refactor(mcp-parser): Generic method handling and improved logging

[huang195]

Summary

• Remove hardcoded method switch in MCP parser — all JSON-RPC methods are now handled uniformly
• All methods logged at Info level with method name; payload logged at Debug (truncated to 128 chars)
• MCPExtension simplified: stores raw Params map instead of method-specific sub-structs (Tool/Resource/Prompt)
• Forward-compatible with future MCP protocol changes without code modifications

Logging behavior

• level=INFO msg=mcp-parser method=tools/call
• level=INFO msg=mcp-parser method=initialize
• level=DEBUG msg="mcp-parser: payload" method=tools/call body={...truncated to 128 chars...}

Test plan

• All authlib tests pass
• All listener tests pass (extproc, extauthz, reverseproxy, forwardproxy)
• Deploy and verify logs show method names for all MCP calls at Info level

Assisted-By: Claude (Anthropic AI) noreply@anthropic.com

[esnible]

Clean refactor that simplifies the MCP parser by removing method-specific handling in favor of storing raw params. Forward-compatible design — new MCP methods won't require code changes.

One stale doc reference needs fixing (references a removed struct field), and two helper methods are now dead code.

Areas reviewed: Go (code + tests), Documentation (3 READMEs)
Commits: 3 commits, all signed-off ✓
CI status: all passing ✓

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must-fix: authbridge/demos/mcp-parser/README.md line 288 still references pctx.Extensions.MCP.Tool.Name — this struct field no longer exists after this refactor. Readers trying to write policy plugins will get a compile error. Update to pctx.Extensions.MCP.Params["name"].

suggestion: authbridge/authlib/plugins/mcpparser.go — stringParam() and mapParam() methods (lines 68-77) are now dead code with no callers. Consider removing them.

nit: authbridge/authlib/plugins/mcpparser.go line 12 — doc comment still says "populates … with the parsed method, tool name, resource URI, or prompt name" but now it stores raw params. A one-line update would keep this accurate.

[huang195]

All three items addressed:

1. must-fix (README stale reference): Updated pctx.Extensions.MCP.Tool.Name → pctx.Extensions.MCP.Params["name"] (0b20251)
2. suggestion (dead code): Removed stringParam() and mapParam() (983dba2). PR feat: Add A2A parser plugin for inbound request inspection #363 will re-add them when it merges.
3. nit (doc comment): Updated to reflect "method, RPC ID, and raw params" (0b20251)