diff --git a/pipeline_opportunity/opp_ability.py b/pipeline_opportunity/opp_ability.py
index 2dc5b38..7a8a77f 100644
--- a/pipeline_opportunity/opp_ability.py
+++ b/pipeline_opportunity/opp_ability.py
@@ -600,9 +600,13 @@ async def _h_promote_to_project(sor, p, ctx):
     rid = (p.get("report_id") or "").strip()
     if not rid:
         return _fmt(False, "report_id 必填")
-    ok, pid = await promote_to_project(sor, rid, ctx)
+    ok, res = await promote_to_project(sor, rid, ctx)
     if not ok:
-        return _fmt(False, pid)
+        return _fmt(False, res)
+    if isinstance(res, dict) and res.get("reused"):
+        return _fmt(True, "本报告已立项（幂等）：project_id=%s 项目「%s」，不重复建"
+                    % (res.get("project_id"), res.get("project_name", "")))
+    pid = res.get("project_id") if isinstance(res, dict) else res
     return _fmt(True, "已立项 project_id=%s（pipeline=opportunity_general，"
                       "project_type=demand_mining）" % pid)
 
diff --git a/pipeline_opportunity/opp_feasibility.py b/pipeline_opportunity/opp_feasibility.py
index 03cb37a..55bfd9d 100644
--- a/pipeline_opportunity/opp_feasibility.py
+++ b/pipeline_opportunity/opp_feasibility.py
@@ -285,12 +285,21 @@ async def promote_to_project(sor, report_id, ctx):
         return False, "报告未过人工确认门禁（status=%s），不能立项" % (rep.get("status") or "draft")
     if (rep.get("appr_status") or "") != "approved":
         return False, "研发审批未通过（status=%s），不能立项" % (rep.get("appr_status") or "无审批单")
+    # 幂等守卫（2026-09-14 E2E 实测：重复调用会重复建项目）：description 带
+    # report_id 精确标记，立项前先查——已立过则返回既有项目，不再新建。
+    desc = "由需求挖掘可行性报告立项：%s [report_id=%s]" % (rep.get("title"), report_id)
+    exist = await sor.sqlExe(
+        "SELECT id, name FROM sd_projects WHERE description=${d}$ LIMIT 1", {"d": desc})
+    await sor.sqlExe("COMMIT", {})
+    if exist:
+        return True, {"project_id": getattr(exist[0], "id", ""),
+                      "project_name": getattr(exist[0], "name", ""), "reused": True}
     from pipeline_service.project_capability import create_project
     ok, pid = await create_project(
         name="%s 研发项目" % (rep.get("software") or "未命名"),
-        project_type="demand_mining", description="由需求挖掘可行性报告立项：%s" % rep.get("title"),
+        project_type="demand_mining", description=desc,
         org_id=ctx.get("org_id") or "0", created_by=ctx.get("user_id") or "",
         pipeline_id="opportunity_general")
     if not ok:
         return False, "立项失败: %s" % pid
-    return True, pid
+    return True, {"project_id": pid, "reused": False}
diff --git a/scripts/p3_feasibility_e2e.py b/scripts/p3_feasibility_e2e.py
index 4eacdd2..81b3ad7 100644
--- a/scripts/p3_feasibility_e2e.py
+++ b/scripts/p3_feasibility_e2e.py
@@ -280,13 +280,18 @@ async def m():
               np is not None and np.project_type == "demand_mining"
               and np.pipeline_id == "opportunity_general" and np.org_id == "0",
               "%s/%s/%s" % (getattr(np, "project_type", ""), getattr(np, "pipeline_id", ""), getattr(np, "org_id", "")))
-    # 重复立项行为记录（当前实现无幂等守卫，重复调用会再建项目——如实记录，清理兜底）
+    # 幂等守卫：重复 promote 必须复用既有项目，不再新建
     l2 = await call("opp_promote_to_project", {"report_id": RID})
-    DUP = l2.startswith("OK:") and "project_id=" in l2
-    if DUP:
-        DUPPID = l2.split("project_id=")[1].split("（")[0].strip()
-        print("-- FINDING: promote 重复调用再建项目 %s（无幂等守卫）--" % DUPPID, flush=True)
-    check("L3 重复立项行为已记录", l2.startswith("OK:") or l2.startswith("ERROR:"), l2[:120])
+    DUPPID = ""
+    if l2.startswith("OK:") and "project_id=" in l2:
+        cand = l2.split("project_id=")[1].split("（")[0].split(" ")[0].strip()
+        if cand and cand != NEWPID:
+            DUPPID = cand
+    n_prj = await sql("SELECT COUNT(*) n FROM sd_projects WHERE description LIKE ${p}$",
+                      {"p": "由需求挖掘可行性报告立项%%[report_id=%s]%%" % RID}, one=True)
+    check("L3 重复立项幂等(不重复建)", l2.startswith("OK:") and "幂等" in l2
+          and not DUPPID and getattr(n_prj, "n", 99) == 1,
+          "%s | dup=%s | n=%s" % (l2[:120], DUPPID or "-", getattr(n_prj, "n", "?")))
 
     # ── M. 清理（报告+PPT保留供浏览器验收；立项项目删除）──
     PROMOTED = [x for x in (NEWPID, locals().get("DUPPID", "")) if x]