diff --git a/docs/development-plan.md b/docs/development-plan.md
index b9ea5cf..cd6bb9c 100644
--- a/docs/development-plan.md
+++ b/docs/development-plan.md
@@ -134,6 +134,7 @@
   - Done（**2026-07-31 订正**：原来写"REQ-03 happy/boundary 通过"，但 happy 用例（"产出 code_diff 与 test_report...unit+integration test 全部通过"）需要真实 Coder 会话写代码 + `c_artifact_write`（U-011 已记录的缺口，至今没有 Unit 认领），U-013 单靠 U-012 做不到——第五次出现同一类问题）：REQ-03 **boundary** 通过（两个独立节点各自用 `git worktree add` 隔离，`run_fn` 各写一个文件并 commit，`merge --no-ff` 合并回主分支，`git log` 确认两次提交都在，且 `work_node_execution.git_worktree_ref` 各不相同）；happy 用例随 `c_artifact_write` 落地后累计满足
   - **精度提升（2026-07-31，实现后补充）**：03-C §3.6 给出了 `USAGE_LIMIT_REACHED` 的精确探测正则 `/hit your (session|weekly|Opus) limit/i`，比 U-010/U-012 当时用的短语近似匹配更准——U-013 按这条正则实现，且真正写回 `work_node_execution.quota_wait_started_at`/`quota_limit_type`（U-010/U-012 阶段这两张表字段还没有真实归属）。`c_work_node_run` 是内部接口（03-C 原话"不对外暴露 HTTP，供 c_work_graph_execute 调用"），退避重试从 U-012 的整图级别下沉到这里的单节点级别
   - 覆盖：01-M `work_node_execution`；03-C `c_work_node_run`；REQ-03（boundary）
+  - **真实 bug（2026-08-02/03，U-042 第一次真实自举压测时发现）**：`RealGitWorktreeIsolationTest` 从 U-013 建成那天起，`run_fn` 一直是测试自己写的、写完文件后主动 `git add` + `git commit` 的假实现——这个盲区从没被真实 Coder 会话踩过，因为 PH1~PH4 所有真实调用都没启用 `needs_worktree=True`（development-plan.md U-031 的实现补充里已经记过这条），直到 U-035 让 self-target 场景无条件强制 worktree，U-042 第一次真实自举跑起来后才第一次真正踩中。真实现象：Coder 在 worktree 里确实编辑了文件，自己也验证过（`git status`/`git diff --stat` 都在它自己的 `test_report` 里回显了），但从未 `git commit`——Coder 人设里没有任何一处要求它提交自己的改动。`merge_worktree()` 只会 `git merge` 已提交的分支，worktree 分支上如果压根没有新提交，merge 就是个真正的空操作（"Already up to date"，不产生新 commit），紧接着 `remove_worktree()` 把这个还带着未提交改动的目录直接删掉——一次真实、已验证过的 Coder 改动就这样被无声吞掉，`implement_code()` 算出来的 `code_diff` 自然是空的。修复：新增 `work_node_run.ensure_worktree_committed()`，在 `merge_worktree()` 之前检查 worktree 是否有未提交改动（`git status --porcelain`），有则自动 `git add -A` + 提交一条 `graphlemon: auto-commit uncommitted worktree changes for <node_exec_id>`，worktree 本来就干净（比如纯排查、没有真的改代码）时什么也不做。新增两个回归测试：`test_uncommitted_worktree_changes_are_auto_committed_before_merge`（复现"改了但没提交"场景，断言改动最终真的落到主分支）、`test_clean_worktree_with_no_changes_is_still_a_valid_merge`（确认"确实没什么好改"这种合法结果不会被误伤）。这是"判断用 Agent，机制用代码"原则的又一次体现——不指望靠给人设加一条"记得 commit"的提示词来保证正确性，而是在系统层面兜底，人设漂移/遗忘不应该导致真实工作成果被无声丢弃。
 
