Answer the review, and keep the opening node's bank

Nine findings from a review of the phase-14 stack. The one about a retry
withdrawing a memory is not a bug — a memory anchored to a node describes that
node, and it goes when the node goes. The root is the exception, and it is the
only one: migration 62 parked every memory written before memories had
coordinates on depth 0, so withdrawing the opening node would retire a whole
bank nobody attached there. A memory with no source range covers no story and
now stays; a summary that genuinely ends there is still withdrawn.

The rest are repairs.

* The adventure list quoted whichever attempt was written last rather than the
  one the story tells, so switching back left the index disagreeing with the
  page.
* A v1 import gave a typed memory no depth, rebuilding the NULL the migration
  exists to remove — invisible until the imported adventure forked.
* The action cap counted a v1 file's turns, and a turn expands into a row per
  saved attempt, so a file inside the cap could write a multiple of it.
* Forking a live node on a borrowed ancestor promoted a sibling on a branch the
  caller never named. It is a branch switch, and now says so.
* Switching attempts left the state, status and memory panels reading the
  previous take: the story does not change length, so nothing keyed on its
  length noticed. Same class as the branch-switch bug this phase already fixed.
* A retry after switching back numbered the new attempt into the middle of the
  group instead of the end.
* The cursor backfill numbered every action in the table once per adventure;
  correlated to the adventure being updated, it is an index lookup instead.
* Renaming a branch answered own_actions=0.

And one behaviour change recorded rather than repaired: script-visible history
and actionCount no longer count blank-text rows. That is the right shape and
there is no reading compatible with both, so plan/14 says so.

409 tests.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015H5qiyiR7gtFQaoDphHZ3g

backend/tests/test_branch_forking.py

@@ -321,10 +321,11 @@ def test_forking_a_turn_that_is_already_the_story_is_a_no_op(client):
     assert len(_branches(client)) == 1
 
 
-def test_forking_a_single_take_on_another_branch_is_refused(client):
-    """The only way to reach the refusal, and it names the wrong tool: a node
-    with no siblings is not a divergence, so what the caller wants is to switch
-    to the branch it is on."""
+def test_forking_a_live_node_on_another_branch_is_refused(client):
+    """A live node off the path is another line's story, not an attempt going
+    spare — so the refusal names the tool that would actually do it. It used to
+    answer "only one take", which was true of the group and no help at all: the
+    caller does not want another take, it wants the branch this one is on."""
     discarded = _divergent_story(client)
     _fork(client, discarded)
     parent_id = [b for b in _branches(client) if b["parent_branch_id"] is None][0]["id"]
@@ -333,7 +334,9 @@ def test_forking_a_single_take_on_another_branch_is_refused(client):
 
     r = _fork(client, stranded)
     assert r.status_code == 400
-    assert "one take" in r.json()["detail"]
+    assert "another branch" in r.json()["detail"]
+    # And refusing left the tree alone — the bug this guards is a fork that
+    # promotes a sibling on the branch it was called against.
     assert len(_branches(client)) == 2