feat: implement health_check for Oracle

[tianzhou]

Closes the one gap #433 called out: health_check now works on Oracle sources.

Implementation (src/connectors/oracle/index.ts)

• Connection pool from V$SESSION, counting user sessions other than the diagnostic one. ACTIVE sessions are active, INACTIVE ones idle; the transitional KILLED / SNIPED / CACHED states count toward the total only. TADDR non-null marks an open transaction (idle-in-transaction); LAST_CALL_ET gives the age of the current call for active sessions or of the idle period otherwise. The ceiling is the sessions parameter from V$PARAMETER. idle_in_transaction_aborted is omitted: Oracle rolls back a failed statement on its own and leaves the transaction usable, so there is no aborted-but-open state.
• Buffer cache from V$SYSSTAT: logical reads are db block gets + consistent gets, physical reads are physical reads, ratio via the shared computeHitRatioPct.
• Graceful degradation, matching the SQL Server connector: without SELECT_CATALOG_ROLE / SELECT ANY DICTIONARY Oracle reports the V$ views as non-existent, so each section falls back to a notes entry naming the grant instead of failing the whole call.

Tests and docs

• Deterministic integration tests. The test image gives SYSTEM the same password as the application user, so the suite grants SELECT_CATALOG_ROLE to the app user and creates a second user without it. The privileged path asserts both sections populated with no notes; the restricted path asserts no sections and exactly the two notes. Both pass in CI.
• docs/tools/health-check.mdx (features, privilege table row), docs/tools/overview.mdx, skills/dbhub/SKILL.md, CLAUDE.md, and dbhub.toml.example list Oracle as supported.

Review

Copilot's one inline finding and two summary-only findings (session status handling, deterministic tests) are addressed in the second commit.

🤖 Generated with Claude Code

https://claude.ai/code/session_0189BHv585xi8iqEp9JvmgKY

[Copilot]

Copilot review overview

🟡 Changes recommended

Moderate implementation and test-coverage issues remain, and the skill support matrix is inconsistent.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1

Open (1)

• Document Oracle support in the DBHub health_check skill · New

What changed in this PR

Adds Oracle support to the opt-in health_check tool using dynamic performance views with privilege-aware fallback behavior.

Changes:

• Implements Oracle session and buffer-cache metrics.
• Adds Oracle integration coverage.
• Updates documentation and configuration examples.

File	Summary
src/​connectors/​oracle/​index.ts	Implements Oracle health metrics and fallback notes. Moderate finding (1 vote): handle V$SESSION.STATUS values beyond ACTIVE and INACTIVE.
src/​connectors/​__tests__/​oracle.integration.test.ts	Adds health-check integration coverage. Moderate findings (1 vote each): add deterministic privileged-path and restricted-privilege tests.
docs/​tools/​overview.mdx	Lists Oracle health-check support.
docs/​tools/​health-check.mdx	Documents Oracle metrics and privileges. Nit (2 votes): also update skills/dbhub/SKILL.md to avoid contradictory support guidance.
dbhub.toml.example	Updates health-check configuration guidance.
CLAUDE.md	Updates architecture support documentation.

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