Subscribe to MCP catalog and resource change notifications

[Aaronontheweb]

Outcome

Netclaw reacts to remote MCP changes without a poll delay.

The existing poll remains the repair and reconciliation path.

Context

Issue #1769 and PR #1771 added catalog polling.

The SDK exposes notification handlers.

MCP revision 2026-07-28 uses subscriptions/listen.

Requirements

• Listen for tool list changes.
• Listen for prompt list changes.
• Listen for resource list changes.
• Listen for updates to subscribed resource URIs.
• Refresh a candidate catalog before publication.
• Publish one immutable generation after a successful refresh.
• Recreate subscriptions after reconnect.
• Remove stale handlers and subscriptions.
• Deduplicate repeated notifications.
• Keep the last good generation after a failed refresh.
• Keep poll reconciliation for missed events and unsupported servers.
• Report unsupported methods and subscription failures in diagnostics.

Proof

• Test notification delivery.
• Test duplicate delivery.
• Test reconnect and subscription renewal.
• Test a missed notification that the poll repairs.
• Test unsupported subscription methods.

Sources

• MCP transport and subscriptions, revision 2026-07-28
• MCP resources, revision 2026-07-28