## What changed
Add `exec_tools_update_hint` and `exec_tools_removed_definitions_header` to `model_messages.tools.incremental_tools` and use them when rendering Code Mode catalog updates and removals.
Overrides are literal strings limited to 512 UTF-8 bytes per field. Missing, null, or oversized values use the existing bundled wording. Empty strings omit the guidance while retaining changed definitions and removal keys. Wording changes alone do not trigger catalog updates.
## Testing
Extend unit coverage for defaults, null fields, independent fallback, and UTF-8 byte limits. Add scenario assertions and a snapshot covering custom and empty wording, model switches, catalog changes, and restoration after compaction.
GitOrigin-RevId: da9e00fdb5197a2b5fa39ce533ba87c76ff3e82c
## What changed
Add `model_messages.tools.incremental_tools` overrides for the update hint, tool and namespace removal headers, and namespace instruction update and clearing messages. Missing, null, or over-512-byte values fall back to bundled wording; empty strings omit static text while retaining runtime names and instructions.
Substitute `{name}` in namespace message templates and append runtime instructions verbatim. Wording changes alone do not trigger tool catalog updates.
## Testing
Extend unit tests and MCP request-history snapshots to cover custom wording, empty notices, tool removal and restoration, and namespace instruction changes and clearing without repeating unchanged tools or notices.
GitOrigin-RevId: 22dea0a6fb4cfcd646f5e65346424834c8b7d5a2
Alex Kira