DRY pass #3: unlinking a device by id or by its own token is one tail (#5373)

revoke_self and revoke_device each loaded the caller's DeviceToken, deleted
it, committed and audited DEVICE_UNLINKED; _unlink_device(which) is that,
owner-scoped as before, with each route keeping only how it names the row.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/inkwell/auth.py

@@ -659,21 +659,9 @@ async def revoke_own_device():
         # using" is meaningless rather than merely unauthorized. The web app
         # revokes by id.
         return json_error("no device token was presented", 400)
-    async with session_scope() as db:
+    # Owner-scoped like every other device route. The hash already pins a single
-        row = await db.scalar(
+    # row; the guarantee shouldn't rest on one column.
-            select(DeviceToken).where(
+    return await _unlink_device(DeviceToken.token_hash == hash_token(token))
-                DeviceToken.token_hash == hash_token(token),
-                # Owner-scoped like every other device route. The hash already pins
-                # a single row; the guarantee shouldn't rest on one column.
-                DeviceToken.user_id == g.user_id,
-            )
-        )
-        if row is None:
-            return not_found()
-        await db.delete(row)
-        await db.commit()
-        await audit.record(audit.DEVICE_UNLINKED, user_id=g.user_id, email=await _email_of(db), detail=row.name)
-        return jsonify({"ok": True})
 
 
 @bp.delete("/devices/<device_id>")
@@ -682,10 +670,13 @@ async def revoke_device(device_id: str):
     did = parse_uuid(device_id)
     if did is None:
         return not_found()
+    return await _unlink_device(DeviceToken.id == did)
+
+
+async def _unlink_device(which):
+    """Delete the caller's device token matching `which`, and say so in the audit log."""
     async with session_scope() as db:
-        row = await db.scalar(
+        row = await db.scalar(select(DeviceToken).where(which, DeviceToken.user_id == g.user_id))
-            select(DeviceToken).where(DeviceToken.id == did, DeviceToken.user_id == g.user_id)
-        )
         if row is None:
             return not_found()
         await db.delete(row)