A time in no particular zone, and a preview missing what it previews

The first audit pass: everything from 0.8.1 to 0.9.8 read as a whole rather
than one feature at a time, starting with what a model is actually told.

Four of these had shipped as correct. The date line carried a timezone
variable that resolves to nothing until somebody chooses one -- so every
default account was told times were "in  unless they say otherwise", while
two comments asserted the line disappeared instead. The prompt preview
built its variables without a chat, which is what eleven fragments are
gated on, so the whole agent surface was absent from it whatever was
ticked. Plan mode was instructed to keep its plan current with a tool that
mode withdraws. And knowledge_get returned a document whole where every
sibling reader caps and says so, its description promising exactly that.

The subagent guidance was wrong in both directions at once: it denied a
documented parameter and named seven of twenty-three allowed commands.
Both halves are pinned by tests against the real list and the real schema
now, because prose and a constant drift the moment one is edited alone.

docs/notes/audit-0.9.md carries the findings that are not fixed here, with
why -- the ones whose fix would change what a feature does are the user's
call, not this pass's.

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

tests/test_tools.py

@@ -415,6 +415,56 @@ async def test_a_failed_fetch_does_not_kill_the_reply(monkeypatch):
     assert "not reachable" in outcome.content
 
 
+async def test_a_long_knowledge_document_is_cut_and_the_model_told(db, user_id):
+    """It was the one reader with no bound at all. `fetch` caps and says so,
+    `file_read` caps and says so, the memories block, the skill index and the
+    project listing all carry budgets -- and `knowledge_get` returned
+    `extracted_text` whole. Its description said "in full", which is why this
+    read as correct: the tool did exactly what it claimed, and what it claimed
+    was one call away from filling the window with nothing reporting it.
+    """
+    from lembas.db.models import User
+    from lembas.services.library import documents as documents_service
+
+    owner = db.get(User, user_id)
+    base = documents_service.create_base(db, owner=owner, name="Long")
+    document = documents_service.store_upload(
+        db, owner=owner, payload=b"x" * 90_000, filename="big.txt",
+        title="Big", base=base,
+    )
+
+    outcome = await tools_service.run_tool(
+        tools_service.ToolContext(owner_id=user_id),
+        "knowledge_get",
+        json.dumps({"id": document.id}),
+    )
+    assert len(outcome.content) < tools_service.MAX_DOCUMENT_CHARS + 500
+    assert "Cut off here" in outcome.content
+    assert outcome.event["truncated"] is True
+
+
+async def test_a_short_knowledge_document_is_returned_whole(db, user_id):
+    """The cap must not become a truncation notice on ordinary documents."""
+    from lembas.db.models import User
+    from lembas.services.library import documents as documents_service
+
+    owner = db.get(User, user_id)
+    base = documents_service.create_base(db, owner=owner, name="Short")
+    document = documents_service.store_upload(
+        db, owner=owner, payload=b"The mallorn is golden.", filename="a.txt",
+        title="Mallorn", base=base,
+    )
+
+    outcome = await tools_service.run_tool(
+        tools_service.ToolContext(owner_id=user_id),
+        "knowledge_get",
+        json.dumps({"id": document.id}),
+    )
+    assert "The mallorn is golden." in outcome.content
+    assert "Cut off here" not in outcome.content
+    assert "truncated" not in outcome.event
+
+
 async def test_a_long_page_is_cut_and_the_model_told(monkeypatch):
     """120_000 characters is roughly thirty thousand tokens. One call would fill
     an ordinary window and spend an agent chat's whole output budget."""