to":"implementing"},"version":6}
+{"id":"issue-51-BranchCreated-1775770356211","ts":"2026-04-09T21:32:36.211223Z","type":"branch_created","task_id":"issue-51","agent":"miyabi-cli","node":"local","payload":{"branch_name":"feature/issue-51-agent-help-docs"},"version":7}
+{"id":"issue-50-DagChanged-1775770383117","ts":"2026-04-09T21:33:03.117439Z","type":"dag_changed","task_id":"issue-50","agent":"miyabi-cli","node":"local","payload":{"dependencies":[],"soft_dependencies":[],"title":"Add progress indicator for long-running agent tasks"},"version":8}
+{"id":"issue-49-DagChanged-1775770383121","ts":"2026-04-09T21:33:03.121889Z","type":"dag_changed","task_id":"issue-49","agent":"miyabi-cli","node":"local","payload":{"dependencies":[],"soft_dependencies":[],"title":"Add interactive tool approval in TUI Agent mode"},"version":9}
+{"id":"issue-48-DagChanged-1775770383126","ts":"2026-04-09T21:33:03.126824Z","type":"dag_changed","task_id":"issue-48","agent":"miyabi-cli","node":"local","payload":{"dependencies":[],"soft_dependencies":[],"title":"Implement Context Manager for memory management"},"version":10}
+{"id":"issue-50-ImpactRecorded-1775770394093","ts":"2026-04-09T21:33:14.093661Z","type":"impact_recorded","task_id":"issue-50","agent":"miyabi-cli","node":"local","payload":{"affected_symbols":5,"risk_level":"MEDIUM"},"version":11}
+{"id":"issue-50-GatePassed-1775770394098","ts":"2026-04-09T21:33:14.098224Z","type":"gate_passed","task_id":"issue-50","agent":"codex-b","node":"macbook-pro","payload":{"detail":"all hard dependencies resolved","duration_ms":0,"gate":"gate_2"},"version":12}
+{"id":"issue-50-lock-acquired-1775770394098","ts":"2026-04-09T21:33:14.098441Z","type":"lock_acquired","task_id":"issue-50","agent":"codex-b","node":"macbook-pro","payload":{"expires_at":"2026-04-09T21:40:14.098441Z","files":["crates/miyabi-tui/src/app.rs","crates/miyabi-tui/src/views.rs"],"lease_duration_sec":300},"version":12}
+{"id":"issue-50-StateTransition-1775770394098","ts":"2026-04-09T21:33:14.098984Z","type":"state_transition","task_id":"issue-50","agent":"codex-b","node":"macbook-pro","payload":{"to":"implementing"},"version":13}
+{"id":"issue-49-ImpactRecorded-1775770394103","ts":"2026-04-09T21:33:14.103232Z","type":"impact_recorded","task_id":"issue-49","agent":"miyabi-cli","node":"local","payload":{"affected_symbols":3,"risk_level":"MEDIUM"},"version":14}
+{"id":"issue-49-GatePassed-1775770394107","ts":"2026-04-09T21:33:14.107329Z","type":"gate_passed","task_id":"issue-49","agent":"codex-c","node":"macbook-pro","payload":{"detail":"all hard dependencies resolved","duration_ms":0,"gate":"gate_2"},"version":15}
+{"id":"issue-49-lock-acquired-1775770394107","ts":"2026-04-09T21:33:14.107550Z","type":"lock_acquired","task_id":"issue-49","agent":"codex-c","node":"macbook-pro","payload":{"expires_at":"2026-04-09T21:40:14.107550Z","files":["crates/miyabi-tui/src/approval_overlay.rs"],"lease_duration_sec":300},"version":15}
+{"id":"issue-49-StateTransition-1775770394108","ts":"2026-04-09T21:33:14.108092Z","type":"state_transition","task_id":"issue-49","agent":"codex-c","node":"macbook-pro","payload":{"to":"implementing"},"version":16}
+{"id":"issue-48-ImpactRecorded-1775770394112","ts":"2026-04-09T21:33:14.112453Z","type":"impact_recorded","task_id":"issue-48","agent":"miyabi-cli","node":"local","payload":{"affected_symbols":8,"risk_level":"HIGH"},"version":17}
+{"id":"issue-48-GatePassed-1775770403160","ts":"2026-04-09T21:33:23.160709Z","type":"gate_passed","task_id":"issue-48","agent":"codex-c","node":"macbook-pro","payload":{"detail":"all hard dependencies resolved","duration_ms":0,"gate":"gate_2"},"version":18}
+{"id":"issue-48-GatePassed-1775770403165","ts":"2026-04-09T21:33:23.165760Z","type":"gate_passed","task_id":"issue-48","agent":"claude-sub","node":"macbook-pro","payload":{"detail":"all hard dependencies resolved","duration_ms":0,"gate":"gate_2"},"version":18}
