Add window-scoped session closure fallback

docs/collectivespec-pilot-design-20260713.md

@@ -200,3 +200,16 @@ diverge，因此做 ragged verifier”这一表述太宽，不能作为实现前
 queue policy。若全部通过，最小原型的边界也只应是 verifier-side compaction：当前
 EAGLE 仍按 Kmax 产生 candidate，短 `k_i` 不会自动消除 draft-side work，不能把 verifier
 节省误报为完整 draft+verify speedup。
+
+### Trace 数据可用性与 window-closure fallback
+
+本轮发现 `prepare_trace_windows.py` 依赖的 2026-03-27 原始格式化 trace span 在 dash0
+已不存在，不能把它的 streaming full-session root 当作已经复验。现有的完整 600 秒
+materialized window 仍含 prompt、`chat_id` 与 `parent_chat_id`，因此新增的 fallback 仅将
+窗口内图的 connected component 作为选择原子：保留 384/384 条窗口内 parent edge，且把
+同一个窗口外 parent 的 sibling 归为同一 component。该窗口有 15,479 requests、15,095
+components；414 条 non-root edge 中 30 条（7.25%）父节点落在窗口外。
+
+这只能称为 **window-session-closed**，不等于 full-session coherent：任何结果都必须报告
+这 30 条 boundary-parent residual，且不能据此声称跨窗口 KV reuse。若原始 span 恢复，必须
+重新从完整 source resolve root 与重新采样，不能沿用 fallback 的 score/threshold。

scripts/collectivespec/create_controlled_greedy_window.py

@@ -86,7 +86,9 @@ def main() -> int:
     if not source_trace.is_file():
         raise SystemExit(f"source trace does not exist: {source_trace}")
     source_sampling_strategy = source_window.get("sampling_strategy")
-    session_coherent_source = source_sampling_strategy == "session_coherent_uniform_score"
+    full_session_source = source_sampling_strategy == "session_coherent_uniform_score"
+    window_session_source = source_sampling_strategy == "window_session_closed_uniform_score"
+    session_closed_source = full_session_source or window_session_source
 
     args.output_dir.mkdir(parents=True, exist_ok=True)
     output_trace = args.output_dir / f"{args.output_window_id}.jsonl"
@@ -105,10 +107,10 @@ def main() -> int:
                 raise SystemExit(f"row {row_index}: expected an object")
             sampling_u = numeric(row.get("sampling_u"), field="sampling_u", row_index=row_index)
             session_entry: dict[str, int] | None = None
-            if session_coherent_source:
+            if session_closed_source:
                 if "session_root" not in row:
                     raise SystemExit(
-                        f"row {row_index}: session-coherent source has no session_root"
+                        f"row {row_index}: session-closed source has no session_root"
                     )
                 session_key = stable_session_key(row["session_root"])
                 session_entry = session_counts.setdefault(
@@ -153,8 +155,12 @@ def main() -> int:
             "num_requests": selected,
             "sampling_strategy": (
                 "session_coherent_uniform_score_then_greedy_temperature"
-                if session_coherent_source
+                if full_session_source
+                else (
+                    "window_session_closed_uniform_score_then_greedy_temperature"
+                    if window_session_source
                     else "fixed_uniform_score_then_greedy_temperature"
+                )
             ),
             "collectivespec_source_window_id": args.window_id,
             "collectivespec_sampling_u_threshold": threshold,
@@ -162,7 +168,10 @@ def main() -> int:
             "collectivespec_source_trace_path": str(source_trace),
             "collectivespec_source_trace_sha256": sha256(source_trace),
             "collectivespec_source_sampling_strategy": source_sampling_strategy,
-            "collectivespec_session_closed_within_window": session_coherent_source,
+            "collectivespec_session_closed_within_window": session_closed_source,
+            "collectivespec_session_closure_scope": (
+                "full_session" if full_session_source else "window_only" if window_session_source else None
+            ),
         }
     )
     output_windows = {
@@ -197,13 +206,14 @@ def main() -> int:
         },
         "temperature": {"distinct_value_count": 1, "all_zero": True},
         "session": {
-            "source_is_session_coherent": session_coherent_source,
+            "source_is_session_coherent": full_session_source,
-            "session_root_count": len(session_counts) if session_coherent_source else None,
+            "source_is_window_session_closed": window_session_source,
+            "session_root_count": len(session_counts) if session_closed_source else None,
             "selected_session_count": (
-                len(selected_session_turn_counts) if session_coherent_source else None
+                len(selected_session_turn_counts) if session_closed_source else None
             ),
-            "split_session_count": len(split_sessions) if session_coherent_source else None,
+            "split_session_count": len(split_sessions) if session_closed_source else None,
-            "all_selected_or_dropped": not split_sessions if session_coherent_source else None,
+            "all_selected_or_dropped": not split_sessions if session_closed_source else None,
             "selected_turns": {
                 "min": min(selected_session_turn_counts)
                 if selected_session_turn_counts

