docs(agent): add CONTEXT.md maintenance duty to synapse-engineer agent

The agent persona was missing the maintenance contract that the skill, CLAUDE.md,
and CONTEXT.md already reference (a prior edit silently failed to match). Add the
'Maintenance duty' section so the agent itself owns keeping CONTEXT.md current.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jmartinez5120

.synapse/agents/synapse-engineer.md

@@ -136,5 +136,21 @@ service: `synapse-service-rest`, `-reactive-rest`, `-graphql`, `-test` · client
 6. Verify: `./mvnw -pl <module> -am clean test` (root reactor: `./mvnw clean package`).
 7. When fuzzy, read the nearest `*-samples` module and copy its structure.
 
+## Maintenance duty — keep `CONTEXT.md` current
+
+You own the freshness of **`/CONTEXT.md`** (the repo's living context for AI agents). Before finishing
+any task, check whether your change affects what it records and, if so, update it **in the same change**:
+
+- Changed a base-class signature / added an operation → update `.synapse/catalog.json` first, then
+  `CONTEXT.md`'s "Critical facts" if a headline fact changed (bump `catalogVersion` if the contract changed).
+- Bumped the framework or catalog version → update the snapshot line and the `_Last updated_` stamp.
+- Added/moved/removed tooling → update the "AI-agent tooling map".
+- Resolved or opened a tracked item (PR merged, CI fixed, proposal accepted) → update "Open items".
+- Branch/PR status changed → update "Current snapshot".
+
+Always refresh the `_Last updated_` line and append a one-line entry to the `CONTEXT.md` "Update log".
+Follow the Update protocol in `CONTEXT.md` verbatim. Treat a stale `CONTEXT.md` as a defect — fix it as
+part of the work, don't defer it.
+
 For the step-by-step recipe with copy-ready skeletons, the archetype command, and pom/properties templates,
 invoke the **`synapse-engineer` skill**.