Say which memories the model can actually see

Retrieval has been path-scoped since SP3: a memory on a branch this story
never travelled is never sent to the AI. The drawer listed every memory
alike, so on a fork you read "Fell down the cellar stairs; badly hurt" and
reasonably concluded the model knew it. It does not. That is worse than
either hiding the row or retrieving it — it is the screen claiming
something the engine contradicts.

Hiding them is not the answer either; that was the original comment's
point, and it stands. A memory nobody can list is a memory nobody can
delete, in a phase whose rule is that nothing is removed automatically.

So the whole bank still lists, and the rows off the current path are set
back, dashed, and labelled "another branch". MemoryOut.on_path carries it,
computed from the predicate retrieval itself uses rather than a second
spelling of the same idea — two spellings drift, and the failure mode here
is a badge that says the opposite of what the model gets. Pinning does not
override it: the path clause runs before pinning is considered.

The relationship is asymmetric and there is now a test that says so. A fork
borrows its ancestors, so a memory written on the parent is on the fork's
path too; the reverse never is. Worth pinning before somebody makes it
symmetric on the grounds that it looks wrong.

399 tests, three new, egress ceilings intact — the flag costs one id-only
query. Verified in a browser on tools/branch_fixture.py.

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

backend/app/routers/adventures.py

@@ -4,7 +4,7 @@ import threading
 
 from fastapi import APIRouter, Body, Depends, HTTPException, Request
 from fastapi.responses import StreamingResponse
-from sqlalchemy import func
+from sqlalchemy import func, select
 from sqlalchemy.orm import Session, load_only, undefer
 from sqlalchemy.orm.attributes import set_committed_value
 
@@ -1874,7 +1874,7 @@ def action_context(
 def list_memories(
     adventure_id: int, db: Session = Depends(get_db), user: models.User = CurrentUser
 ):
-    get_adventure_or_404(adventure_id, db, user)
+    adventure = get_adventure_or_404(adventure_id, db, user)
     # A query naming its columns, not a walk of `adventure.memories`. The walk
     # is what retrieval used to do, and it is the reason a turn cost megabytes:
     # a relationship load takes whole entities, so it picks up whatever the
@@ -1885,13 +1885,32 @@ def list_memories(
     # the story being played, the drawer manages the bank. Hiding a branch's
     # memories from the drawer would mean memories nobody can find to delete,
     # in a phase whose rule is that nothing is ever removed automatically.
-    return (
+    rows = (
         db.query(models.Memory)
         .options(load_only(*MEMORY_LIST_COLUMNS))
         .filter(models.Memory.adventure_id == adventure_id)
         .order_by(models.Memory.id)
         .all()
     )
+    # ...but listing them alike would be its own lie. A memory on a branch this
+    # story never travelled is never retrieved, so showing it beside one that is
+    # tells the player the model remembers something it cannot see. The ids come
+    # from **the predicate retrieval itself uses**, deliberately: two spellings
+    # of "on this path" would eventually disagree, and the failure would be a
+    # badge that says the opposite of what the model gets.
+    on_path = {
+        row[0] for row in db.execute(
+            select(models.Memory.id).where(
+                models.Memory.adventure_id == adventure_id,
+                lineage.path_of(db, adventure).clause(
+                    models.Memory, unanchored=True
+                ),
+            )
+        )
+    }
+    for row in rows:
+        row.on_path = row.id in on_path
+    return rows
 
 
 @router.post("/{adventure_id}/memories", response_model=schemas.MemoryOut, status_code=201)

backend/app/schemas.py

@@ -289,6 +289,12 @@ class MemoryOut(ORMModel):
     last_used_at: datetime | None
     source_start: int | None
     source_end: int | None
+    # Whether this memory is on the story currently being read (Phase 14, SP7).
+    # The drawer lists the whole bank so nothing becomes impossible to find and
+    # delete, but a memory belonging to another branch will never be retrieved
+    # into context — and a list that showed the two alike would be telling the
+    # player the model knows something it cannot see.
+    on_path: bool = True
     created_at: datetime