scripts/collectivespec/create_window_session_closed_windows.py

@@ -0,0 +1,290 @@
+#!/usr/bin/env python3
+"""Build a session-closed replay window from an already materialized trace.
+
+This is deliberately a *window-scoped fallback* for when the raw trace span
+needed by ``prepare_trace_windows.py`` is unavailable.  It closes every known
+parent/child edge within the supplied window and groups siblings whose common
+parent lies outside the window.  It cannot recover turns outside the window;
+the manifest records that residual rather than calling the result fully
+session-coherent.
+"""
+
+from __future__ import annotations
+
+import argparse
+import hashlib
+import json
+import math
+from collections import Counter
+from pathlib import Path
+from typing import Any
+
+
+SCORE_ALGORITHM = "collectivespec-window-cc-v1"
+
+
+def sha256(path: Path) -> str:
+    digest = hashlib.sha256()
+    with path.open("rb") as handle:
+        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
+            digest.update(chunk)
+    return digest.hexdigest()
+
+
+def typed_id(value: Any) -> str:
+    """Encode IDs without conflating values such as ``1`` and ``"1"``."""
+    return json.dumps(
+        {"type": type(value).__name__, "value": value},
+        ensure_ascii=False,
+        sort_keys=True,
+        separators=(",", ":"),
+    )
+
+
+def session_uniform(*, seed: int, window_id: str, component_key: str) -> float:
+    payload = json.dumps(
+        {
+            "algorithm": SCORE_ALGORITHM,
+            "seed": seed,
+            "window_id": window_id,
+            "component_key": component_key,
+        },
+        sort_keys=True,
+        separators=(",", ":"),
+    ).encode("utf-8")
+    digest = hashlib.blake2b(payload, digest_size=8).digest()
+    return int.from_bytes(digest, byteorder="big", signed=False) / float(1 << 64)
+
+
+def resolve_trace_path(windows_path: Path, trace_file: str) -> Path:
+    candidate = Path(trace_file)
+    if candidate.is_absolute():
+        return candidate
+    return (windows_path.parent / candidate).resolve()
+
+
+def is_root_parent(value: Any) -> bool:
+    return value is None or (
+        isinstance(value, (int, float)) and not isinstance(value, bool) and int(value) < 0
+    )
+
+
+class UnionFind:
+    def __init__(self) -> None:
+        self.parent: dict[str, str] = {}
+
+    def add(self, item: str) -> None:
+        self.parent.setdefault(item, item)
+
+    def find(self, item: str) -> str:
+        parent = self.parent[item]
+        if parent != item:
+            self.parent[item] = self.find(parent)
+        return self.parent[item]
+
+    def union(self, left: str, right: str) -> None:
+        left_root, right_root = self.find(left), self.find(right)
+        if left_root != right_root:
+            # A canonical representative makes the component key independent
+            # of trace order and union order.
+            self.parent[max(left_root, right_root)] = min(left_root, right_root)
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--windows-path", type=Path, required=True)
+    parser.add_argument("--window-id", required=True)
+    parser.add_argument("--sample-seed", type=int, default=20260325)
+    parser.add_argument("--output-dir", type=Path, required=True)
+    parser.add_argument("--output-window-id", required=True)
+    args = parser.parse_args()
+
+    source_payload = json.loads(args.windows_path.read_text(encoding="utf-8"))
+    source_windows = source_payload.get("windows") if isinstance(source_payload, dict) else source_payload
+    if not isinstance(source_windows, list):
+        raise SystemExit("windows payload must contain a list")
+    source_window = next(
+        (item for item in source_windows if item.get("window_id") == args.window_id),
+        None,
+    )
+    if not isinstance(source_window, dict):
+        raise SystemExit(f"window id not found: {args.window_id}")