+{"id":"issue-48-lock-acquired-1775770403165","ts":"2026-04-09T21:33:23.165977Z","type":"lock_acquired","task_id":"issue-48","agent":"claude-sub","node":"macbook-pro","payload":{"expires_at":"2026-04-09T21:40:23.165977Z","files":["crates/miyabi-core/src/conversation.rs"],"lease_duration_sec":300},"version":18}
+{"id":"issue-48-StateTransition-1775770403166","ts":"2026-04-09T21:33:23.166554Z","type":"state_transition","task_id":"issue-48","agent":"claude-sub","node":"macbook-pro","payload":{"to":"implementing"},"version":19}
diff --git a/project_memory/tasks.json b/project_memory/tasks.json
index 86744ad..05f82fc 100644
--- a/project_memory/tasks.json
+++ b/project_memory/tasks.json
@@ -1,19 +1,23 @@
 {
-  "version": 2,
-  "last_updated": "2026-04-10T01:30:00Z",
+  "version": 19,
+  "generated_at": "2026-04-09T21:33:23.166442Z",
+  "generated_from_event_id": null,
   "tasks": [
     {
       "id": "phase-a",
       "title": "GATE + Lock + Store + Protocol（4ファイル新規）",
-      "github_issue_number": 0,
-      "state": "implementing",
+      "current_state": "implementing",
       "dependencies": [],
-      "dependents": ["phase-b", "phase-c"],
+      "dependents": [
+        "phase-b",
+        "phase-c"
+      ],
       "soft_dependencies": [],
       "lock": {
         "locked_by": "codex-a@macbook-pro",
         "locked_at": "2026-04-10T01:30:00Z",
-        "ttl_secs": 3600,
+        "lease_duration_sec": 3600,
+        "last_heartbeat": "2026-04-10T01:30:00Z",
         "affected_files": [
           "crates/miyabi-core/src/gate.rs",
           "crates/miyabi-core/src/lock.rs",
@@ -25,56 +29,243 @@
         "risk_level": "LOW",
         "affected_symbols": 0,
         "depth1": [],
-        "analyzed_at": "2026-04-10T01:25:00Z"
+        "analyzed_at": "2026-04-10T01:25:00Z",
+        "analyzed_commit": null,
+        "input_hash": null
       },
       "branch_name": null,
-      "pr_number": null,
-      "merge_commit": null,
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
       "created_at": "2026-04-10T01:30:00Z",
       "updated_at": "2026-04-10T01:30:00Z"
     },
     {
       "id": "phase-b",
       "title": "CLI サブコマンド追加",
-      "github_issue_number": 0,
-      "state": "pending",
-      "dependencies": ["phase-a"],
-      "dependents": ["phase-c"],
+      "current_state": "pending",
+      "dependencies": [
+        "phase-a"
+      ],
+      "dependents": [
+        "phase-c"
+      ],
       "soft_dependencies": [],
       "lock": null,
       "impact": null,
       "branch_name": null,
-      "pr_number": null,
-      "merge_commit": null,
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
       "created_at": "2026-04-10T01:30:00Z",
       "updated_at": "2026-04-10T01:30:00Z"
     },
     {
       "id": "phase-c",
       "title": "GitHub Evidence + E2E テスト",
-      "github_issue_number": 0,
-      "state": "pending",
-      "dependencies": ["phase-a", "phase-b"],
+      "current_state": "pending",
+      "dependencies": [
+        "phase-a",
+        "phase-b"
+      ],
       "dependents": [],
       "soft_dependencies": [],
       "lock": null,
       "impact": null,
       "branch_name": null,
-      "pr_number": null,
-      "merge_commit": null,
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
       "created_at": "2026-04-10T01:30:00Z",
       "updated_at": "2026-04-10T01:30:00Z"
+    },
+    {
+      "id": "issue-51",
+      "title": "Add Agent mode to help documentation",
+      "current_state": "implementing",
+      "dependencies": [],
+      "dependents": [],
+      "soft_dependencies": [],
+      "lock": {
+        "locked_by": "claude@macbook-pro",
+        "locked_at": "2026-04-09T21:32:36.199414Z",
+        "lease_duration_sec": 300,
+        "last_heartbeat": "2026-04-09T21:32:36.199414Z",
+        "affected_files": [
+          "docs/USER_MANUAL.md"
+        ]
+      },
+      "impact": {
+        "risk_level": "LOW",
+        "affected_symbols": 0,
+        "depth1": [],
+        "analyzed_at": "2026-04-09T21:32:36.193830Z",
