harness2: per-role models, sweep batch, task file assets endpoint

- Role models: run_improvement_via_tasks gains role_models
  (probe/editor/selector/reflector) plus --model-<role> CLI flags;
  missing/empty falls back to shared --model, both empty means
  server default, so default behavior is unchanged.
- Sweep: run_sweep + examples/harness2_sweep.py manifest CLI with
  shared library_root (library restore), per-run failure isolation
  and sweep-report.json summary; preflight gates task creation.
- Deliverable assets: GET /tasks/{id}/files for local-executor
  tasks (safe path resolution, UTF-8 text <=256KB, listing <=200;
  docker/cloud/cross-host 409 with explicit reason, since tenant
  Docker shares one /app/work per project and per-task attribution
  would misattribute); probe rollout deliverable_files from the
  endpoint plus DELIVERABLE FILE reply blocks (endpoint wins on
  collision, bad blocks dropped), surfaced in
  deliverables/<label>/files/ context and full_result summary.
- Docs: harness2.md comparison table updated for all three items.

cloud/harness2.py

@@ -241,6 +241,56 @@ def parse_harness_files(text: str) -> dict[str, str]:
     return out
 
 
+_DELIVERABLE_FILE_START_RX = re.compile(r"^=== DELIVERABLE FILE:\s*(.+?)\s*===$")
+_DELIVERABLE_FILE_END = "=== END DELIVERABLE FILE ==="
+_DELIVERABLE_FILE_MAX = 8
+_DELIVERABLE_FILE_MAX_CHARS = 65536
+
+
+def _is_safe_deliverable_path(path: str) -> bool:
+    if not path or path.startswith("/") or "\x00" in path:
+        return False
+    return all(p not in ("", ".", "..") for p in path.split("/"))
+
+
+def parse_deliverable_files(text: str) -> dict[str, str]:
+    """解析探针回复里的产物文件块，返回 {相对路径: 内容}。
+
+    与编辑文件块的严格语义不同：这里故意宽容——坏块（未闭合、
+    非法路径、超量、超长）只丢弃该块、不抛错，因为产物文件是
+    交付文本之外的 enrichment，绝不能因为一块坏内容毁掉整轮
+    交付物。超长内容截断并打截断标记，让评审知道它不完整；
+    超过 8 块时只取前 8 块。同一路径出现两次时后一块覆盖前一块。
+    """
+    out: dict[str, str] = {}
+    cur_path: str | None = None
+    cur_lines: list[str] = []
+    for line in (text or "").splitlines():
+        m = _DELIVERABLE_FILE_START_RX.match(line.strip())
+        if m:
+            if cur_path is not None:
+                cur_path = None
+                cur_lines = []
+            path = m.group(1).strip()
+            if _is_safe_deliverable_path(path) and len(out) < _DELIVERABLE_FILE_MAX:
+                cur_path = path
+                cur_lines = []
+            continue
+        if line.strip() == _DELIVERABLE_FILE_END:
+            if cur_path is not None:
+                content = "\n".join(cur_lines) + ("\n" if cur_lines else "")
+                if len(content) > _DELIVERABLE_FILE_MAX_CHARS:
+                    content = (content[:_DELIVERABLE_FILE_MAX_CHARS]
+                               + "\n...[truncated]")
+                out[cur_path] = content
+            cur_path = None
+            cur_lines = []
+            continue
+        if cur_path is not None:
+            cur_lines.append(line)
+    return out
+
+
 MAX_K = 3
 STAGE_ATTEMPTS = 2  # 提议被拒后给一次按反馈修正的机会，再拒就回落
 
@@ -490,6 +540,7 @@ class Rollout:
     trajectory: str = ""
     cost_usd: float = 0.0
     error: str = ""
+    deliverable_files: dict[str, str] = field(default_factory=dict)
 
 
 @dataclass
@@ -589,7 +640,12 @@ def build_context(
             (dd / f"{r.label}.md").write_text(
                 r.deliverable_text or "(no deliverable)", encoding="utf-8"
             )
-        lines.append("context/deliverables/           what each rollout produced")
+            for name, content in (r.deliverable_files or {}).items():
+                dest = dd / r.label / "files" / name
+                dest.parent.mkdir(parents=True, exist_ok=True)
+                dest.write_text(content, encoding="utf-8")
+        lines.append("context/deliverables/           what each rollout produced"
+                     " (+ <label>/files/ when it produced files)")
     write_tree(harness, root / "harness")
     lines.append("context/harness/                the harness tree you may edit, and ONLY this")
     if library_dir and Path(library_dir).is_dir():
@@ -842,6 +898,7 @@ class ModeResult:
                     "delivered": r.delivered,
                     "error": (r.error or "")[:400],
                     "deliverable_text": (r.deliverable_text or "")[:500],
+                    "deliverable_files": sorted(r.deliverable_files or {}),
                 }
                 for lbl, r in self.rollouts.items()
             },