Add |middletruncate:n, |start:n, and |end:n pipe filters to the
{{MESSAGES}} template variable, enabling per-message character
truncation for task models (title, tags, follow-up, etc.).
Example: {{MESSAGES:END:2|middletruncate:500}}
This optimizes task model prompt size for conversations with very
long messages (e.g. pasted documents), reducing latency for local
models and API costs.
Closes#21499
9d8f590fc5