 ### PH1-S3 端到端验收（收口）
 
diff --git a/docs/sdd/unit_matrix.json b/docs/sdd/unit_matrix.json
index dffeca7..c493a8c 100644
--- a/docs/sdd/unit_matrix.json
+++ b/docs/sdd/unit_matrix.json
@@ -25,7 +25,7 @@
     {"id": "U-010", "phase": "PH1", "sub_phase": "PH1-S1", "name": "c_org_node_trigger 完整实现（三段前向状态迁移，见 development-plan.md 2026-07-31 范围说明）", "classification": "Value Path", "depends_on": ["U-005", "U-009"], "coverage": {"model": [], "view": [], "controller": ["c_org_node_trigger"], "process": [], "requirement": []}, "done": "三个 Org Agent 分别可被触发（真实 claude --agent 调用），task.status 按 queued→planning_brd_prd_sdd→coding→validating 正确流转；重试/路由/blocked_pending_human 不在本 Unit 范围"},
     {"id": "U-011", "phase": "PH1", "sub_phase": "PH1-S2", "name": "c_work_graph_plan 实现（只规划不执行，见 development-plan.md 2026-07-31 订正）", "classification": "Value Path", "depends_on": ["U-004", "U-010"], "coverage": {"model": ["artifact", "work_graph_run"], "view": [], "controller": ["c_work_graph_plan"], "process": [], "requirement": ["REQ-02"]}, "done": "graph_manifest 通过结构校验（brd/prd/sdd/benchmark 四节点+依赖链），work_graph_run(status=planning) 落地；REQ-02 happy 用例整体随 U-012/U-013 累计满足。c_artifact_write（03-C §3.7）目前没有任何 Unit 认领，是已知缺口"},
     {"id": "U-012", "phase": "PH1", "sub_phase": "PH1-S2", "name": "c_work_graph_execute 完整实现（见 development-plan.md 2026-07-31 范围说明）", "classification": "Value Path", "depends_on": ["U-006", "U-011"], "coverage": {"model": [], "view": [], "controller": ["c_work_graph_execute"], "process": ["p_work_graph_execution", "p_usage_limit_wait"], "requirement": ["REQ-07", "REQ-14"]}, "done": "REQ-07 boundary/failure 通过（happy 需 PH2 REQ-04/05/06 就绪后累计满足）；REQ-14 happy 通过。退避重试是整图级别，非逐节点；CLASSIFIER_BLOCKED 用单次调用 permission_denials≥3 近似判定"},
-    {"id": "U-013", "phase": "PH1", "sub_phase": "PH1-S2", "name": "c_work_node_run + git worktree 隔离（见 development-plan.md 2026-07-31 订正）", "classification": "Value Path", "depends_on": ["U-012"], "coverage": {"model": ["work_node_execution"], "view": [], "controller": ["c_work_node_run"], "process": [], "requirement": ["REQ-03"]}, "done": "REQ-03 boundary 通过（真实 git worktree 隔离+merge，无冲突）；happy 需 c_artifact_write 落地后累计满足"},
+    {"id": "U-013", "phase": "PH1", "sub_phase": "PH1-S2", "name": "c_work_node_run + git worktree 隔离（见 development-plan.md 2026-07-31 订正、2026-08-02/03 真实 bug 修复）", "classification": "Value Path", "depends_on": ["U-012"], "coverage": {"model": ["work_node_execution"], "view": [], "controller": ["c_work_node_run"], "process": [], "requirement": ["REQ-03"]}, "done": "REQ-03 boundary 通过（真实 git worktree 隔离+merge，无冲突）；happy 需 c_artifact_write 落地后累计满足。2026-08-02/03：U-042 第一次真实自举压测发现 Coder 编辑 worktree 后从不 commit、merge_worktree 空操作、真实改动被 remove_worktree 静默吞掉的真实 bug，新增 ensure_worktree_committed() 兜底自动提交，已修复并补测试"},
     {"id": "U-014", "phase": "PH1", "sub_phase": "PH1-S3", "name": "贪吃蛇场景端到端验收（含补建 c_artifact_write，见 development-plan.md 2026-07-31 实现补充）", "classification": "Value Path", "depends_on": ["U-011", "U-012", "U-013"], "coverage": {"model": ["artifact"], "view": [], "controller": ["c_artifact_write"], "process": [], "requirement": []}, "done": "架构文档 §11 验收标准第 1-3 条全部达成；plan_documents（Planner 四件套+血缘）真实验证过，Coder/Validator 全流程真实跑通待用户确认后执行"},
 
     {"id": "U-015", "phase": "PH2", "sub_phase": "PH2-S1", "name": "p_validator_root_cause_trace 实现", "classification": "Risk Gate", "depends_on": ["U-013"], "coverage": {"model": ["bug_record"], "view": [], "controller": ["c_bug_record_create"], "process": ["p_validator_root_cause_trace"], "requirement": ["REQ-04"]}, "done": "REQ-04 happy/boundary/failure 通过"},
diff --git a/src/test_work_node_run.py b/src/test_work_node_run.py
index 46e9a35..5cd3c33 100644
--- a/src/test_work_node_run.py
+++ b/src/test_work_node_run.py
@@ -381,6 +381,50 @@ class RealGitWorktreeIsolationTest(WorkNodeRunTestBase):
         self.assertIn("module_a.txt", log.stdout)
         self.assertIn("module_b.txt", log.stdout)
 
