feat(node): standalone health and readiness helpers

[pratyush618]

Closes #519.

Health and readiness were reachable only through the dashboard route table, so
a deployment without a dashboard had no probe to call. New src/health.ts
holds them standalone:

• checkHealth() → { status: "ok" } — liveness, never touches storage.
• checkReadiness(queue) → { status: "ready" | "degraded", checks } over
  storage, workers, and worker resources. Never throws: a failing dependency is
  reported as "error: <message>" in checks and degrades the status, so a
  probe endpoint can always answer.
• resourceStatus(queue) — per-resource health aggregated across every live
  worker's heartbeat, moved here from the dashboard handlers (readiness needs
  it, and a core module shouldn't reach into dashboard/).

Typed returns (HealthReport, ReadinessReport, ReadinessChecks,
WorkersCheck, ResourcesCheck, ResourceStatusEntry), all exported from the
package root. Payload shapes are unchanged, so the dashboard JSON contract
holds.

Three call sites now share the one implementation instead of carrying their
own: the dashboard's /health and /readiness, the KEDA scaler server's
/health (previously an inline literal), and the Express/Fastify REST table,
which gains health, readiness, and resources routes under the same route
names the other SDK shells use. Readiness answers 503 when degraded so
orchestrators drain the instance. dashboard/handlers/ops.ts keeps only the
scaler payload and re-exports the helpers, leaving the dashboard route table
untouched.

Docs: a Health & readiness section in the node monitoring guide, the probe rows
in the Express/Fastify route tables, and a no-router snippet on the shared
deployment page.

Testing

• pnpm test — 609 tests across 86 files, all passing (9 new health tests, 1
  new REST probe-route test).
• pnpm typecheck, pnpm lint, docs lint + typecheck clean.

Summary by CodeRabbit

• New Features
  • Added standalone health, readiness, and resource-status checks for Node applications, including safe readiness reporting.
  • Exposed /health, /readiness, and /resources operational endpoints across REST, dashboard, scaler, Express, and Fastify integrations.
• Documentation
  • Updated monitoring and integration guides with probe semantics, response formats, and custom-route/load-balancer examples.
• Tests
  • Added and expanded integration and unit tests for health/readiness outcomes, degraded behavior, and resource aggregation (including malformed payload handling).

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📒 Files selected for processing (1)

• docs/content/docs/node/guides/observability/monitoring.mdx

🚧 Files skipped from review as they are similar to previous changes (1)

• docs/content/docs/node/guides/observability/monitoring.mdx

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📝 Walkthrough

Walkthrough

The Node SDK adds standalone checkHealth(), checkReadiness(queue), and resourceStatus(queue) helpers, exports their types, wires them into REST, dashboard, and scaler endpoints, adds coverage, and updates integration and deployment documentation.

Changes

Health probe implementation

Layer / File(s)	Summary
Health and resource status helpers sdks/node/src/health.ts, sdks/node/test/observability/health.test.ts	Adds liveness, readiness, resource aggregation, error reporting, and malformed-payload handling with tests.
Probe endpoint wiring and exports sdks/node/src/index.ts, sdks/node/src/contrib/rest.ts, sdks/node/src/dashboard/*, sdks/node/src/scaler/server.ts, sdks/node/test/integrations/rest.test.ts	Exports the helpers and exposes /health, /readiness, and /resources; degraded readiness returns HTTP 503.
Probe integration documentation docs/content/docs/node/guides/integrations/*, docs/content/docs/node/guides/observability/monitoring.mdx, docs/content/docs/shared/guides/operations/deployment.mdx	Documents route availability, report semantics, resource checks, and custom Express probe routes.

Estimated code review effort: 4 (Complex) | ~45 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant ProbeEndpoint
  participant HealthHelpers
  participant Queue
  Client->>ProbeEndpoint: Request /health or /readiness
  ProbeEndpoint->>HealthHelpers: checkHealth() or checkReadiness(queue)
  HealthHelpers->>Queue: stats() and listWorkers()
  Queue-->>HealthHelpers: Queue and worker results
  HealthHelpers-->>ProbeEndpoint: HealthReport or ReadinessReport
  ProbeEndpoint-->>Client: JSON response with status 200 or 503

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Possibly related PRs

• ByteVeda/taskito#378: Adds the worker resource and heartbeat data consumed by resource health aggregation.
• ByteVeda/taskito#385: Previously implemented the dashboard operational health handlers that this change centralizes and re-exports.

Suggested labels: docs, tests

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 53.85% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title is concise and accurately names the main change: standalone Node health and readiness helpers.
Linked Issues check	✅ Passed	The PR delivers standalone checkHealth/checkReadiness helpers and exports them at the package root, matching #519.
Out of Scope Changes check	✅ Passed	The code, route, test, and docs changes all support the health/readiness helper work and do not appear unrelated.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/node-health-helpers

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@sdks/node/src/scaler/server.ts`:
- Line 43: Update the scaler request handler in server.ts to recognize the
`/readiness` route alongside `/health`, call the existing readiness check, and
return HTTP 503 when the scaler is degraded while preserving the current healthy
response behavior.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

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Configuration used: defaults

Review profile: CHILL

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Run ID: fe1d89a6-a2a1-411e-a661-dc097ae94753

📥 Commits

Reviewing files that changed from the base of the PR and between ba8086d and 31141c8.

📒 Files selected for processing (12)

• docs/content/docs/node/guides/integrations/express.mdx
• docs/content/docs/node/guides/integrations/fastify.mdx
• docs/content/docs/node/guides/observability/monitoring.mdx
• docs/content/docs/shared/guides/operations/deployment.mdx
• sdks/node/src/contrib/rest.ts
• sdks/node/src/dashboard/handlers/ops.ts
• sdks/node/src/dashboard/server.ts
• sdks/node/src/health.ts
• sdks/node/src/index.ts
• sdks/node/src/scaler/server.ts
• sdks/node/test/integrations/rest.test.ts
• sdks/node/test/observability/health.test.ts