Require a token for writes and quarantine what nobody vouches for

Sixteen mutating routes now refuse a caller who cannot present the token the
server started with; queries stay open, because a question is not a write. The
environment variable is ELY_EYE_AUTH_TOKEN, following the repo's env_prefix
convention — the shorter name I reached for first returned 403 where the smoke
expected 401, and the server printed the reason.

Words from a stranger are quarantined on the way in: an HTTP upload is
third_party by definition, and a sentence carrying an instruction-shaped phrase
is quarantined whoever wrote it. A quarantined atom stays findable and stays out
of the compiled context until a second, live, unquarantined source agrees with
its rarest words. Corroboration is computed at read time because it is a
property of the corpus now, not of the moment a memory was written; it is
term-level, and the docstring says so.

forget now erases the source row and the compiled contexts beside the atoms, so
a forgotten memory leaves nothing that can still speak. The semantic cache key
carries a store revision, which fixes a real staleness: a context compiled
before new evidence arrived kept its old quarantine decision forever.

bench.audit --product still pointed at evals.py, which the p1-6 split moved into
backend/src/ely_eye/proofs/. It failed fast, but the anti-self-justification
rule had quietly stopped auditing the product; it now walks the package, and a
test pins that the package exists and holds no re-roll.

Gates: pytest 306 passed; ruff clean; mypy cold cache 24 errors in 9 files, the
recorded baseline, net zero; pyright 0 errors on the 23 backend files and the 2
bench files; go build/vet/test and gofmt clean; npm run build 221.39 kB with
eslint exit 0; bench/filesize_check clean; bench.audit --product clean over 31
harness files; scripts/mcp_write_smoke.sh PASS with the gate live across two
servers and the MCP child.

backend/tests/test_memory_write.py

@@ -9,6 +9,8 @@ from typing import Any
 
 import pytest
 
+from ely_eye.cache_fabric import CacheFabric
+from ely_eye.cartridge_store import add_membership
 from ely_eye.config import Settings
 from ely_eye.db import Database
 from ely_eye.memory import MemoryService
@@ -136,14 +138,21 @@ def test_forget_reaches_every_copy_of_a_memory(
         [{"from_atom_id": "seed-1:text", "to_atom_id": "other", "relation": "cites", "confidence": 1.0}]
     )
     service.db.log_cache_event(layer="compiler", cache_key="k", event="hit", bytes_estimate=10)
+    CacheFabric(service.settings, service.db).write_semantic_cache("compiled-1", {"packed_text": KEYS})
     VectorIndex(service.settings, service.db, fake_embeddings()).sync()
 
     report = service.forget(atom_id="seed-1:text", reason="the drawer is empty")
 
     assert report.atoms_deleted == 1
     assert report.edges_deleted == 1
-    assert report.cache_entries_cleared == 1
+    assert report.cache_entries_cleared == 2
     assert report.vectors_dropped == 1
+    assert report.semantic_cache_cleared == 1
+    assert not (service.settings.cache_dir / "semantic" / "compiled-1.json").exists()
+    with service.db.connect() as connection:
+        assert connection.execute("SELECT COUNT(*) FROM sources").fetchone()[0] == 0, (
+            "a forgotten memory leaves no record of where it came from"
+        )
     assert VectorIndex(service.settings, service.db, fake_embeddings()).stats()["vectors"] == 0
     assert service.db.atom_count() == 0
     with service.db.connect() as connection:
@@ -170,8 +179,13 @@ def test_forget_names_the_cartridge_that_exported_the_source(service: MemoryServ
         token_equivalent=6,
         created_at=NOW,
     )
+    add_membership(service.db, "cart-1", ["seed-1:text"])
     report = service.forget(source_id="seed-1")
     assert report.affected_cartridges == [{"cartridge_id": "cart-1", "contains_source": True}]
+    with service.db.connect() as connection:
+        assert connection.execute("SELECT COUNT(*) FROM cartridge_atoms").fetchone()[0] == 0, (
+            "a cartridge must stop holding a memory that no longer exists"
+        )
 
 
 def test_forget_refuses_a_request_that_names_nothing(service: MemoryService) -> None: