brain: board publish idempotence ignores the timestamp

The unchanged-observation check compared exact file text, but the
payload embeds ts — so a re-publish crossing a second boundary pushed a
no-op commit and re-triggered the board (caught by the 3.13 CI leg
racing the clock; 3.12 ran inside one second). Compare with ts stripped:
an unchanged observation never re-pushes. Test pins ts-insensitivity
explicitly.

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

Author: claude

board/_publish.py

@@ -160,9 +160,20 @@ def main(argv=None):
         return 2
 
     DEVBOX_FILE.parent.mkdir(parents=True, exist_ok=True)
-    if DEVBOX_FILE.exists() and DEVBOX_FILE.read_text() == text:
-        print("board publish: devbox observation already current — nothing to push")
-        return 0
+    # Idempotence ignores the timestamp: an unchanged observation must not
+    # bump the file (and re-trigger brain_board.yml) just because the clock
+    # moved between two runs.
+    if DEVBOX_FILE.exists():
+        try:
+            prev = json.loads(DEVBOX_FILE.read_text())
+        except (json.JSONDecodeError, OSError):
+            prev = None
+        if prev is not None and \
+                {k: v for k, v in prev.items() if k != "ts"} == \
+                {k: v for k, v in payload.items() if k != "ts"}:
+            print("board publish: devbox observation already current — "
+                  "nothing to push")
+            return 0
     DEVBOX_FILE.write_text(text)
 
     rel = os.path.relpath(DEVBOX_FILE, PUBLISH_REPO)

tests/test_board.py

@@ -519,10 +519,19 @@ def test_publish_commits_and_pushes_to_main_only(tmp_path):
     assert shown.returncode == 0
     assert json.loads(shown.stdout)["worktrees"][0]["repo"] == "RepoA"
     assert "hygiene" not in json.loads(shown.stdout)  # --no-hygiene
-    # Re-publishing an identical observation pushes nothing new.
+    # Re-publishing an identical observation pushes nothing new — and the
+    # comparison ignores the timestamp by design (an unchanged observation
+    # must not re-trigger the board just because the clock moved).
     r2 = subprocess.run([str(BRAIN), "board", "publish", "--no-hygiene"],
                         capture_output=True, text=True, env=env, cwd=tmp_path)
     assert "nothing to push" in r2.stdout
+    state_file = brain / "state" / "devbox_board.json"
+    stored = json.loads(state_file.read_text())
+    stored["ts"] = "2020-01-01T00:00:00Z"
+    state_file.write_text(json.dumps(stored, indent=2, sort_keys=True) + "\n")
+    r2b = subprocess.run([str(BRAIN), "board", "publish", "--no-hygiene"],
+                         capture_output=True, text=True, env=env, cwd=tmp_path)
+    assert "nothing to push" in r2b.stdout
     # Off main, publish refuses (guard against feature-branch commits).
     subprocess.run(["git", "-C", str(brain), "checkout", "-qb", "other"],
                    check=True)