+    def _write_file_never_commit_run_fn(self, filename, content):
+        """Unlike _write_file_run_fn, deliberately edits and leaves the
+        worktree DIRTY -- reproducing a real Coder Work Node, which is
+        never instructed to `git commit` its own edits (found via a real
+        self-hosting run, 2026-08-02: a real, verified Coder edit was
+        silently discarded because nothing committed it before merge)."""
+        def run_fn(cwd, model=None):
+            with open(os.path.join(cwd, filename), "w") as f:
+                f.write(content)
+            return {"value": filename}
+
+        return run_fn
+
+    def test_uncommitted_worktree_changes_are_auto_committed_before_merge(self):
+        work_node_run.run_work_node(
+            self.conn, "node-1", {"goal": "x"}, _IN_SCHEMA, _OUT_SCHEMA,
+            run_fn=self._write_file_never_commit_run_fn("uncommitted.txt", "real edit, never committed"),
+            needs_worktree=True, repo_path=self.tmp.name,
+        )
+
+        merged_path = os.path.join(self.tmp.name, "uncommitted.txt")
+        self.assertTrue(os.path.isfile(merged_path), "the Coder's edit must survive merge even if it never committed")
+        with open(merged_path) as f:
+            self.assertEqual(f.read(), "real edit, never committed")
+
+        status = subprocess.run(
+            ["git", "status", "--porcelain"], cwd=self.tmp.name, check=True, capture_output=True, text=True
+        ).stdout
+        self.assertEqual(status.strip(), "", "main checkout must be clean after merge, not carrying a stray dirty file")
+
+    def test_clean_worktree_with_no_changes_is_still_a_valid_merge(self):
+        # A node that legitimately makes no changes (e.g. a pure
+        # investigation, see the real self-hosting run this fix responds
+        # to) must not error just because there's nothing to auto-commit.
+        work_node_run.run_work_node(
+            self.conn, "node-1", {"goal": "x"}, _IN_SCHEMA, _OUT_SCHEMA,
+            run_fn=lambda cwd, model=None: {"value": "investigated, no changes needed"},
+            needs_worktree=True, repo_path=self.tmp.name,
+        )
+        status = subprocess.run(
+            ["git", "status", "--porcelain"], cwd=self.tmp.name, check=True, capture_output=True, text=True
+        ).stdout
+        self.assertEqual(status.strip(), "")
+
 
 class BreakpointRecoveryTest(WorkNodeRunTestBase):
     """U-021 / REQ-06: run_work_node called again for a node_exec_id that was
diff --git a/src/work_node_run.py b/src/work_node_run.py
index d10723f..bafefb4 100644
--- a/src/work_node_run.py
+++ b/src/work_node_run.py
@@ -117,6 +117,31 @@ def create_worktree(repo_path, node_exec_id):
     return worktree_path
 
 
+def ensure_worktree_committed(worktree_path, node_exec_id):
+    """A Coder Work Node is never actually required to `git commit` its own
+    edits before finishing -- nothing in its persona instructs it to, and
+    every prior test's `run_fn` happened to commit its own changes, so this
+    gap went unnoticed until a real self-hosting run (2026-08-02) exposed
+    it: the Coder made a real, verified edit, never committed it, and
+    merge_worktree() found nothing to merge (a no-op "Already up to date"
+    merge) -- remove_worktree() then silently discarded the dirty working
+    tree along with the real work. Auto-commits any uncommitted state left
+    in the worktree before it gets merged, so "the Coder said it edited a
+    file" and "the change actually lands" can't diverge silently. No-op
+    when the worktree is already clean (a node that legitimately made no
+    changes, e.g. a pure investigation)."""
+    status = subprocess.run(
+        ["git", "status", "--porcelain"], cwd=worktree_path, check=True, capture_output=True, text=True,
+    ).stdout
+    if not status.strip():
+        return
+    subprocess.run(["git", "add", "-A"], cwd=worktree_path, check=True, capture_output=True)
+    subprocess.run(
+        _prefix_git(["commit", "-m", "graphlemon: auto-commit uncommitted worktree changes for " + node_exec_id]),
+        cwd=worktree_path, check=True, capture_output=True, text=True,
+    )
+
+
 def merge_worktree(repo_path, node_exec_id):
     """Merges the node's branch back into whichever branch is currently
     checked out in the main worktree at repo_path."""
@@ -316,6 +341,7 @@ def run_work_node(
                 )
                 conn.commit()
                 if worktree_path:
+                    ensure_worktree_committed(worktree_path, node_exec_id)
                     merge_worktree(repo_path, node_exec_id)
                     remove_worktree(repo_path, worktree_path)  # 03-C §3.6: "执行完成后清理 worktree"
                 return output_payload