fix: small correctness/security cleanups in experimental skill scripts

[jamesbroadhead]

Summary

Batch of small, contained fixes surfaced by a parallel GPT 5.4 + Gemini 3.1 Pro code review. None of these are introduced by recent changes — they are pre-existing issues that ought to land regardless. Each fix is local and review-by-eye.

Commit history

• 6a3bdb1 — initial set (see per-file breakdown below)
• c28037e — round-2: round-1 self-review findings
  • mas_manager._build_agent_list: reject empty / whitespace-only UC segments (catalog..fn)
  • mas_manager.main(): catch ValueError from _build_agent_list so malformed configs exit cleanly via stderr
  • compute.get_cluster_status: add success: True to happy-path return for contract coherence
  • compute.cmd_manage_cluster: drop redundant DatabricksError clause + unused import
  • .tests/test_agent_bricks_manager.py: drop stale add_examples_queued import (was failing collection), fix sys.path, add TestBuildAgentListValidation / TestAddExamplesBatch / TestDeleteResponseHandling
• 2fbbb4b — round-3: neighbouring consistency + polish
  • mas_manager: typed MASNotFound exception (replaces "does not exist" in str(e) substring matching in MASManager.get())
  • mas_manager: factor empty-body / non-JSON tolerance into _safe_json, apply symmetrically to _get / _post / _patch (was _delete-only)
  • compute.cmd_list_compute: apply the same NotFound handling cmd_manage_cluster got — was missing
  • fm-parallel-calls.py: explicit "Speedup: N/A (total_time below resolution)" instead of silently dropping the line
  • 5-serving-and-vector-search.py: replace dim-3 placeholder with [0.0] * 768 and a comment listing common embedding dimensions
  • .tests/test_agent_bricks_manager.py: add TestResponseErrorHandling covering the typed-404 path and symmetric empty-body handling

Per-file summary

databricks-skills/databricks-agent-bricks/scripts/mas_manager.py

• _delete tolerates empty / non-JSON DELETE response bodies; _get / _post / _patch do too via shared _safe_json helper.
• add_examples_batch short-circuits on empty input (ThreadPoolExecutor rejects max_workers=0).
• _build_agent_list validates uc_function_name has 3 non-empty dotted parts and rejects missing endpoint_name with a clear error.
• main() wraps dispatch in try/except ValueError for clean stderr/exit on bad agent configs.
• MASManager.get() uses typed MASNotFound instead of substring-matching error messages.

databricks-skills/databricks-execution-compute/scripts/compute.py

• manage-cluster --action get keys off the SDK's typed NotFound exception (was substring-matching "does not exist").
• Same NotFound handling extended to cmd_list_compute clusters resource path.
• Happy-path get_cluster_status includes success: True so the contract is consistent across all return paths.

databricks-skills/databricks-app-python/examples/llm_config.py (security)

• OAuth error no longer interpolates the full token-endpoint payload (which can contain id_token / refresh material). Logs the present key names instead.
• DATABRICKS_MODEL validation error drops the response.text[:300] echo so server bodies don't end up in operator-visible error text.

databricks-skills/databricks-app-python/examples/fm-minimal-chat.py

• Docstring + app.yaml examples reference the actual filename (fm-minimal-chat.py), not 2-minimal-chat-app.py.

databricks-skills/databricks-app-python/examples/fm-parallel-calls.py

• Guard Speedup division on total_time > 0; prints "Speedup: N/A (total_time below resolution)" when the metric can't be computed.
• Convert the trailing standalone triple-quoted string (dead code) to real # comments.

databricks-skills/databricks-python-sdk/examples/5-serving-and-vector-search.py

• Replace the dim-3 literal-Ellipsis [0.1, 0.2, 0.3, ...] with [0.0] * 768 and a comment naming common embedding dimensions (768 / 1024 / 1536).

databricks-skills/.tests/test_agent_bricks_manager.py

• Unbreak collection (stale add_examples_queued import + wrong sys.path).
• New negative tests for _build_agent_list ValueError branches, add_examples_batch([]), _delete empty/non-JSON bodies, MASNotFound typed-404 path, and _post symmetric empty-body handling.

CI caveat

Nothing under databricks-skills/.tests/ is currently wired into CI — .github/workflows/ci.yml only lints databricks-tools-core, databricks-mcp-server, and .test/src. That's why the broken add_examples_queued import had gone unnoticed. The new tests run via local pytest databricks-skills/.tests/ only. Wiring them into CI is a separate concern.

Companion PR

Equivalent (smaller) PR for main — mas_manager.py and compute.py don't exist under databricks-skills/ on main: #535

Test plan

• python3 -m py_compile on all modified files
• WORKTREE=<branch> python3 /tmp/tdd_verify.py — 12 / 12 pass post-fix on this branch
• Full test_agent_bricks_manager.py run — 18 / 18 unit tests pass
• cmd_list_compute NotFound path verified via mocked SDK
• CI green

This pull request and its description were written by Isaac.

[jamesbroadhead]

Hi @calreynolds — could you take a look at this when you have a moment? Small set of fixes from a code review. Companion PR for main is #535.

— this comment was written by Claude