feat(views): RecentChanges merged change feed (WP-0010 T3)

One newest-first feed merging the coordination journal (overlay/alias/fork/merge/
binding decisions, with actor + payload) and shard change signals (page
source_rev / mtime). Each entry carries provenance: the originating shard for an
edit, or 'coordination' (and the actor) for a decision. Non-temporal revision
tokens are skipped gracefully. Derived/recomputable; notify-streaming later.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_views_recentchanges.py

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+"""Tests for the RecentChanges merged feed (SHARD-WP-0010 T3)."""
+
+import os
+from datetime import datetime, timezone
+
+from shard_wiki.adapters import FolderAdapter
+from shard_wiki.coordination import DecisionLog, EventType
+from shard_wiki.union import UnionGraph
+from shard_wiki.views import recent_changes
+
+
+def _shard(tmp_path, name, files, mtime=None):
+    root = tmp_path / name
+    for rel, text in files.items():
+        p = root / rel
+        p.parent.mkdir(parents=True, exist_ok=True)
+        p.write_text(text, encoding="utf-8")
+        if mtime is not None:
+            os.utime(p, (mtime, mtime))
+    return FolderAdapter(name, root)
+
+
+def test_edit_and_alias_both_appear_newest_first(tmp_path):
+    # Page edit signal pinned to an old mtime; the alias decision happens "now" → alias is newest.
+    old = datetime(2020, 1, 1, tzinfo=timezone.utc).timestamp()
+    u = UnionGraph("space")
+    u.attach(_shard(tmp_path, "shardA", {"Home.md": "home"}, mtime=old))
+    log = DecisionLog()
+    log.append("space", EventType.ALIAS_SET, {"alias": "Start", "target": "shardA:Home"})
+
+    feed = recent_changes(u, log, "space")
+    kinds = [e.kind for e in feed]
+    assert "edit" in kinds and "alias" in kinds
+    assert feed[0].kind == "alias"  # newest first
+    assert feed[-1].kind == "edit"
+    # Monotonic non-increasing by time.
+    assert all(feed[i].when >= feed[i + 1].when for i in range(len(feed) - 1))
+
+
+def test_per_shard_attribution_present(tmp_path):
+    u = UnionGraph("space")
+    u.attach(_shard(tmp_path, "shardA", {"A.md": "a"}))
+    u.attach(_shard(tmp_path, "shardB", {"B.md": "b"}))
+    feed = recent_changes(u, DecisionLog(), "space")
+    edits = {e.ref: e.source for e in feed if e.kind == "edit"}
+    assert edits["shardA:A"] == "shardA"
+    assert edits["shardB:B"] == "shardB"  # each edit attributed to its shard
+
+
+def test_coordination_entries_carry_actor_and_ref(tmp_path):
+    u = UnionGraph("space")
+    u.attach(_shard(tmp_path, "shardA", {"Doc.md": "x"}))
+    log = DecisionLog()
+    log.append(
+        "space", EventType.PAGE_FORKED, {"source": "shardA:Doc", "fork": "shardB:Doc"}, actor="ana"
+    )
+    fork = next(e for e in recent_changes(u, log, "space") if e.kind == "fork")
+    assert fork.source == "coordination"
+    assert fork.actor == "ana"
+    assert fork.ref == "shardA:Doc→shardB:Doc"
+
+
+def test_limit_truncates_to_newest(tmp_path):
+    u = UnionGraph("space")
+    u.attach(_shard(tmp_path, "shardA", {"A.md": "a", "B.md": "b", "C.md": "c"}))
+    feed = recent_changes(u, DecisionLog(), "space", limit=2)
+    assert len(feed) == 2