+    trace_file = source_window.get("trace_file")
+    if not isinstance(trace_file, str) or not trace_file:
+        raise SystemExit(f"window {args.window_id} has no trace_file")
+    source_trace = resolve_trace_path(args.windows_path, trace_file)
+    if not source_trace.is_file():
+        raise SystemExit(f"source trace does not exist: {source_trace}")
+
+    rows: list[dict[str, Any]] = []
+    id_to_index: dict[str, int] = {}
+    with source_trace.open("r", encoding="utf-8") as source_handle:
+        for row_index, raw in enumerate(source_handle):
+            if not raw.strip():
+                continue
+            row = json.loads(raw)
+            if not isinstance(row, dict):
+                raise SystemExit(f"row {row_index}: expected an object")
+            if "chat_id" not in row or "parent_chat_id" not in row:
+                raise SystemExit(f"row {row_index}: chat_id and parent_chat_id are required")
+            if "timestamp" not in row:
+                raise SystemExit(f"row {row_index}: timestamp is required")
+            try:
+                timestamp = float(row["timestamp"])
+            except (TypeError, ValueError) as error:
+                raise SystemExit(f"row {row_index}: timestamp must be numeric") from error
+            if not math.isfinite(timestamp):
+                raise SystemExit(f"row {row_index}: timestamp must be finite")
+            key = typed_id(row["chat_id"])
+            if key in id_to_index:
+                raise SystemExit(f"row {row_index}: duplicate chat_id {row['chat_id']!r}")
+            id_to_index[key] = len(rows)
+            rows.append(row)
+    if not rows:
+        raise SystemExit("source trace has no rows")
+
+    union_find = UnionFind()
+    for chat_key in id_to_index:
+        union_find.add(chat_key)
+    known_parent_edges = 0
+    absent_parent_edges = 0
+    root_request_count = 0
+    for row in rows:
+        chat_key = typed_id(row["chat_id"])
+        parent = row["parent_chat_id"]
+        if is_root_parent(parent):
+            root_request_count += 1
+            continue
+        parent_key = typed_id(parent)
+        union_find.add(parent_key)
+        if parent_key in id_to_index:
+            union_find.union(chat_key, parent_key)
+            known_parent_edges += 1
+        else:
+            # Keep the absent parent as a virtual node. This groups siblings
+            # with a common boundary parent without pretending that the parent
+            # turn itself is in this window.
+            union_find.union(chat_key, parent_key)
+            absent_parent_edges += 1
+
+    component_members: dict[str, list[str]] = {}
+    for node in union_find.parent:
+        component_members.setdefault(union_find.find(node), []).append(node)
+    component_key_by_chat: dict[str, str] = {}
+    for members in component_members.values():
+        # Virtual boundary parents intentionally participate: they ensure all
+        # children of an unavailable parent share a deterministic component.
+        component_key = min(members)
+        for chat_key in (member for member in members if member in id_to_index):
+            component_key_by_chat[chat_key] = component_key
+    for row in rows:
+        parent = row["parent_chat_id"]
+        if is_root_parent(parent):
+            continue
+        parent_key = typed_id(parent)
+        if parent_key in id_to_index and union_find.find(typed_id(row["chat_id"])) != union_find.find(parent_key):
+            raise SystemExit("same-window parent edge did not close into one component")
+
+    args.output_dir.mkdir(parents=True, exist_ok=True)
+    trace_dir = args.output_dir / "traces"
+    trace_dir.mkdir(exist_ok=True)
+    output_trace = trace_dir / f"{args.output_window_id}.jsonl"
+    score_values: list[float] = []
+    timestamps: list[float] = []
+    component_counts: Counter[str] = Counter()
