Register the self-hosted Sentry MCP server and keep OAuth sign-ins across updates

link-mcp gains a stdio transport: the servers row names a launcher under user/agents/mcp/, run from the checkout so every machine runs the same script, and the token reaches it as MCP_TOKEN. sentry-gbrown is the first, pointing Sentry's MCP server at sentry.gbrown.org with a read-only token from the ignored env file.

A server already registered exactly as its row would register it is now left alone. Re-adding it every run threw away the sign-in of the OAuth servers, bill-tracker and atlassian, on every update.

user/agents/mcp/servers

@@ -1,6 +1,9 @@
 # MCP servers registered with the local agent runtimes.
 #
-#   <name>  <transport>  <url>  <token variable>
+#   <name>  <transport>  <url or launcher>  <token variable>
+#
+# transport is http (third column is a URL) or stdio (third column is a launcher
+# under user/agents/mcp/, which receives the token as MCP_TOKEN).
 #
 # The token variable names an entry in user/agents/mcp/env, which is ignored by
 # git. This file carries no secret, so it is tracked like the rest of user/ and
@@ -29,3 +32,8 @@ atlassian       http  https://mcp.atlassian.com/v1/mcp
 # key from Penpot's Account > Integrations, and Penpot only reads it from the
 # query string, hence {TOKEN}. The same key connects the in-file MCP plugin.
 penpot          http  https://penpot.gbrown.org/mcp/stream?userToken={TOKEN}  PENPOT_MCP_TOKEN
+
+# Sentry for the self-hosted sentry.gbrown.org. A stdio server: the third column
+# is a launcher under user/agents/mcp/, and the token reaches it as MCP_TOKEN.
+# The hosted mcp.sentry.dev only speaks to sentry.io.
+sentry-gbrown   stdio  bin/sentry-gbrown  SENTRY_GBROWN_TOKEN