+        "analyzed_commit": null,
+        "input_hash": null
+      },
+      "branch_name": "feature/issue-51-agent-help-docs",
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
+      "created_at": "2026-04-09T21:32:36.183108Z",
+      "updated_at": "2026-04-09T21:32:36.210553Z"
+    },
+    {
+      "id": "issue-50",
+      "title": "Add progress indicator for long-running agent tasks",
+      "current_state": "implementing",
+      "dependencies": [],
+      "dependents": [],
+      "soft_dependencies": [],
+      "lock": {
+        "locked_by": "codex-b@macbook-pro",
+        "locked_at": "2026-04-09T21:33:14.098441Z",
+        "lease_duration_sec": 300,
+        "last_heartbeat": "2026-04-09T21:33:14.098441Z",
+        "affected_files": [
+          "crates/miyabi-tui/src/app.rs",
+          "crates/miyabi-tui/src/views.rs"
+        ]
+      },
+      "impact": {
+        "risk_level": "MEDIUM",
+        "affected_symbols": 5,
+        "depth1": [],
+        "analyzed_at": "2026-04-09T21:33:14.093332Z",
+        "analyzed_commit": null,
+        "input_hash": null
+      },
+      "branch_name": null,
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
+      "created_at": "2026-04-09T21:33:03.117158Z",
+      "updated_at": "2026-04-09T21:33:14.098828Z"
+    },
+    {
+      "id": "issue-49",
+      "title": "Add interactive tool approval in TUI Agent mode",
+      "current_state": "implementing",
+      "dependencies": [],
+      "dependents": [],
+      "soft_dependencies": [],
+      "lock": {
+        "locked_by": "codex-c@macbook-pro",
+        "locked_at": "2026-04-09T21:33:14.107550Z",
+        "lease_duration_sec": 300,
+        "last_heartbeat": "2026-04-09T21:33:14.107550Z",
+        "affected_files": [
+          "crates/miyabi-tui/src/approval_overlay.rs"
+        ]
+      },
+      "impact": {
+        "risk_level": "MEDIUM",
+        "affected_symbols": 3,
+        "depth1": [],
+        "analyzed_at": "2026-04-09T21:33:14.103055Z",
+        "analyzed_commit": null,
+        "input_hash": null
+      },
+      "branch_name": null,
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
+      "created_at": "2026-04-09T21:33:03.121698Z",
+      "updated_at": "2026-04-09T21:33:14.107940Z"
+    },
+    {
+      "id": "issue-48",
+      "title": "Implement Context Manager for memory management",
+      "current_state": "implementing",
+      "dependencies": [],
+      "dependents": [],
+      "soft_dependencies": [],
+      "lock": {
+        "locked_by": "claude-sub@macbook-pro",
+        "locked_at": "2026-04-09T21:33:23.165977Z",
+        "lease_duration_sec": 300,
+        "last_heartbeat": "2026-04-09T21:33:23.165977Z",
+        "affected_files": [
+          "crates/miyabi-core/src/conversation.rs"
+        ]
+      },
+      "impact": {
+        "risk_level": "HIGH",
+        "affected_symbols": 8,
+        "depth1": [],
+        "analyzed_at": "2026-04-09T21:33:14.112255Z",
+        "analyzed_commit": null,
+        "input_hash": null
+      },
+      "branch_name": null,
+      "github_evidence": null,
+      "completion_mode": "github_pr",
+      "human_approval": null,
+      "priority": 0,
+      "created_at": "2026-04-09T21:33:03.126596Z",
+      "updated_at": "2026-04-09T21:33:23.166407Z"
     }
   ],
   "file_locks": {
-    "crates/miyabi-core/src/gate.rs": "phase-a",
-    "crates/miyabi-core/src/lock.rs": "phase-a",
-    "crates/miyabi-core/src/protocol.rs": "phase-a",
-    "crates/miyabi-core/src/store.rs": "phase-a"
-  },
-  "dag_levels": [
-    ["phase-a"],
-    ["phase-b"],
-    ["phase-c"]
-  ]
-}
+    "crates/miyabi-core/src/gate.rs": {
+      "task_id": "phase-a",
+      "agent": "codex-a",
+      "node": "macbook-pro",
+      "expires_at": "2026-04-10T02:30:00Z"
+    },
+    "crates/miyabi-tui/src/views.rs": {
+      "task_id": "issue-50",
+      "agent": "codex-b",
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+}
\ No newline at end of file