A hand-written memory used to carry a NULL depth, described in the model as
"belongs to the adventure rather than to a path". That sounds harmless and
is not: a NULL is a coordinate no fork can cap, so a note typed on one line
followed the reader onto branches whose story it never described. It takes
the head now — the story you were reading when you wrote it — and obeys
exactly the rule a summarised memory obeys.
The unanchored escape clause in lineage.Path.clause existed for that single
case and is deleted rather than left unused. Its docstring argued that a
capped depth would drop a typed memory the moment its branch stopped being
the newest entry; anchoring answers the same worry better, because the
memory is not exempt from the path, it is on one.
The drawer now shows the path being read and nothing else, filtered by the
clause retrieval itself uses, so the bank you can see is the bank the model
can see. Nothing is stranded: a memory lives on a branch, switching to that
branch shows it, and deleting the branch deletes it. Pinning decides order,
the path decides existence.
Migration 62 lands existing NULL-depth memories at depth 0 of their branch
rather than at the tip. 0 is at or before every fork point, so every memory
stays visible from exactly the paths it is visible from today — nobody's
bank loses a row on deploy. The tip is the tidier-sounding choice and would
have emptied them out of every branch forked earlier than they were typed.
This supersedes the on_path flag and the "another branch" badge from
earlier today; anchoring makes them redundant, and they are removed.
Four tests changed because they asserted the old contract, not because
they broke. The one worth reading is the pair replacing
test_a_hand_written_memory_is_not_lost_at_the_first_fork: typed on shared
trunk it still survives a fork, and typed on ground the fork never
travelled it no longer follows you.
402 tests. Verified on tools/branch_fixture.py: each branch's drawer holds
its own memory and not the other's.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015H5qiyiR7gtFQaoDphHZ3g
Attempts pile up at the tip as leaves and cost nothing. The moment the
player takes the story down one the line has already moved past, the two
futures have to coexist — so `tree.fork` gives that attempt a branch of
its own, forked at the depth just before it, and the line it leaves
keeps every turn it has.
One row is inserted and one row is moved. Nothing is copied: everything
before the fork is borrowed through the lineage cached on the branch
row. Measured on a 40-turn story forked twenty times — 21 branches, 140
rows, an 80-action story — the page load costs 31,652 B against the
31,433 B the same story flat costs, and a branch is 103 B of ancestry.
Nothing derived moves either, and that is the part worth keeping: a
memory hangs off the coordinate the parent's attempt still occupies, and
the lineage caps the parent one depth short of it. The fork simply
cannot see it, so it resummarizes that ground from the text it actually
tells, without a line of bookkeeping.
Two things had to change underneath. A new node's depth now comes from
the tip of its branch rather than from the adventure-wide `index`, which
would have left a hole in a fork's path the width of the other branch.
And undo stops at the fork — the turns before it belong to the branch
this one grew out of.
`GET /branches`, `POST /branches/{id}/switch` and
`POST /actions/{id}/fork` are the endpoints SP7's tree view is drawn on.
365 tests green, 18 of them new in test_branch_forking.py.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017Dvvqn9ZDR4ixeFPHNbww7
