Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
System RemindersArea: what it touches
Internal ChangesKind: in v2.1.281,
Internal ChangesSection of the release
What
Claude Code reserves certain tags, including system-reminder, for notes it adds to the conversation for the model. A new sanitizer neutralises these reserved tags when they appear in content. For text that looks like JSON, a common data format, it first decodes string escapes such as \u sequences. These escapes can spell out characters indirectly. It then escapes any reserved tags it finds in place.
Why
A reserved tag written in escaped form inside JSON is now caught as well, so content cannot pass one along just by encoding its characters differently.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtThe finding does not say which content passes through this sanitizer.