+    with output_trace.open("w", encoding="utf-8") as handle:
+        for row in rows:
+            chat_key = typed_id(row["chat_id"])
+            component_key = component_key_by_chat[chat_key]
+            component_id = f"window-component:{component_key}"
+            out = dict(row)
+            out["collectivespec_original_sampling_u"] = out.get("sampling_u")
+            out["session_root"] = component_id
+            out["sampling_u"] = session_uniform(
+                seed=args.sample_seed,
+                window_id=args.window_id,
+                component_key=component_key,
+            )
+            handle.write(json.dumps(out, ensure_ascii=False, separators=(",", ":")) + "\n")
+            score_values.append(float(out["sampling_u"]))
+            timestamps.append(float(out["timestamp"]))
+            component_counts[component_id] += 1
+
+    component_sizes = list(component_counts.values())
+    output_window = dict(source_window)
+    output_window.update(
+        {
+            "window_id": args.output_window_id,
+            "trace_file": str(output_trace.resolve()),
+            "num_requests": len(rows),
+            "sampling_strategy": "window_session_closed_uniform_score",
+            "sampling_seed": args.sample_seed,
+            "collectivespec_sampling_algorithm": SCORE_ALGORITHM,
+            "collectivespec_source_window_id": args.window_id,
+            "collectivespec_source_trace_path": str(source_trace),
+            "collectivespec_source_trace_sha256": sha256(source_trace),
+            "collectivespec_session_closure_scope": "window_only",
+            "collectivespec_known_parent_edges": known_parent_edges,
+            "collectivespec_absent_parent_edges": absent_parent_edges,
+        }
+    )
+    output_windows = {
+        "kind": "collectivespec_window_session_closed_fallback",
+        "source_windows_path": str(args.windows_path.resolve()),
+        "source_window_id": args.window_id,
+        "sample_seed": args.sample_seed,
+        "windows": [output_window],
+    }
+    output_manifest = args.output_dir / "windows.json"
+    output_manifest.write_text(
+        json.dumps(output_windows, ensure_ascii=False, indent=2, sort_keys=True) + "\n",
+        encoding="utf-8",
+    )
+    sanity = {
+        "n": len(rows),
+        "timestamp": {
+            "min": min(timestamps),
+            "max": max(timestamps),
+            "non_negative": all(value >= 0 for value in timestamps),
+            "nondecreasing": all(
+                timestamps[index] >= timestamps[index - 1]
+                for index in range(1, len(timestamps))
+            ),
+        },
+        "sampling_u": {
+            "min": min(score_values),
+            "max": max(score_values),
+            "distinct_value_count": len(set(score_values)),
+            "within_0_1": all(0 <= value < 1 for value in score_values),
+        },
+        "window_session_closure": {
+            "component_count": len(component_sizes),
+            "component_size_min": min(component_sizes),
+            "component_size_max": max(component_sizes),
+            "component_size_distinct_value_count": len(set(component_sizes)),
+            "known_parent_edges": known_parent_edges,
+            "absent_parent_edges": absent_parent_edges,
+            "root_request_count": root_request_count,
+            "all_known_parent_edges_closed": True,
+            "scope": "window_only",
+        },
+        "source_trace_sha256": sha256(source_trace),
+        "output_trace_sha256": sha256(output_trace),
+    }
+    print(
+        json.dumps(
+            {
+                "windows_path": str(output_manifest),
+                "trace_path": str(output_trace),
+                "data_sanity": sanity,
+            },
+            ensure_ascii=False,
+            indent=2,
+            sort_keys=True,
+        )
+    )
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())