Grants that outlive what they name, and a rule you can read

sharing.forget_principal has existed since shares did, documented as the thing
that stops a recycled id inheriting somebody's grant, and was called by nobody.
Deleting a group left every grant naming it; deleting an account left both the
grants to it and the grants of its own work -- that second half is the one
nothing else could catch, since their rows cascade and the shares of those rows
have nothing to cascade from. Both now run before the delete, while the rows are
still findable, and a deleted resource forgets its own.

library.share defaulted to False, which meant sharing shipped documented as done
and unreachable: the panel only renders for somebody holding it, so out of the
box nobody could share anything and nothing said why. It is on.

The panel itself was checkboxes inside the resource's *save form*, listing every
group and every account on the instance, unpaginated, on every detail page -- and
a tick only took effect if you also saved the resource. It is its own routes now:
search, one grant per POST, the panel re-rendered from what is stored. Anything
already shared stays listed whatever the search says, or removing a grant would
mean searching for the name it was given to.

Reports join the shareable set and memories still do not: a finished piece of
work is the thing somebody most wants to hand over, and a record about a person
is not content to pass round. reports.visible became sharing.visible_to, which is
the one line its own docstring predicted. Two things fell out: `owned` beside
`get`, because sharing grants reading and deleting is the owner's alone; and
reading somebody else's report no longer clears their unread dot.

Permissions gained the answer to "what can this person actually do?" --
explain() is resolve()'s working shown rather than thrown away, naming admin, the
baseline, or the groups that granted each one. That is the simulation the union
rule exists to make unnecessary, and until now the only way to get it was to open
every group and read the grids by eye. Users and groups are list-plus-detail, and
membership is edited from one side: it was on both, and a full-form POST from
either overwrote what the other had shown.

Read and write are split for notes, memory and skills -- checked on the tool's
declared risk, after the gate so it can only narrow, and defaulting on.

Quotas are the union rule applied to numbers, with the corner that makes it
interesting: zero means "no limit" and wins outright, or a group saying unlimited
would count for less than one saying a million. Absent means "no opinion".
_narrower folds a group's ceiling with the instance's and is deliberately not
min, for the same reason. Five axes, enforced where each is knowable -- before a
reply is built, before a second one starts, on an agent reply's clock, before a
minute of GPU, and beside the helper cap -- and usage is recorded even for a
reply that was stopped or errored, because an endpoint charges either way.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/lembas/services/reports.py

@@ -20,6 +20,7 @@ from sqlalchemy import func, select
 from sqlalchemy.orm import Session as DBSession
 
 from lembas.db.models import CHUNK_REPORT, SOURCE_MANUAL, SOURCES, Report, User
+from lembas.services import sharing
 from lembas.services.library import retrieval
 
 log = logging.getLogger(__name__)
@@ -33,21 +34,35 @@ SNIPPET_CHARS = 400
 
 
 def visible(user: User | None):
-    """Every report this person owns.
+    """Every report this person owns or has been shared.
 
     Takes no session because it builds a query rather than running one, and
     takes `None` to mean nobody so an unauthenticated caller gets an empty
-    result instead of an exception -- the same shape `sharing.visible_to` has,
-    so a later move to shared reports is a change of one line here.
+    result instead of an exception.
+
+    It said "a later move to shared reports is a change of one line here", and
+    it was: `sharing.visible_to` is that line. Every listing, search and detail
+    page went through this already, which is what made the move safe.
     """
-    if user is None:
-        return select(Report).where(Report.id.is_(None))
-    return select(Report).where(Report.owner_id == user.id)
+    return select(Report).where(sharing.visible_to(Report, user))
 
 
 def get(db: DBSession, report_id: str, user: User | None) -> Report | None:
     report = db.get(Report, report_id)
-    if report is None or user is None or report.owner_id != user.id:
+    if report is None or not sharing.can_read(db, report, user):
+        return None
+    return report
+
+
+def owned(db: DBSession, report_id: str, user: User | None) -> Report | None:
+    """The same, but only when they own it.
+
+    Sharing grants **reading**, so deleting and marking-as-read are the owner's
+    alone. Two functions rather than a flag, because a route that wants one and
+    calls the other is a bug you can see in the name.
+    """
+    report = db.get(Report, report_id)
+    if report is None or not sharing.can_write(report, user):
         return None
     return report
 
@@ -202,6 +217,10 @@ def mark_read(db: DBSession, report: Report) -> Report:
 
 
 def delete(db: DBSession, report: Report) -> None:
+    # Shares carry no foreign key to their resource, so nothing cascades and
+    # this has to be said. A grant left behind names a report that has gone --
+    # harmless now and a grant to whoever next holds that id later.
+    sharing.forget_resource(db, report)
     db.delete(report)
     db.commit()