Add connectivity verification and troubleshooting to Config skill

[CheeYuTan]

Summary

The databricks-config skill was a 22-line stub with just a manage_workspace reference. Expanded to 242 lines with connectivity verification, workspace switching, and troubleshooting.

No new files — just an expanded SKILL.md. No install_skills.sh changes needed.

What's new (220 lines added)

Section	What it covers
Quick Start	2-step connectivity verification shortcut
MCP Tools Reference	get_current_user (return fields, use cases), manage_workspace (intent-to-action mapping), cross-refs to compute tools
Connectivity Verification Workflow	5-step: identity → workspace → resources → SQL → catalogs
Workspace Switching Workflow	4-step: list → present → switch → verify
Troubleshooting	5 auth failure symptoms, token/profile issues, 4 CLI fallbacks, 3 common misconfigs

Test evidence — 10 iterations

Live MCP tool tests

Tool	Input	Output	Status
get_current_user	{}	{"username": "steven.tan@databricks.com", "home_path": "/Workspace/Users/steven.tan@databricks.com/"}	PASS
execute_sql	SELECT current_user(), current_catalog(), current_schema()	["steven.tan@databricks.com", "main", "default"]	PASS
execute_sql	SHOW CATALOGS	Returns catalog list	PASS

CLI fallback tests

Command	Result	Status
databricks auth describe	Shows host, profile, auth_type	PASS
grep '^\[' ~/.databrickscfg	Lists all profile sections	PASS
databricks clusters list --output json	Returns JSON cluster list	PASS

MCP tool schema verification

Tool	Schema source	Params match?	Return format match?
get_current_user	user.py source code	PASS — no params	PASS — {username, home_path}
manage_workspace	workspace.py source code	PASS — action required, profile/host optional	PASS — 4 actions verified

What the 10 iterations fixed

Fix	Before	After	Evidence
current_catalog() return value	"" (empty string)	"main"	Live SQL query returned "main"
Unauthenticated get_current_user	"returns error"	"returns null username and null home_path"	Source code: returns dict with None values
OAuth token expiry	Claimed "1 hour"	Confirmed "1 hour" (3600s)	Live test: expires_in: 3600

18/18 checklist items passed

All tool schemas, response formats, workflow steps, troubleshooting entries, CLI commands, cross-references, and edge cases verified.

Test plan

• CI validation passes (26 skills)
• SKILL.md frontmatter valid
• All MCP tool schemas verified against source code
• Live tests for get_current_user and execute_sql
• CLI fallback commands tested
• Cross-reference to databricks-compute verified bidirectional
• Edge cases: unauthenticated returns null (not error), OAuth expiry = 3600s