Keep automated review publication comment-only

doc/architecture/SPEC/engine/steps/pr.md

@@ -1,6 +1,6 @@
 # engine/steps/pr/ —— 规范
 
-<!-- verified-against: 2026-09-08 -->
+<!-- verified-against: 2026-09-22 -->
 
 `LOC ~1390（6 个文件） · step 库（PR） · refactor-status: ok`
 
@@ -30,7 +30,7 @@
 `extract_signature`（由 `utils` 再导出；供测试使用）。
 
 ## 不变量
-- `ci.push` 把全部安全判断委托给 `guard_push`（**C4**）。
+- `ci.push` 对 `pr_review` / `pr_quality` 无条件拒绝推送；其他任务仍委托给 `guard_push`（**C4**）。
 - **`pr.fetch_diff`：一个 head 统治一切**（PR2 重构后）。head 由
   `_resolve_pr_head` **恰好解析一次**，stale 门、fetch、diff、worktree 全部
   从这一个答案推导（`_fetch_at_one_head`）。fetch 走 run 域强制目的 ref
@@ -49,6 +49,7 @@
   事件 `expected_head_mismatch`，`contract.build_review_result` 据此上报
   stale）；且每条"降级回 live checkout"的路径都变成硬 BLOCK —— 钉了快照
   还静默评错树，比停下更糟。
+- **`pr.post_review` 始终使用 `event="COMMENT"`**，模型 verdict 不授予批准或阻塞 PR 的权限。
 - **`pr.post_review` 只发一条 GitHub review + inline thread**，且先把每条发现的位置
   对照已抓取的 diff 校验过 —— **绝不是一串独立评论**。
 - `diff_text` 和 `gate_report` 都可以经 state 注入，因此网络之下的每条路径都可离线测试；

src/infermatrix_copilot/engine/steps/pr/publish.py

@@ -16,7 +16,6 @@
 from ...step import FailureKind, StepContext, StepResult, StepSpec
 from ..review.anchor import diff_index
 from ..review.anchor import normalize_path as _normalize_path
-from ..review.utils import _review_verdict
 from .._common import gh as _gh
 from .._common import register_step, step
 from .._common import repo_path as _repo_path
@@ -36,6 +35,9 @@ async def _push(ctx: StepContext) -> StepResult:
     (the default), it stays a dry run — reports the command it *would* run, never
     executes. Only with pushes enabled does it run the git command; a non-zero
     exit returns ESCALATE with the stderr tail."""
+    if _task_spec(ctx).get("kind") in {"pr_review", "pr_quality"}:
+        return StepResult(False, FailureKind.FORBIDDEN,
+                          "Review and quality tasks have comment-only authority")
     repo = _repo_path(ctx)
     raw = ctx.state.get("push_policy")
     policy = raw if isinstance(raw, PushPolicy) else PushPolicy(**(raw or {}))
@@ -228,22 +230,8 @@ def render(comment: dict) -> str:
 
 def _event_for_review(comments: list[dict], pr_state: str = "",
                       review_text: str = "") -> str:
-    """Translate the product verdict to a submitted GitHub review event."""
-    if comments:
-        verdict = _review_verdict(comments, pr_state)
-    else:
-        match = re.search(
-            r"\*\*Verdict:\*\*\s*(REQUEST CHANGES|COMMENT|APPROVE)",
-            review_text or "", re.IGNORECASE)
-        verdict = match.group(1).upper() if match else _review_verdict([], pr_state)
-    event = {
-        "REQUEST CHANGES": "REQUEST_CHANGES",
-        "COMMENT": "COMMENT",
-        "APPROVE": "APPROVE",
-    }.get(verdict, "COMMENT")
-    if str(pr_state).upper() != "OPEN" and event != "COMMENT":
-        return "COMMENT"
-    return event
+    """A review assessment never changes GitHub approval/blocking state."""
+    return "COMMENT"
 
 
 def _review_payload(state: dict, *, current_head: str = "") -> tuple[dict, int]:

test/test_pr_steps.py

@@ -225,7 +225,7 @@ def test_review_payload_validates_diff_lines_and_preserves_fallbacks():
     }
     payload, downgraded = _review_payload(state)
 
-    assert payload["event"] == "REQUEST_CHANGES"
+    assert payload["event"] == "COMMENT"
     assert payload["commit_id"] == "a" * 40
     assert payload["comments"] == [{
         "path": "a.py",
@@ -259,9 +259,9 @@ def test_review_payload_downgrades_all_comments_when_head_changed():
 @pytest.mark.parametrize(
     ("comments", "pr_state", "review_text", "event"),
     [
-        ([_finding("a.py", 10, "major")], "OPEN", "", "REQUEST_CHANGES"),
+        ([_finding("a.py", 10, "major")], "OPEN", "", "COMMENT"),
         ([_finding("a.py", 10, "minor")], "OPEN", "", "COMMENT"),
-        ([], "OPEN", "**Verdict:** APPROVE", "APPROVE"),
+        ([], "OPEN", "**Verdict:** APPROVE", "COMMENT"),
         ([_finding("a.py", 10, "major")], "MERGED", "", "COMMENT"),
     ],
 )
@@ -312,7 +312,7 @@ def fake_gh(args, cwd=None):
     assert len(captured["payload"]["comments"]) == 1
     assert result.outputs["inline"] == 1
     assert result.outputs["downgraded"] == 1
-    assert result.outputs["event"] == "REQUEST_CHANGES"
+    assert result.outputs["event"] == "COMMENT"
     assert result.outputs["url"].endswith("#review")
 
 
@@ -698,3 +698,17 @@ def test_fetch_diff_matching_expected_head_proceeds(settings, trace, tmp_path,
 
     assert result.ok, result.summary
     assert result.outputs["state_updates"]["pr_head_sha"] == sha
+
+
+@pytest.mark.parametrize("kind", ["pr_review", "pr_quality"])
+def test_review_tasks_cannot_push_even_with_allow_push(registry, settings, trace, tmp_path, monkeypatch, kind):
+    from infermatrix_copilot.engine.steps.pr import publish
+    settings.allow_push = True
+    state = {"repo_path": str(tmp_path), "task_spec": {"kind": kind},
+             "push_policy": PushPolicy(allowed=True, remote="origin", branch="feature")}
+    def unexpected(*args, **kwargs):
+        raise AssertionError("review task attempted a git command")
+    monkeypatch.setattr(publish.subprocess, "run", unexpected)
+    result = asyncio.run(registry.get("ci.push").handler(_ctx(settings, trace, tmp_path, state)))
+    assert not result.ok
+    assert "comment-only" in result.summary